JP4127071B2 - Data transfer control device, electronic device, and data transfer control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data transfer control device, an electronic device, and a data transfer control method.
[0002]
[Background Art and Problems to be Solved by the Invention]
Called USB On-The-Go (OTG) by the USB Implementers Forum (USB-IF) as the market for USB (Universal Serial Bus) 2.0 supporting HS (High Speed) mode is steadily expanding An interface standard was established. The OTG standard (OTG1.0) formulated in the form of extending USB 2.0 has the potential to create new added value of the USB interface, and the appearance of applications that take advantage of its characteristics is awaited.
[0003]
According to this OTG, a peripheral (peripheral device) that has been connected to a host (personal computer or the like) via a USB can be provided with a host function. As a result, it is possible to transfer data by connecting peripherals to each other via USB. For example, it is possible to directly connect a digital camera and a printer to print an image of the digital camera. In addition, data can be stored by connecting a digital camera or digital video camera to the storage device.
[0004]
However, a peripheral having a host function by OTG generally incorporates a low-performance CPU (processing unit). Therefore, if the CPU (firmware) processing load of the peripheral becomes heavy due to the addition of the host function or the processing becomes complicated, other processing may be hindered or the device design period may be prolonged. Arise.
[0005]
The present invention has been made in view of the technical problems as described above, and an object of the present invention is to provide a data transfer control device, an electronic apparatus, and a data transfer capable of reducing the processing load of the processing unit. It is to provide a control method.
[0006]
[Means for Solving the Problems]
The present invention is a data transfer control device for data transfer via a bus, in which each pipe area is secured corresponding to each end point, and data transferred between each end point is each pipe area The buffer controller that performs access control for the packet buffer having a plurality of pipe areas stored in the memory, and transfer condition information for data transfer between each pipe area and each endpoint are set in each transfer condition register. Automatically generates a transaction for the endpoint based on the transfer condition information set in the transfer condition register and a register section that includes a plurality of transfer condition registers, and between the pipe area and the endpoint corresponding to the pipe area. Thus, the present invention relates to a data transfer control device including a transfer controller for automatically transferring data.
[0007]
In the present invention, a plurality of pipe areas (buffer areas) are allocated for the packet buffer. In this case, each pipe area is secured corresponding to each end point of the bus. Each pipe area stores (buffers) data transferred (transmitted or received) to / from each corresponding endpoint. The buffer controller performs access control (area management) of the packet buffer (buffer) in which such a pipe area is secured.
[0008]
In the present invention, transfer condition information (endpoint information, pipe information) for data transfer between each pipe area and each endpoint is set in each transfer condition register (pipe register). The transfer controller automatically generates a transaction for each endpoint based on the transfer condition information set in each transfer condition register, and automatically transfers data between each pipe area and each endpoint. Thereby, it is possible to reduce the processing load of the processing unit that controls the data transfer control device.
[0009]
In the present invention, the transfer condition information set in the transfer condition register includes a total size of data transferred to and from an endpoint, a maximum packet size, and a data transfer direction. The total size data may be automatically transferred between a pipe area and an end point corresponding to the pipe area in a direction specified by the transfer direction using a packet having a payload of the maximum packet size. Good.
[0010]
In this way, data can be automatically transferred simply by setting transfer condition information such as the total size, the maximum packet size, and the transfer direction in the transfer condition register, and the processing load on the processing unit can be reduced. .
[0011]
In the present invention, the transfer condition information set in the transfer condition register includes a transfer type of data transfer, and the transfer controller sets the data of each pipe area to the transfer type data set in each transfer condition register. Automatic transfer may be performed by transfer.
[0012]
In this way, data in each pipe area can be transferred by data transfer of an arbitrary transfer type (for example, periodic transfer such as isochronous and interrupt, aperiodic transfer such as bulk and control).
[0013]
In the present invention, the transfer condition information set in the transfer condition register includes transfer ratio information between a plurality of pipe areas, and the transfer controller sets each pipe area at a transfer ratio set by the transfer ratio information. The data may be automatically transferred.
[0014]
In this way, data in a plurality of pipe areas can be transferred at an arbitrary transfer ratio, and efficient scheduling of data transfer becomes possible.
[0015]
In the present invention, the transfer ratio information may be the number of continuous executions of transactions in each pipe area.
[0016]
In this way, for example, after the data transfer transaction of the Kth pipe area is executed (generated) continuously a plurality of times, the data transfer transaction of the (K + 1) th pipe area can be executed.
[0017]
In the present invention, the transfer condition information set in the transfer condition register includes a token issue period in interrupt transfer, and the transfer controller uses the token issue period set in the transfer condition register to generate a token packet for interrupt transfer. May be forwarded automatically.
[0018]
In this way, an interrupt transfer token packet can be issued without using a binary tree structure descriptor or the like.
[0019]
In the present invention, the pipe area may include a pipe area dedicated to the control transfer endpoint and a general-purpose pipe area that can be assigned to any endpoint.
[0020]
In this way, for example, it is possible to dynamically change the correspondence between the pipe region and the end point, thereby enabling efficient scheduling of data transfer.
[0021]
The present invention also includes an interface circuit that transfers data between another bus different from the bus and the packet buffer, and the processing unit instructs the interface circuit and the transfer controller to start data transfer. When the interface circuit performs data transfer via another bus, the transfer controller performs data transfer via the bus, and when the data transfer is completed, the transfer controller May generate an interrupt.
[0022]
In this way, the processing unit sets a transfer condition and issues an interrupt after instructing the start of data transfer via the bus and other buses (such as the processing unit bus or the system memory bus). Until then, the control of the data transfer control device is not necessary. Thereby, the processing load of the processing unit can be reduced.
[0023]
Further, the present invention includes a state controller that controls a plurality of states including a host operation state that operates as a host role and a peripheral operation state that operates as a peripheral role. A host controller that performs data transfer as a host and a peripheral controller that performs data transfer as a peripheral during a peripheral operation, and a plurality of pipe areas are secured for a packet buffer during the host operation. The controller may automatically transfer data between the reserved pipe area and the endpoint corresponding to the pipe area.
[0024]
According to the present invention, for example, when the state controlled by the state controller becomes the host operation state, the host controller performs data transfer as the role of the host. When the state controlled by the state controller becomes a peripheral operation state, the peripheral controller performs data transfer as a role of the peripheral. As a result, a so-called dual-role device function can be realized.
[0025]
In the present invention, during host operation, a plurality of pipe areas are reserved for the packet buffer, and data is automatically transferred between the reserved pipe areas and the endpoints. As a result, a dual-role device function can be realized, and the processing load on the processing unit during host operation can be reduced.
[0026]
In the present invention, data transfer conforming to the USB (Universal Serial Bus) OTG (On-The-Go) standard may be performed.
[0027]
According to another aspect of the present invention, there is provided a data transfer control device according to any one of the above, an apparatus that performs an output process, a capture process, or a storage process of data transferred via the data transfer control apparatus and a bus, and the data transfer control apparatus. The present invention relates to an electronic device including a processing unit that controls data transfer.
[0028]
The present invention is also a data transfer control method for data transfer via a bus, wherein a plurality of pipe areas in which data transferred to and from each end point is stored in each pipe area are provided in a packet buffer. And transfer condition information for data transfer between each pipe area and each endpoint is set in each transfer condition register of a plurality of transfer condition registers, and based on the transfer condition information set in the transfer condition register The present invention relates to a data transfer control method for automatically generating a transaction for an endpoint and automatically transferring data between a pipe area and an endpoint corresponding to the pipe area.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, this embodiment will be described.
[0030]
In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. Further, not all of the configurations described in the present embodiment are essential as a solution means of the present invention.
[0031]
1. OTG
First, OTG (USB On-The-Go) will be briefly described.
[0032]
1.1 A device, B device
In OTG, a Mini-A plug and a Mini-B plug as shown in FIG. 1A are defined as connector standards. A Mini-AB receptacle is defined as a connector that can connect both the Mini-A plug and the Mini-B plug (first and second plugs of the cable in a broad sense).
[0033]
For example, as shown in FIG. 1B, when the electronic device P is connected to the Mini-A plug of the USB cable and the electronic device Q is connected to the Mini-B plug, the electronic device P is set to the A device, The electronic device Q is set as the B device. On the other hand, as shown in FIG. 1C, when the Mini-B plug and Mini-A plug are connected to the electronic devices P and Q, the electronic devices P and Q are set to the B device and the A device, respectively. The
[0034]
In the Mini-A plug, the ID pin is connected to GND, and in the Mini-B plug, the ID pin is in a floating state. The electronic device detects whether it is connected to the Mini-A plug or the Mini-B plug by detecting the voltage level of this ID pin using the built-in pull-up resistor circuit. To do.
