/* * message.c - synchronous message handling */ #include <linux/pci.h> /* for scatterlist macros */#include <linux/usb.h>#include <linux/module.h>#include <linux/slab.h>#include <linux/init.h>#include <linux/mm.h>#include <linux/timer.h>#include <linux/ctype.h>#include <linux/nls.h>#include <linux/device.h>#include <linux/scatterlist.h>#include <linux/usb/quirks.h>#include <linux/usb/hcd.h> /* for usbcore internals */#include <asm/byteorder.h> #include "usb.h" static void cancel_async_set_config(struct usb_device *udev); struct api_context { struct completion done; int status;}; static void usb_api_blocking_completion(struct urb *urb){ struct api_context *ctx = urb->context; ctx->status = urb->status; complete(&ctx->done);} /* * Starts urb and waits for completion or timeout. Note that this call * is NOT interruptible. Many device driver i/o requests should be * interruptible and therefore these drivers should implement their * own interruptible routines. */static int usb_start_wait_urb(struct urb *urb, int timeout, int *actual_length){ struct api_context ctx; unsigned long expire; int retval; init_completion(&ctx.done); urb->context = &ctx; urb->actual_length = 0; retval = usb_submit_urb(urb, GFP_NOIO); if (unlikely(retval)) goto out; expire = timeout ? msecs_to_jiffies(timeout) : MAX_SCHEDULE_TIMEOUT; if (!wait_for_completion_timeout(&ctx.done, expire)) { usb_kill_urb(urb); retval = (ctx.status == -ENOENT ? -ETIMEDOUT : ctx.status); dev_dbg(&urb->dev->dev, "%s timed out on ep%d%s len=%u/%u\n", current->comm, usb_endpoint_num(&urb->ep->desc), usb_urb_dir_in(urb) ? "in" : "out", urb->actual_length, urb->transfer_buffer_length); } else retval = ctx.status;out: if (actual_length) *actual_length = urb->actual_length; usb_free_urb(urb); return retval;} /*-------------------------------------------------------------------*//* returns status (negative) or length (positive) */static int usb_internal_control_msg(struct usb_device *usb_dev, unsigned int pipe, struct usb_ctrlrequest *cmd, void *data, int len, int timeout){ struct urb *urb; int retv; int length; urb = usb_alloc_urb(0, GFP_NOIO); if (!urb) return -ENOMEM; usb_fill_control_urb(urb, usb_dev, pipe, (unsigned char *)cmd, data, len, usb_api_blocking_completion, NULL); retv = usb_start_wait_urb(urb, timeout, &length); if (retv < 0) return retv; else return length;} /** * usb_control_msg - Builds a control urb, sends it off and waits for completion * @dev: pointer to the usb device to send the message to * @pipe: endpoint "pipe" to send the message to * @request: USB message request value * @requesttype: USB message request type value * @value: USB message value * @index: USB message index value * @data: pointer to the data to send * @size: length in bytes of the data to send * @timeout: time in msecs to wait for the message to complete before timing * out (if 0 the wait is forever) * * Context: !in_interrupt () * * This function sends a simple control message to a specified endpoint and * waits for the message to complete, or timeout. * * Don't use this function from within an interrupt context, like a bottom half * handler. If you need an asynchronous message, or need to send a message * from within interrupt context, use usb_submit_urb(). * If a thread in your driver uses this call, make sure your disconnect() * method can wait for it to complete. Since you don't have a handle on the * URB used, you can't cancel the request. * * Return: If successful, the number of bytes transferred. Otherwise, a negative * error number. */int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request, __u8 requesttype, __u16 value, __u16 index, void *data, __u16 size, int timeout){ struct usb_ctrlrequest *dr; int ret; dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO); if (!dr) return -ENOMEM; dr->bRequestType = requesttype; dr->bRequest = request; dr->wValue = cpu_to_le16(value); dr->wIndex = cpu_to_le16(index); dr->wLength = cpu_to_le16(size); ret = usb_internal_control_msg(dev, pipe, dr, data, size, timeout); kfree(dr); return ret;}EXPORT_SYMBOL_GPL(usb_control_msg); /** * usb_interrupt_msg - Builds an interrupt urb, sends it off and waits for