HID: add hidraw interface

hidraw is an interface that is going to obsolete hiddev one
day.

Many userland applications are using libusb instead of using
kernel-provided hiddev interface. This is caused by various
reasons - the HID parser in kernel doesn't handle all the
HID hardware on the planet properly, some devices might require
its own specific quirks/drivers, etc.

hiddev interface tries to do its best to parse all the received
reports properly, and presents only parsed usages into userspace.
This is however often not enough, and that's the reason why
many userland applications just don't use hiddev at all, and
rather use libusb to read raw USB events and process them on
their own.

Another drawback of hiddev is that it is USB-specific.

hidraw interface provides userspace readers with really raw HID
reports, no matter what the low-level transport layer is (USB/BT),
and gives the userland applications all the freedom to process
the HID reports in a way they wish to.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 395 insertions, 0 deletions

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
new file mode 100644
index 000000000000..20ebba1032b8
--- /dev/null
+++ b/drivers/hid/hidraw.c
@@ -0,0 +1,395 @@
+/*
+ * HID raw devices, giving access to raw HID events.
+ *
+ * In comparison to hiddev, this device does not process the
+ * hid events at all (no parsing, no lookups). This lets applications
+ * to work on raw hid events as they want to, and avoids a need to
+ * use a transport-specific userspace libhid/libusb libraries.
+ *
+ *  Copyright (c) 2007 Jiri Kosina
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * 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.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/cdev.h>
+#include <linux/poll.h>
+#include <linux/device.h>
+#include <linux/major.h>
+#include <linux/hid.h>
+#include <linux/mutex.h>
+
+#include <linux/hidraw.h>
+
+static int hidraw_major;
+static struct cdev hidraw_cdev;
+static struct class *hidraw_class;
+static struct hidraw *hidraw_table[HIDRAW_MAX_DEVICES];
+static DEFINE_SPINLOCK(minors_lock);
+
+static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
+{
+	struct hidraw_list *list = file->private_data;
+	int ret = 0, len;
+	char *report;
+	DECLARE_WAITQUEUE(wait, current);
+
+	while (ret == 0) {
+
+		mutex_lock(&list->read_mutex);
+
+		if (list->head == list->tail) {
+			add_wait_queue(&list->hidraw->wait, &wait);
+			set_current_state(TASK_INTERRUPTIBLE);
+
+			while (list->head == list->tail) {
+				if (file->f_flags & O_NONBLOCK) {
+					ret = -EAGAIN;
+					break;
+				}
+				if (signal_pending(current)) {
+					ret = -ERESTARTSYS;
+					break;
+				}
+				if (!list->hidraw->exist) {
+					ret = -EIO;
+					break;
+				}
+
+				/* allow O_NONBLOCK to work well from other threads */
+				mutex_unlock(&list->read_mutex);
+				schedule();
+				mutex_lock(&list->read_mutex);
+				set_current_state(TASK_INTERRUPTIBLE);
+			}
+
+			set_current_state(TASK_RUNNING);
+			remove_wait_queue(&list->hidraw->wait, &wait);
+		}
+
+		if (ret)
+			goto out;
+
+		report = list->buffer[list->tail].value;
+		len = list->buffer[list->tail].len > count ?
+			count : list->buffer[list->tail].len;
+
+		if (copy_to_user(buffer, list->buffer[list->tail].value, len)) {
+			ret = -EFAULT;
+			goto out;
+		}
+		ret += len;
+