[0035]
In OTG, the A device (master) is the side (supplier) that supplies power (VBUS), and the B device (slave) is the side that receives power (supplier). The default state of the A device is a host, and the default state of the B device is a peripheral (peripheral device).
[0036]
1.2 Dual-role device
In OTG, a dual-role device is defined which can have both a role as a host (simple host) and a role as a peripheral.
[0037]
Dual-role devices can be either hosts or peripherals. When the partner connected to the dual-role device is a host or peripheral in the conventional USB standard, the role of the dual-role device is uniquely determined. That is, if the connection partner is a host, the dual-role device becomes a peripheral, and if the connection partner is a peripheral, the dual-role device becomes a host.
[0038]
On the other hand, if the connection partner is a dual-role device, both dual-role devices can exchange host and peripheral roles with each other.
[0039]
1.3 SRP, HNP
The dual-role device has functions of a session start request procedure SRP (Session Request Protocol) and a host exchange procedure HNP (Host Negotiation Protocol) as shown in FIGS.
[0040]
Here, the session start request procedure SRP is a protocol in which the B device requests the A device to supply VBUS (power).
[0041]
In the case of not using the bus, in the OTG, the A device can stop supplying the VBUS. Thereby, when the A device is, for example, a small portable device, wasteful power consumption can be prevented. Then, when the B device wants the V device to supply the VBUS after the A device stops supplying the VBUS, this SRP is used to request the A device to resume the supply of the VBUS.
[0042]
FIG. 2A shows the flow of SRP. As shown in FIG. 2A, the B device requests the A device to supply VBUS by performing data line pulsing and VBUS pulsing. Then, after the supply of VBUS by the A device, the peripheral operation of the B device (peripheral operation) and the host operation of the A device (host operation) start.
[0043]
As described in FIGS. 1 (A) to 1 (C), in the connection between dual-role devices, the A device on the side to which the Mini-A plug is connected becomes the default host, and the Mini-B plug is The connected B device becomes the default peripheral. In OTG, the roles of the host and the peripheral can be exchanged without plugging and unplugging. HNP is a protocol for exchanging the roles of this host and peripheral.
[0044]
The flow of HNP is shown in FIG. When the A device operating as the default host finishes using the bus, the bus becomes idle. After that, when the B device disables the pull-up resistor of the data signal line DP (D +), the A device enables the DP pull-up resistor. As a result, the role of the A device is changed from the host to the peripheral, and the operation as the peripheral is started. In addition, the role of the B device is changed from the peripheral to the host, and the operation as the host is started.
[0045]
After that, when the B device finishes using the bus and the A device disables the DP pull-up resistor, the B device enables the DP pull-up resistor. Thereby, the role of the B device returns from the host to the peripheral, and the operation as the peripheral is resumed. Also, the role of the A device returns from the peripheral to the host and resumes the operation as the host.
[0046]
According to the OTG described above, a portable device such as a cellular phone or a digital camera can be operated as a USB host, and data can be transferred by connecting the portable devices with each other in a peer-to-peer manner. As a result, a new added value can be created in the USB interface, and an application that has not existed before can be created.
[0047]
2. OHCI
In the conventional USB, the data transfer control device (host controller) of the personal computer that is the host complies with standards such as OHCI (Open Host Controller Interface) and UHCI (Universal Host Controller Interface) proposed by Microsoft. It was. Also, the OS (Operating System) used is limited to Microsoft Windows and Apple Macintosh OS.
[0048]
However, in a small portable device that is a target application of OTG, the architecture of the CPU to be incorporated and the OS used are various. Furthermore, OHCI and UHCI standardized for personal computer host controllers are premised on the full implementation of USB host functions, and are not optimal for mounting on small portable devices.
[0049]
For example, FIG. 3A shows an example of a descriptor having a list structure used in OHCI.
[0050]
In FIG. 3A, endpoint descriptors ED1, ED2, and ED3 are linked by link pointers, and contain information necessary for communication with endpoints 1, 2, and 3. The transfer descriptors TD11 to TD13, TD21, and TD31 to TD32 are further linked to these ED1, ED2, and ED3 by link pointers. These transfer descriptors include information necessary for packet data transferred between the end points 1, 2, and 3.
[0051]
The descriptor having the list structure in FIG. 3A is created by firmware (host controller / driver) operating on the CPU 610 (processor in a broad sense) in FIG. 3B and written in the system memory 620. That is, the firmware assigns endpoint descriptors to endpoints in the system, and creates endpoint descriptors and transfer descriptors based on endpoint information and the like. These descriptors are linked by a link pointer and written to the system memory 620.
[0052]
The data transfer control device 600 (host controller) reads the descriptor having the list structure written in the system memory 620, and executes data transfer based on the information described in the endpoint descriptor and the transfer descriptor.
[0053]
Specifically, the data transfer control device 600 (host controller) sets information on the endpoint 1 based on ED1, and performs data transfer with the endpoint 1 based on TD11 linked to ED1. . Next, the information of the endpoint 2 is set based on the ED2, and the data is transferred to the endpoint 2 based on the TD21 linked to the ED2. Similarly, the data transfer control device 600 executes data transfer based on TD31, TD12, TD32, and TD13.
[0054]
When interrupt transfer is performed, the firmware (host controller / driver) operating on the CPU 610 creates a binary tree structure descriptor as shown in FIG. For example, for an endpoint that performs interrupt transfer polling every 1 ms, the descriptor is set in a placeholder 700 in FIG. Similarly, for an endpoint that polls every 2 ms, its descriptor is set in placeholders 701 and 702, and for an end pointer that polls every 4 ms, it is set in placeholders 703, 704, 705, and 706.
[0055]
When polling is performed, a binary tree search is sequentially performed from the placeholder of the lowest layer according to the index of the interrupt head pointer. That is, as shown by a path 710 in FIG. 4, first, a binary tree search is performed for the index 0 from the lowest layer. Next, as shown in the path 711, a binary tree search is performed for the index 1. Similarly, a binary tree search is performed for indexes 2 to 31. As a result, the endpoint corresponding to the placeholder 700 is interrupted every 1 ms (one frame), the endpoint corresponding to 701 and 702 is interrupted every 2 ms, and the endpoint corresponding to 703 to 706 is interrupted every 4 ms. Will be done.
[0056]
As described above, in the OHCI-compliant data transfer control device (host controller), the firmware (host controller / driver) operating on the CPU creates a descriptor having a complicated structure as shown in FIGS. Must be created. Therefore, the processing load on the CPU is very heavy.
[0057]
In this case, in the conventional USB, only a personal computer is assigned the host role, and this personal computer has a high-performance CPU. Accordingly, it is possible to create a descriptor having a complicated structure as shown in FIGS. 3A and 4 with a margin.
[0058]
However, a CPU (embedded CPU) incorporated in a small portable device (digital camera, mobile phone, etc.), which is an OTG target application, generally has a significantly lower performance than a personal computer CPU. Accordingly, if the OTG host operation is performed in the portable device, an excessive load is applied to the CPU incorporated in the portable device, which causes problems such as troubles in other processes and a decrease in data transfer performance.
[0059]
3. Configuration example
FIG. 5 shows a configuration example of the data transfer control device of this embodiment that can solve the above-described problems. Note that the data transfer control device of this embodiment does not need to include all the circuit blocks in FIG. 5, and some of the circuit blocks may be omitted.
[0060]
The transceiver 10 (hereinafter referred to as Xcvr as appropriate) is a circuit that transmits and receives USB (bus in a broad sense) data using differential data signals DP and DM, and includes a USB physical layer (PHY) circuit 12. More specifically, the transceiver 10 generates DP and DM line states (J, K, SE0, etc.), serial / parallel conversion, parallel / serial conversion, bit stuffing, bit unstuffing, NRZI decoding, NRZI encoding, and the like. Do. The transceiver 10 may be provided outside the data transfer control device.
[0061]
The OTG controller 20 (state controller in a broad sense, hereinafter referred to as OTGC as appropriate) performs various processes for realizing the STG function and the HNP function (see FIGS. 2A and 2B) of the OTG. That is, the OTG controller 20 controls a plurality of states including a host operation state operating as a host role and a peripheral operation state operating as a peripheral role.
[0062]
More specifically, the OTG standard defines a state transition at the time of the A device of the dual role device (see FIGS. 1B and 1C) and a state transition at the time of the B device. The OTG controller 20 includes a state machine for realizing these state transitions. The OTG controller 20 includes a circuit that detects (monitors) the USB data line state, the VBUS level, and the ID pin state. The state machine included in the OTG controller 20 changes its state (for example, a state such as a host, peripheral, suspend, or idle) based on the detection information. The state transition in this case may be realized by a hardware circuit, or may be realized by the firmware setting a state command in a register. When the state transitions, the OTG controller 20 controls VBUS or controls connection / disconnection of the pull-up / pull-down resistors DP and DM based on the state after the transition. It also controls enable / disable of the host controller 50 (hereinafter referred to as HC as appropriate) and the peripheral controller 60 (hereinafter referred to as PC as appropriate).
