JP2006252334A - Data transfer control method, and data transfer controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a framework capable of reducing a burden for memory management processing, and capable of transferring data efficiently and stably without enlarging a shared memory size used for the data transfer, when transferring the data using a USB host controller. <P>SOLUTION: This data transfer control method is provided with a process for allocating a fixed size of buffer area on the share memory to a pipe, and a process for controlling the USB host controller to transfer the data between a USB host unit and a USB device unit, via the fixed size of buffer area allocated to the pipe. The allocation process is provided with a process for securing a fixed size of memory area on the shared memory in every USB port, and a process for setting the buffer area of the pipe requested to transfer the data as to a USB device, in the fixed size of memory area secured as to the USB port connected to the USB device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a data transfer control method and a data transfer control device.

  The USB (Universal Serial Bus) 2.0 standard is a standard capable of realizing a data transfer rate of 480 Mbps (HS mode) faster than USB 1.1 while having compatibility with the USB 1.1 standard. An EHCI (Enhanced Host Controller Interface) is known as a definition of a USB host controller corresponding to the USB 2.0 standard.

  When performing data transfer based on the USB standard, normally, a USB host device (an application running on the USB host device) and the USB device device are connected via a buffer secured on a shared memory in the USB host device. Perform data transfer.

  Conventionally, a buffer used for this data transfer has been dynamically secured on a shared memory in accordance with the size of data requested by the application side, and is normally released after the end of the transfer.

  However, in such a conventional framework, processing is complicated in that it is necessary to monitor an available area of the shared memory and confirm whether or not a buffer has been secured when receiving a data transfer request. In addition, for example, when there is a transfer request with a large data size for a plurality of USB devices at the same time, there may be a situation where a buffer for data transfer cannot be secured on the shared memory. Furthermore, since the memory area is dynamically secured, for example, when the USB device is frequently inserted and removed, the memory area secured on the shared memory is not properly released (memory leak). If such a memory leak occurs, there is a possibility that the system performance is lowered or the operation becomes unstable and the system hangs.

  Here, if the size of the shared memory is increased, it is considered that the memory shortage problem can be solved to some extent. However, increasing the shared memory size is limited due to cost and mounting reasons, and is not an essential solution to memory leaks.

  Therefore, the present invention reduces the burden of memory management processing when transferring data to and from a USB device using a USB host controller, and increases the efficiency without increasing the size of the shared memory used for data transfer. The purpose is to provide a framework that can perform data transfer well and stably.

  The data transfer control method of the present invention is a data transfer control method in the case of performing data transfer using a USB host controller, and includes a step of allocating a fixed size buffer area on a shared memory to a pipe, And a step of controlling the USB host controller so as to transfer data between the USB host device and the USB device device via the fixed size buffer area. The USB host controller may be, for example, an EHCI standard USB host controller.

  According to such a configuration, when data transfer is performed using a USB host controller, it is not necessary to monitor the available area of the shared memory and confirm whether or not the buffer area has been secured. Can be reduced.

  Preferably, the step of allocating a fixed-size buffer area on the shared memory to the pipe includes a step of securing a fixed-size memory area on the shared memory for each USB port, and securing a USB port to which the USB device is connected. And a step of setting a buffer area of a pipe for which a data transfer request has been made with respect to the USB device, in the fixed-size memory area.

  According to such a configuration, the size of the buffer area required on the shared memory is fixedly determined by the number of USB ports and the fixed size. Therefore, even if the number of pipes, transfer data size, and the like vary, There is no situation where the buffer area cannot be secured. Further, since the memory area is secured statically (fixedly), there is no possibility that a memory leak occurs even if the USB device device is frequently inserted and removed. As a result, data transfer can be performed efficiently and stably while suppressing the size of the shared memory used for data transfer.

  Preferably, the fixed-size memory area on the shared memory includes at least two buffer areas A and B, and the step of controlling the USB host controller uses the one buffer area for the USB device apparatus side. The buffer area A and B are alternately specified so that the data transfer to the USB host device is performed using the other buffer area, and the transfer request is notified to the USB host controller. A process is provided.

  According to such a configuration, data transfer with the USB device device side and data transfer with the USB host device side can be performed in parallel, and data transfer can be executed at high speed.