+		kfree(list->buffer[list->tail].value);
+		list->tail = (list->tail + 1) & (HIDRAW_BUFFER_SIZE - 1);
+	}
+out:
+	mutex_unlock(&list->read_mutex);
+	return ret;
+}
+
+/* the first byte is expected to be a report number */
+static ssize_t hidraw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
+{
+	unsigned int minor = iminor(file->f_path.dentry->d_inode);
+	struct hid_device *dev = hidraw_table[minor]->hid;
+	__u8 *buf;
+	int ret = 0;
+
+	if (!dev->hid_output_raw_report)
+		return -ENODEV;
+
+	if (count > HID_MIN_BUFFER_SIZE) {
+		printk(KERN_WARNING "hidraw: pid %d passed too large report\n",
+				current->pid);
+		return -EINVAL;
+	}
+
+	if (count < 2) {
+		printk(KERN_WARNING "hidraw: pid %d passed too short report\n",
+				current->pid);
+		return -EINVAL;
+	}
+
+	buf = kmalloc(count * sizeof(__u8), GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (copy_from_user(buf, buffer, count)) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	ret = dev->hid_output_raw_report(dev, buf, count);
+out:
+	kfree(buf);
+	return ret;
+}
+
+static unsigned int hidraw_poll(struct file *file, poll_table *wait)
+{
+	struct hidraw_list *list = file->private_data;
+
+	poll_wait(file, &list->hidraw->wait, wait);
+	if (list->head != list->tail)
+		return POLLIN | POLLRDNORM;
+	if (!list->hidraw->exist)
+		return POLLERR | POLLHUP;
+	return 0;
+}
+
+static int hidraw_open(struct inode *inode, struct file *file)
+{
+	unsigned int minor = iminor(inode);
+	struct hidraw *dev;
+	struct hidraw_list *list;
+	int err = 0;
+
+	if (!(list = kzalloc(sizeof(struct hidraw_list), GFP_KERNEL))) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	spin_lock(&minors_lock);
+	if (!hidraw_table[minor]) {
+		printk(KERN_EMERG "hidraw device with minor %d doesn't exist\n",
+				minor);
+		kfree(list);
+		err = -ENODEV;
+		goto out_unlock;
+	}
+
+	list->hidraw = hidraw_table[minor];
+	mutex_init(&list->read_mutex);
+	list_add_tail(&list->node, &hidraw_table[minor]->list);
+	file->private_data = list;
+
+	dev = hidraw_table[minor];
+	if (!dev->open++)
+		dev->hid->hid_open(dev->hid);
+
+out_unlock:
+	spin_unlock(&minors_lock);
+out:
+	return err;
+
+}
+
+static int hidraw_release(struct inode * inode, struct file * file)
+{
+	unsigned int minor = iminor(inode);
+	struct hidraw *dev;
+	struct hidraw_list *list = file->private_data;
+
+	if (!hidraw_table[minor]) {
+		printk(KERN_EMERG "hidraw device with minor %d doesn't exist\n",
+				minor);
+		return -ENODEV;
+	}
+
+	list_del(&list->node);
+	dev = hidraw_table[minor];
+	if (!dev->open--) {
+		if (list->hidraw->exist)
+			dev->hid->hid_close(dev->hid);
+		else
+			kfree(list->hidraw);
+	}
+
+	return 0;
+}
+
+static int hidraw_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
+{
+	unsigned int minor = iminor(inode);
+	struct hidraw *dev = hidraw_table[minor];
+	void __user *user_arg = (void __user*) arg;
+
+	switch (cmd) {
+		case HIDIOCGRDESCSIZE:
+			if (put_user(dev->hid->rsize, (int __user *)arg))
+				return -EFAULT;
+			return 0;
+
+		case HIDIOCGRDESC:
+			{
+				__u32 len;
+
+				if (get_user(len, (int __user *)arg))
+					return -EFAULT;
+				if (copy_to_user(*((__u8 **)(user_arg +
+							sizeof(__u32))),
+							dev->hid->rdesc, len))
+						return -EFAULT;
+				return 0;
+			}
+		case HIDIOCGRAWINFO:
+			{
+				struct hidraw_devinfo dinfo;
+
+				dinfo.bustype = dev->hid->bus;
+				dinfo.vendor = dev->hid->vendor;
