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From: Alan Ott on 8 Jun 2010 00:00
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 <alan(a)signal11.us>
---
Instead of creating a new function to handle Set_Report(Feature) requests,
and to promote a bit of re-use, I re-named hidraw_write() to
hidraw_send_report() and made hidraw_write() call hidraw_send_report().
hidraw_send_report() takes one additional parameter, allowing it to handle
OUTPUT and FEATURE reports. Since hidraw_send_report() is called from both
hidraw_write() and from hidraw_ioctl(), the locking of minors_mutex had to
be moved outside of hidraw_send_report() into hidraw_write(), because
hidraw_send_report() locks minors_mutex.

To implement the Get_Report(Feature) request (ioctl HIDIOCGFEATURE), I made
a new function in usbhid/hid-core.c (usbhid_get_raw_report()) to
perform the transfer. To make it available to hidraw, I added an additional
function pointer into include/linux/hid.h, similar to the existing
hid_output_raw_report() pointer.

The steps I used to create this patch are as follows:
1. In hidraw.c Rename the current hidraw_write() function to
hidraw_send_report(), and add report_type parameter to it.

2. Change the call to hid->hid_output_raw_report() to use the new passed-in
report_type parameter.

3. Create a new hidraw_write() which calls hidraw_send_report() with the
minors_mutex held.

4. Remove the minors_mutex locking from hidraw_send_report() because it will
now be called from hidraw_write() and from hidraw_ioctl(). Locking must be
done outside it now (the reason for step 3).

5. Create a hidraw_get_report() function which is similar to
hidraw_set_report() except that it calls hid->hid_get_raw_report() instead
of hid->hid_output_raw_report().

6. Modify hidraw_ioctl() to accept read/write string arguments (remove the
check for _IOC_DIR(cmd) being _IOC_READ).

7. Add the two new ioctls, HIDIOCSFEATURE(len) and HIDIOCGFEATURE(len) which
make calls to hidraw_send_report() and hidraw_get_report(), respectively.

8. In usbhid/hid-core.c, create a new function usb_hid_get_raw_report()
which calls usb_control_msg with a GET_REPORT command.

9. Modify usbhid_output_raw_report() to NOT use the interrupt OUT endpoint
for Feature Reports (as dictated by the USB HID standard).

10. Create a new pointer in hid.h suitable for handling our new
*_get_raw_report() function.

11. Back in usbhid/hid-core.c, set the pointer to hid_get_raw_report to
usbhid_get_raw_report().

12. In include/linux/hidraw.h, add the two new ioctls for our Set and Get
Feature Reports.

Alan.

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 3ccd478..f611300 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -103,14 +103,14 @@ out:
}

/* 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);
dev = hidraw_table[minor]->hid;

if (!dev->hid_output_raw_report) {
@@ -143,14 +143,93 @@ static ssize_t hidraw_write(struct file *file, const char __user *buffer, size_t
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;
+}
+
static unsigned int hidraw_poll(struct file *file, poll_table *wait)
{
struct hidraw_list *list = file->private_data;
@@ -283,7 +362,24 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
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;
}
@@ -315,7 +411,7 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
-EFAULT : len;
break;
}
- }
+ }

ret = -ENOTTY;
}
diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 1ebd324..986b5ac 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -798,6 +798,34 @@ static int hid_alloc_buffers(struct usb_device *dev, struct hid_device *hid)
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 ret;
+
+ /* Byte 0 is the report number. Report data starts at byte 1.*/
+ buf[0] = report_number;
+
+ 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 + 1, count - 1,
+ USB_CTRL_SET_TIMEOUT);
+
+ /* count also the report id */
+ if (ret > 0) {
+ ret++;
+ }
+
+ return ret;
+}
+
static int usbhid_output_raw_report(struct hid_device *hid, __u8 *buf, size_t count,
unsigned char report_type)
{
@@ -807,7 +835,7 @@ static int usbhid_output_raw_report(struct hid_device *hid, __u8 *buf, size_t co
struct usb_host_interface *interface = intf->cur_altsetting;
int ret;

- if (usbhid->urbout) {
+ if (usbhid->urbout && report_type != HID_FEATURE_REPORT) {
int actual_length;
int skipped_report_id = 0;
if (buf[0] == 0x0) {
@@ -1142,6 +1170,7 @@ static int usbhid_probe(struct usb_interface *intf, const struct usb_device_id *

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
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 895001f..e6796c5 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -502,6 +502,9 @@ struct hid_device { /* device report descriptor */
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);

diff --git a/include/linux/hidraw.h b/include/linux/hidraw.h
index dd8d692..4b88e69 100644
--- a/include/linux/hidraw.h
+++ b/include/linux/hidraw.h
@@ -35,6 +35,9 @@ struct hidraw_devinfo {
#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

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Prev: [Regression] mptsas won't boot with 2.6.35-rc2
Next: [PATCH 02/12] arch/powerpc: Remove unnecessary kmalloc casts