/*
* 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 <linux/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
#define USB_TEST_VENDOR_ID 0xfff0
#define USB_TEST_PRODUCT_ID 0xfff0
/* table of devices that work with this driver */
static const struct usb_device_id skel_table[] = {
{ USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
{USB_DEVICE(USB_TEST_VENDOR_ID,USB_TEST_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 */
// 定义一种我们需要的设备驱动结构体类型.usb_driver 是要驱动这个类型的设备. 把usb_device
/* 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 */
struct urb *bulk_in_urb; /* the urb to read data with */
unsigned char *bulk_in_buffer; /* the buffer to receive data */
size_t bulk_in_size; /* the size of the receive buffer */
size_t bulk_in_filled; /* number of bytes in the buffer */
size_t bulk_in_copied; /* already copied to user space */
__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 */
bool ongoing_read; /* a read is going on */
bool processed_urb; /* indicates we haven't processed the urb */
spinlock_t err_lock; /* lock for errors */
struct kref kref;
struct mutex io_mutex; /* synchronize I/O with disconnect */
struct completion bulk_in_completion; /* to wait for an ongoing read */
};
struct usb_test {
struct usb_device *udev;
struct usb_interface *interface;
struct semaphore limit_sem;
struct usb_anchor submitted;
struct urb *bulk_in_urb;
unsigned char *bulk_in_buffer;
size_t bulk_in_size; /* the size of the receive buffer */
size_t bulk_in_filled; /* number of bytes in the buffer */
size_t bulk_in_copied; /* already copied to user space */
__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 */
bool ongoing_read; /* a read is going on */
bool processed_urb; /* indicates we haven't processed the urb */
spinlock_t err_lock; /* lock for errors */
struct kref kref;
struct mutex io_mutex; /* synchronize I/O with disconnect */
struct completion bulk_in_completion; /* to wait for an ongoing read */
}
#define to_skel_dev(d) container_of(d, struct usb_skel, kref)
# define to
static struct usb_driver skel_driver;
static struct usb_driver test_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_free_urb(dev->bulk_in_urb);
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 = 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 = 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 void skel_read_bulk_callback(struct urb *urb)
{
struct usb_skel *dev;
dev = urb->context;
spin_lock(&dev->err_lock);
/* 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);
dev->errors = urb->status;
} else {
dev->bulk_in_filled = urb->actual_length;
}
dev->ongoing_read = 0;
spin_unlock(&dev->err_lock);
complete(&dev->bulk_in_completion);
}
static int skel_do_read_io(struct usb_skel *dev, size_t count)
{
int rv;
/* prepare a read */
usb_fill_bulk_urb(dev->bulk_in_urb,
dev->udev,
usb_rcvbulkpipe(dev->udev,
dev->bulk_in_endpointAddr),
dev->bulk_in_buffer,
min(dev->bulk_in_size, count),
skel_read_bulk_callback,
dev);
/* tell everybody to leave the URB alone */
spin_lock_irq(&dev->err_lock);
dev->ongoing_read = 1;
spin_unlock_irq(&dev->err_lock);
/* do it */
rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
if (rv < 0) {
err("%s - failed submitting read urb, error %d",
__func__, rv);
dev->bulk_in_filled = 0;
rv = (rv == -ENOMEM) ? rv : -EIO;
spin_lock_irq(&dev->err_lock);
dev->ongoing_read = 0;
spin_unlock_irq(&dev->err_lock);
}
return rv;
}
static ssize_t skel_read(struct file *file, char *buffer, size_t count,
loff_t *ppos)
{
struct usb_skel *dev;
int rv;
bool ongoing_io;
dev = file->private_data;
/* if we cannot read at all, return EOF */
if (!dev->bulk_in_urb || !count)
return 0;
/* no concurrent readers */
rv = mutex_lock_interruptible(&dev->io_mutex);
if (rv < 0)
return rv;
if (!dev->interface) { /* disconnect() was called */
rv = -ENODEV;
goto exit;
}
/* if IO is under way, we must not touch things */
retry:
spin_lock_irq(&dev->err_lock);
ongoing_io = dev->ongoing_read;
spin_unlock_irq(&dev->err_lock);
if (ongoing_io) {
/* nonblocking IO shall not wait */