completion * @usb_dev: pointer to the usb device to send the message to * @pipe: endpoint "pipe" to send the message to * @data: pointer to the data to send * @len: length in bytes of the data to send * @actual_length: pointer to a location to put the actual length transferred * in bytes * @timeout: time in msecs to wait for the message to complete before * timing out (if 0 the wait is forever) * * Context: !in_interrupt () * * This function sends a simple interrupt message to a specified endpoint and * waits for the message to complete, or timeout. * * Don't use this function from within an interrupt context, like a bottom half * handler. If you need an asynchronous message, or need to send a message * from within interrupt context, use usb_submit_urb() If a thread in your * driver uses this call, make sure your disconnect() method can wait for it to * complete. Since you don't have a handle on the URB used, you can't cancel * the request. * * Return: * If successful, 0. Otherwise a negative error number. The number of actual * bytes transferred will be stored in the @actual_length paramater. */int usb_interrupt_msg(struct usb_device *usb_dev, unsigned int pipe, void *data, int len, int *actual_length, int timeout){ return usb_bulk_msg(usb_dev, pipe, data, len, actual_length, timeout);}EXPORT_SYMBOL_GPL(usb_interrupt_msg); /** * usb_bulk_msg - Builds a bulk urb, sends it off and waits for completion * @usb_dev: pointer to the usb device to send the message to * @pipe: endpoint "pipe" to send the message to * @data: pointer to the data to send * @len: length in bytes of the data to send * @actual_length: pointer to a location to put the actual length transferred * in bytes * @timeout: time in msecs to wait for the message to complete before * timing out (if 0 the wait is forever) * * Context: !in_interrupt () * * This function sends a simple bulk message to a specified endpoint * and waits for the message to complete, or timeout. * * Don't use this function from within an interrupt context, like a bottom half * handler. If you need an asynchronous message, or need to send a message * from within interrupt context, use usb_submit_urb() If a thread in your * driver uses this call, make sure your disconnect() method can wait for it to * complete. Since you don't have a handle on the URB used, you can't cancel * the request. * * Because there is no usb_interrupt_msg() and no USBDEVFS_INTERRUPT ioctl, * users are forced to abuse this routine by using it to submit URBs for * interrupt endpoints. We will take the liberty of creating an interrupt URB * (with the default interval) if the target is an interrupt endpoint. * * Return: * If successful, 0. Otherwise a negative error number. The number of actual * bytes transferred will be stored in the @actual_length paramater. * */int usb_bulk_msg(struct usb_device *usb_dev, unsigned int pipe, void *data, int len, int *actual_length, int timeout){ struct urb *urb; struct usb_host_endpoint *ep; ep = usb_pipe_endpoint(usb_dev, pipe); if (!ep || len < 0) return -EINVAL; urb = usb_alloc_urb(0, GFP_KERNEL); if (!urb) return -ENOMEM; if ((ep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT) { pipe = (pipe & ~(3 << 30)) | (PIPE_INTERRUPT << 30); usb_fill_int_urb(urb, usb_dev, pipe, data, len, usb_api_blocking_completion, NULL, ep->desc.bInterval); } else usb_fill_bulk_urb(urb, usb_dev, pipe, data, len, usb_api_blocking_completion, NULL); return usb_start_wait_urb(urb, timeout, actual_length);}EXPORT_SYMBOL_GPL(usb_bulk_msg); /*-------------------------------------------------------------------*/ static void sg_clean(struct usb_sg_request *io){ if (io->urbs) { while (io->entries--) usb_free_urb(io->urbs[io->entries]); kfree(io->urbs); io->urbs = NULL; } io->dev = NULL;} static void sg_complete(struct urb *urb){ struct usb_sg_request *io = urb->context; int status = urb->status; spin_lock(&io->lock); /* In 2.5 we require hcds' endpoint queues not to progress after fault * reports, until the completion callback (this!) returns. That lets * device driver code (like this routine) unlink queued urbs first, * if it needs to, since the HC won't work on them at