[0063]
The HC / PC switching circuit 30 (HC / PC / common circuit) controls switching of connection between the transceiver 10 and the host controller 50 or the peripheral controller 60. Also, the transceiver 10 is instructed to generate a line state of USB data (DP, DM). The connection switching control is realized by the HC / PC selector 32, and the line state generation instruction is realized by the line state controller.
[0064]
For example, when the OTG controller 20 activates the HC enable signal during host operation (in the host state), the HC / PC switching circuit 30 (HC / PC selector 32) connects the transceiver 10 and the host controller 50. On the other hand, when the OTG controller 20 activates the PC enable signal during the peripheral operation (in the peripheral state), the HC / PC switching circuit 30 connects the transceiver 10 and the peripheral controller 60. By doing so, the host controller 50 and the peripheral controller 60 can be operated exclusively.
[0065]
The transfer controller 40 is a circuit that controls data transfer via a USB (bus in a broad sense), and includes a host controller 50 (HC) and a peripheral controller 60 (PC).
[0066]
Here, the host controller 50 is a circuit that performs data transfer control as the role of the host when the host is operating (when the HC enable signal from the OTG controller 20 is active).
[0067]
That is, the host controller 50 is connected to the transceiver 10 by the HC / PC switching circuit 30 during host operation. Then, the host controller 50 automatically generates a transaction for the endpoint based on the transfer condition information set in the transfer condition register unit 72 of the register unit 70. Then, automatic transfer (processing) of data (packets) between the pipe area (PIPE0 to PIPEe, hereinafter referred to as PIPE as appropriate) allocated in the packet buffer 100 and an endpoint corresponding to the pipe area. Data transfer by a hardware circuit without intervening parts).
[0068]
More specifically, the host controller 50 performs arbitration between a plurality of pipe transfers, frame time management, transfer scheduling, retransmission management, and the like. Also, transfer condition information (operation information) for pipe transfer is managed via the register unit 70. It also manages transactions, generates / disassembles packets, and instructs suspend / resume / reset state generation.
[0069]
On the other hand, the peripheral controller 60 is a circuit that performs data transfer control as a role of the peripheral during the peripheral operation (when the PC enable signal from the OTG controller 20 is active).
[0070]
That is, the peripheral controller 60 is connected to the transceiver 10 by the HC / PC switching circuit 30 during the peripheral operation. Then, based on the transfer condition information set in the transfer condition register unit 72 of the register unit 70, data is transferred between the endpoint area (EP0 to EPe, hereinafter referred to as EP as appropriate) reserved in the packet buffer 100 and the host. Forward.
[0071]
More specifically, the peripheral controller 60 manages the transfer condition information (operation information) for endpoint transfer via the register unit 70. It also manages transactions, generates / disassembles packets, and gives instructions for generating remote wakeup signals.
[0072]
An end point is a point (part) on a peripheral (device) to which a unique address can be assigned. All data transfer between the host and the peripheral (device) is performed via this endpoint. The transaction is composed of a token packet, an optional data packet, and an optional handshake packet.
[0073]
The register unit 70 includes various registers for performing data transfer (pipe transfer, endpoint transfer) control, buffer access control, buffer management, interrupt control, block control, or DMA control. Note that the register included in the register unit 70 may be realized by a memory such as a RAM or a D flip-flop. In addition, the registers of the register unit 70 may be distributed in each block (HC, PC, OTGC, Xcvr, etc.) instead of being combined into one.
[0074]
The register unit 70 includes a transfer condition register unit 72. The transfer condition register unit 72 stores transfer condition information (transfer control information) for data transfer between the pipe area (PIPE0 to PIPEe) secured in the packet buffer 100 during host operation and the end point. including. Each of these transfer condition registers is provided corresponding to each pipe area of the packet buffer 100.
[0075]
During the peripheral operation, the endpoint area (EP0 to EPe) is secured in the packet buffer 100. Based on the transfer condition information set in the transfer condition register unit 72, data transfer is performed between the data transfer control device and the host.
[0076]
The buffer controller 80 (FIFO manager) performs access (read / write) control and area management for the packet buffer 100. More specifically, it generates and manages an access address to the packet buffer 100 by a CPU (processing unit in a broad sense), DMA (Direct Memory Access), and USB. Also, arbitration of access to the packet buffer 100 by the CPU, DMA, and USB is performed.
[0077]
For example, during host operation, the buffer controller 80 sets a data transfer path between the interface circuit 110 (CPU or DMA) and the packet buffer 100 and a data transfer path between the packet buffer 100 and the host controller 50 (USB) ( Establish.
[0078]
On the other hand, during the peripheral operation, the buffer controller 80 sets a data transfer path between the interface circuit 110 (CPU or DMA) and the packet buffer 100 and a data transfer path between the packet buffer 100 and the peripheral controller 60 (USB). .
[0079]
The packet buffer 100 (FIFO, packet memory, buffer) temporarily stores (buffers) data (transmission data or reception data) transferred via the USB. The packet buffer 100 can be composed of, for example, a RAM (Random Access Memory). The packet buffer 100 may be provided outside the data transfer control device (may be an external memory).
[0080]
During host operation, the packet buffer 100 is used as a pipe transfer FIFO (First-In First-Out). That is, in the packet buffer 100, pipe areas PIPE0 to PIPEe (buffer areas in a broad sense) are secured so as to correspond to the respective endpoints of the USB (bus). In each of the pipe areas PIPE0 to PIPEe, data (transmission data or reception data) transferred between the corresponding endpoints is stored.
[0081]
On the other hand, during the peripheral operation, the packet buffer 100 is used as a FIFO for endpoint transfer. That is, endpoint areas EP0 to EPe (buffer areas in a broad sense) are secured in the packet buffer 100. Each endpoint area EP0 to EPe stores data (transmission data or reception data) transferred with the host.
[0082]
Note that the buffer area secured in the packet buffer 100 (the area set in the pipe area during the host operation and the end point area during the peripheral operation) is stored such that the previously input information is output first. It is set in the area (FIFO area).
[0083]
PIPE0 is a pipe area dedicated to the control transfer endpoint 0, and PIPEa to PIPEe are general-purpose pipe areas that can be assigned to any endpoint.
[0084]
That is, in USB, the end point 0 is set as an end point dedicated for control transfer. Therefore, it is possible to prevent the user from being confused by making PIPE0 a pipe area dedicated for control transfer as in this embodiment. Also, by making PIPEa to PIPEe pipe areas that can be assigned to arbitrary endpoints, the pipe areas corresponding to the endpoints can be dynamically changed. As a result, the degree of freedom of scheduling for pipe transfer can be improved and the efficiency of data transfer can be improved.
[0085]
In this embodiment, the buffer area (pipe area or endpoint area) is set by the maximum packet size MaxPktSize (page size in a broad sense) and the number of pages BufferPage (RSize = MaxPktSize × BufferPage). . In this way, the area size and the number of pages (number of pages) of the buffer area can be arbitrarily set, and the resources of the packet buffer 100 can be effectively used.
[0086]
The interface circuit 110 is a circuit for transferring data between a DMA (system memory) bus or CPU bus, which is another bus different from USB, and the packet buffer 100. The interface circuit 110 includes a DMA handler circuit 112 for performing DMA transfer between the packet buffer 100 and an external system memory. Also included is a CPU interface circuit 114 for performing PIO (Parallel I / O) transfer between the packet buffer 100 and an external CPU. Note that a CPU (processing unit) may be incorporated in the data transfer control device.
[0087]
The clock controller 120 generates various clocks used inside the data transfer control device based on a built-in PLL or an external input clock.
[0088]
4). Pipe area
In this embodiment, as shown in FIG. 6A, pipe areas PIPE0 to PIPEe are allocated in the packet buffer 100 during host operation. Data is transferred between each of the pipe areas PIPE0 to PIPEe and each end point of the peripheral.
[0089]
Here, the “pipe” in the pipe area of this embodiment is a “pipe” defined by USB (a logical abstraction representing a relationship between an endpoint on a device and software on a host, a logical Route) is slightly different in meaning.
[0090]
As shown in FIG. 6A, the pipe area according to the present embodiment is secured on the packet buffer 100 in correspondence with each endpoint included in the peripheral connected to the USB (bus). For example, in FIG. 6A, the pipe region PIPEa corresponds to the end point 1 (bulk IN) of the peripheral 1, and PIPEb corresponds to the end point 2 (bulk OUT) of the peripheral 1. PIPEc corresponds to the end point 1 (bulk IN) of the peripheral 2, and PIPEd corresponds to the end point 2 (bulk OUT) of the peripheral 2. PIPEe corresponds to the end point 1 (interrupt IN) of the peripheral 3. Note that PIPE0 is a pipe area dedicated to the end point 0 of the control transfer.
