HID: Add Support for Setting and Getting Feature Reports from hidraw

Per the HID Specification, Feature reports must be sent and received on
the Configuration endpoint (EP 0) through the Set_Report/Get_Report
interfaces. This patch adds two ioctls to hidraw to set and get feature
reports to and from the device. Modifications were made to hidraw and
usbhid.

New hidraw ioctls:
HIDIOCSFEATURE - Perform a Set_Report transfer of a Feature report.
HIDIOCGFEATURE - Perform a Get_Report transfer of a Feature report.

Signed-off-by: Alan Ott <[e-mail]>
Signed-off-by: Antonio Ospite <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/hidraw.c

···
 }
 
 /* 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)
+/* This function is to be called with the minors_lock mutex held */
+static ssize_t hidraw_send_report(struct file *file, const char __user *buffer, size_t count, unsigned char report_type)
 {
 	unsigned int minor = iminor(file->f_path.dentry->d_inode);
 	struct hid_device *dev;
 	__u8 *buf;
 	int ret = 0;
-
-	mutex_lock(&minors_lock);
 
 	if (!hidraw_table[minor]) {
 		ret = -ENODEV;
···
 		goto out_free;
 	}
 
-	ret = dev->hid_output_raw_report(dev, buf, count, HID_OUTPUT_REPORT);
+	ret = dev->hid_output_raw_report(dev, buf, count, report_type);
 out_free:
 	kfree(buf);
 out:
+	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)
+{
+	ssize_t ret;
+	mutex_lock(&minors_lock);
+	ret = hidraw_send_report(file, buffer, count, HID_OUTPUT_REPORT);
 	mutex_unlock(&minors_lock);
+	return ret;
+}
+
+
+/* This function performs a Get_Report transfer over the control endpoint
+   per section 7.2.1 of the HID specification, version 1.1.  The first byte
+   of buffer is the report number to request, or 0x0 if the defice does not
+   use numbered reports. The report_type parameter can be HID_FEATURE_REPORT
+   or HID_INPUT_REPORT.  This function is to be called with the minors_lock
+   mutex held.  */
+static ssize_t hidraw_get_report(struct file *file, char __user *buffer, size_t count, unsigned char report_type)
+{
+	unsigned int minor = iminor(file->f_path.dentry->d_inode);
+	struct hid_device *dev;
+	__u8 *buf;
+	int ret = 0, len;
+	unsigned char report_number;
+
+	dev = hidraw_table[minor]->hid;
+
+	if (!dev->hid_get_raw_report) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	if (count > HID_MAX_BUFFER_SIZE) {
+		printk(KERN_WARNING "hidraw: pid %d passed too large report\n",
+				task_pid_nr(current));
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (count < 2) {
+		printk(KERN_WARNING "hidraw: pid %d passed too short report\n",
+				task_pid_nr(current));
+		ret = -EINVAL;
+		goto out;
+	}
+
+	buf = kmalloc(count * sizeof(__u8), GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	/* Read the first byte from the user. This is the report number,
+	   which is passed to dev->hid_get_raw_report(). */
+	if (copy_from_user(&report_number, buffer, 1)) {
+		ret = -EFAULT;
+		goto out_free;
+	}
+
+	ret = dev->hid_get_raw_report(dev, report_number, buf, count, report_type);
+
+	if (ret < 0)
+		goto out_free;
+
+	len = (ret < count) ? ret : count;
+
+	if (copy_to_user(buffer, buf, len)) {
+		ret = -EFAULT;
+		goto out_free;
+	}
+
+	ret = len;
+
+out_free:
+	kfree(buf);
+out:
 	return ret;
 }
 
···
 		default:
 			{
 				struct hid_device *hid = dev->hid;
-				if (_IOC_TYPE(cmd) != 'H' || _IOC_DIR(cmd) != _IOC_READ) {
+				if (_IOC_TYPE(cmd) != 'H') {
+					ret = -EINVAL;
+					break;
+				}
+
+				if (_IOC_NR(cmd) == _IOC_NR(HIDIOCSFEATURE(0))) {
+					int len = _IOC_SIZE(cmd);
+					ret = hidraw_send_report(file, user_arg, len, HID_FEATURE_REPORT);
+					break;
+				}
+				if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGFEATURE(0))) {
+					int len = _IOC_SIZE(cmd);
+					ret = hidraw_get_report(file, user_arg, len, HID_FEATURE_REPORT);
+					break;
+				}
+
+				/* Begin Read-only ioctls. */
+				if (_IOC_DIR(cmd) != _IOC_READ) {
 					ret = -EINVAL;
 					break;
 				}
···
 						-EFAULT : len;
 					break;
 				}
-		}
+			}
 
 		ret = -ENOTTY;
 	}

drivers/hid/usbhid/hid-core.c

···
 	return 0;
 }
 
+static int usbhid_get_raw_report(struct hid_device *hid,
+		unsigned char report_number, __u8 *buf, size_t count,
+		unsigned char report_type)
+{
+	struct usbhid_device *usbhid = hid->driver_data;
+	struct usb_device *dev = hid_to_usb_dev(hid);
+	struct usb_interface *intf = usbhid->intf;
+	struct usb_host_interface *interface = intf->cur_altsetting;
+	int skipped_report_id = 0;
+	int ret;
+
+	/* Byte 0 is the report number. Report data starts at byte 1.*/
+	buf[0] = report_number;
+	if (report_number == 0x0) {
+		/* Offset the return buffer by 1, so that the report ID
+		   will remain in byte 0. */
+		buf++;
+		count--;
+		skipped_report_id = 1;
+	}
+	ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+		HID_REQ_GET_REPORT,
+		USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+		((report_type + 1) << 8) | report_number,
+		interface->desc.bInterfaceNumber, buf, count,
+		USB_CTRL_SET_TIMEOUT);
+
+	/* count also the report id */
+	if (ret > 0 && skipped_report_id)
+		ret++;
+
+	return ret;
+}
+
 static int usbhid_output_raw_report(struct hid_device *hid, __u8 *buf, size_t count,
 		unsigned char report_type)
 {
···
 
 	usb_set_intfdata(intf, hid);
 	hid->ll_driver = &usb_hid_driver;
+	hid->hid_get_raw_report = usbhid_get_raw_report;
 	hid->hid_output_raw_report = usbhid_output_raw_report;
 	hid->ff_init = hid_pidff_init;
 #ifdef CONFIG_USB_HIDDEV

include/linux/hid.h

···
 				  struct hid_usage *, __s32);
 	void (*hiddev_report_event) (struct hid_device *, struct hid_report *);
 
+	/* handler for raw input (Get_Report) data, used by hidraw */
+	int (*hid_get_raw_report) (struct hid_device *, unsigned char, __u8 *, size_t, unsigned char);
+
 	/* handler for raw output data, used by hidraw */
 	int (*hid_output_raw_report) (struct hid_device *, __u8 *, size_t, unsigned char);
 

include/linux/hidraw.h

···
 #define HIDIOCGRAWINFO		_IOR('H', 0x03, struct hidraw_devinfo)
 #define HIDIOCGRAWNAME(len)     _IOC(_IOC_READ, 'H', 0x04, len)
 #define HIDIOCGRAWPHYS(len)     _IOC(_IOC_READ, 'H', 0x05, len)
+/* The first byte of SFEATURE and GFEATURE is the report number */
+#define HIDIOCSFEATURE(len)    _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x06, len)
+#define HIDIOCGFEATURE(len)    _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x07, len)
 
 #define HIDRAW_FIRST_MINOR 0
 #define HIDRAW_MAX_DEVICES 64