all. So it's * not possible for page N+1 to overwrite page N, and so on. * * That's only for "hard" faults; "soft" faults (unlinks) sometimes * complete before the HCD can get requests away from hardware, * though never during cleanup after a hard fault. */ if (io->status && (io->status != -ECONNRESET || status != -ECONNRESET) && urb->actual_length) { dev_err(io->dev->bus->controller, "dev %s ep%d%s scatterlist error %d/%d\n", io->dev->devpath, usb_endpoint_num(&urb->ep->desc), usb_urb_dir_in(urb) ? "in" : "out", status, io->status); /* BUG (); */ } if (io->status == 0 && status && status != -ECONNRESET) { int i, found, retval; io->status = status; /* the previous urbs, and this one, completed already. * unlink pending urbs so they won't rx/tx bad data. * careful: unlink can sometimes be synchronous... */ spin_unlock(&io->lock); for (i = 0, found = 0; i < io->entries; i++) { if (!io->urbs[i] || !io->urbs[i]->dev) continue; if (found) { retval = usb_unlink_urb(io->urbs[i]); if (retval != -EINPROGRESS && retval != -ENODEV && retval != -EBUSY && retval != -EIDRM) dev_err(&io->dev->dev, "%s, unlink --> %d\n", __func__, retval); } else if (urb == io->urbs[i]) found = 1; } spin_lock(&io->lock); } /* on the last completion, signal usb_sg_wait() */ io->bytes += urb->actual_length; io->count--; if (!io->count) complete(&io->complete); spin_unlock(&io->lock);} /** * usb_sg_init - initializes scatterlist-based bulk/interrupt I/O request * @io: request block being initialized. until usb_sg_wait() returns, * treat this as a pointer to an opaque block of memory, * @dev: the usb device that will send or receive the data * @pipe: endpoint "pipe" used to transfer the data * @period: polling rate for interrupt endpoints, in frames or * (for high speed endpoints) microframes; ignored for bulk * @sg: scatterlist entries * @nents: how many entries in the scatterlist * @length: how many bytes to send from the scatterlist, or zero to * send every byte identified in the list. * @mem_flags: SLAB_* flags affecting memory allocations in this call * * This initializes a scatter/gather request, allocating resources such as * I/O mappings and urb memory (except maybe memory used by USB controller * drivers). * * The request must be issued using usb_sg_wait(), which waits for the I/O to * complete (or to be canceled) and then cleans up all resources allocated by * usb_sg_init(). * * The request may be canceled with usb_sg_cancel(), either before or after * usb_sg_wait() is called. * * Return: Zero for success, else a negative errno value. */int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev, unsigned pipe, unsigned period, struct scatterlist *sg, int nents, size_t length, gfp_t mem_flags){ int i; int urb_flags; int use_sg; if (!io || !dev || !sg || usb_pipecontrol(pipe) || usb_pipeisoc(pipe) || nents <= 0) return -EINVAL; spin_lock_init(&io->lock); io->dev = dev; io->pipe = pipe; if (dev->bus->sg_tablesize > 0) { use_sg = true; io->entries = 1; } else { use_sg = false; io->entries = nents; } /* initialize all the urbs we'll use */ io->urbs = kmalloc(io->entries * sizeof(*io->urbs), mem_flags); if (!io->urbs) goto nomem; urb_flags = URB_NO_INTERRUPT; if (usb_pipein(pipe)) urb_flags |= URB_SHORT_NOT_OK; for_each_sg(sg, sg, io->entries, i) { struct urb *urb; unsigned len; urb = usb_alloc_urb(0, mem_flags); if (!urb) { io->entries = i; goto nomem; } io->urbs[i] = urb; urb->dev = NULL; urb->pipe = pipe; urb->interval = period; urb->transfer_flags = urb_flags; urb->complete = sg_complete; urb->context = io; urb->sg = sg; if (use_sg) { /* There is no single transfer buffer */ urb->transfer_buffer = NULL; urb->num_sgs = nents; /* A length of zero means transfer the whole sg list */ len = length; if (len == 0) { struct scatterlist *sg2; int j; for_each_sg(sg, sg2, nents, j) len += sg2->length; } } else { /* * Some systems can't use DMA; they use PIO instead. * For their sakes, transfer_buffer is set whenever * possible. */ if (!PageHighMem(sg_page(sg))) urb->transfer_buffer = sg_virt(sg); else urb->transfer_buffer = NULL; len = sg->length; if (length) { len = min_t(size_t, len, length); length -= len; if (length == 0) io->entries = i + 1; } } urb->transfer_buffer_length = len; } io->urbs[--i]->transfer_flags &= ~URB_NO_INTERRUPT; /* transaction state */ io->count = io->entries; io->status = 0; io->bytes = 0; init_completion(&io->complete); return 0; nomem: sg_clean(io); return -ENOMEM;}EXPORT_SYMBOL_GPL(usb_sg_init); /** * usb_sg_wait - synchronously execute scatter/gather request * @io: request block handle, as initialized with usb_sg_init(). * some fields become accessible when this call returns. * Context: !in_interrupt () * * This function blocks until the specified I/O operation completes. It * leverages the grouping of the related I/O requests to get good transfer * rates, by queueing the requests. At higher speeds, such queuing can * significantly improve USB throughput. * * There are three kinds of completion for this function. * (1) success, where io->status is zero. The number of io->bytes * transferred is as requested. * (2) error, where io->status is a negative errno value. The number * of io->bytes transferred before the error is usually less * than requested, and can be nonzero. * (3) cancellation, a type of error with status -ECONNRESET that * is initiated by usb_sg_cancel(). * * When this function returns, all memory allocated through usb_sg_init() or * this call will have been freed. The request block parameter may still be * passed to usb_sg_cancel(), or it may be freed. It could also be * reinitialized and then reused. * * Data Transfer Rates: * * Bulk transfers are valid for full or high speed endpoints. * The best full speed data rate is 19 packets of 64 bytes each * per frame, or 1216 bytes per millisecond. * The best high speed data rate is 13 packets of 512 bytes each * per microframe, or 52 KBytes per millisecond. * * The reason to use interrupt transfers through this API would most likely * be to reserve high speed bandwidth, where up to 24 KBytes per millisecond * could be transferred. That capability is less useful for low or full * speed interrupt endpoints, which allow at most one packet per millisecond,Lines 1–500 of 2008. Load more
/* * message.c - synchronous message handling */ #include <linux/pci.h> /* for scatterlist macros */ #include <linux/usb.h> #include <linux/module.h> #include <linux/slab.h> #include <linux/init.h> #include <linux/mm.h> #include <linux/timer.h> #include <linux/ctype.h> #include <linux/nls.h> #include <linux/device.h> #include <linux/scatterlist.h> #include <linux/usb/quirks.h> #include <linux/usb/hcd.h> /* for usbcore internals */ #include <asm/byteorder.h> #include "usb.h" static void cancel_async_set_config(struct usb_device *udev); struct api_context { struct completion done; int status; }; static void usb_api_blocking_completion(struct urb *urb) { struct api_context *ctx = urb->context; ctx->status = urb->status; complete(&ctx->done); } /* * Starts urb and waits for completion or timeout. Note that this call * is NOT interruptible. Many device driver i/o requests should be * interruptible and therefore these drivers should implement their * own interruptible routines. */ static int usb_start_wait_urb(struct urb *urb, int timeout, int *actual_length) { struct api_context ctx; unsigned long expire; int retval; init_completion(&ctx.done); urb->context = &ctx; urb->actual_length = 0; retval = usb_submit_urb(urb, GFP_NOIO); if (unlikely(retval)) goto out; expire = timeout ? msecs_to_jiffies(timeout) : MAX_SCHEDULE_TIMEOUT; if (!wait_for_completion_timeout(&ctx.done, expire)) { usb_kill_urb(urb); retval = (ctx.status == -ENOENT ? -ETIMEDOUT : ctx.status); dev_dbg(&urb->dev->dev, "%s timed out on ep%d%s len=%u/%u\n", current->comm, usb_endpoint_num(&urb->ep->desc), usb_urb_dir_in(urb) ? "in" : "out", urb->actual_length, urb->transfer_buffer_length); } else retval = ctx.status; out: if (actual_length) *actual_length = urb->actual_length; usb_free_urb(urb); return retval; } /*-------------------------------------------------------------------*/ /* returns status (negative) or length (positive) */ static int usb_internal_control_msg(struct usb_device *usb_dev, unsigned int pipe, struct usb_ctrlrequest *cmd, void *data, int len, int timeout) { struct urb *urb; int retv; int length; urb = usb_alloc_urb(0, GFP_NOIO); if (!urb) return -ENOMEM; usb_fill_control_urb(urb, usb_dev, pipe, (unsigned char *)cmd, data, len, usb_api_blocking_completion, NULL); retv = usb_start_wait_urb(urb, timeout, &length); if (retv < 0) return retv; else return length; } /** * usb_control_msg - Builds a control urb, sends it off and waits for completion * @dev: pointer to the usb device to send the message to * @pipe: endpoint "pipe" to send the message to * @request: USB message request value * @requesttype: USB message request type value * @value: USB message value * @index: USB message index value * @data: pointer to the data to send * @size: length in bytes of the data to send * @timeout: time in msecs to wait for the message to complete before timing * out (if 0 the wait is forever) * * Context: !in_interrupt () * * This function sends a simple control message to a specified endpoint and * waits for the message to complete, or timeout. * * Don't use this function from within an interrupt context, like a bottom half * handler. If you need an asynchronous message, or need to send a message * from within interrupt context, use usb_submit_urb(). * If a thread in your driver uses this call, make sure your disconnect() * method can wait for it to complete. Since you don't have a handle on the * URB used, you can't cancel the request. * * Return: If successful, the number of bytes transferred. Otherwise, a negative * error number. */ int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request, __u8 requesttype, __u16 value, __u16 index, void *data, __u16 size, int timeout) { struct usb_ctrlrequest *dr; int ret; dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO); if (!dr) return -ENOMEM; dr->bRequestType = requesttype; dr->bRequest = request; dr->wValue = cpu_to_le16(value); dr->wIndex = cpu_to_le16(index); dr->wLength = cpu_to_le16(size); ret = usb_internal_control_msg(dev, pipe, dr, data, size, timeout); kfree(dr); return ret; } EXPORT_SYMBOL_GPL(usb_control_msg); /** * usb_interrupt_msg - Builds an interrupt urb, sends it off and waits for completion * @usb_dev: pointer to the usb device to send the message to * @pipe: endpoint "pipe" to send the message to * @data: pointer to the data to send * @len: length in bytes of the data to send * @actual_length: pointer to a location to put the actual length transferred * in bytes * @timeout: time in msecs to wait for the message to complete before * timing out (if 0 the wait is forever) * * Context: !in_interrupt () * * This function sends a simple interrupt message to a specified endpoint and * waits for the message to complete, or timeout. * * Don't use this function from within an interrupt context, like a bottom half * handler. If you need an asynchronous message, or need to send a message * from within interrupt context, use usb_submit_urb() If a thread in your * driver uses this call, make sure your disconnect() method can wait for it to * complete. Since you don't have a handle on the URB used, you can't cancel * the request. * * Return: * If successful, 0. Otherwise a negative error number. The number of actual * bytes transferred will be stored in the @actual_length paramater. */ int usb_interrupt_msg(struct usb_device *usb_dev, unsigned int pipe, void *data, int len, int *actual_length, int timeout) { return usb_bulk_msg(usb_dev, pipe, data, len, actual_length, timeout); } EXPORT_SYMBOL_GPL(usb_interrupt_msg); /** * usb_bulk_msg - Builds a bulk urb, sends it off and waits for completion * @usb_dev: pointer to the usb device to send the message to * @pipe: endpoint "pipe" to send the message to * @data: pointer to the data to send * @len: length in bytes of the data to send * @actual_length: pointer to a location to put the actual length transferred * in bytes * @timeout: time in msecs to wait for the message to complete before * timing out (if 0 the wait is forever) * * Context: !in_interrupt () * * This function sends a simple bulk message to a specified endpoint * and waits for the message to complete, or timeout. * * Don't use this function from within an interrupt context, like a bottom half * handler. If