devices.c

linux core 函数例程

			  desc->bDeviceClass,
			  class_decode (desc->bDeviceClass),
			  desc->bDeviceSubClass,
			  desc->bDeviceProtocol,
			  desc->bMaxPacketSize0,
			  desc->bNumConfigurations);
	if (start > end)
		return start;
	start += sprintf(start, format_device2,
			 desc->idVendor, desc->idProduct,
			 desc->bcdDevice >> 8, desc->bcdDevice & 0xff);
	return start;
}

/*
 * Dump the different strings that this device holds.
 */
static char *usb_dump_device_strings (char *start, char *end, struct usb_device *dev)
{
	char *buf;

	if (start > end)
		return start;
	buf = kmalloc(128, GFP_KERNEL);
	if (!buf)
		return start;
	if (dev->descriptor.iManufacturer) {
		if (usb_string(dev, dev->descriptor.iManufacturer, buf, 128) > 0)
			start += sprintf(start, format_string_manufacturer, buf);
	}				
	if (start > end)
		goto out;
	if (dev->descriptor.iProduct) {
		if (usb_string(dev, dev->descriptor.iProduct, buf, 128) > 0)
			start += sprintf(start, format_string_product, buf);
	}
	if (start > end)
		goto out;
#ifdef ALLOW_SERIAL_NUMBER
	if (dev->descriptor.iSerialNumber) {
		if (usb_string(dev, dev->descriptor.iSerialNumber, buf, 128) > 0)
			start += sprintf(start, format_string_serialnumber, buf);
	}
#endif
 out:
	kfree(buf);
	return start;
}

static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
{
	int i;

	if (start > end)
		return start;
		
	start = usb_dump_device_descriptor(start, end, &dev->descriptor);

	if (start > end)
		return start;
	
	start = usb_dump_device_strings (start, end, dev);
	
	for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
		if (start > end)
			return start;
		start = usb_dump_config(dev->speed,
				start, end, dev->config + i,
				/* active ? */
				(dev->config + i) == dev->actconfig);
	}
	return start;
}


#ifdef PROC_EXTRA /* TBD: may want to add this code later */

static char *usb_dump_hub_descriptor(char *start, char *end, const struct usb_hub_descriptor * desc)
{
	int leng = USB_DT_HUB_NONVAR_SIZE;
	unsigned char *ptr = (unsigned char *)desc;

	if (start > end)
		return start;
	start += sprintf(start, "Interface:");
	while (leng && start <= end) {
		start += sprintf(start, " %02x", *ptr);
		ptr++; leng--;
	}
	*start++ = '\n';
	return start;
}

static char *usb_dump_string(char *start, char *end, const struct usb_device *dev, char *id, int index)
{
	if (start > end)
		return start;
	start += sprintf(start, "Interface:");
	if (index <= dev->maxstring && dev->stringindex && dev->stringindex[index])
		start += sprintf(start, "%s: %.100s ", id, dev->stringindex[index]);
	return start;
}

#endif /* PROC_EXTRA */

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

/* This is a recursive function. Parameters:
 * buffer - the user-space buffer to write data into
 * nbytes - the maximum number of bytes to write
 * skip_bytes - the number of bytes to skip before writing anything
 * file_offset - the offset into the devices file on completion
 */
static ssize_t usb_device_dump(char **buffer, size_t *nbytes, loff_t *skip_bytes, loff_t *file_offset,
				struct usb_device *usbdev, struct usb_bus *bus, int level, int index, int count)
{
	int chix;
	int ret, cnt = 0;
	int parent_devnum = 0;
	char *pages_start, *data_end, *speed;
	unsigned int length;
	ssize_t total_written = 0;
	
	/* don't bother with anything else if we're not writing any data */
	if (*nbytes <= 0)
		return 0;
	
	if (level > MAX_TOPO_LEVEL)
		return total_written;
	/* allocate 2^1 pages = 8K (on i386); should be more than enough for one device */
        if (!(pages_start = (char*) __get_free_pages(GFP_KERNEL,1)))
                return -ENOMEM;
		
	if (usbdev->parent && usbdev->parent->devnum != -1)
		parent_devnum = usbdev->parent->devnum;
	/*
	 * So the root hub's parent is 0 and any device that is
	 * plugged into the root hub has a parent of 0.
	 */
	switch (usbdev->speed) {
	case USB_SPEED_LOW:
		speed = "1.5"; break;
	case USB_SPEED_UNKNOWN:		/* usb 1.1 root hub code */
	case USB_SPEED_FULL:
		speed = "12 "; break;
	case USB_SPEED_HIGH:
		speed = "480"; break;
	default:
		speed = "?? ";
	}
	data_end = pages_start + sprintf(pages_start, format_topo,
			bus->busnum, level, parent_devnum,
			index, count, usbdev->devnum,
			speed, usbdev->maxchild);
	/*
	 * level = topology-tier level;
	 * parent_devnum = parent device number;
	 * index = parent's connector number;
	 * count = device count at this level
	 */
	/* If this is the root hub, display the bandwidth information */
	if (level == 0) {
		int	max;