[0091]
In the example of FIG. 6A, USB bulk IN transfer is performed between the pipe area PIPEa and the end point 1 of the peripheral 1, and bulk OUT transfer is performed between the PIPEb and the end point 2 of the peripheral 1. Is called. Also, bulk IN transfer is performed between PIPEc and the end point 1 of the peripheral 2, and bulk OUT transfer is performed between the PIPEd and the end point 2 of the peripheral 2. Further, interrupt IN transfer is performed between PIPEe and the end point 1 of the peripheral 3.
[0092]
As described above, in the present embodiment, arbitrary data transfer (isochronous transfer, bulk transfer, interrupt transfer) can be performed between a pipe area (general-purpose) and the corresponding endpoint.
[0093]
In this embodiment, data in a given data unit (a data unit specified by the total size) is transferred between the pipe area and the corresponding endpoint. As a data unit in this case, for example, a data unit requested to be transferred by an IRP (I / O request packet) or a data unit obtained by dividing the data unit into an appropriate size can be considered. This data unit data transfer (a series of transactions) to the endpoint can be called a “pipe” in the present embodiment. An area for storing such “pipe” data (transmission data, reception data) is a pipe area.
[0094]
When the transfer of a given data unit using the pipe area is completed, the pipe area can be released. The released pipe area can be assigned to an arbitrary endpoint. As described above, in this embodiment, the association between the pipe region and the end point can be dynamically changed.
[0095]
In the present embodiment, as shown in FIG. 6B, the endpoint areas EP0 to EPe are secured (set) in the packet buffer 100 during the peripheral operation. Data is transferred between the endpoint areas EP0 to EPe and the host (host controller, system memory).
[0096]
As described above, in this embodiment, the buffer area of the packet buffer 100 is assigned to the pipe area during the host operation, and is assigned to the endpoint area during the peripheral operation. As a result, the resources of the packet buffer 100 can be shared (shared) during the host operation and the peripheral operation, and the used storage capacity of the packet buffer 100 can be saved.
[0097]
The number of pipe regions and endpoint regions is not limited to six and is arbitrary.
[0098]
5. Transfer condition register (shared register)
In the present embodiment, as shown in FIG. 7, during host operation, transfer condition information for data transfer performed between the pipe areas PIPE0 to PIPEe and the endpoint is set in the transfer condition registers TREG0 to TREGe. That is, the transfer condition information of PIPE0, PIPEa, PIPEb, PIPEc, PIPEd, and PIPEe is set (stored) in TREG0, TREGa, TREGb, TREGc, TREGd, and TREGe, respectively. This setting is performed by, for example, firmware (CPU).
[0099]
The host controller 50 (transfer controller in a broad sense) generates a transaction for the endpoint based on the transfer condition information set in the transfer condition registers TREG0 to TREGe. Then, data (packets) is automatically transferred between the pipe area and the corresponding endpoint.
[0100]
As described above, in this embodiment, each transfer condition register is provided corresponding to each pipe area (buffer area). Based on the transfer condition information set in each transfer condition register, the pipe transfer ( Transfer of a given data unit) is automatically performed by the host controller 50. Therefore, after setting the transfer condition information in the transfer condition register, the firmware (driver, software) does not need to be involved in the data transfer control until the data transfer is completed. When the pipe transfer of a given data unit is completed, an interrupt is generated and the completion of the transfer is transmitted to the firmware. Thereby, the processing load of the firmware (CPU) can be significantly reduced.
[0101]
In the present embodiment, as shown in FIG. 8, during the peripheral operation, transfer condition information for data transfer performed between the endpoint areas EP0 to EPe and the host is set in the transfer condition registers TREG0 to TREGe. The peripheral controller 60 (transfer controller in a broad sense) performs data transfer between the endpoint area and the host based on the transfer condition information set in the transfer condition registers TREG0 to TREGe.
[0102]
As described above, in the present embodiment, the transfer condition registers TREG0 to TREGe are shared (shared) by the host operation and the peripheral operation. Thereby, the resource of the register unit 70 can be saved, and the data transfer control device can be reduced in size.
[0103]
FIG. 9 shows a register configuration example of the register unit 70. A part of the register of the register unit 70 may be included in each block (OTGC, HC, PC, Xcvr, etc.).
[0104]
As shown in FIG. 9, the transfer condition registers (TREG0 to TREGe) of the register unit 70 are HC / PC shared registers (HC, PIPE) and HC / PC shared registers (PC, EP) shared during the peripheral operation (PC, EP). Shared transfer condition register). It also includes an HC (PIPE) register (host transfer condition register) that is used only during host operation. It also includes a PC (EP) register (peripheral transfer condition register) used only during the peripheral operation. Further, it is a register for performing access control of the packet buffer (FIFO) and the like, and includes an access control register shared during host operation and peripheral operation.
[0105]
For example, during host operation of the dual role device, the host controller 50 (HC) transfers data (packets) based on transfer condition information set in the HC / PC shared register and the HC register.
[0106]
On the other hand, during the peripheral operation, the peripheral controller 60 (PC) transfers data (packets) based on transfer condition information set in the HC / PC shared register and the PC register.
[0107]
In both the host operation and the peripheral operation, the buffer controller 80 controls access to the packet buffer 100 (read / write address generation, data read / write, access access) based on the shared access control register. Mediation).
[0108]
The HC / PC shared register in FIG. 9 includes data transfer direction (IN, OUT, SETUP, etc.), transfer type (type of transaction such as isochronous, bulk, interrupt, control, etc.), endpoint number (end of each USB device) The number associated with the point) and the maximum packet size (maximum payload size of the packet that can be transmitted or received by the endpoint, page size) are set. In addition, the number of pages (the number of buffer areas) in the buffer area (pipe area, endpoint area) is set. Information indicating whether or not there is a DMA connection (whether or not DMA transfer is used by the DMA handler circuit 112 in FIG. 5) is set.
[0109]
In the HC (PIPE) register, a token issuing period (interrupt transaction start period, interval) for interrupt transfer is set. In addition, the number of continuous executions of a transaction (information for setting a transfer ratio between pipe areas. The number of continuous executions of transactions in each pipe area) is set. In addition, a function address (USB address of a function having an end point) and a total size of transfer data (total size of data transferred through each pipe area, data unit such as IRP) are set. In addition, an automatic transaction start instruction (an instruction to start automatic transaction processing for the host controller) is set. Also, an instruction for an automatic control transfer mode (an instruction for a mode for automatically generating a control transfer setup stage, data stage, and status stage transaction) is set.
[0110]
In the PC (EP) register, endpoint enable (endpoint enable / disable instruction) and handshake designation (handshake designation performed in each transaction) are set.
[0111]
In the shared access control register for the packet buffer (FIFO), a buffer I / O port (I / O port when PIO transfer is performed by the CPU) is set. Also, buffer full / empty (full notification of each buffer area, notification of empty) and buffer / remaining data size (remaining data size of each buffer area) are set.
[0112]
The register unit 70 includes an interrupt system register, a block system register, a DMA control register, and the like.
[0113]
The interrupt system registers include an interrupt status register for indicating an interrupt status (factor) to the CPU, and an interrupt enable register for setting interrupt enable / disable (non-mask, mask). The interrupt includes interrupts of the OTG controller 20 system, the host controller 50 system, and the peripheral controller 60 system.
[0114]
The block system register includes an inter-block shared register shared between blocks and a block register used in each block (Xcvr, OTGC, HC, PC).
[0115]
The inter-block shared register includes a register that instructs resetting of each block. The block register includes a register for controlling the transceiver 10 (Xcvr), a state command register of the OTG controller 20 (OTGC), a state command register of the host controller 50 (HC), a register for setting a frame number, etc. There is.
[0116]
As described above, in this embodiment, the register unit 70 is provided with a register (HC / PC shared register, shared access control register) shared during host operation and peripheral operation. This makes it possible to reduce the size of the register unit 70 as compared to the case where the register for host operation and the register for peripheral operation are provided completely separately. Further, the access address of the shared register viewed from the firmware (driver) operating on the CPU can be the same during the host operation and during the peripheral operation. Therefore, the firmware can manage these shared registers with the same address, and the firmware processing can be simplified.