you need an asynchronous message, or need to send a message * from within interrupt context, use usb_submit_urb() If a thread in your * driver uses this call, make sure your disconnect() method can wait for it to * complete. Since you don't have a handle on the URB used, you can't cancel * the request. * * Because there is no usb_interrupt_msg() and no USBDEVFS_INTERRUPT ioctl, * users are forced to abuse this routine by using it to submit URBs for * interrupt endpoints. We will take the liberty of creating an interrupt URB * (with the default interval) if the target is an interrupt endpoint. * * Return: * If successful, 0. Otherwise a negative error number. The number of actual * bytes transferred will be stored in the @actual_length paramater. * */ int usb_bulk_msg(struct usb_device *usb_dev, unsigned int pipe, void *data, int len, int *actual_length, int timeout) { struct urb *urb; struct usb_host_endpoint *ep; ep = usb_pipe_endpoint(usb_dev, pipe); if (!ep || len < 0) return -EINVAL; urb = usb_alloc_urb(0, GFP_KERNEL); if (!urb) return -ENOMEM; if ((ep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT) { pipe = (pipe & ~(3 << 30)) | (PIPE_INTERRUPT << 30); usb_fill_int_urb(urb, usb_dev, pipe, data, len, usb_api_blocking_completion, NULL, ep->desc.bInterval); } else usb_fill_bulk_urb(urb, usb_dev, pipe, data, len, usb_api_blocking_completion, NULL); return usb_start_wait_urb(urb, timeout, actual_length); } EXPORT_SYMBOL_GPL(usb_bulk_msg); /*-------------------------------------------------------------------*/ static void sg_clean(struct usb_sg_request *io) { if (io->urbs) { while (io->entries--) usb_free_urb(io->urbs[io->entries]); kfree(io->urbs); io->urbs = NULL; } io->dev = NULL; } static void sg_complete(struct urb *urb) { struct usb_sg_request *io = urb->context; int status = urb->status; spin_lock(&io->lock); /* In 2.5 we require hcds' endpoint queues not to progress after fault * reports, until the completion callback (this!) returns. That lets * device driver code (like this routine) unlink queued urbs first, * if it needs to, since the HC won't work on them at all. So it's * not possible for page N+1 to overwrite page N, and so on. * * That's only for "hard" faults; "soft" faults (unlinks) sometimes * complete before the HCD can get requests away from hardware, * though never during cleanup after a hard fault. */ if (io->status && (io->status != -ECONNRESET || status != -ECONNRESET) && urb->actual_length) { dev_err(io->dev->bus->controller, "dev %s ep%d%s scatterlist error %d/%d\n", io->dev->devpath, usb_endpoint_num(&urb->ep->desc), usb_urb_dir_in(urb) ? "in" : "out", status, io->status); /* BUG (); */ } if (io->status == 0 && status && status != -ECONNRESET) { int i, found, retval; io->status = status; /* the previous urbs, and this one, completed already. * unlink pending urbs so they won't rx/tx bad data. * careful: unlink can sometimes be synchronous... */ spin_unlock(&io->lock); for (i = 0, found = 0; i < io->entries; i++) { if (!io->urbs[i] || !io->urbs[i]->dev) continue; if (found) { retval = usb_unlink_urb(io->urbs[i]); if (retval != -EINPROGRESS && retval != -ENODEV && retval != -EBUSY && retval != -EIDRM) dev_err(&io->dev->dev, "%s, unlink --> %d\n", __func__, retval); } else if (urb == io->urbs[i]) found = 1; } spin_lock(&io->lock); } /* on the last completion, signal usb_sg_wait() */ io->bytes += urb->actual_length; io->count--; if (!io->count) complete(&io->complete); spin_unlock(&io->lock); } /** * usb_sg_init - initializes scatterlist-based bulk/interrupt I/O request * @io: request block being initialized. until usb_sg_wait() returns, * treat this as a pointer to an opaque block of memory, * @dev: the usb device that will send or receive the data * @pipe: endpoint "pipe" used to transfer the data * @period: polling rate for interrupt endpoints, in frames or * (for high speed endpoints) microframes; ignored for bulk * @sg: scatterlist entries * @nents: how many entries in the scatterlist * @length: how many bytes to send from the scatterlist, or zero to * send every byte identified in the list. * @mem_flags: SLAB_* flags affecting memory allocations in this