devio.c

linux core 函数例程

/*****************************************************************************/

/*
 *      devio.c  --  User space communication with USB devices.
 *
 *      Copyright (C) 1999-2000  Thomas Sailer ([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; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *  $Id: devio.c,v 1.7 2000/02/01 17:28:48 fliegl Exp $
 *
 *  This file implements the usbdevfs/x/y files, where
 *  x is the bus number and y the device number.
 *
 *  It allows user space programs/"drivers" to communicate directly
 *  with USB devices without intervening kernel driver.
 *
 *  Revision history
 *    22.12.1999   0.1   Initial release (split from proc_usb.c)
 *    04.01.2000   0.2   Turned into its own filesystem
 */

/*****************************************************************************/

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/signal.h>
#include <linux/poll.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usbdevice_fs.h>
#include <asm/uaccess.h>
#include <asm/byteorder.h>


struct async {
        struct list_head asynclist;
        struct dev_state *ps;
	struct task_struct *task;
	unsigned int signr;
	void *userbuffer;
        void *userurb;
        struct urb *urb;
};

static loff_t usbdev_lseek(struct file *file, loff_t offset, int orig)
{
	loff_t ret;

	lock_kernel();

	switch (orig) {
	case 0:
		file->f_pos = offset;
		ret = file->f_pos;
		break;
	case 1:
		file->f_pos += offset;
		ret = file->f_pos;
		break;
	case 2:
	default:
		ret = -EINVAL;
	}

	unlock_kernel();
	return ret;
}

static ssize_t usbdev_read(struct file *file, char * buf, size_t nbytes, loff_t *ppos)
{
	struct dev_state *ps = (struct dev_state *)file->private_data;
	ssize_t ret = 0;
	unsigned len;
	loff_t pos;
	int i;

	pos = *ppos;
	down_read(&ps->devsem);
	if (!ps->dev) {
		ret = -ENODEV;
		goto err;
	} else if (pos < 0) {
		ret = -EINVAL;
		goto err;
	}

	if (pos < sizeof(struct usb_device_descriptor)) {
		len = sizeof(struct usb_device_descriptor) - pos;
		if (len > nbytes)
			len = nbytes;
		if (copy_to_user(buf, ((char *)&ps->dev->descriptor) + pos, len)) {
			ret = -EFAULT;
			goto err;
		}

		*ppos += len;
		buf += len;
		nbytes -= len;
		ret += len;
	}

	pos = sizeof(struct usb_device_descriptor);
	for (i = 0; nbytes && i < ps->dev->descriptor.bNumConfigurations; i++) {
		struct usb_config_descriptor *config =
			(struct usb_config_descriptor *)ps->dev->rawdescriptors[i];
		unsigned int length = le16_to_cpu(config->wTotalLength);

		if (*ppos < pos + length) {
			len = length - (*ppos - pos);
			if (len > nbytes)
				len = nbytes;

			if (copy_to_user(buf,
			    ps->dev->rawdescriptors[i] + (*ppos - pos), len)) {
				ret = -EFAULT;
				goto err;
			}

			*ppos += len;
			buf += len;
			nbytes -= len;
			ret += len;
		}

		pos += length;
	}

err:
	up_read(&ps->devsem);
	return ret;
}

extern inline unsigned int ld2(unsigned int x)
{
        unsigned int r = 0;
        
        if (x >= 0x10000) {
                x >>= 16;
                r += 16;
        }
        if (x >= 0x100) {
                x >>= 8;
                r += 8;
        }
        if (x >= 0x10) {
                x >>= 4;
                r += 4;
        }
        if (x >= 4) {
                x >>= 2;
                r += 2;
        }
        if (x >= 2)
                r++;
        return r;
}

/*
 * async list handling
 */

static struct async *alloc_async(unsigned int numisoframes)
{
        unsigned int assize = sizeof(struct async) + numisoframes * sizeof(struct usb_iso_packet_descriptor);
        struct async *as = kmalloc(assize, GFP_KERNEL);
        if (!as)
                return NULL;
        memset(as, 0, assize);
	as->urb = usb_alloc_urb(numisoframes, GFP_KERNEL);
	if (!as->urb) {
		kfree(as);
		return NULL;
	}
        return as;
}

static void free_async(struct async *as)
{
        if (as->urb->transfer_buffer)
                kfree(as->urb->transfer_buffer);
        if (as->urb->setup_packet)
                kfree(as->urb->setup_packet);
	usb_free_urb(as->urb);
        kfree(as);
}

extern __inline__ void async_newpending(struct async *as)
{
        struct dev_state *ps = as->ps;
        unsigned long flags;
        
        spin_lock_irqsave(&ps->lock, flags);
        list_add_tail(&as->asynclist, &ps->async_pending);
        spin_unlock_irqrestore(&ps->lock, flags);
}

extern __inline__ void async_removepending(struct async *as)
{
        struct dev_state *ps = as->ps;
        unsigned long flags;
        
        spin_lock_irqsave(&ps->lock, flags);
        list_del(&as->asynclist);
        INIT_LIST_HEAD(&as->asynclist);
        spin_unlock_irqrestore(&ps->lock, flags);
}

extern __inline__ struct async *async_getcompleted(struct dev_state *ps)
{
        unsigned long flags;
        struct async *as = NULL;

        spin_lock_irqsave(&ps->lock, flags);
        if (!list_empty(&ps->async_completed)) {
                as = list_entry(ps->async_completed.next, struct async, asynclist);
                list_del(&as->asynclist);
                INIT_LIST_HEAD(&as->asynclist);
        }
        spin_unlock_irqrestore(&ps->lock, flags);
        return as;
}