[0117]
Also, by providing an HC register or a PC register, transfer conditions specific to host operation (PIPE) transfer and peripheral operation (EP) transfer can be set. For example, by setting the token issue cycle, it is possible to issue interrupt transfer tokens at a desired cycle during host operation without using the method described in FIG. Also, by setting the number of continuous executions, the transfer ratio between pipe areas can be arbitrarily set during host operation. Also, by setting the total size, it is possible to arbitrarily set the size of data that is automatically transferred through the pipe area during host operation. In addition, the firmware can instruct the start of an automatic transaction or the on / off of the automatic control transfer mode during host operation.
[0118]
FIG. 10 shows a detailed example of a register map of general-purpose transfer condition (PIPE / EP) registers TREGa to TREGe (TREGx: x = a to e), and FIG. 11 shows a transfer condition register TREG0 for control transfer. The detailed example of a register map is shown. 12A, 12B, and 13 show transfer condition information (JoinDMA, FIFOClr, ToggleMode, AutoZeroLen, BufferPage, DirPID, TranType, EPNumber, MaxPktSize) set in each bit field of these transfer condition registers. Etc.) is shown.
[0119]
For example, in FIG. 10, the access addresses 0x0, 0x1,0x2, and 0x3 of the shared registers xConfig_0, xConfig_1, xMaxPktSize_H, and xMaxPktSize_L are the same during the host operation and the peripheral operation. The same information is set in these registers by the firmware during the host operation and the peripheral operation.
[0120]
6). Automatic transaction
FIG. 14 shows an example of a flowchart of firmware processing at the time of automatic transaction (IN, OUT) processing of the host controller 50.
[0121]
First, the firmware (processing unit, driver) sets transfer condition information (pipe information) in the transfer condition register described with reference to FIG. 9 and the like (step S1). More specifically, the total size of transfer data, the maximum packet size (MaxPktSize), the number of pages (BufferPage), the transfer direction (IN, OUT or SETUP), the transfer type (isochronous, bulk, control, interrupt), the endpoint number The number of consecutive executions (transfer ratio) of the transactions in the pipe area, the interrupt issue token issuing period, and the like are set in the transfer condition register.
[0122]
Next, a transfer path is set between the external system memory and the packet buffer 100 (step S2). That is, a DMA transfer path through the DMA handler circuit 112 in FIG. 5 is set.
[0123]
Next, the firmware issues a DMA transfer start instruction (step S3). That is, the DMA transfer start instruction bit of the DMA control register of FIG. 9 is made active. In the transfer by the CPU, the packet buffer 100 can be accessed by accessing the buffer / I / O port of FIG.
[0124]
Next, the firmware gives an instruction to start an automatic transaction (step S4). That is, the automatic transaction start instruction bit of the HC register (pipe register) in FIG. 9 is activated. Thus, automatic transaction processing, packet processing (packet generation and decomposition), and scheduling processing are performed by the host controller 50. That is, the host controller 50 automatically transfers the data designated by the total size in the direction (IN, OUT) designated by the transfer direction, using the packet of the maximum packet size payload.
[0125]
Note that the order of processing in steps S3 and S4 is not limited, and a DMA transfer start instruction may be issued after an automatic transaction start instruction.
[0126]
Next, the firmware waits for an interrupt to notify completion of pipe transfer (step S5). When an interrupt occurs, the firmware checks the interrupt status (factor) of the interrupt register in FIG. Then, the process is completed normally or ends with an error (step S6).
[0127]
Thus, according to the present embodiment, the firmware sets transfer condition information for each pipe area (step S1), and issues a DMA transfer start instruction (step S3) and an automatic transaction start instruction (step S4). Thus, the subsequent data transfer processing is automatically performed by the hardware circuit of the host controller 50. Therefore, compared with the OHCI-compliant method described in FIGS. 3A, 3B, and 4, a data transfer control device optimal for a portable device in which the processing load of firmware is reduced and a low-performance CPU is incorporated. Can be provided.
[0128]
15 and 16 show examples of signal waveforms during automatic transaction processing by the host controller 50. FIG. In these drawings, “H → P” represents “a packet is transferred from the host to the peripheral”, and “P → H” represents “a packet is transferred from the peripheral to the host”.
[0129]
FIG. 15 shows an example of a signal waveform in the case of an IN transaction (when the transfer type is IN).
[0130]
When the firmware instructs to start an automatic transaction in step S4 in FIG. 14, PipeXTranGo (transfer request signal from the firmware for PipeX) becomes active as indicated by C1 in FIG. As a result, automatic transaction processing by the host controller 50 for the PipeX (X = 0 to e) is started.
[0131]
When PipeTranGo (transfer request signal from the HC sequence management circuit in the host controller 50) becomes active as shown at C2, the host controller 50 generates an IN token packet as shown at C3, via USB. To the peripheral. When the IN data packet is transferred from the peripheral to the host controller 50 as indicated by C4, the host controller 50 generates a handshake packet (ACK) as indicated by C5 and transfers it to the peripheral. As a result, TranCmpACK becomes active as indicated by C6.
[0132]
Similarly, when PipeTranGo becomes active as indicated by C7, packet transfer indicated by C8, C9, and C10 is performed, and TranCmpACK becomes active as indicated by C11. Then, as shown in C12, PipeXTranComp (transfer end notification signal of IRP data unit to firmware) becomes active. By this interruption by PipeXTranComp, the firmware can know that the transfer for the pipe has been completed.
[0133]
When PipeXTranComp becomes active, PipeXTranGo becomes inactive as indicated by C13, indicating that the pipe is in a non-transfer state.
[0134]
FIG. 16 is a signal waveform example in the case of an OUT transaction (when the transfer type is OUT).
[0135]
When the firmware gives an instruction to start an automatic transaction, PipeXTranGo becomes active as indicated by E1, and PipeTranGo becomes active as indicated by E2. Then, the host controller 50 transfers the OUT token packet to the peripheral as indicated by E3, and transfers the OUT data packet as indicated by E4. When a handshake packet (ACK) is returned from the peripheral as indicated by E5, TranCmpACK becomes active as indicated by E6.
[0136]
Similarly, when PipeTranGo becomes active as indicated by E7, packet transfer indicated by E8, E9 and E10 is performed, and TranCmpACK becomes active as indicated by E11. Then, PipeXTranComp becomes active as indicated by E12. By this interruption by PipeXTranComp, the firmware can know that the transfer for the pipe has been completed. When PipeXTranComp becomes active, PipeXTranGo becomes inactive as indicated by E13.
[0137]
7). Number of consecutive transaction executions
In this embodiment, the number of continuous executions of transactions (pipe transfer) (transfer ratio information between a plurality of pipe areas in a broad sense) can be set in the transfer condition register. Specifically, as described with reference to FIG. 9, the number of continuous executions is set in the transfer condition register for HC.
[0138]
For example, in FIG. 17A, the number of consecutive executions of transactions in the pipe areas PIPEa, PIPEb, and PIPEc is set to “1”. In this case, pipe area data is automatically transferred at the same transfer ratio, such as PIPEa, PIPEb, PIPEc, PIPEa, PIPEb, PIPEc...
[0139]
On the other hand, in FIG. 17B, the number of consecutive executions of the PIPEa and PIPEc transactions is set to “3” and “2”, respectively. In this case, in the present embodiment, pipe area data is automatically transferred as PIPEa, PIPEa, PIPEa, PIPEb, PIPEc, PIPEc, PIPEa, PIPEa, PIPEa,. In other words, the transfer ratio of PIPEa, PIPEb, and PIPEc (relative ratio of pipe transfer) is set to 3 to 1: 2.
[0140]
Thereby, for example, when the total size of the transfer data of PIPEa and PIPEc is larger than PIPEb, the data of PIPEa and PIPEc can be transferred efficiently and efficient scheduling becomes possible.
[0141]
In the case of FIG. 17B, PIPEa and PIPEc data may not be automatically transferred continuously. That is, for example, data may be automatically transferred in the order of PIPEa, PIPEb, PIPEc, PIPEa, PIPEc, PIPEa,. Even in this case, the transfer ratio of PIPEa, PIPEb, and PIPEc can be set to 3 to 1: 2.
[0142]
8). Interrupt transfer token issue cycle
Four types of transfer methods are defined for USB. One of them, interrupt transfer, is transfer in which a host (or device) is polled by periodically issuing a token.
[0143]
In the conventional OHCI-compliant data transfer control device, the firmware needs to create a binary tree structure descriptor as shown in FIG. 4 in order to set a token issuing period for interrupt transfer. For this reason, there has been a problem that the processing load of the firmware becomes heavy.
[0144]
Thus, in this embodiment, the token transfer period for interrupt transfer can be set directly in the transfer condition register, for example, in frame order (ms). Specifically, as described with reference to FIG. 9, this token issuing period is set in the transfer condition register for HC.