  For example, in the step of controlling the USB host controller, one of the buffer areas A and B is set as a processing surface, the other is set as a standby surface, and descriptor information for data transfer is set for the processing surface. A step of designating the processing surface and notifying a transfer request to the USB host controller, a step of determining whether or not the transfer has been completed for all data requested to be transferred, and a case where the transfer has not been completed. And setting the descriptor information for data transfer with respect to the standby surface, and when receiving a data transfer completion notification from the USB host controller for the processing surface, the processing surface and the standby surface for the buffer areas A and B And a step of exchanging the settings.

  According to this configuration, when the data requested to be transferred is larger than the fixed size, the descriptor information for data transfer is set in a plurality of times in a fixed size unit. It is possible to instruct data transfer without being aware of the fixed size.

  The data transfer control method of the present invention can be executed by a CPU in a USB host device. A computer program therefor can be installed in a computer through various media such as a CD-ROM, a magnetic disk, a semiconductor memory, and a communication network. Can be loaded.

  The data transfer control device of the present invention is a data transfer control device for performing data transfer using a USB host controller, and has a function of allocating a fixed size buffer area on a shared memory to a pipe, And a function of controlling the USB host controller so as to transfer data between the USB host device and the USB device device via the fixed-size buffer area.

  As described above, according to the present invention, when data is transferred to or from a USB device using a USB host controller, the burden of memory management processing can be reduced and the size of the shared memory used for data transfer can be increased. Data transfer can be performed efficiently and stably.

  FIG. 1 is a schematic diagram of a functional configuration of a data transfer system according to the present embodiment. As shown in FIG. 1, a USB host device 1 includes a client driver 10, a USBD (Universal Bus Driver) 11, a CHCD (Companion Host Controller Driver) 12, a CHCI (Companion Host Controller Interface) 13, and an EHCD (Enhanced Host Controller Driver). 14, EHCI 15, shared memory 16, etc., and is connected to the USB device device 2 by USB.

  The client driver 10 is a driver that provides an access function or the like to the USB device device 2 for an application operating on the USB host device 1, and can be implemented as a part of the OS, for example.

  The USBD 11 is a driver that performs processing that does not depend on hardware (for example, processing that does not depend on the type of the USB host controller), and has the same function as a conventional USB general-purpose driver.

  The CHCD 12 is a device driver that performs processing dependent on the CHCI 13, and has the same function as the conventional USB 1.1 device driver.

  The CHCI 13 is a USB host controller compliant with the USB 1.1 standard, and has the same functions as the conventional USB 1.1 host controller, such as transaction management, packet generation / disassembly, and instructions for generating a suspend / resume / reset state. . The CHCI 13 may be based on either OHCI (Open Host Controller Interface) or UHCI (Universal Host Controller Interface).

  The EHCD 14 is a device driver that performs processing dependent on the EHCI 15, and in principle has the same functions as the conventional USB 2.0 device driver.

  However, the EHCD 14 of the present embodiment allocates a fixed size buffer area on the shared memory 16 to the pipe, and transmits data between the USB host device and the USB device device via the fixed size buffer area allocated to the pipe. This is different from the prior art in that the EHCI 15 is controlled to perform the transfer.

  The EHCI 15 is a USB host controller compliant with the EHCI standard, and has the same functions as the conventional USB 2.0 host controller, such as transaction management, packet generation / disassembly, and instructions for generating a suspend / resume / reset state.

  Each driver can be realized as a functional unit by the CPU executing a program stored in a ROM or RAM in the USB host device 1 or an external storage medium. Further, although not shown, the data transfer system is a USB-based data such as a transceiver that transmits and receives data using the differential data signals D + and D−, and a root hub that provides a connection between the CHCI 13 or the EHCI 15 and the USB port. The functional configuration normally provided in the transfer system is similarly provided.

  FIG. 2 is a diagram for explaining a data transfer scheme in USB. The data transfer scheme in USB can be described using the concept of endpoints and pipes. In other words, the USB host device and the USB device device are provided with FIFO buffers called endpoints, and these buffers are connected to each other through a logical communication path called a pipe. The USB host device can perform device data transmission / reception (data transmission to a desired endpoint or data reception from a desired endpoint) by designating a device address, a pipe number, an endpoint number, and the like. it can.

  Some endpoints are used for control transfer called endpoint 0, and configuration such as setup and transfer of setting parameters is executed using this control transfer. When the usage of the USB device is set by configuration, a new end point is added and a corresponding pipe is configured.

  USB transfer modes include bulk transfer, interrupt transfer, and isochronous transfer in addition to the control transfer described above, and the USB device device holds which transfer mode to use as configuration data. . Then, after the USB connection is made, the data is transmitted from the USB device device to the USB host device using control transfer, and the USB host device determines the transfer mode based on this data, and the address of the USB device device. Assigns pipe numbers and endpoint numbers.