if (file->f_flags & O_NONBLOCK) {
rv = -EAGAIN;
goto exit;
}
/*
* IO may take forever
* hence wait in an interruptible state
*/
rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
if (rv < 0)
goto exit;
/*
* by waiting we also semiprocessed the urb
* we must finish now
*/
dev->bulk_in_copied = 0;
dev->processed_urb = 1;
}
if (!dev->processed_urb) {
/*
* the URB hasn't been processed
* do it now
*/
wait_for_completion(&dev->bulk_in_completion);
dev->bulk_in_copied = 0;
dev->processed_urb = 1;
}
/* errors must be reported */
rv = dev->errors;
if (rv < 0) {
/* any error is reported once */
dev->errors = 0;
/* to preserve notifications about reset */
rv = (rv == -EPIPE) ? rv : -EIO;
/* no data to deliver */
dev->bulk_in_filled = 0;
/* report it */
goto exit;
}
/*
* if the buffer is filled we may satisfy the read
* else we need to start IO
*/
if (dev->bulk_in_filled) {
/* we had read data */
size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
size_t chunk = min(available, count);
if (!available) {
/*
* all data has been used
* actual IO needs to be done
*/
rv = skel_do_read_io(dev, count);
if (rv < 0)
goto exit;
else
goto retry;
}
/*
* data is available
* chunk tells us how much shall be copied
*/
if (copy_to_user(buffer,
dev->bulk_in_buffer + dev->bulk_in_copied,
chunk))
rv = -EFAULT;
else
rv = chunk;
/*copied counts from driver space .*/
dev->bulk_in_copied += chunk;
/*
* if we are asked for more than we have,
* we start IO but don't wait
*/
if (available < count)
skel_do_read_io(dev, count - chunk);
} else {
/* no data in the buffer */
rv = skel_do_read_io(dev, count);
if (rv < 0)
goto exit;
else if (!(file->f_flags & O_NONBLOCK))
goto retry;
rv = -EAGAIN;
}
exit:
mutex_unlock(&dev->io_mutex);
return rv;
}
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_free_coherent(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 = 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 (!(file->f_flags & O_NONBLOCK)) {
if (down_interruptible(&dev->limit_sem)) {
retval = -ERESTARTSYS;
goto exit;
}
} else {
if (down_trylock(&dev->limit_sem)) {
retval = -EAGAIN;
goto exit;
}
}
spin_lock_irq(&dev->err_lock);
retval = dev->errors;
if (retval < 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_alloc_coherent(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_free_coherent(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,
.llseek = noop_llseek,
};
/*
* 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)
{
//指向我们定义的usb_kel 这个类型的结构体
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 */
/*分配dev结构体 并初始化*/
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);
init_completion(&dev->bulk_in_completion);
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)) { // first builk 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;
}
dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
if (!dev->bulk_in_urb) {
err("Could not allocate bulk_in_urb");
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)) { // first builk out endpoint
err("Could not find both bulk-in and bulk-out endpoints");
goto error;
}
/* save our data pointer in this interface device */
/* something prevented us from registering this driver */
/*
//usb_set_intfdata, 把刚才初始化得到的dev（usb_skel类型＃如open函数中，dev = usb_get_intfdata(interface)。
//保存在usb_interface中，以便其他函数使用。这样做是因为?
//┈dev是一个局部变量，其他函数没法获得，
//但其他函数（比如open）可以访问usb_interface，这样，也就可以访问usb_skel里的具体字段.
一个USB interface对应一种USB逻辑设备，比如鼠标、键盘、音频流。
所以，在USB范畴中，device一般就是指一个interface。一个驱动只控制一个interface。这样，usb_register_dev自然是注册一个interface，所以usb_register_dev的第一个参数是interface（usb_interface类型）。
*/
usb_set_intfdata(interface, dev);
/* we can register the device now, as it is ready */
retval = usb_register_dev(interface, &skel_class);
if (retval) {
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);
usb_kill_urb(dev->bulk_in_urb);
}
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);
}
/*
-ENOMEM 内存不足
-ENODEV 没有设备可用
-EPIPE 端点停止
-EAGAIN 排队等候同步传输的太多
-EFBIG 请求ISO frame的太多
-EINVAL 无效的中断间隔
*/
module_init(usb_skel_init);
module_exit(usb_skel_exit);
MODULE_LICENSE("GPL");