[0145]
When the firmware (processing unit) sets the token issuance period in the transfer condition register, the host controller 50 (transfer controller) automatically generates an interrupt transfer token packet at the set token issuance period and sends it to the peripheral. Forward.
[0146]
That is, in this embodiment, transfer to a certain endpoint is managed as a pipe that is one transfer order. Then, the firmware determines the pipe for interrupt transfer, and directly sets the token issuing period as a numerical value in the transfer condition register of the pipe. Then, the host controller 50 issues an interrupt transfer token in the issue cycle in the pipe (pipe area).
[0147]
For example, in FIG. 18A, “1” is set in the token issue cycle register (one of the transfer condition registers). In this case, an interrupt transfer token packet is automatically transferred by the host controller 50 at an interval of one frame. In FIGS. 18B and 18C, “2” and “4” are set in the token issue cycle register. In this case, token packets are automatically transferred at intervals of 2 frames and 4 frames. Is done.
[0148]
By doing so, it is not necessary to create a binary tree structure descriptor as shown in FIG. 4 in order to realize interrupt transfer, and the processing load of the firmware can be reduced.
[0149]
In particular, OHCI employs a binary tree structure descriptor as shown in FIG. 4 so as to be able to cope with a case where a large number of endpoints are connected to the USB.
[0150]
However, in OTG, in many cases, peer-to-peer connection is planned, and using a binary tree structure descriptor as shown in FIG. 4 is a waste of processing.
[0151]
In the present embodiment, attention is paid to such waste of processing, and attention is paid to the fact that a transfer condition register is prepared for each pipe area, so that the token issuing period can be directly set in each transfer condition register. There are features.
[0152]
9. Detailed configuration example of each block
Next, a detailed configuration example of each block will be described.
[0153]
9.1 OTG controller
FIG. 19 shows a configuration example of the OTG controller 20.
[0154]
The OTG controller 20 includes an OTG register unit 22. The OTG register unit 22 includes a monitor register and a control register of the OTG controller 20. It also includes a circuit that decodes the OTG state command written by the firmware (CPU).
[0155]
The OTG controller 20 includes an OTG control circuit 23. The OTG control circuit 23 includes an OTG management circuit 24 that manages the OTG state, an ID detection circuit 25 that detects the voltage level of the ID pin, a VBUS detection circuit 26 that detects the voltage level of the VBUS, and DP and DM lines. A line state detection circuit 27 for detecting the state is included.
[0156]
The OTG controller 20 includes a timer 28 that measures a time that is one of the transition determination conditions of the OTG state.
[0157]
Information to be detected in order to change the OTG state is ID, VBUS voltage level, and DP / DM line state. The OTG controller 20 of this embodiment detects these pieces of information and transmits them to the firmware (CPU) via the monitor register.
[0158]
The firmware changes its own state based on the detection information, and informs the OTG controller 20 of the next state to be changed using an OTG state command.
[0159]
The OTG controller 20 decodes the OTG state command, performs VBUS drive control, pull-up / pull-down resistor connection control, and the like based on the decoding result, and performs the SRP and the SRP described with reference to FIGS. Realize HNP.
[0160]
As described above, in this embodiment, the OTG controller 20 is in charge of OTG control for each state, and the firmware can concentrate on state transition management. As a result, the processing load of the firmware (CPU) can be reduced and efficient firmware development can be achieved as compared with the case where all state control is realized by firmware.
[0161]
The determination of the OTG state transition may be performed by a hardware circuit without the firmware. Alternatively, almost all the processing of the OTG controller 20 (for example, processing other than VBUS control, pull-up / pull-down resistance control, ID detection, VBUS detection, and line state detection) may be realized by firmware (software).
[0162]
9.2 Host controller and peripheral controller
FIG. 20A shows a configuration example of the host controller 50.
[0163]
The host controller 50 includes an HC sequence management circuit 52. The HC sequence management circuit 52 performs arbitration of pipe transfer (data transfer using a pipe region), time management, scheduling of pipe transfer, retransmission management, and the like.
[0164]
More specifically, the HC sequence management circuit 52 issues a frame number count or SOF (Start-Of-Frame) packet transmission instruction. Also, processing for preferentially executing isochronous transfer at the head of each frame is performed, or processing for preferentially handling interrupt transfer after isochronous transfer is performed. Also, processing for instructing each pipe transfer is performed in accordance with the order of pipe transfer. It also manages the number of consecutive executions of transactions and performs confirmation processing for the remaining frame time. Also, processing is performed on the handshake packet (ACK, NAK) returned from the peripheral. It also performs error handling during transaction execution.
[0165]
The host controller 50 includes a target pipe management circuit 54. The target pipe management circuit 54 performs handling processing of transfer condition information set in the transfer condition register of the register unit 70 and the like.
[0166]
More specifically, the target pipe management circuit 54 performs transfer condition information selection processing and interrupt signal generation processing. When the start of an automatic transaction is instructed, the total size of transfer data in the pipe area is loaded. Then, the remaining transfer data size is counted (decremented). In addition, processing for confirming the state of the buffer (FIFO) area is performed when data is transmitted to and received from the buffer controller 80. Also, a transfer instruction to the transaction management circuit 56 is given. In addition, a process for determining reception of an unexpected short packet or a process for determining reception of a packet larger than the maximum packet size is performed. If the mode for automatically transferring zero-length packets is set, the transaction management circuit 56 is instructed to transmit the last zero-length packet. Also, sequence management is performed in the automatic control transfer mode.
[0167]
The host controller 50 includes a transaction management circuit 56. The transaction management circuit 56 manages the type and transfer order of transfer packets (transaction sequence management). Also, a timeout monitoring process is performed. In addition, a transaction end notification process is performed.
[0168]
The host controller 50 includes a packet handler circuit 58. The packet handler circuit 58 performs packet generation and disassembly processing. Also, PID check, CRC decoding and encoding are performed. In addition, the buffer area packet payload read / write processing and SOF packet transmission processing are performed. Also, transmission / reception data count processing is performed.
[0169]
FIG. 20B shows a configuration example of the peripheral controller 60.
[0170]
The peripheral controller 60 includes a transaction management circuit 62 and a packet handler circuit 64. These transaction management circuit 62 and packet handler circuit 64 perform substantially the same processing as the transaction management circuit 56 and packet handler circuit 58 of the host controller 50.
[0171]
9.3 Buffer controller
FIG. 21 shows a configuration example of the buffer controller 80.
[0172]
The buffer controller 80 includes an area allocation circuit 82. The area securing circuit 82 is a circuit that secures a buffer area (an area set in the pipe area during the host operation and set as the endpoint area during the peripheral operation) in the packet buffer 100.
[0173]
The area securing circuit 82 includes an area calculation circuit 83. The area calculation circuit 83 is a circuit that calculates the area size, start address, end address, etc. of the buffer area based on the maximum packet size (page size in a broad sense) and the number of pages.
[0174]
For example, in the buffer areas PIPE0 / EP0, PIPEa / EPa, PIPEb / EPb, and PIPEc / EPc shown in FIG. 22A, the maximum packet size (MaxPktSize) is set to 32, 64, 64, and 64 bytes, respectively. The number (BufferPage) is set to 1, 1, 3, 2 pages, respectively. The area calculation circuit 83 calculates the area size, start address, and end address of the buffer areas PIPE0 / EP0 to PIPEc / EPc based on the maximum packet size and the number of pages. For example, in FIG. 22A, the area sizes of PIPE0 / EP0, PIPEa / EPa, PIPEb / EPb, and PIPEc / EPc are 32 (= 32 × 1), 64 (= 64 × 1), and 192 (= 64, respectively. × 3) and 128 (= 64 × 2) bytes.
[0175]
The pointer assignment circuit 84 assigns the write pointer WP (WP0, WPa, WPb, WPc) and the read pointer RP (RP0, RPa, RPb, RPc) of each buffer area to the DMA pointer, CPU pointer, and USB pointer. Circuit.
[0176]
For example, as shown in FIG. 22B, when data is transmitted (when data is transferred from the DMA or the CPU to the USB side via the packet buffer 100) and when DMA transfer is used, the buffer area is written. The pointer WP is assigned to a DMA (DMA access) pointer, and the read pointer RP is assigned to a USB (USB access) pointer. When data is transmitted and the CPU (PIO) transfer is used, the write pointer WP of the buffer area is assigned to a CPU (CPU access) pointer, and the read pointer RP is assigned to a USB pointer.
[0177]
On the other hand, as shown in FIG. 22C, when data is received (when data is transferred from the USB to the DMA or CPU side via the packet buffer 100) and when DMA transfer is used, the buffer area The write pointer WP is assigned to the USB pointer, and the read pointer RP is assigned to the DMA pointer. When data is received and CPU transfer is used, the write pointer WP of the buffer area is assigned to the USB pointer, and the read pointer RP is assigned to the CPU pointer.
