$FreeBSD$ DESCRIPTION OF THE NEW USB API The new USB 2.0 API consists of 5 functions. All transfer types are managed using these functions. There is no longer need for separate functions to setup INTERRUPT- and ISOCHRONOUS- transfers. +--------------------------------------------------------------+ | | | "usb2_transfer_setup" - This function will allocate all | | necessary DMA memory and might | | sleep! | | | | "usb2_transfer_unsetup" - This function will stop the USB | | transfer, if it is currently | | active, release all DMA | | memory and might sleep! | | | | "usb2_transfer_start" - This function will start an USB | | transfer, if not already started.| | This function is always | | non-blocking. ** | | | | "usb2_transfer_stop" - This function will stop an USB | | transfer, if not already stopped.| | The callback function will be | | called before this function | | returns. This function is always | | non-blocking. ** | | | | "usb2_transfer_drain" - This function will stop an USB | | transfer, if not already stopped | | and wait for any additional | | DMA load operations to complete. | | Buffers that are loaded into DMA | | using "usb2_set_frame_data" can | | safely be freed after that | | this function has returned. This | | function can block the caller. | | | | ** These functions must be called with the private driver's | | lock locked. | | | | NOTE: These USB API functions are NULL safe, with regard | | to the USB transfer structure pointer. | +--------------------------------------------------------------+ Reference: /sys/dev/usb/usb_transfer.c /* * A simple USB callback state-machine: * * +->-----------------------+ * | | * +-<-+-------[tr_setup]--------+-<-+-<-[start/restart] * | | * | | * | | * +------>-[tr_transferred]---------+ * | | * +--------->-[tr_error]------------+ */ void usb2_default_callback(struct usb2_xfer *xfer) { /* * NOTE: it is not allowed to return * before "USB_CHECK_STATUS()", * even if the system is tearing down! */ switch (USB_GET_STATE(xfer)) { case USB_ST_SETUP: /* * Setup xfer->frlengths[], xfer->nframes * and write data to xfer->frbuffers[], if any */ /**/ usb2_start_hardware(xfer); return; case USB_ST_TRANSFERRED: /* * Read data from xfer->frbuffers[], if any. * "xfer->frlengths[]" should now have been * updated to the actual length. */ return; default: /* Error */ /* print error message and clear stall for example */ return; } } === Notes for USB control transfers === An USB control transfer has three parts. First the SETUP packet, then DATA packet(s) and then a STATUS packet. The SETUP packet is always pointed to by "xfer->frbuffers[0]" and the length is stored in "xfer->frlengths[0]" also if there should not be sent any SETUP packet! If an USB control transfer has no DATA stage, then "xfer->nframes" should be set to 1. Else the default value is "xfer->nframes" equal to 2. Example1: SETUP + STATUS xfer->nframes = 1; xfer->frlenghts[0] = 8; usb2_start_hardware(xfer); Example2: SETUP + DATA + STATUS xfer->nframes = 2; xfer->frlenghts[0] = 8; xfer->frlenghts[1] = 1; usb2_start_hardware(xfer); Example3: SETUP + DATA + STATUS - split 1st callback: xfer->nframes = 1; xfer->frlenghts[0] = 8; usb2_start_hardware(xfer); 2nd callback: /* IMPORTANT: frbuffer[0] must still point at the setup packet! */ xfer->nframes = 2; xfer->frlenghts[0] = 0; xfer->frlenghts[1] = 1; usb2_start_hardware(xfer); Example4: SETUP + STATUS - split 1st callback: xfer->nframes = 1; xfer->frlenghts[0] = 8; xfer->flags.manual_status = 1; usb2_start_hardware(xfer); 2nd callback: xfer->nframes = 1; xfer->frlenghts[0] = 0; xfer->flags.manual_status = 0; usb2_start_hardware(xfer); === General USB transfer notes === 1) Something that one should be aware of is that all USB callbacks support recursation. That means one can start/stop whatever transfer from the callback of another transfer one desires. Also the transfer that is currently called back. Recursion is handled like this that when the callback that wants to recurse returns it is called one more time. 2) After that the "usb2_start_hardware()" function has been called in the callback one can always depend on that "tr_error" or "tr_transferred" will get jumped afterwards. Always! 3) Sleeping functions can only be called from the attach routine of the driver. Else one should not use sleeping functions unless one has to. It is very difficult with sleep, because one has to think that the device might have detached when the thread returns from sleep. 