call * * This initializes a scatter/gather request, allocating resources such as * I/O mappings and urb memory (except maybe memory used by USB controller * drivers). * * The request must be issued using usb_sg_wait(), which waits for the I/O to * complete (or to be canceled) and then cleans up all resources allocated by * usb_sg_init(). * * The request may be canceled with usb_sg_cancel(), either before or after * usb_sg_wait() is called. * * Return: Zero for success, else a negative errno value. */ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev, unsigned pipe, unsigned period, struct scatterlist *sg, int nents, size_t length, gfp_t mem_flags) { int i; int urb_flags; int use_sg; if (!io || !dev || !sg || usb_pipecontrol(pipe) || usb_pipeisoc(pipe) || nents <= 0) return -EINVAL; spin_lock_init(&io->lock); io->dev = dev; io->pipe = pipe; if (dev->bus->sg_tablesize > 0) { use_sg = true; io->entries = 1; } else { use_sg = false; io->entries = nents; } /* initialize all the urbs we'll use */ io->urbs = kmalloc(io->entries * sizeof(*io->urbs), mem_flags); if (!io->urbs) goto nomem; urb_flags = URB_NO_INTERRUPT; if (usb_pipein(pipe)) urb_flags |= URB_SHORT_NOT_OK; for_each_sg(sg, sg, io->entries, i) { struct urb *urb; unsigned len; urb = usb_alloc_urb(0, mem_flags); if (!urb) { io->entries = i; goto nomem; } io->urbs[i] = urb; urb->dev = NULL; urb->pipe = pipe; urb->interval = period; urb->transfer_flags = urb_flags; urb->complete = sg_complete; urb->context = io; urb->sg = sg; if (use_sg) { /* There is no single transfer buffer */ urb->transfer_buffer = NULL; urb->num_sgs = nents; /* A length of zero means transfer the whole sg list */ len = length; if (len == 0) { struct scatterlist *sg2; int j; for_each_sg(sg, sg2, nents, j) len += sg2->length; } } else { /* * Some systems can't use DMA; they use PIO instead. * For their sakes, transfer_buffer is set whenever * possible. */ if (!PageHighMem(sg_page(sg))) urb->transfer_buffer = sg_virt(sg); else urb->transfer_buffer = NULL; len = sg->length; if (length) { len = min_t(size_t, len, length); length -= len; if (length == 0) io->entries = i + 1; } } urb->transfer_buffer_length = len; } io->urbs[--i]->transfer_flags &= ~URB_NO_INTERRUPT; /* transaction state */ io->count = io->entries; io->status = 0; io->bytes = 0; init_completion(&io->complete); return 0; nomem: sg_clean(io); return -ENOMEM; } EXPORT_SYMBOL_GPL(usb_sg_init); /** * usb_sg_wait - synchronously execute scatter/gather request * @io: request block handle, as initialized with usb_sg_init(). * some fields become accessible when this call returns. * Context: !in_interrupt () * * This function blocks until the specified I/O operation completes. It * leverages the grouping of the related I/O requests to get good transfer * rates, by queueing the requests. At higher speeds, such queuing can * significantly improve USB throughput. * * There are three kinds of completion for this function. * (1) success, where io->status is zero. The number of io->bytes * transferred is as requested. * (2) error, where io->status is a negative errno value. The number * of io->bytes transferred before the error is usually less * than requested, and can be nonzero. * (3) cancellation, a type of error with status -ECONNRESET that * is initiated by usb_sg_cancel(). * * When this function returns, all memory allocated through usb_sg_init() or * this call will have been freed. The request block parameter may still be * passed to usb_sg_cancel(), or it may be freed. It could also be * reinitialized and then reused. * * Data Transfer Rates: * * Bulk transfers are valid for full or high speed endpoints. * The best full speed data rate is 19 packets of 64 bytes each * per frame, or 1216 bytes per millisecond. * The best high speed data rate is 13 packets of 512 bytes each * per microframe, or 52 KBytes per millisecond. * * The reason to use interrupt transfers through this API would most likely * be to reserve high speed bandwidth, where up to 24 KBytes per millisecond * could be transferred. That capability is less useful for low or full * speed interrupt endpoints, which allow at most one packet per millisecond,