usb-skeleton.c 之 01--首先整体欣赏欣赏usb-skeleton.c 多的了得！！

/* * USB Skeleton driver - 2.2 * * Copyright (C) 2001-2004 Greg Kroah-Hartman ([e-mail]) * *This program is free software; you can redistribute it and/or *modify it under the terms of the GNU General Public License as *published by the Free Software Foundation, version 2. * * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c * but has been rewritten to be easier to read and use. * */#include <linux/kernel.h>#include <linux/errno.h>#include <linux/init.h>#include <linux/slab.h>#include <linux/module.h>#include <linux/kref.h>#include <asm/uaccess.h>#include <linux/usb.h>#include <linux/mutex.h>/* Define these values to match your devices */#define USB_SKEL_VENDOR_ID0xfff0#define USB_SKEL_PRODUCT_ID0xfff0/* table of devices that work with this driver */static struct usb_device_id skel_table [] = {{ USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },{ }/* Terminating entry */};MODULE_DEVICE_TABLE(usb, skel_table);/* Get a minor range for your devices from the usb maintainer */#define USB_SKEL_MINOR_BASE192/* our private defines. if this grows any larger, use your own .h file */#define MAX_TRANSFER(PAGE_SIZE - 512)/* MAX_TRANSFER is chosen so that the VM is not stressed by allocations > PAGE_SIZE and the number of packets in a page is an integer 512 is the largest possible packet on EHCI */#define WRITES_IN_FLIGHT8/* arbitrarily chosen *//* Structure to hold all of our device specific stuff */struct usb_skel {struct usb_device*udev;/* the usb device for this device */struct usb_interface*interface;/* the interface for this device */struct semaphorelimit_sem;/* limiting the number of writes in progress */struct usb_anchorsubmitted;/* in case we need to retract our submissions */unsigned char *bulk_in_buffer;/* the buffer to receive data */size_tbulk_in_size;/* the size of the receive buffer */__u8bulk_in_endpointAddr;/* the address of the bulk in endpoint */__u8bulk_out_endpointAddr;/* the address of the bulk out endpoint */interrors;/* the last request tanked */intopen_count;/* count the number of openers */spinlock_terr_lock;/* lock for errors */struct krefkref;struct mutexio_mutex;/* synchronize I/O with disconnect */};#define to_skel_dev(d) container_of(d, struct usb_skel, kref)static struct usb_driver skel_driver;static void skel_draw_down(struct usb_skel *dev);static void skel_delete(struct kref *kref){struct usb_skel *dev = to_skel_dev(kref);usb_put_dev(dev->udev);kfree(dev->bulk_in_buffer);kfree(dev);}static int skel_open(struct inode *inode, struct file *file){struct usb_skel *dev;struct usb_interface *interface;int subminor;int retval = 0;subminor = iminor(inode);interface = usb_find_interface(&skel_driver, subminor);if (!interface) {err ("%s - error, can't find device for minor %d", __func__, subminor);retval = -ENODEV;goto exit;}dev = usb_get_intfdata(interface);if (!dev) {retval = -ENODEV;goto exit;}/* increment our usage count for the device */kref_get(&dev->kref);/* lock the device to allow correctly handling errors * in resumption */mutex_lock(&dev->io_mutex);if (!dev->open_count++) {retval = usb_autopm_get_interface(interface);if (retval) {dev->open_count--;mutex_unlock(&dev->io_mutex);kref_put(&dev->kref, skel_delete);goto exit;}} /* else { //uncomment this block if you want exclusive openretval = -EBUSY;dev->open_count--;mutex_unlock(&dev->io_mutex);kref_put(&dev->kref, skel_delete);goto exit;} *//* prevent the device from being autosuspended *//* save our object in the file's private structure */file->private_data = dev;mutex_unlock(&dev->io_mutex);exit:return retval;}static int skel_release(struct inode *inode, struct file *file){struct usb_skel *dev;dev = (struct usb_skel *)file->private_data;if (dev == NULL)return -ENODEV;/* allow the device to be autosuspended */mutex_lock(&dev->io_mutex);if (!