+				dinfo.product = dev->hid->product;
+				if (copy_to_user(user_arg, &dinfo, sizeof(dinfo)))
+					return -EFAULT;
+
+				return 0;
+			}
+		default:
+			printk(KERN_EMERG "hidraw: unsupported ioctl() %x\n",
+					cmd);
+	}
+	return -EINVAL;
+}
+
+static const struct file_operations hidraw_ops = {
+	.owner =        THIS_MODULE,
+	.read =         hidraw_read,
+	.write =        hidraw_write,
+	.poll =         hidraw_poll,
+	.open =         hidraw_open,
+	.release =      hidraw_release,
+	.ioctl =        hidraw_ioctl,
+};
+
+void hidraw_report_event(struct hid_device *hid, u8 *data, int len)
+{
+	struct hidraw *dev = hid->hidraw;
+	struct hidraw_list *list;
+
+	list_for_each_entry(list, &dev->list, node) {
+		list->buffer[list->head].value = kmemdup(data, len, GFP_ATOMIC);
+		list->buffer[list->head].len = len;
+		list->head = (list->head + 1) & (HIDRAW_BUFFER_SIZE - 1);
+		kill_fasync(&list->fasync, SIGIO, POLL_IN);
+	}
+
+	wake_up_interruptible(&dev->wait);
+}
+EXPORT_SYMBOL_GPL(hidraw_report_event);
+
+int hidraw_connect(struct hid_device *hid)
+{
+	int minor, result = -EINVAL;
+	struct hidraw *dev;
+
+	/* TODO currently we accept any HID device. This should later
+	 * probably be fixed to accept only those devices which provide
+	 * non-input applications
+	 */
+
+	if (!(dev = kzalloc(sizeof(struct hidraw), GFP_KERNEL)))
+		return -1;
+
+	spin_lock(&minors_lock);
+
+	for (minor = 0; minor < HIDRAW_MAX_DEVICES; minor++) {
+		if (hidraw_table[minor])
+			continue;
+		hidraw_table[minor] = dev;
+		result = 0;
+		break;
+	}
+
+	spin_unlock(&minors_lock);
+
+	if (result)
+		goto out;
+
+	dev->dev = device_create(hidraw_class, NULL, MKDEV(hidraw_major, minor),
+				"%s%d", "hidraw", minor);
+
+	if (IS_ERR(dev->dev)) {
+		spin_lock(&minors_lock);
+		hidraw_table[minor] = NULL;
+		spin_unlock(&minors_lock);
+		result = PTR_ERR(dev->dev);
+		goto out;
+	}
+
+	init_waitqueue_head(&dev->wait);
+	INIT_LIST_HEAD(&dev->list);
+
+	dev->hid = hid;
+	dev->minor = minor;
+
+	dev->exist = 1;
+	hid->hidraw = dev;
+
+out:
+	return result;
+
+}
+EXPORT_SYMBOL_GPL(hidraw_connect);
+
+void hidraw_disconnect(struct hid_device *hid)
+{
+	struct hidraw *hidraw = hid->hidraw;
+
+	hidraw->exist = 0;
+
+	spin_lock(&minors_lock);
+	hidraw_table[hidraw->minor] = NULL;
+	spin_unlock(&minors_lock);
+
+	device_destroy(hidraw_class, MKDEV(hidraw_major, hidraw->minor));
+
+	if (hidraw->open) {
+		hid->hid_close(hid);
+		wake_up_interruptible(&hidraw->wait);
+	} else {
+		kfree(hidraw);
+	}
+}
+EXPORT_SYMBOL_GPL(hidraw_disconnect);
+
+int __init hidraw_init(void)
+{
+	int result;
+	dev_t dev_id;
+
+	result = alloc_chrdev_region(&dev_id, HIDRAW_FIRST_MINOR,
+			HIDRAW_MAX_DEVICES, "hidraw");
+
+	hidraw_major = MAJOR(dev_id);
+
+	if (result < 0) {
+		printk(KERN_WARNING "hidraw: can't get major number\n");
+		result = 0;
+		goto out;
+	}
+
+	hidraw_class = class_create(THIS_MODULE, "hidraw");
+	if (IS_ERR(hidraw_class)) {
+		result = PTR_ERR(hidraw_class);
+		unregister_chrdev(hidraw_major, "hidraw");
+		goto out;
+	}
+
+        cdev_init(&hidraw_cdev, &hidraw_ops);
+        cdev_add(&hidraw_cdev, dev_id, HIDRAW_MAX_DEVICES);
+out:
+	return result;
+}
+
+void __exit hidraw_exit(void)
+{
+	dev_t dev_id = MKDEV(hidraw_major, 0);
+
+	cdev_del(&hidraw_cdev);
+	class_destroy(hidraw_class);
+	unregister_chrdev_region(dev_id, HIDRAW_MAX_DEVICES);
+
+}