  Hereinafter, the flow of data transfer in the data transfer system of this embodiment will be described with reference to the flowcharts of FIGS. In addition, each process (including the partial process to which the code | symbol is not provided) can be arbitrarily changed in order within the range which does not produce contradiction in the processing content, or can be performed in parallel.

(Processing from USB device device 2 connection to pipe opening: Fig. 3)
When the USB device device 2 is connected to the USB port, the EHCI 15 detects the connection (S100). As a method for detecting the connection, for example, it may be detected that one of the signal lines (D +, D−) in the USB cable becomes a predetermined voltage (3.3 V).

  The EHCD 14 monitors connection detection by the EHCI 15 and, when the EHCI 15 detects connection, notifies the USBD 11 that the USB device device 2 is connected (S101).

  Upon receiving the connection notification from the EHCD 14, the USBD 11 requests the EHCD 14 to reset (S102).

  When the EHCD 14 receives the request, the EHCD 14 instructs the EHCI 15 to reset (S103).

  When receiving a reset instruction from the EHCD 14, the EHCI 15 resets the USB port setting and outputs a reset signal to the USB device device 2 (for example, both D + and D− are set to LOW) (S104). ). When the USB device device 2 detects the reset signal, the USB device device 2 executes an internal reset and shifts to a default state. In this default state, only control transfer using the endpoint 0 (pipe 0) is possible.

  Next, the EHCI 15 acquires the status of the USB port, and when the status is normal, executes configuration with the USB device device 2 using control transfer, and notifies the EHCD 14 of the configuration result. (S105).

  When the configuration is successful, the EHCD 14 has a fixed size (for example, 20 Kbytes) memory for each USB port managed by the EHCI 15 on the shared memory 16 provided on the USB host device 1 side for data transfer. An area is secured (S106).

  Here, the memory area is secured so that at least two buffer areas A and B, each of which can be used as an I / O buffer area for data transfer, can be set. Further, when securing a memory area of a fixed size, the address of the memory area is secured in a fixed manner corresponding to the USB port, such as address X for USB port 1 and address Y for USB port 2. May be.

  Next, the EHCD 14 notifies the USBD 11 of the configuration result (S107).

  When the notification is a notification of configuration failure (S107: configuration failure), the process for data transfer using the CHCI 13 is executed by the same process as the data transfer process based on the conventional USB 1.1 standard. (S108). For example, after the USBD 11 requests the CHCD 12 to reset, and the USB port setting is reset by the CHCI 13, the configuration is executed. If the configuration is successful, the CHCD 12 secures a buffer area on the shared memory and opens the pipe.

  On the other hand, if the USBD 11 receives a notification of successful configuration from the EHCD 14 (S107: successful configuration), the USBD 11 transfers the notification to the client driver 10 (S109).

  When the client driver 10 receives a notification from the USBD 11 that the configuration is successful, the client driver 10 instructs the USBD 11 to open a pipe following the opening instruction of the USB device device 2 (S110).

  When the USBD 11 receives an instruction to open a pipe, the USBD 11 requests the EHCD 14 to open the pipe (S111).

  When receiving the request, the EHCD 14 selects a pipe based on the configuration result, and instructs the EHCI 15 to open the selected pipe (S112).

  The EHCI 15 opens the pipe designated by the EHCD 14 (S113). As a result, the data transfer system shifts to a state in which data transfer can be performed using the EHCI 15.

(Data transfer processing: FIGS. 4 and 5)
When the data transfer system is in a state in which data transfer can be performed using the EHCI 15, the client driver 10 waits for an access function call to the USB device device 2 from an application operating on the USB host device 1 (S200). ).

  When an access function is called from the application, the client driver 10 designates a pipe or the like based on an argument or the like of the access function, and instructs the USBD 11 to transfer data (S201).

  When the USBD 11 receives the instruction, the USBD 11 designates a pipe or the like and requests data transfer to the EHCD 14 (S202).

  When the EHCD 14 receives the request, the EHCD 14 selects the designated pipe (endpoint), and allocates the fixed-size memory area secured in S106 to the selected pipe (the selected pipe is assigned to the fixed-size memory area). (S203). Note that the fixed-size memory area secured for each USB port is shared and used exclusively among a plurality of pipes corresponding to the USB port. This exclusive control is executed by the client driver 10, for example. Is done.