[0178]
The pointer information (position information) of the write pointer WP and the read pointer RP of each buffer area is held in each transfer condition register (PIPE / EP register) of the register unit 70.
[0179]
The pointer management circuit 86 is a circuit that generates a real address for accessing the packet buffer 100 while updating the pointer.
[0180]
The pointer management circuit 86 includes a CPU address generation circuit 87, a DMA address generation circuit 88, and a USB address generation circuit 89. These generation circuits 87, 88, and 89 generate a CPU address, a DMA address, and a USB address based on the CPU pointer, DMA pointer, and USB pointer allocated by the pointer allocation circuit 84, respectively. . Also, the pointer is updated every time the CPU (CPU interface circuit) and DMA (DMA handler circuit) access, or every time the USB (HC or PC) transaction ends (handshake transmission / reception such as ACK and NAK). . The updated pointer information is written back to each transfer condition register of the register unit 70 via the area securing circuit 82.
[0181]
The buffer management circuit 90 is a circuit that manages access to the packet buffer 100.
[0182]
The buffer management circuit 90 includes a buffer interface circuit 92. The buffer interface circuit 92 receives a CPU address, a DMA address, a USB address, and the like from the pointer management circuit 86, and inputs / outputs data to / from the packet buffer 100, addresses, output enable, write enable, read enable, etc. Is output.
[0183]
The buffer management circuit 90 includes an arbitration circuit 93. The arbitration circuit 93 is a circuit that arbitrates accesses from the CPU (CPU interface circuit), DMA (DMA handler circuit), and USB (host controller or peripheral controller). Based on the arbitration result, one of the CPU address, DMA address, and USB address is output as the access address of the packet buffer 100, and the data transfer path between the CPU, DMA or USB and the packet buffer 100 Is set.
[0184]
The HC / PC selector 94 performs switching control of connection between the buffer management circuit 90 (buffer controller 80) and the host controller 50 (HC) or the peripheral controller 60 (PC). For example, the host controller 50 and the buffer management circuit 90 are connected during the host operation, and the peripheral controller 60 and the buffer management circuit 90 are connected during the peripheral operation. This connection switching control is performed based on the HC / PC enable signal from the OTG controller 20 (OTGC).
[0185]
10. Firmware processing
Next, a detailed example of processing of the firmware (processing unit) will be described.
[0186]
FIG. 23 is a flowchart of firmware processing during host operation.
[0187]
First, it is confirmed whether or not a pipe (buffer) area has already been secured (step S11). If the pipe area is secured, a pipe area data clear instruction [FIFOClr] is issued (step S12).
[0188]
Next, end point (transfer condition) information is set in the transfer condition register (step S13). In other words, endpoint number [EPNumber], function address [FuncAddr], transfer direction [DirPID] such as IN / OUT / SETUP, transfer type [TranType] such as isochronous, bulk, control, interrupt, Max packet size [MaxPktSize], etc. Set.
[0189]
Next, the transfer type [TranType] is determined (step S14). If the transfer type is isochronous, the process proceeds to step S18. When the transfer type is interrupt transfer, the token issue period [Interval] is specified and the toggle mode [ToggleMode] is specified (steps S15 and S16). If the transfer type is neither isochronous nor interrupt (bulk or control), HC scheduling [number of continuous executions: Continuity] is specified (step S17).
[0190]
Next, an initial value [Toggle] of toggle bits is set, and a total size [TotalSize] of transfer data is set (steps S18 and S19). In the case of isochronous transfer, it is not necessary to set the initial value of the toggle bit. The setting order of steps S13 to S19 is arbitrary.
[0191]
Next, the number of pages [BufferPage] in the pipe (buffer) area is set (step S20), and an instruction [SetAllocation] for securing the pipe area is performed (step S21).
[0192]
Next, it is determined whether or not DMA is used, and if it is used, a DMA bus connection instruction [JoinDMA] is issued (steps S22 and S23). Also, an automatic transaction start instruction [TranGo] is issued (step S24).
[0193]
Then, waiting for an interrupt to occur (step S25), normal completion, STALL response, handshake wait time-out processing, etc. are performed (step S26).
[0194]
FIG. 24 is a flowchart of the firmware process during the peripheral operation.
[0195]
First, a data clear instruction [FIFOClr] for the endpoint (buffer) area is issued (step S31). Then, the toggle bit initial value [Toggle] is set (step S32).
[0196]
Next, end point (transfer condition) information is set (step S33). That is, the endpoint number [EPNumber], the transfer direction [DirPID], the transfer type [TranType], the maximum packet size [MaxPktSize], and the like are set.
[0197]
Next, an endpoint enable instruction [EnEndPoint] is performed (step S34). Then, the transfer type [TranType] is determined, and in the case of interrupt transfer, the toggle mode [ToggleMode] is designated (steps S35 and S36).
[0198]
Next, the number of pages [BufferPage] in the endpoint (buffer) area is set (step S37), and an instruction [SetAllocation] for securing the endpoint area is issued (step S38).
[0199]
Next, it is determined whether or not DMA is used. When DMA is used, a DMA bus connection instruction [JoinDMA] is issued (steps S39 and S40).
[0200]
Next, a token reception state from the host is entered (step S41). Then, it waits for an interrupt to occur (step S42), performs normal completion (ACK reception), NAK reply, STALL reply, handshake wait time-out process, etc. (step S43).
[0201]
11. Electronics
Next, an example of an electronic device including the data transfer control device of this embodiment will be described.
[0202]
For example, FIG. 25A shows an internal block diagram of a printer which is one of electronic devices, and FIG. 26A shows an external view thereof. A CPU 510 (processing unit) controls the entire system. An operation unit 511 is used by a user to operate the printer. The ROM 516 stores control programs, fonts, and the like, and the RAM 517 (system memory) functions as a work area for the CPU 510. The DMAC 518 is a DMA controller for performing data transfer without going through the CPU 510. A display panel 519 is for informing the user of the operation state of the printer.
[0203]
Serial print data (print data, image data) sent from another device such as a personal computer, a digital camera, or a digital video camera via USB is converted into parallel print data by the data transfer control device 500. . The converted parallel print data is sent to the print processing unit (printer engine) 512 by the CPU 510 or the DMAC 518. A given process is performed on the parallel print data in the print processing unit 512, and the print unit (device that performs data output processing) 514 including a print header is printed on paper.
[0204]
FIG. 25B shows an internal block diagram of a digital camera which is one of electronic devices, and FIG. 26B shows an external view thereof. The CPU 520 controls the entire system. The operation unit 521 (shutter button, operation button, etc.) is for the user to operate the digital camera. The ROM 526 stores a control program and the like, and the RAM 527 functions as a work area for the CPU 520. The DMAC 528 is a DMA controller.
[0205]
An image is picked up by an image pickup unit (device that performs data fetching processing) 522 including a CCD, a lens, and the like, and data of the picked up image is processed by an image processing unit 524. Then, the processed image data is sent to the data transfer control device 500 by the CPU 520 or the DMAC 528. The data transfer control device 500 converts the parallel image data into serial data and transmits it to other devices such as a printer, a storage device, and a personal computer via the USB.
[0206]
FIG. 25C shows an internal block diagram of a CD-RW drive (storage device) which is one of electronic devices, and FIG. 26C shows an external view thereof. The CPU 530 controls the entire system. The operation unit 531 is for the user to operate the CD-RW. The ROM 536 stores a control program and the like, and the RAM 537 functions as a work area for the CPU 530. The DMAC 538 is a DMA controller.
[0207]
Data read from the CD-RW 532 by a reading and writing unit (a device for performing data fetching processing or a device for performing data storage processing) 533 including a laser, a motor, an optical system, and the like is input to the signal processing unit 534. Then, given signal processing such as error correction processing is performed. Then, the data subjected to the signal processing is sent to the data transfer control device 500 by the CPU 530 or the DMAC 538. The data transfer control device 500 converts this parallel data into serial data and transmits it to another device via the USB.
[0208]
On the other hand, serial data sent from another device via the USB is converted into parallel data by the data transfer control device 500. The parallel data is sent to the signal processing unit 534 by the CPU 530 or the DMAC 538. The signal processing unit 534 performs given signal processing on the parallel data, and the reading and writing unit 533 stores the data in the CD-RW 532.
[0209]
25A, 25B, and 25C, in addition to the CPUs 510, 520, and 530, a CPU for data transfer control in the data transfer control device 500 may be provided separately.
[0210]
If the data transfer control device of this embodiment is used in an electronic device, an electronic device having an OTG function can be realized. In other words, it becomes possible to give the electronic device a role as a host or a role as a device, and an application that has not existed before can be created.
