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646 lines
15 KiB
646 lines
15 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* USB Skeleton driver - 2.2 |
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* |
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* Copyright (C) 2001-2004 Greg Kroah-Hartman ([email protected]) |
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* |
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* This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c |
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* but has been rewritten to be easier to read and use. |
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*/ |
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|
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#include <linux/kernel.h> |
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#include <linux/errno.h> |
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#include <linux/slab.h> |
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#include <linux/module.h> |
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#include <linux/kref.h> |
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#include <linux/uaccess.h> |
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#include <linux/usb.h> |
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#include <linux/mutex.h> |
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/* Define these values to match your devices */ |
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#define USB_SKEL_VENDOR_ID 0xfff0 |
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#define USB_SKEL_PRODUCT_ID 0xfff0 |
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/* table of devices that work with this driver */ |
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static const struct usb_device_id skel_table[] = { |
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{ USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) }, |
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{ } /* Terminating entry */ |
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}; |
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MODULE_DEVICE_TABLE(usb, skel_table); |
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/* Get a minor range for your devices from the usb maintainer */ |
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#define USB_SKEL_MINOR_BASE 192 |
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/* our private defines. if this grows any larger, use your own .h file */ |
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#define MAX_TRANSFER (PAGE_SIZE - 512) |
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/* |
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* MAX_TRANSFER is chosen so that the VM is not stressed by |
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* allocations > PAGE_SIZE and the number of packets in a page |
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* is an integer 512 is the largest possible packet on EHCI |
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*/ |
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#define WRITES_IN_FLIGHT 8 |
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/* arbitrarily chosen */ |
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/* Structure to hold all of our device specific stuff */ |
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struct usb_skel { |
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struct usb_device *udev; /* the usb device for this device */ |
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struct usb_interface *interface; /* the interface for this device */ |
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struct semaphore limit_sem; /* limiting the number of writes in progress */ |
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struct usb_anchor submitted; /* in case we need to retract our submissions */ |
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struct urb *bulk_in_urb; /* the urb to read data with */ |
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unsigned char *bulk_in_buffer; /* the buffer to receive data */ |
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size_t bulk_in_size; /* the size of the receive buffer */ |
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size_t bulk_in_filled; /* number of bytes in the buffer */ |
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size_t bulk_in_copied; /* already copied to user space */ |
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__u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */ |
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__u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */ |
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int errors; /* the last request tanked */ |
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bool ongoing_read; /* a read is going on */ |
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spinlock_t err_lock; /* lock for errors */ |
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struct kref kref; |
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struct mutex io_mutex; /* synchronize I/O with disconnect */ |
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unsigned long disconnected:1; |
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wait_queue_head_t bulk_in_wait; /* to wait for an ongoing read */ |
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}; |
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#define to_skel_dev(d) container_of(d, struct usb_skel, kref) |
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|
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static struct usb_driver skel_driver; |
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static void skel_draw_down(struct usb_skel *dev); |
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static void skel_delete(struct kref *kref) |
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{ |
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struct usb_skel *dev = to_skel_dev(kref); |
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usb_free_urb(dev->bulk_in_urb); |
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usb_put_intf(dev->interface); |
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usb_put_dev(dev->udev); |
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kfree(dev->bulk_in_buffer); |
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kfree(dev); |
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} |
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static int skel_open(struct inode *inode, struct file *file) |
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{ |
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struct usb_skel *dev; |
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struct usb_interface *interface; |
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int subminor; |
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int retval = 0; |
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subminor = iminor(inode); |
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interface = usb_find_interface(&skel_driver, subminor); |
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if (!interface) { |
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pr_err("%s - error, can't find device for minor %d\n", |
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__func__, subminor); |
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retval = -ENODEV; |
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goto exit; |
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} |
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dev = usb_get_intfdata(interface); |
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if (!dev) { |
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retval = -ENODEV; |
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goto exit; |
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} |
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retval = usb_autopm_get_interface(interface); |
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if (retval) |
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goto exit; |
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/* increment our usage count for the device */ |
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kref_get(&dev->kref); |
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/* save our object in the file's private structure */ |
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file->private_data = dev; |
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exit: |
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return retval; |
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} |
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static int skel_release(struct inode *inode, struct file *file) |