4) Polling. use_polling This flag can be used with any callback and will cause the "usb2_transfer_start()" function to wait using "DELAY()", without exiting any mutexes, until the transfer is finished or has timed out. This flag can be changed during operation. NOTE: If polling is used the "timeout" field should be non-zero! NOTE: USB_ERR_CANCELLED is returned in case of timeout instead of USB_ERR_TIMEOUT! USB device driver examples: /sys/dev/usb/net/if_axe.c /sys/dev/usb/net/if_aue.c QUICK REFERENCE =============== /*------------------------------------------------------------------------* * usb2_error_t * usb2_transfer_setup(udev, ifaces, pxfer, setup_start, * n_setup, priv_sc, priv_mtx) *------------------------------------------------------------------------*/ - "udev" is a pointer to "struct usb2_device". - "ifaces" array of interface index numbers to use. See "if_index". - "pxfer" is a pointer to an array of USB transfer pointers that are initialized to NULL, and then pointed to allocated USB transfers. - "setup_start" is a pointer to an array of USB config structures. - "n_setup" is a number telling the USB system how many USB transfers should be setup. - "priv_sc" is the private softc pointer, which will be used to initialize "xfer->priv_sc". - "priv_mtx" is the private mutex protecting the transfer structure and the softc. This pointer is used to initialize "xfer->priv_mtx". /*------------------------------------------------------------------------* * void * usb2_transfer_unsetup(pxfer, n_setup) *------------------------------------------------------------------------*/ - "pxfer" is a pointer to an array of USB transfer pointers, that may be NULL, that should be freed by the USB system. - "n_setup" is a number telling the USB system how many USB transfers should be unsetup NOTE: This function can sleep, waiting for active mutexes to become unlocked! NOTE: It is not allowed to call "usb2_transfer_unsetup" from the callback of a USB transfer. /*------------------------------------------------------------------------* * void * usb2_transfer_start(xfer) *------------------------------------------------------------------------*/ - "xfer" is pointer to a USB transfer that should be started NOTE: this function must be called with "priv_mtx" locked /*------------------------------------------------------------------------* * void * usb2_transfer_stop(xfer) *------------------------------------------------------------------------*/ - "xfer" is a pointer to a USB transfer that should be stopped NOTE: this function must be called with "priv_mtx" locked NOTE: if the transfer was in progress, the callback will called with "xfer->error=USB_ERR_CANCELLED", before this function returns /*------------------------------------------------------------------------* * struct usb2_config { * type, endpoint, direction, interval, timeout, frames, index * flags, bufsize, callback * }; *------------------------------------------------------------------------*/ - The "type" field selects the USB pipe type. Valid values are: UE_INTERRUPT, UE_CONTROL, UE_BULK, UE_ISOCHRONOUS. The special value UE_BULK_INTR will select BULK and INTERRUPT pipes. This field is mandatory. - The "endpoint" field selects the USB endpoint number. A value of 0xFF, "-1" or "UE_ADDR_ANY" will select the first matching endpoint. This field is mandatory. - The "direction" field selects the USB endpoint direction. A value of "UE_DIR_ANY" will select the first matching endpoint. Else valid values are: "UE_DIR_IN" and "UE_DIR_OUT". "UE_DIR_IN" and "UE_DIR_OUT" can be binary ORed by "UE_DIR_SID" which means that the direction will be swapped in case of USB_MODE_DEVICE. Note that "UE_DIR_IN" refers to the data transfer direction of the "IN" tokens and "UE_DIR_OUT" refers to the data transfer direction of the "OUT" tokens. This field is mandatory. - The "interval" field selects the interrupt interval. The value of this field is given in milliseconds and is independent of device speed. Depending on the endpoint type, this field has different meaning: UE_INTERRUPT) "0" use the default interrupt interval based on endpoint descriptor. "Else" use the given value for polling rate. UE_ISOCHRONOUS) "0" use default. "Else" the value is ignored. UE_BULK) UE_CONTROL) "0" no transfer pre-delay. "Else" a delay as given by this field in milliseconds is inserted before the hardware is started when "usb2_start_hardware()" is called. NOTE: The transfer timeout, if any, is started after that the pre-delay