2 * USB Skeleton driver - 2.2
4 * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation, version 2.
10 * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
11 * but has been rewritten to be easier to read and use.
15 #include <linux/kernel.h>
16 #include <linux/errno.h>
17 #include <linux/init.h>
18 #include <linux/slab.h>
19 #include <linux/module.h>
20 #include <linux/kref.h>
21 #include <asm/uaccess.h>
22 #include <linux/usb.h>
23 #include <linux/mutex.h>
26 /* Define these values to match your devices */
27 #define USB_SKEL_VENDOR_ID 0xfff0
28 #define USB_SKEL_PRODUCT_ID 0xfff0
30 /* table of devices that work with this driver */
31 static struct usb_device_id skel_table [] = {
32 { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
33 { } /* Terminating entry */
35 MODULE_DEVICE_TABLE(usb, skel_table);
38 /* Get a minor range for your devices from the usb maintainer */
39 #define USB_SKEL_MINOR_BASE 192
41 /* our private defines. if this grows any larger, use your own .h file */
42 #define MAX_TRANSFER (PAGE_SIZE - 512)
43 /* MAX_TRANSFER is chosen so that the VM is not stressed by
44 allocations > PAGE_SIZE and the number of packets in a page
45 is an integer 512 is the largest possible packet on EHCI */
46 #define WRITES_IN_FLIGHT 8
47 /* arbitrarily chosen */
49 /* Structure to hold all of our device specific stuff */
51 struct usb_device *udev; /* the usb device for this device */
52 struct usb_interface *interface; /* the interface for this device */
53 struct semaphore limit_sem; /* limiting the number of writes in progress */
54 unsigned char *bulk_in_buffer; /* the buffer to receive data */
55 size_t bulk_in_size; /* the size of the receive buffer */
56 __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
57 __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
59 struct mutex io_mutex; /* synchronize I/O with disconnect */
61 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
63 static struct usb_driver skel_driver;
65 static void skel_delete(struct kref *kref)
67 struct usb_skel *dev = to_skel_dev(kref);
69 usb_put_dev(dev->udev);
70 kfree(dev->bulk_in_buffer);
74 static int skel_open(struct inode *inode, struct file *file)
77 struct usb_interface *interface;
81 subminor = iminor(inode);
83 interface = usb_find_interface(&skel_driver, subminor);
85 err ("%s - error, can't find device for minor %d",
86 __FUNCTION__, subminor);
91 dev = usb_get_intfdata(interface);
97 /* increment our usage count for the device */
100 /* prevent the device from being autosuspended */
101 retval = usb_autopm_get_interface(interface);
103 kref_put(&dev->kref, skel_delete);
107 /* save our object in the file's private structure */
108 file->private_data = dev;
114 static int skel_release(struct inode *inode, struct file *file)
116 struct usb_skel *dev;
118 dev = (struct usb_skel *)file->private_data;
122 /* allow the device to be autosuspended */
123 mutex_lock(&dev->io_mutex);
125 usb_autopm_put_interface(dev->interface);
126 mutex_unlock(&dev->io_mutex);
128 /* decrement the count on our device */
129 kref_put(&dev->kref, skel_delete);
133 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
135 struct usb_skel *dev;
139 dev = (struct usb_skel *)file->private_data;
141 mutex_lock(&dev->io_mutex);
142 if (!dev->interface) { /* disconnect() was called */
147 /* do a blocking bulk read to get data from the device */
148 retval = usb_bulk_msg(dev->udev,
149 usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
151 min(dev->bulk_in_size, count),
154 /* if the read was successful, copy the data to userspace */
156 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
163 mutex_unlock(&dev->io_mutex);
167 static void skel_write_bulk_callback(struct urb *urb)
169 struct usb_skel *dev;
171 dev = (struct usb_skel *)urb->context;
173 /* sync/async unlink faults aren't errors */
175 !(urb->status == -ENOENT ||
176 urb->status == -ECONNRESET ||
177 urb->status == -ESHUTDOWN)) {
178 err("%s - nonzero write bulk status received: %d",
179 __FUNCTION__, urb->status);
182 /* free up our allocated buffer */
183 usb_buffer_free(urb->dev, urb->transfer_buffer_length,
184 urb->transfer_buffer, urb->transfer_dma);
188 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
190 struct usb_skel *dev;
192 struct urb *urb = NULL;
194 size_t writesize = min(count, (size_t)MAX_TRANSFER);
196 dev = (struct usb_skel *)file->private_data;
198 /* verify that we actually have some data to write */
202 /* limit the number of URBs in flight to stop a user from using up all RAM */