  Next, the EHCD 14 sets one of the buffer areas A and B as a processing surface and the other as a standby surface (S204). The processing surface corresponds to a buffer area (so-called double buffer table buffer) used when the EHCI 15 performs data transfer, and the standby surface is used for the next data transfer while the EHCI 15 is transferring data. This corresponds to a buffer area (so-called double buffer back buffer) used for preparation.

  Next, the EHCD 14 sets descriptor information for data transfer (qTD (Queue Element Transfer Descriptor) or the like) for the processing surface, and stores it in the memory area allocated to the pipe (S205).

  Next, when the data transfer request is OUT (S206: YES), the EHCD 14 copies the transfer target data stored in the RAM or the like of the USB host device 1 to the processing surface (S207).

  Next, the EHCD 14 designates a processing surface and notifies the transfer request to the EHCI 15 (S208). In response to this, the EHCI 15 executes data transfer via the processing surface based on the set descriptor information. That is, when the data transfer request is OUT, the transfer target data stored in the processing surface is transferred to the USB device device 2. When the data transfer request is IN, the transfer target data is read from the USB device device 2 and processed. To store. When the data transfer is completed, the EHCI 15 notifies the EHCD 14 of the information.

  Next, the EHCD 14 determines whether or not the transfer has been completed for all the data requested to be transferred (S209), and if it has been completed, the process proceeds to the process of S213.

  On the other hand, if not completed, the EHCD 14 sets descriptor information for data transfer for the standby surface and stores it in the memory area allocated to the pipe (S210).

  Next, when the data transfer request is OUT (S211: YES), untransferred data among the transfer target data stored in the RAM or the like of the USB host device 1 is copied to the standby surface (S212).

  Next, the EHCD 14 waits for a data transfer completion notification from the EHCI 15 (S213).

  When the notification of data transfer completion is received, the EHCD 14 determines whether or not descriptor information for data transfer is set and stored for the standby surface (S214).

  When the descriptor information is not set / stored for the standby surface, the EHCD 14 determines whether the data transfer notified of the completion of the data transfer is IN (S215).

  In the case of IN, the EHCD 14 copies the transfer target data stored in the processing surface to the RAM or the like of the USB host device 1 (S216).

  Next, the EHCD 14 notifies the USBD 11 that all requested data transfer has been completed (S217).

  When the USBD 11 receives the notification from the EHCD 14, the USBD 11 transfers the notification to the client driver 10 (S218).

  When the client driver 10 receives the notification, the client driver 10 returns to the process of S200 (S219).

  On the other hand, when the descriptor information is set and stored for the standby surface, the EHCD 14 switches the settings of the processing surface and the standby surface (S220). For example, if the buffer area A is set as the processing plane and the buffer area B is set as the standby plane, the buffer area B is set as the processing plane and the buffer area A is set as the standby plane.

  Next, the EHCD 14 designates a processing surface and notifies the transfer request to the EHCI 15 (S221). In response to this, the EHCI 15 executes data transfer via the processing surface based on the set descriptor information as described above.

  Next, the EHCD 14 determines whether or not the data transfer notified of the completion of the data transfer is IN (S222).

  If it is IN, the EHCD 14 copies the transfer target data stored in the standby surface to the RAM or the like of the USB host device 1 (S223).

  Next, the EHCD 14 determines whether or not the transfer has been completed for all the data requested to be transferred (S224). If completed, the process returns to the step S213.

  On the other hand, if not completed, the EHCD 14 sets descriptor information for data transfer for the standby surface and stores it in the memory area allocated to the pipe (S225).

  Next, when the data transfer request is OUT (S226: YES), the EHCD 14 copies the transfer target data stored in the RAM or the like of the USB host device 1 to the standby surface (S227), and then in S213. If the process returns to IN (S226: NO), the process returns to S213 as it is.

  According to this configuration, when data transfer is performed using the EHCI 15, a fixed size memory area is secured on the shared memory 16 for each USB port, and the secured fixed size memory area is allocated to each pipe of the USB port. Therefore, it is not necessary to monitor the usable area of the shared memory 16 to confirm whether the buffer area has been secured, and the burden of memory management processing can be reduced.

  In addition, since the size of the buffer area required on the shared memory 16 is fixedly determined by the number of USB ports and the fixed size, even if the number of pipes, transfer data size, etc. fluctuate, the buffer area on the shared memory 16 There will be no situation where it is impossible to secure Further, since the memory area is secured statically (fixedly), there is no possibility that a memory leak occurs even if the USB device device is frequently inserted and removed. As a result, data transfer can be performed efficiently and stably while suppressing the size of the shared memory used for data transfer.