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{ |
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struct usb_skel *dev; |
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dev = file->private_data; |
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if (dev == NULL) |
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return -ENODEV; |
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/* allow the device to be autosuspended */ |
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usb_autopm_put_interface(dev->interface); |
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/* decrement the count on our device */ |
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kref_put(&dev->kref, skel_delete); |
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return 0; |
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} |
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static int skel_flush(struct file *file, fl_owner_t id) |
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{ |
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struct usb_skel *dev; |
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int res; |
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dev = file->private_data; |
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if (dev == NULL) |
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return -ENODEV; |
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/* wait for io to stop */ |
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mutex_lock(&dev->io_mutex); |
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skel_draw_down(dev); |
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/* read out errors, leave subsequent opens a clean slate */ |
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spin_lock_irq(&dev->err_lock); |
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res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0; |
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dev->errors = 0; |
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spin_unlock_irq(&dev->err_lock); |
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mutex_unlock(&dev->io_mutex); |
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return res; |
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} |
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static void skel_read_bulk_callback(struct urb *urb) |
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{ |
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struct usb_skel *dev; |
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unsigned long flags; |
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dev = urb->context; |
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spin_lock_irqsave(&dev->err_lock, flags); |
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/* sync/async unlink faults aren't errors */ |
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if (urb->status) { |
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if (!(urb->status == -ENOENT || |
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urb->status == -ECONNRESET || |
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urb->status == -ESHUTDOWN)) |
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dev_err(&dev->interface->dev, |
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"%s - nonzero write bulk status received: %d\n", |
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__func__, urb->status); |
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dev->errors = urb->status; |
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} else { |
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dev->bulk_in_filled = urb->actual_length; |
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} |
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dev->ongoing_read = 0; |
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spin_unlock_irqrestore(&dev->err_lock, flags); |
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wake_up_interruptible(&dev->bulk_in_wait); |
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} |
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static int skel_do_read_io(struct usb_skel *dev, size_t count) |
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{ |
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int rv; |
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/* prepare a read */ |
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usb_fill_bulk_urb(dev->bulk_in_urb, |
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dev->udev, |
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usb_rcvbulkpipe(dev->udev, |
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dev->bulk_in_endpointAddr), |
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dev->bulk_in_buffer, |
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min(dev->bulk_in_size, count), |
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skel_read_bulk_callback, |
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dev); |
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/* tell everybody to leave the URB alone */ |
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spin_lock_irq(&dev->err_lock); |
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dev->ongoing_read = 1; |
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spin_unlock_irq(&dev->err_lock); |
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/* submit bulk in urb, which means no data to deliver */ |
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dev->bulk_in_filled = 0; |
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dev->bulk_in_copied = 0; |
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/* do it */ |
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rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL); |
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if (rv < 0) { |
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dev_err(&dev->interface->dev, |
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"%s - failed submitting read urb, error %d\n", |
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__func__, rv); |
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rv = (rv == -ENOMEM) ? rv : -EIO; |
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spin_lock_irq(&dev->err_lock); |
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dev->ongoing_read = 0; |
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spin_unlock_irq(&dev->err_lock); |
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} |
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return rv; |
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} |
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static ssize_t skel_read(struct file *file, char *buffer, size_t count, |
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loff_t *ppos) |
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{ |
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struct usb_skel *dev; |
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int rv; |
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bool ongoing_io; |
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dev = file->private_data; |
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if (!count) |
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return 0; |
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/* no concurrent readers */ |
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rv = mutex_lock_interruptible(&dev->io_mutex); |
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if (rv < 0) |
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return rv; |
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if (dev->disconnected) { /* disconnect() was called */ |
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rv = -ENODEV; |
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goto exit; |
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} |
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/* if IO is under way, we must not touch things */ |
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retry: |
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spin_lock_irq(&dev->err_lock); |
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ongoing_io = dev->ongoing_read; |
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spin_unlock_irq(&dev->err_lock); |
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if (ongoing_io) { |
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/* nonblocking IO shall not wait */ |
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if (file->f_flags & O_NONBLOCK) { |
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rv = -EAGAIN; |
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goto exit; |
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} |