203 if (down_interruptible(&dev->limit_sem)) {
204 retval = -ERESTARTSYS;
208 /* create a urb, and a buffer for it, and copy the data to the urb */
209 urb = usb_alloc_urb(0, GFP_KERNEL);
215 buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
221 if (copy_from_user(buf, user_buffer, writesize)) {
226 /* this lock makes sure we don't submit URBs to gone devices */
227 mutex_lock(&dev->io_mutex);
228 if (!dev->interface) { /* disconnect() was called */
229 mutex_unlock(&dev->io_mutex);
234 /* initialize the urb properly */
235 usb_fill_bulk_urb(urb, dev->udev,
236 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
237 buf, writesize, skel_write_bulk_callback, dev);
238 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
240 /* send the data out the bulk port */
241 retval = usb_submit_urb(urb, GFP_KERNEL);
242 mutex_unlock(&dev->io_mutex);
244 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
248 /* release our reference to this urb, the USB core will eventually free it entirely */
256 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
265 static const struct file_operations skel_fops = {
266 .owner = THIS_MODULE,
270 .release = skel_release,
274 * usb class driver info in order to get a minor number from the usb core,
275 * and to have the device registered with the driver core
277 static struct usb_class_driver skel_class = {
280 .minor_base = USB_SKEL_MINOR_BASE,
283 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
285 struct usb_skel *dev;
286 struct usb_host_interface *iface_desc;
287 struct usb_endpoint_descriptor *endpoint;
290 int retval = -ENOMEM;
292 /* allocate memory for our device state and initialize it */
293 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
295 err("Out of memory");
298 kref_init(&dev->kref);
299 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
300 mutex_init(&dev->io_mutex);
302 dev->udev = usb_get_dev(interface_to_usbdev(interface));
303 dev->interface = interface;
305 /* set up the endpoint information */
306 /* use only the first bulk-in and bulk-out endpoints */
307 iface_desc = interface->cur_altsetting;
308 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
309 endpoint = &iface_desc->endpoint[i].desc;
311 if (!dev->bulk_in_endpointAddr &&
312 usb_endpoint_is_bulk_in(endpoint)) {
313 /* we found a bulk in endpoint */
314 buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
315 dev->bulk_in_size = buffer_size;
316 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
317 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
318 if (!dev->bulk_in_buffer) {
319 err("Could not allocate bulk_in_buffer");
324 if (!dev->bulk_out_endpointAddr &&
325 usb_endpoint_is_bulk_out(endpoint)) {
326 /* we found a bulk out endpoint */
327 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
330 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
331 err("Could not find both bulk-in and bulk-out endpoints");
335 /* save our data pointer in this interface device */
336 usb_set_intfdata(interface, dev);
338 /* we can register the device now, as it is ready */
339 retval = usb_register_dev(interface, &skel_class);
341 /* something prevented us from registering this driver */
342 err("Not able to get a minor for this device.");
343 usb_set_intfdata(interface, NULL);
347 /* let the user know what node this device is now attached to */
348 info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
353 /* this frees allocated memory */
354 kref_put(&dev->kref, skel_delete);
358 static void skel_disconnect(struct usb_interface *interface)
360 struct usb_skel *dev;
361 int minor = interface->minor;
363 dev = usb_get_intfdata(interface);
364 usb_set_intfdata(interface, NULL);
366 /* give back our minor */
367 usb_deregister_dev(interface, &skel_class);
369 /* prevent more I/O from starting */
370 mutex_lock(&dev->io_mutex);
371 dev->interface = NULL;
372 mutex_unlock(&dev->io_mutex);
374 /* decrement our usage count */
375 kref_put(&dev->kref, skel_delete);
377 info("USB Skeleton #%d now disconnected", minor);
380 static struct usb_driver skel_driver = {
383 .disconnect = skel_disconnect,
384 .id_table = skel_table,
385 .supports_autosuspend = 1,
388 static int __init usb_skel_init(void)
392 /* register this driver with the USB subsystem */
393 result = usb_register(&skel_driver);
395 err("usb_register failed. Error number %d", result);
400 static void __exit usb_skel_exit(void)
402 /* deregister this driver with the USB subsystem */
403 usb_deregister(&skel_driver);
406 module_init(usb_skel_init);
407 module_exit(usb_skel_exit);
409 MODULE_LICENSE("GPL");