extern __inline__ struct async *async_getpending(struct dev_state *ps, void *userurb)
{
        unsigned long flags;
        struct async *as;
        struct list_head *p;

        spin_lock_irqsave(&ps->lock, flags);
        for (p = ps->async_pending.next; p != &ps->async_pending; ) {
                as = list_entry(p, struct async, asynclist);
                p = p->next;
                if (as->userurb != userurb)
                        continue;
                list_del(&as->asynclist);
                INIT_LIST_HEAD(&as->asynclist);
                spin_unlock_irqrestore(&ps->lock, flags);
                return as;
        }
        spin_unlock_irqrestore(&ps->lock, flags);
        return NULL;
}

static void async_completed(struct urb *urb)
{
        struct async *as = (struct async *)urb->context;
        struct dev_state *ps = as->ps;
	struct siginfo sinfo;

        spin_lock(&ps->lock);
        list_del(&as->asynclist);
        list_add_tail(&as->asynclist, &ps->async_completed);
        spin_unlock(&ps->lock);
        wake_up(&ps->wait);
	if (as->signr) {
		sinfo.si_signo = as->signr;
		sinfo.si_errno = as->urb->status;
		sinfo.si_code = SI_ASYNCIO;
		sinfo.si_addr = as->userurb;
		send_sig_info(as->signr, &sinfo, as->task);
	}
}

static void destroy_all_async(struct dev_state *ps)
{
        struct async *as;
        unsigned long flags;

        spin_lock_irqsave(&ps->lock, flags);
        while (!list_empty(&ps->async_pending)) {
                as = list_entry(ps->async_pending.next, struct async, asynclist);
                list_del(&as->asynclist);
                INIT_LIST_HEAD(&as->asynclist);
                spin_unlock_irqrestore(&ps->lock, flags);
                /* usb_unlink_urb calls the completion handler with status == -ENOENT */
                usb_unlink_urb(as->urb);
                spin_lock_irqsave(&ps->lock, flags);
        }
        spin_unlock_irqrestore(&ps->lock, flags);
        while ((as = async_getcompleted(ps)))
                free_async(as);
}

/*
 * interface claims are made only at the request of user level code,
 * which can also release them (explicitly or by closing files).
 * they're also undone when devices disconnect.
 */

static void *driver_probe(struct usb_device *dev, unsigned int intf,
			  const struct usb_device_id *id)
{
	return NULL;
}

static void driver_disconnect(struct usb_device *dev, void *context)
{
	struct dev_state *ps = (struct dev_state *)context;

	if (!ps)
		return;

	/* this waits till synchronous requests complete */
	down_write (&ps->devsem);

	/* prevent new I/O requests */
	ps->dev = 0;
	ps->ifclaimed = 0;

	/* force async requests to complete */
	destroy_all_async (ps);

	up_write (&ps->devsem);
}

struct usb_driver usbdevfs_driver = {
	name:		"usbfs",
	probe:		driver_probe,
	disconnect:	driver_disconnect,
};

static int claimintf(struct dev_state *ps, unsigned int intf)
{
	struct usb_device *dev = ps->dev;
	struct usb_interface *iface;
	int err;

	if (intf >= 8*sizeof(ps->ifclaimed) || !dev || intf >= dev->actconfig->bNumInterfaces)
		return -EINVAL;
	/* already claimed */
	if (test_bit(intf, &ps->ifclaimed))
		return 0;
	iface = &dev->actconfig->interface[intf];
	err = -EBUSY;
	lock_kernel();
	if (!usb_interface_claimed(iface)) {
		usb_driver_claim_interface(&usbdevfs_driver, iface, ps);
		set_bit(intf, &ps->ifclaimed);
		err = 0;
	}
	unlock_kernel();
	return err;
}

static int releaseintf(struct dev_state *ps, unsigned int intf)
{
	struct usb_device *dev;
	struct usb_interface *iface;
	int err;

	if (intf >= 8*sizeof(ps->ifclaimed))
		return -EINVAL;
	err = -EINVAL;
	lock_kernel();
	dev = ps->dev;
	if (dev && test_and_clear_bit(intf, &ps->ifclaimed)) {
		iface = &dev->actconfig->interface[intf];
		usb_driver_release_interface(&usbdevfs_driver, iface);
		err = 0;
	}
	unlock_kernel();
	return err;
}

static int checkintf(struct dev_state *ps, unsigned int intf)
{
	if (intf >= 8*sizeof(ps->ifclaimed))
		return -EINVAL;
	if (test_bit(intf, &ps->ifclaimed))
		return 0;
	/* if not yet claimed, claim it for the driver */
	printk(KERN_WARNING "usbfs: process %d (%s) did not claim interface %u before use\n",
	       current->pid, current->comm, intf);
	return claimintf(ps, intf);
}

static int findintfep(struct usb_device *dev, unsigned int ep)
{
	unsigned int i, j, e;
        struct usb_interface *iface;
	struct usb_interface_descriptor *alts;
	struct usb_endpoint_descriptor *endpt;

	if (ep & ~(USB_DIR_IN|0xf))
		return -EINVAL;
	for (i = 0; i < dev->actconfig->bNumInterfaces; i++) {
		iface = &dev->actconfig->interface[i];
		for (j = 0; j < iface->num_altsetting; j++) {
                        alts = &iface->altsetting[j];
			for (e = 0; e < alts->bNumEndpoints; e++) {
				endpt = &alts->endpoint[e];
				if (endpt->bEndpointAddress == ep)
					return i;
			}
		}
	}
	return -ENOENT; 
}

static int findintfif(struct usb_device *dev, unsigned int ifn)
{
	unsigned int i, j;
        struct usb_interface *iface;
	struct usb_interface_descriptor *alts;

	if (ifn & ~0xff)