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/* |
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* IO may take forever |
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* hence wait in an interruptible state |
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*/ |
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rv = wait_event_interruptible(dev->bulk_in_wait, (!dev->ongoing_read)); |
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if (rv < 0) |
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goto exit; |
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} |
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/* errors must be reported */ |
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rv = dev->errors; |
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if (rv < 0) { |
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/* any error is reported once */ |
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dev->errors = 0; |
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/* to preserve notifications about reset */ |
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rv = (rv == -EPIPE) ? rv : -EIO; |
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/* report it */ |
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goto exit; |
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} |
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/* |
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* if the buffer is filled we may satisfy the read |
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* else we need to start IO |
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*/ |
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if (dev->bulk_in_filled) { |
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/* we had read data */ |
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size_t available = dev->bulk_in_filled - dev->bulk_in_copied; |
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size_t chunk = min(available, count); |
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if (!available) { |
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/* |
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* all data has been used |
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* actual IO needs to be done |
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*/ |
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rv = skel_do_read_io(dev, count); |
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if (rv < 0) |
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goto exit; |
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else |
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goto retry; |
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} |
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/* |
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* data is available |
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* chunk tells us how much shall be copied |
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*/ |
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if (copy_to_user(buffer, |
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dev->bulk_in_buffer + dev->bulk_in_copied, |
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chunk)) |
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rv = -EFAULT; |
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else |
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rv = chunk; |
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dev->bulk_in_copied += chunk; |
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/* |
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* if we are asked for more than we have, |
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* we start IO but don't wait |
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*/ |
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if (available < count) |
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skel_do_read_io(dev, count - chunk); |
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} else { |
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/* no data in the buffer */ |
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rv = skel_do_read_io(dev, count); |
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if (rv < 0) |
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goto exit; |
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else |
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goto retry; |
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} |
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exit: |
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mutex_unlock(&dev->io_mutex); |
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return rv; |
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} |
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static void skel_write_bulk_callback(struct urb *urb) |
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{ |
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struct usb_skel *dev; |
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unsigned long flags; |
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dev = urb->context; |
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/* sync/async unlink faults aren't errors */ |
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if (urb->status) { |
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if (!(urb->status == -ENOENT || |
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urb->status == -ECONNRESET || |
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urb->status == -ESHUTDOWN)) |
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dev_err(&dev->interface->dev, |
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"%s - nonzero write bulk status received: %d\n", |
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__func__, urb->status); |
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spin_lock_irqsave(&dev->err_lock, flags); |
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dev->errors = urb->status; |
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spin_unlock_irqrestore(&dev->err_lock, flags); |
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} |
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/* free up our allocated buffer */ |
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usb_free_coherent(urb->dev, urb->transfer_buffer_length, |
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urb->transfer_buffer, urb->transfer_dma); |
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up(&dev->limit_sem); |
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} |
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static ssize_t skel_write(struct file *file, const char *user_buffer, |
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size_t count, loff_t *ppos) |
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{ |
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struct usb_skel *dev; |
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int retval = 0; |
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struct urb *urb = NULL; |
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char *buf = NULL; |
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size_t writesize = min(count, (size_t)MAX_TRANSFER); |
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dev = file->private_data; |
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/* verify that we actually have some data to write */ |
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if (count == 0) |
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goto exit; |
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/* |
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* limit the number of URBs in flight to stop a user from using up all |
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* RAM |
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*/ |
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if (!(file->f_flags & O_NONBLOCK)) { |
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if (down_interruptible(&dev->limit_sem)) { |
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retval = -ERESTARTSYS; |
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goto exit; |
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} |
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} else { |
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if (down_trylock(&dev->limit_sem)) { |
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retval = -EAGAIN; |
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goto exit; |
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} |
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} |
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spin_lock_irq(&dev->err_lock); |