[0211]
If the data transfer control device of this embodiment is used in an electronic device, the processing load on a CPU (processing unit) incorporated in the electronic device is reduced, and an inexpensive CPU can be used. Further, the CPU can perform processing other than the data transfer control processing with a margin, and the performance of the electronic device can be improved and the cost can be reduced. In addition, the firmware program operating on the CPU can be simplified, and the development period of the electronic device can be shortened.
[0212]
In addition to the above, the electronic apparatus to which the data transfer control device of the present embodiment can be applied includes, for example, various optical disk drives (CD-ROM, DVD), magneto-optical disk drives (MO), hard disk drives, digital video cameras, Various things such as a mobile phone, a scanner, a TV, a VTR, an audio device, a telephone, a projector, a personal computer, an electronic notebook, or a word processor can be considered.
[0213]
In addition, this invention is not limited to this embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.
[0214]
For example, the configuration of the data transfer control device of the present invention is not limited to the configuration described with reference to FIG. 5 and the like, and various modifications can be made.
[0215]
Further, the configuration of each block (HC, PC, OTGC, etc.) of the data transfer control device is not limited to that described in the present embodiment, and various modifications can be made.
[0216]
Also, the transfer condition information set in the transfer condition register is not limited to the information described in the present embodiment.
[0217]
In addition, terms (OTG controller, CPU / firmware, host controller / peripheral controller) cited as broad terms (state controller, processing unit, transfer controller, bus, transfer ratio information, buffer area, etc.) in the description in the specification. USB, continuous execution count, pipe area / endpoint area, etc.) can be replaced by broad terms in other descriptions in the specification.
[0218]
In the invention according to the dependent claims of the present invention, a part of the constituent features of the dependent claims can be omitted. Moreover, the principal part of the invention according to one independent claim of the present invention may be made dependent on another independent claim.
[0219]
In this embodiment, the application example to the USB OTG standard has been described. However, the present invention is not limited to the OTG standard. For example, the present invention can be applied to data transfer in a standard based on the same idea as the OTG standard or a standard developed from the OTG standard.
[Brief description of the drawings]
FIGS. 1A, 1B, and 1C are diagrams for explaining a USB OTG standard. FIG.
FIGS. 2A and 2B are diagrams for explaining procedures of SRP and HNP.
FIGS. 3A and 3B are diagrams for explaining a descriptor having an OHCI list structure. FIG.
FIG. 4 is a diagram for explaining a descriptor having an OHCI binary tree structure;
FIG. 5 is a diagram illustrating a configuration example of a data transfer control device according to the present embodiment;
FIGS. 6A and 6B are diagrams for explaining a pipe region and an endpoint region.
FIG. 7 is a diagram for explaining an operation at the time of hosting of the data transfer control device;
FIG. 8 is a diagram for explaining an operation at the time of a peripheral of the data transfer control device;
FIG. 9 is a diagram for explaining a register unit;
FIG. 10 is a detailed example of a register map of a general-purpose transfer condition register.
FIG. 11 is a detailed example of a register map of a transfer condition register for control transfer.
FIGS. 12A and 12B are diagrams showing an outline of transfer condition information set in each bit field of the transfer condition register.
FIG. 13 is a diagram showing an outline of transfer condition information set in each bit field of the transfer condition register.
FIG. 14 is a flowchart for explaining an example of firmware processing;
FIG. 15 is a signal waveform example of automatic transaction processing in an IN transaction.
FIG. 16 is a signal waveform example of automatic transaction processing in an OUT transaction.
FIGS. 17A and 17B are diagrams for explaining a method of setting the number of continuous executions of a transaction.
FIGS. 18A, 18B, and 18C are diagrams for explaining a method of setting a token issuing period for interrupt transfer.
FIG. 19 is a diagram illustrating a detailed configuration example of an OTG controller.
20A and 20B are diagrams illustrating detailed configuration examples of a host controller and a peripheral controller.
FIG. 21 is a diagram illustrating a detailed configuration example of a buffer controller.
FIGS. 22A, 22B, and 22C are diagrams for explaining an area securing method and a pointer allocation method.
FIG. 23 is a flowchart illustrating a detailed processing example of firmware during host operation.
FIG. 24 is a flowchart illustrating a detailed processing example of the firmware during the peripheral operation.
FIGS. 25A, 25B, and 25C are examples of internal block diagrams of various electronic devices.
26A, 26B, and 26C are examples of external views of various electronic devices.
[Explanation of symbols]
PIPE0 to PIPEe Pipe (buffer) area,
EP0 to EPe Endpoint (buffer) area,
TREG0 to TREGe transfer condition register (shared register),
10 transceiver, 12 physical layer circuit, 20 OTG controller (state controller), 30 HC / PC switching circuit, 32 HC / PC selector, 34 line state controller, 40 transfer controller,
50 host controller, 60 peripheral controller, 70 register unit, 72 transfer condition register unit (shared register), 80 buffer controller, 100 packet buffer (FIFO, RAM), 110 interface circuit, 112 DMA handler circuit, 114 CPU interface circuit, 120 Clock controller

Claims (11)

A data transfer control device that is incorporated in an electronic device connected to a USB (Universal Serial Bus) and transmits / receives data via the USB,
A buffer controller that secures a pipe area in the packet buffer corresponding to the endpoint, and performs access control on the packet buffer;
A register unit including a transfer condition register in which transfer condition information for data transfer between the pipe area and the endpoint is set;
Based on the transfer condition information set in the transfer condition register, includes a transaction for the endpoint, and includes a pipe area and a transfer controller that transfers data between the endpoint corresponding to the pipe area,
The buffer controller
When the transfer of a given data unit is completed, the pipe area is released,
A data transfer control device, wherein a pipe area is reassigned to the packet buffer from which the pipe area has been released in correspondence with an end point. In claim 1,
The transfer condition information set in the transfer condition register includes the total size of data transferred to and from the endpoint, the maximum packet size, and the data transfer direction,
The transfer controller is
The total size data is transferred between a pipe area and an end point corresponding to the pipe area in a direction specified by the transfer direction, using a payload packet of the maximum packet size. Data transfer control device. In claim 1 or 2,
The transfer condition information set in the transfer condition register includes a transfer type of data transfer,
The transfer controller is
A data transfer control device that transfers data in a pipe area by data transfer of a transfer type set in a transfer condition register. In any one of Claims 1 thru | or 3,
The transfer condition information set in the transfer condition register includes transfer ratio information between a plurality of pipe regions,
The transfer controller is
A data transfer control device, wherein data in a pipe area is transferred at a transfer ratio set by the transfer ratio information. In claim 4,
The transfer rate information is
A data transfer control device characterized in that the number of continuous executions of a pipe area transaction. In any one of Claims 1 thru | or 5,
The transfer condition information set in the transfer condition register includes a token issue period in interrupt transfer,
The transfer controller is
A data transfer control device, wherein a token packet for interrupt transfer is transferred at the token issuing period set in a transfer condition register. In any one of Claims 1 thru | or 6.
The pipe region is
A data transfer control apparatus comprising: a dedicated pipe area for an end point of control transfer; and a general-purpose pipe area that can be assigned to an arbitrary end point. In any one of Claims 1 thru | or 7,
An interface circuit for transferring data between another buffer different from the bus and the packet buffer;
When the processing unit instructs the interface circuit and the transfer controller to start data transfer, the interface circuit performs data transfer via another bus, and the transfer controller performs data transfer via the bus. And when the data transfer ends, the transfer controller generates an interrupt to the processing unit. In any one of Claims 1 thru | or 8.
It includes a state controller that controls multiple states including a host operation state that operates as a host role and a peripheral operation state that operates as a peripheral role.
The transfer controller is
A host controller that transfers data as a host during host operation;
Including a peripheral controller that transfers data as a peripheral during peripheral operation,
A pipe area is reserved for a packet buffer during host operation, and the host controller transfers data between the reserved pipe area and an endpoint corresponding to the pipe area. Transfer control device. A data transfer control device according to any one of claims 1 to 9,
An apparatus for performing an output process or a capture process or a storage process of data transferred via the data transfer control device and the bus;
A processing unit for controlling data transfer of the data transfer control device;
An electronic device comprising: A data transfer control method for transmitting and receiving data via USB (Universal Serial Bus),
A pipe area is secured in the packet buffer corresponding to the endpoint,
Set transfer condition information for data transfer between the pipe area and the endpoint in the transfer condition register,
Based on the transfer condition information set in the transfer condition register, a transaction for the endpoint is generated, and data is transferred between the pipe area and the endpoint corresponding to the pipe area.
When the transfer of a given data unit is completed, the pipe area is released,
A data transfer control method, wherein a pipe area is reassigned to the packet buffer from which the pipe area has been released in accordance with an end point.

Images