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 (greg@kroah.com) * * 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_ID 0xfff0 #define USB_SKEL_PRODUCT_ID 0xfff0 /* 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_BASE 192 /* 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_FLIGHT 8 /* 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 semaphore limit_sem; /* limiting the number of writes in progress */ struct usb_anchor submitted; /* in case we need to retract our submissions */ unsigned char *bulk_in_buffer; /* the buffer to receive data */ size_t bulk_in_size; /* the size of the receive buffer */ __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */ __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */ int errors; /* the last request tanked */ int open_count; /* count the number of openers */ spinlock_t err_lock; /* lock for errors */ struct kref kref; struct mutex io_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 open retval = -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; else retval = 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");