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retval = dev->errors; |
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if (retval < 0) { |
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/* any error is reported once */ |
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dev->errors = 0; |
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/* to preserve notifications about reset */ |
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retval = (retval == -EPIPE) ? retval : -EIO; |
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} |
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spin_unlock_irq(&dev->err_lock); |
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if (retval < 0) |
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goto error; |
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/* create a urb, and a buffer for it, and copy the data to the urb */ |
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urb = usb_alloc_urb(0, GFP_KERNEL); |
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if (!urb) { |
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retval = -ENOMEM; |
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goto error; |
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} |
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buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL, |
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&urb->transfer_dma); |
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if (!buf) { |
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retval = -ENOMEM; |
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goto error; |
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} |
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if (copy_from_user(buf, user_buffer, writesize)) { |
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retval = -EFAULT; |
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goto error; |
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} |
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/* this lock makes sure we don't submit URBs to gone devices */ |
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mutex_lock(&dev->io_mutex); |
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if (dev->disconnected) { /* disconnect() was called */ |
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mutex_unlock(&dev->io_mutex); |
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retval = -ENODEV; |
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goto error; |
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} |
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/* initialize the urb properly */ |
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usb_fill_bulk_urb(urb, dev->udev, |
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usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr), |
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buf, writesize, skel_write_bulk_callback, dev); |
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urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; |
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usb_anchor_urb(urb, &dev->submitted); |
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/* send the data out the bulk port */ |
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retval = usb_submit_urb(urb, GFP_KERNEL); |
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mutex_unlock(&dev->io_mutex); |
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if (retval) { |
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dev_err(&dev->interface->dev, |
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"%s - failed submitting write urb, error %d\n", |
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__func__, retval); |
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goto error_unanchor; |
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} |
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/* |
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* release our reference to this urb, the USB core will eventually free |
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* it entirely |
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*/ |
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usb_free_urb(urb); |
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return writesize; |
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error_unanchor: |
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usb_unanchor_urb(urb); |
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error: |
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if (urb) { |
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usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma); |
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usb_free_urb(urb); |
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} |
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up(&dev->limit_sem); |
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exit: |
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return retval; |
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} |
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static const struct file_operations skel_fops = { |
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.owner = THIS_MODULE, |
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.read = skel_read, |
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.write = skel_write, |
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.open = skel_open, |
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.release = skel_release, |
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.flush = skel_flush, |
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.llseek = noop_llseek, |
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}; |
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/* |
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* usb class driver info in order to get a minor number from the usb core, |
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* and to have the device registered with the driver core |
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*/ |
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static struct usb_class_driver skel_class = { |
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.name = "skel%d", |
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.fops = &skel_fops, |
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.minor_base = USB_SKEL_MINOR_BASE, |
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}; |
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static int skel_probe(struct usb_interface *interface, |
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const struct usb_device_id *id) |
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{ |
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struct usb_skel *dev; |
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struct usb_endpoint_descriptor *bulk_in, *bulk_out; |
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int retval; |
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/* allocate memory for our device state and initialize it */ |
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dev = kzalloc(sizeof(*dev), GFP_KERNEL); |
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if (!dev) |
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return -ENOMEM; |
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kref_init(&dev->kref); |
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sema_init(&dev->limit_sem, WRITES_IN_FLIGHT); |
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mutex_init(&dev->io_mutex); |
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spin_lock_init(&dev->err_lock); |
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init_usb_anchor(&dev->submitted); |
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init_waitqueue_head(&dev->bulk_in_wait); |
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dev->udev = usb_get_dev(interface_to_usbdev(interface)); |
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dev->interface = usb_get_intf(interface); |
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/* set up the endpoint information */ |
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/* use only the first bulk-in and bulk-out endpoints */ |
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retval = usb_find_common_endpoints(interface->cur_altsetting, |
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&bulk_in, &bulk_out, NULL, NULL); |
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if (retval) { |
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dev_err(&interface->dev, |
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"Could not find both bulk-in and bulk-out endpoints\n"); |