  Further, in the EHCD 14, when the requested data is larger than the fixed size, the descriptor information for data transfer is set in a plurality of times in a fixed size unit. 10 or the like can instruct data transfer without being aware of the fixed size.

  Further, two buffer areas A and B are provided in the fixed size memory area, and the two buffer areas A and B are alternately set as a processing surface and a standby surface, respectively, and a data transfer request is sent to the EHCI 15 regarding the processing surface. Since the configuration is such that the standby surface is copied to and from the RAM of the USB host device 1, the data transfer processing by the EHCI 15 and the copy processing between the RAM and the like of the USB host device 1 are performed. Can be executed in parallel (that is, data transfer with the USB device device side is performed using one buffer area while data transfer with the USB host device side is performed using the other buffer area), Data transfer can be executed at high speed.

(Other)
The present invention is not limited to the above-described embodiment, and can be variously modified and applied.

  For example, although the case where data transfer is performed using the EHCI 15 has been described in the above embodiment, the present invention can be similarly applied to the case where data transfer is performed using the CHCI 13. That is, a configuration is adopted in which a fixed size memory area is secured on the shared memory 16 for each USB port managed by the CHCI 13, and the secured fixed size memory area is assigned to each pipe of the USB port as a buffer area. Also good. When the present invention is applied to both the EHCI 15 and the CHCI 13, the fixed-size memory area secured for the same USB port can be shared by the EHCD 14 and the CHCD 12 and set exclusively as a buffer area.

  The present invention can also be applied to a data transfer control method in the USB 1.1 standard, the USB 2.0 standard, a standard based on the same idea as these standards, or a standard developed from these standards.

It is a block diagram which shows the function structure of the data transfer system in this embodiment. It is a figure for demonstrating the scheme of the data transfer in USB. It is a flowchart which shows the processing content from the connection of the USB device apparatus 2 in this embodiment to a pipe open. It is a flowchart which shows the content of the data transfer process in this embodiment. It is a flowchart which shows the content of the data transfer process in this embodiment.

Explanation of symbols

1 USB host device; 10 client driver; 11 USBD; 12 CHCD; 13 CHCI; 14 EHCD; 15 EHCI; 16 shared memory; 2 USB device device

Claims (7)

A data transfer control method for transferring data using a USB host controller,
Allocating a fixed-size buffer area on the shared memory to the pipe;
And a step of controlling the USB host controller so as to transfer data between the USB host device and the USB device device via the fixed-size buffer area allocated to the pipe. Transfer control method.   2. The data transfer control method according to claim 1, wherein the USB host controller is an EHCI standard USB host controller. The step of allocating a fixed-size buffer area on the shared memory to the pipe is as follows:
Securing a fixed-size memory area on the shared memory for each USB port;
Setting a buffer area of a pipe for which a data transfer request has been made for the USB device in the fixed-size memory area reserved for the USB port to which the USB device is connected;
The data transfer control method according to claim 1 or 2, further comprising: The fixed-size memory area on the shared memory includes at least two buffer areas A and B,
The step of controlling the USB host controller includes:
Specify buffer areas A and B alternately so that data transfer with the USB host device side is performed using the other buffer area while data transfer with the USB device apparatus side is performed using one buffer area 4. The data transfer control method according to claim 1, further comprising a step of notifying the USB host controller of a transfer request. The fixed-size memory area on the shared memory includes at least two buffer areas A and B,
The step of controlling the USB host controller includes:
A step of setting one of the buffer areas A and B as a processing surface and the other as a standby surface;
A process for setting descriptor information for data transfer for a processing surface;
Designating the processing surface and notifying the USB host controller of a transfer request;
Determining whether or not the transfer has been completed for all the data requested to be transferred;
If not completed, setting the descriptor information for data transfer for the standby side; and
When a notification of data transfer completion is received from the USB host controller with respect to the processing surface, a step of switching the setting of the processing surface and the standby surface with respect to the buffer areas A and B;
The data transfer control method according to any one of claims 1 to 4, further comprising: A data transfer control device for performing data transfer using a USB host controller,
A function that allocates a fixed-size buffer area in shared memory to the pipe;
And a function of controlling the USB host controller so as to transfer data between the USB host device and the USB device device via the fixed-size buffer area allocated to the pipe. Transfer control device. A program for causing a computer to execute the data transfer control method according to any one of claims 1 to 5.

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