has elapsed! - The "timeout" field, if non-zero, will set the transfer timeout in milliseconds. If the "timeout" field is zero and the transfer type is ISOCHRONOUS a timeout of 250ms will be used. - The "frames" field sets the maximum number of frames. If zero is specified it will yield the following results: UE_BULK) UE_INTERRUPT) xfer->nframes = 1; UE_CONTROL) xfer->nframes = 2; UE_ISOCHRONOUS) Not allowed. Will cause an error. - The "ep_index" field allows you to give a number, in case more endpoints match the description, that selects which matching "ep_index" should be used. - The "if_index" field allows you to select which of the interface numbers in the "ifaces" array parameter passed to "usb2_transfer_setup" that should be used when setting up the given USB transfer. - The "flags" field has type "struct usb2_xfer_flags" and allows one to set initial flags an USB transfer. Valid flags are: force_short_xfer This flag forces the last transmitted USB packet to be short. A short packet has a length of less than "xfer->max_packet_size", which derives from "wMaxPacketSize". This flag can be changed during operation. short_xfer_ok This flag allows the received transfer length, "xfer->actlen" to be less than "xfer->sumlen" upon completion of a transfer. This flag can be changed during operation. pipe_bof This flag causes a failing USB transfer to remain first in the PIPE queue except in the case of "xfer->error" equal to "USB_ERR_CANCELLED". No other USB transfers in the affected PIPE queue will be started until either: 1) The failing USB transfer is stopped using "usb2_transfer_stop()". 2) The failing USB transfer performs a successful transfer. The purpose of this flag is to avoid races when multiple transfers are queued for execution on an USB endpoint, and the first executing transfer fails leading to the need for clearing of stall for example. In this case this flag is used to prevent the following USB transfers from being executed at the same time the clear-stall command is executed on the USB control endpoint. This flag can be changed during operation. "BOF" is short for "Block On Failure" NOTE: This flag should be set on all BULK and INTERRUPT USB transfers which use an endpoint that can be shared between userland and kernel. proxy_buffer Setting this flag will cause that the total buffer size will be rounded up to the nearest atomic hardware transfer size. The maximum data length of any USB transfer is always stored in the "xfer->max_data_length". For control transfers the USB kernel will allocate additional space for the 8-bytes of SETUP header. These 8-bytes are not counted by the "xfer->max_data_length" variable. This flag can not be changed during operation. ext_buffer Setting this flag will cause that no data buffer will be allocated. Instead the USB client must supply a data buffer. This flag can not be changed during operation. manual_status Setting this flag prevents an USB STATUS stage to be appended to the end of the USB control transfer. If no control data is transferred this flag must be cleared. Else an error will be returned to the USB callback. This flag is mostly useful for the USB device side. This flag can be changed during operation. no_pipe_ok Setting this flag causes the USB_ERR_NO_PIPE error to be ignored. This flag can not be changed during operation. stall_pipe Setting this flag will cause STALL pids to be sent to the endpoint belonging to this transfer before the transfer is started. The transfer is started at the moment the host issues a clear-stall command on the STALL'ed endpoint. This flag can be changed during operation. This flag does only have effect in USB device side mode except for control endpoints. This flag is cleared when the stall command has been executed. This flag can only be changed outside the callback function by using the functions "usb2_transfer_set_stall()" and "usb2_transfer_clear_stall()" ! - The "bufsize" field sets the total buffer size in bytes. If this field is zero, "wMaxPacketSize" will be used, multiplied by the "frames" field if the transfer type is ISOCHRONOUS. This is useful for setting up interrupt pipes. This field is mandatory. NOTE: For control transfers "bufsize" includes the length of the request structure. - The "callback" pointer sets the USB callback. This field is mandatory. MUTEX NOTE: =========== When you create a mutex using "mtx_init()", don't forget to call "mtx_destroy()" at detach, else you can get "freed memory accessed" panics. --HPS