		/* high speed reserves 80%, full/low reserves 90% */
		if (usbdev->speed == USB_SPEED_HIGH)
			max = 800;
		else
			max = FRAME_TIME_MAX_USECS_ALLOC;

		/* report "average" periodic allocation over a microsecond.
		 * the schedules are actually bursty, HCDs need to deal with
		 * that and just compute/report this average.
		 */
		data_end += sprintf(data_end, format_bandwidth,
				bus->bandwidth_allocated, max,
				(100 * bus->bandwidth_allocated + max / 2)
					/ max,
			         bus->bandwidth_int_reqs,
				 bus->bandwidth_isoc_reqs);
	
	}
	data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256, usbdev);
	
	if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
		data_end += sprintf(data_end, "(truncated)\n");
	
	length = data_end - pages_start;
	/* if we can start copying some data to the user */
	if (length > *skip_bytes) {
		length -= *skip_bytes;
		if (length > *nbytes)
			length = *nbytes;
		if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
			free_pages((unsigned long)pages_start, 1);
			
			if (total_written == 0)
				return -EFAULT;
			return total_written;
		}
		*nbytes -= length;
		*file_offset += length;
		total_written += length;
		*buffer += length;
		*skip_bytes = 0;
	} else
		*skip_bytes -= length;
	
	free_pages((unsigned long)pages_start, 1);
	
	/* Now look at all of this device's children. */
	for (chix = 0; chix < usbdev->maxchild; chix++) {
		if (usbdev->children[chix]) {
			ret = usb_device_dump(buffer, nbytes, skip_bytes, file_offset, usbdev->children[chix],
					bus, level + 1, chix, ++cnt);
			if (ret == -EFAULT)
				return total_written;
			total_written += ret;
		}
	}
	return total_written;
}

static ssize_t usb_device_read(struct file *file, char *buf, size_t nbytes, loff_t *ppos)
{
	struct list_head *buslist;
	struct usb_bus *bus;
	ssize_t ret, total_written = 0;
	loff_t skip_bytes = *ppos;

	if (*ppos < 0)
		return -EINVAL;
	if (nbytes <= 0)
		return 0;
	if (!access_ok(VERIFY_WRITE, buf, nbytes))
		return -EFAULT;

	/* enumerate busses */
	down (&usb_bus_list_lock);
	for (buslist = usb_bus_list.next; buslist != &usb_bus_list; buslist = buslist->next) {
		/* print devices for this bus */
		bus = list_entry(buslist, struct usb_bus, bus_list);
		/* recurse through all children of the root hub */
		ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos, bus->root_hub, bus, 0, 0, 0);
		if (ret < 0)
			return ret;
		total_written += ret;
	}
	up (&usb_bus_list_lock);
	return total_written;
}

/* Kernel lock for "lastev" protection */
static unsigned int usb_device_poll(struct file *file, struct poll_table_struct *wait)
{
	struct usb_device_status *st = (struct usb_device_status *)file->private_data;
	unsigned int mask = 0;

	lock_kernel();
	if (!st) {
		st = kmalloc(sizeof(struct usb_device_status), GFP_KERNEL);
		if (!st) {
			unlock_kernel();
			return POLLIN;
		}
		/*
		 * need to prevent the module from being unloaded, since
		 * proc_unregister does not call the release method and
		 * we would have a memory leak
		 */
		st->lastev = conndiscevcnt;
		file->private_data = st;
		mask = POLLIN;
	}
	if (file->f_mode & FMODE_READ)
                poll_wait(file, &deviceconndiscwq, wait);
	if (st->lastev != conndiscevcnt)
		mask |= POLLIN;
	st->lastev = conndiscevcnt;
	unlock_kernel();
	return mask;
}

static int usb_device_open(struct inode *inode, struct file *file)
{
        file->private_data = NULL;
        return 0;
}

static int usb_device_release(struct inode *inode, struct file *file)
{
	if (file->private_data) {
		kfree(file->private_data);
		file->private_data = NULL;
	}

        return 0;
}

static loff_t usb_device_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;
}

struct file_operations usbdevfs_devices_fops = {
	llseek:		usb_device_lseek,
	read:		usb_device_read,
	poll:		usb_device_poll,
	open:		usb_device_open,
	release:	usb_device_release,
};