--dev->open_count && dev->interface)usb_autopm_put_interface(dev->interface);mutex_unlock(&dev->io_mutex);/* decrement the count on our device */kref_put(&dev->kref, skel_delete);return 0;}static int skel_flush(struct file *file, fl_owner_t id){struct usb_skel *dev;int res;dev = (struct usb_skel *)file->private_data;if (dev == NULL)return -ENODEV;/* wait for io to stop */mutex_lock(&dev->io_mutex);skel_draw_down(dev);/* read out errors, leave subsequent opens a clean slate */spin_lock_irq(&dev->err_lock);res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;dev->errors = 0;spin_unlock_irq(&dev->err_lock);mutex_unlock(&dev->io_mutex);return res;}static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos){struct usb_skel *dev;int retval;int bytes_read;dev = (struct usb_skel *)file->private_data;mutex_lock(&dev->io_mutex);if (!dev->interface) {/* disconnect() was called */retval = -ENODEV;goto exit;}/* do a blocking bulk read to get data from the device */retval = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr), dev->bulk_in_buffer, min(dev->bulk_in_size, count), &bytes_read, 10000);/* if the read was successful, copy the data to userspace */if (!retval) {if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))retval = -EFAULT;elseretval = bytes_read;}exit:mutex_unlock(&dev->io_mutex);return retval;}static void skel_write_bulk_callback(struct urb *urb){struct usb_skel *dev;dev = urb->context;/* sync/async unlink faults aren't errors */if (urb->status) {if(!(urb->status == -ENOENT || urb->status == -ECONNRESET || urb->status == -ESHUTDOWN))err("%s - nonzero write bulk status received: %d", __func__, urb->status);spin_lock(&dev->err_lock);dev->errors = urb->status;spin_unlock(&dev->err_lock);}/* free up our allocated buffer */usb_buffer_free(urb->dev, urb->transfer_buffer_length,urb->transfer_buffer, urb->transfer_dma);up(&dev->limit_sem);}static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos){struct usb_skel *dev;int retval = 0;struct urb *urb = NULL;char *buf = NULL;size_t writesize = min(count, (size_t)MAX_TRANSFER);dev = (struct usb_skel *)file->private_data;/* verify that we actually have some data to write */if (count == 0)goto exit;/* limit the number of URBs in flight to stop a user from using up all RAM */if (down_interruptible(&dev->limit_sem)) {retval = -ERESTARTSYS;goto exit;}spin_lock_irq(&dev->err_lock);if ((retval = dev->errors) < 0) {/* any error is reported once */dev->errors = 0;/* to preserve notifications about reset */retval = (retval == -EPIPE) ? retval : -EIO;}spin_unlock_irq(&dev->err_lock);if (retval < 0)goto error;/* create a urb, and a buffer for it, and copy the data to the urb */urb = usb_alloc_urb(0, GFP_KERNEL);if (!urb) {retval = -ENOMEM;goto error;}buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);if (!buf) {retval = -ENOMEM;goto error;}if (copy_from_user(buf, user_buffer, writesize)) {retval = -EFAULT;goto error;}/* this lock makes sure we don't submit URBs to gone devices */mutex_lock(&dev->io_mutex);if (!dev->interface) {/* disconnect() was called */mutex_unlock(&dev->io_mutex);retval = -ENODEV;goto error;}/* initialize the urb properly */usb_fill_bulk_urb(urb, dev->udev, usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr), buf, writesize, skel_write_bulk_callback, dev);urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;usb_anchor_urb(urb, &dev->submitted);/* send the data out the bulk port */retval = usb_submit_urb(urb, GFP_KERNEL);mutex_unlock(&dev->io_mutex);if (retval) {err("%s - failed submitting write urb, error %d", __func__, retval);goto error_unanchor;}/* release our reference to this urb, the USB core will eventually free it entirely */usb_free_urb(urb);return writesize;error_unanchor:usb_unanchor_urb(urb);error:if (urb) {usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);usb_free_urb(urb);}up(&dev->limit_sem);exit:return retval;}static const struct file_operations skel_fops = {.owner =THIS_MODULE,.read =skel_read,.write =skel_write,.open =skel_open,.release =skel_release,.flush =skel_flush,};/* * usb class driver info in order to get a minor number from the usb core, * and to have the device registered with the driver core */static struct usb_class_driver skel_class = {.name ="skel%d",.fops =&skel_fops,.minor_base =USB_SKEL_MINOR_BASE,};static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id){struct usb_skel *dev;struct usb_host_interface *iface_desc;struct usb_endpoint_descriptor *endpoint;size_t buffer_size;int i;int retval = -ENOMEM;/* allocate memory for our device state and initialize it */dev = kzalloc(sizeof(*dev), GFP_KERNEL);if (!dev) {err("Out of memory");goto error;}kref_init(&dev->kref);sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);mutex_init(&dev->io_mutex);spin_lock_init(&dev->err_lock);init_usb_anchor(&dev->submitted);dev->udev = usb_get_dev(interface_to_usbdev(interface));dev->interface = interface;/* set up the endpoint information *//* use only the first bulk-in and bulk-out endpoints */iface_desc = interface->cur_altsetting;for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {endpoint = &iface_desc->endpoint[i].desc;if (!dev->bulk_in_endpointAddr && usb_endpoint_is_bulk_in(endpoint)) {/* we found a bulk in endpoint */buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);dev->bulk_in_size = buffer_size;dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);if (!dev->bulk_in_buffer) {err("Could not allocate bulk_in_buffer");goto error;}}if (!dev->bulk_out_endpointAddr && usb_endpoint_is_bulk_out(endpoint)) {/* we found a bulk out endpoint */dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;}}if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {err("Could not find both bulk-in and bulk-out endpoints");goto error;}/* save our data pointer in this interface device */usb_set_intfdata(interface, dev);/* we can register the device now, as it is ready */retval = usb_register_dev(interface, &skel_class);if (retval) {/* something prevented us from registering this driver */err("Not able to get a minor for this device.");usb_set_intfdata(interface, NULL);goto error;}/* let the user know what node this device is now attached to */dev_info(&interface->dev, "USB Skeleton device now attached to USBSkel-%d", interface->minor);return 0;error:if (dev)/* this frees allocated memory */kref_put(&dev->kref, skel_delete);return retval;}static void skel_disconnect(struct usb_interface *interface){struct usb_skel *dev;int minor = interface->minor;dev = usb_get_intfdata(interface);usb_set_intfdata(interface, NULL);/* give back our minor */usb_deregister_dev(interface, &skel_class);/* prevent more I/O from starting */mutex_lock(&dev->io_mutex);dev->interface = NULL;mutex_unlock(&dev->io_mutex);usb_kill_anchored_urbs(&dev->submitted);/* decrement our usage count */kref_put(&dev->kref, skel_delete);dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);}static void skel_draw_down(struct usb_skel *dev){int time;time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);if (!time)usb_kill_anchored_urbs(&dev->submitted);}static int skel_suspend(struct usb_interface *intf, pm_message_t message){struct usb_skel *dev = usb_get_intfdata(intf);if (!dev)return 0;skel_draw_down(dev);return 0;}static int skel_resume (struct usb_interface *intf){return 0;}static int skel_pre_reset(struct usb_interface *intf){struct usb_skel *dev = usb_get_intfdata(intf);mutex_lock(&dev->io_mutex);skel_draw_down(dev);return 0;}static int skel_post_reset(struct usb_interface *intf){struct usb_skel *dev = usb_get_intfdata(intf);/* we are sure no URBs are active - no locking needed */dev->errors = -EPIPE;mutex_unlock(&dev->io_mutex);return 0;}static struct usb_driver skel_driver = {.name ="skeleton",.probe =skel_probe,.disconnect =skel_disconnect,.suspend =skel_suspend,.resume =skel_resume,.pre_reset =skel_pre_reset,.post_reset =skel_post_reset,.id_table =skel_table,.supports_autosuspend = 1,};static int __init usb_skel_init(void){int result;/* register this driver with the USB subsystem */result = usb_register(&skel_driver);if (result)err("usb_register failed. Error number %d", result);return result;}static void __exit usb_skel_exit(void){/* deregister this driver with the USB subsystem */usb_deregister(&skel_driver);}module_init(usb_skel_init);module_exit(usb_skel_exit);MODULE_LICENSE("GPL");