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goto error; |
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} |
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dev->bulk_in_size = usb_endpoint_maxp(bulk_in); |
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dev->bulk_in_endpointAddr = bulk_in->bEndpointAddress; |
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dev->bulk_in_buffer = kmalloc(dev->bulk_in_size, GFP_KERNEL); |
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if (!dev->bulk_in_buffer) { |
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retval = -ENOMEM; |
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goto error; |
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} |
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dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL); |
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if (!dev->bulk_in_urb) { |
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retval = -ENOMEM; |
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goto error; |
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} |
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dev->bulk_out_endpointAddr = bulk_out->bEndpointAddress; |
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|
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/* save our data pointer in this interface device */ |
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usb_set_intfdata(interface, dev); |
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|
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/* we can register the device now, as it is ready */ |
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retval = usb_register_dev(interface, &skel_class); |
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if (retval) { |
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/* something prevented us from registering this driver */ |
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dev_err(&interface->dev, |
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"Not able to get a minor for this device.\n"); |
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usb_set_intfdata(interface, NULL); |
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goto error; |
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} |
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/* let the user know what node this device is now attached to */ |
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dev_info(&interface->dev, |
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"USB Skeleton device now attached to USBSkel-%d", |
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interface->minor); |
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return 0; |
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error: |
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/* this frees allocated memory */ |
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kref_put(&dev->kref, skel_delete); |
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|
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return retval; |
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} |
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|
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static void skel_disconnect(struct usb_interface *interface) |
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{ |
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struct usb_skel *dev; |
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int minor = interface->minor; |
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dev = usb_get_intfdata(interface); |
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usb_set_intfdata(interface, NULL); |
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/* give back our minor */ |
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usb_deregister_dev(interface, &skel_class); |
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/* prevent more I/O from starting */ |
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mutex_lock(&dev->io_mutex); |
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dev->disconnected = 1; |
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mutex_unlock(&dev->io_mutex); |
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usb_kill_urb(dev->bulk_in_urb); |
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usb_kill_anchored_urbs(&dev->submitted); |
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/* decrement our usage count */ |
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kref_put(&dev->kref, skel_delete); |
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dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor); |
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} |
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static void skel_draw_down(struct usb_skel *dev) |
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{ |
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int time; |
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time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000); |
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if (!time) |
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usb_kill_anchored_urbs(&dev->submitted); |
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usb_kill_urb(dev->bulk_in_urb); |
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} |
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static int skel_suspend(struct usb_interface *intf, pm_message_t message) |
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{ |
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struct usb_skel *dev = usb_get_intfdata(intf); |
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|
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if (!dev) |
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return 0; |
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skel_draw_down(dev); |
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return 0; |
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} |
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|
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static int skel_resume(struct usb_interface *intf) |
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{ |
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return 0; |
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} |
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static int skel_pre_reset(struct usb_interface *intf) |
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{ |
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struct usb_skel *dev = usb_get_intfdata(intf); |
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mutex_lock(&dev->io_mutex); |
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skel_draw_down(dev); |
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return 0; |
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} |
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static int skel_post_reset(struct usb_interface *intf) |
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{ |
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struct usb_skel *dev = usb_get_intfdata(intf); |
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|
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/* we are sure no URBs are active - no locking needed */ |
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dev->errors = -EPIPE; |
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mutex_unlock(&dev->io_mutex); |
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return 0; |
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} |
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static struct usb_driver skel_driver = { |
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.name = "skeleton", |
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.probe = skel_probe, |
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.disconnect = skel_disconnect, |
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.suspend = skel_suspend, |
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.resume = skel_resume, |
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.pre_reset = skel_pre_reset, |
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.post_reset = skel_post_reset, |
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.id_table = skel_table, |
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.supports_autosuspend = 1, |
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}; |
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|
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module_usb_driver(skel_driver); |
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|
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MODULE_LICENSE("GPL v2");
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