[media] uvcvideo: Add UVCIOC_CTRL_QUERY ioctl

This ioctl extends UVCIOC_CTRL_GET/SET by not only allowing to get/set
XU controls but to also send arbitrary UVC commands to XU controls,
namely GET_CUR, SET_CUR, GET_MIN, GET_MAX, GET_RES, GET_LEN, GET_INFO
and GET_DEF. This is required for applications to work with XU controls,
so that they can properly query the size and allocate the necessary
buffers.

Signed-off-by: Martin Rubli <martin_rubli@logitech.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

3 files changed, 88 insertions, 36 deletions

diff --git a/drivers/media/video/uvc/uvc_ctrl.c b/drivers/media/video/uvc/uvc_ctrl.c
index 59f8a9ad3796..47175ccd2f01 100644
--- a/drivers/media/video/uvc/uvc_ctrl.c
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -1344,32 +1344,33 @@ static int uvc_ctrl_init_xu_ctrl(struct uvc_device *dev,
 }
 
 int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
-        struct uvc_xu_control *xctrl, int set)
+        struct uvc_xu_control_query *xqry)
 {
         struct uvc_entity *entity;
-        struct uvc_control *ctrl = NULL;
+        struct uvc_control *ctrl;
         unsigned int i, found = 0;
-        int restore = 0;
-        __u8 *data;
+        __u32 reqflags;
+        __u16 size;
+        __u8 *data = NULL;
         int ret;
 
         /* Find the extension unit. */
         list_for_each_entry(entity, &chain->entities, chain) {
                 if (UVC_ENTITY_TYPE(entity) == UVC_VC_EXTENSION_UNIT &&
-                    entity->id == xctrl->unit)
+                    entity->id == xqry->unit)
                         break;
         }
 
-        if (entity->id != xctrl->unit) {
+        if (entity->id != xqry->unit) {
                 uvc_trace(UVC_TRACE_CONTROL, "Extension unit %u not found.\n",
-                        xctrl->unit);
-                return -EINVAL;
+                        xqry->unit);
+                return -ENOENT;
         }
 
         /* Find the control and perform delayed initialization if needed. */
         for (i = 0; i < entity->ncontrols; ++i) {
                 ctrl = &entity->controls[i];
-                if (ctrl->index == xctrl->selector - 1) {
+                if (ctrl->index == xqry->selector - 1) {
                         found = 1;
                         break;
                 }
@@ -1377,8 +1378,8 @@ int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
 
         if (!found) {
                 uvc_trace(UVC_TRACE_CONTROL, "Control %pUl/%u not found.\n",
-                        entity->extension.guidExtensionCode, xctrl->selector);
-                return -EINVAL;
+                        entity->extension.guidExtensionCode, xqry->selector);
+                return -ENOENT;
         }
 
         if (mutex_lock_interruptible(&chain->ctrl_mutex))
@@ -1390,43 +1391,72 @@ int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
                 goto done;
         }
 
-        /* Validate control data size. */
-        if (ctrl->info.size != xctrl->size) {
+        /* Validate the required buffer size and flags for the request */
+        reqflags = 0;
+        size = ctrl->info.size;
+
+        switch (xqry->query) {
+        case UVC_GET_CUR:
+                reqflags = UVC_CONTROL_GET_CUR;
+                break;
+        case UVC_GET_MIN:
+                reqflags = UVC_CONTROL_GET_MIN;
+                break;
+        case UVC_GET_MAX:
+                reqflags = UVC_CONTROL_GET_MAX;
+                break;
+        case UVC_GET_DEF:
+                reqflags = UVC_CONTROL_GET_DEF;
+                break;
+        case UVC_GET_RES:
+                reqflags = UVC_CONTROL_GET_RES;
+                break;
+        case UVC_SET_CUR:
+                reqflags = UVC_CONTROL_SET_CUR;
+                break;
+        case UVC_GET_LEN:
+                size = 2;
+                break;
+        case UVC_GET_INFO:
+                size = 1;
+                break;
+        default:
                 ret = -EINVAL;
                 goto done;
         }
 
-        if ((set && !(ctrl->info.flags & UVC_CONTROL_SET_CUR)) ||
-            (!set && !(ctrl->info.flags & UVC_CONTROL_GET_CUR))) {
-                ret = -EINVAL;
+        if (size != xqry->size) {
+                ret = -ENOBUFS;
                 goto done;
         }
 
-        memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP),
-               uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
-               ctrl->info.size);
-        data = uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT);
-        restore = set;
+        if (reqflags && !(ctrl->info.flags & reqflags)) {
+                ret = -EBADRQC;
+                goto done;
+        }
 
-        if (set && copy_from_user(data, xctrl->data, xctrl->size)) {
+        data = kmalloc(size, GFP_KERNEL);
+        if (data == NULL) {
+                ret = -ENOMEM;
+                goto done;
+        }
+
+        if (xqry->query == UVC_SET_CUR &&
+            copy_from_user(data, xqry->data, size)) {
                 ret = -EFAULT;
                 goto done;
         }
 
-        ret = uvc_query_ctrl(chain->dev, set ? UVC_SET_CUR : UVC_GET_CUR,
-                             xctrl->unit, chain->dev->intfnum, xctrl->selector,
-                             data, xctrl->size);
+        ret = uvc_query_ctrl(chain->dev, xqry->query, xqry->unit,
+                             chain->dev->intfnum, xqry->selector, data, size);
         if (ret < 0)
                 goto done;
 
-        if (!set && copy_to_user(xctrl->data, data, xctrl->size))
+        if (xqry->query != UVC_SET_CUR &&
+            copy_to_user(xqry->data, data, size))
                 ret = -EFAULT;
 done:
-        if (ret && restore)
-                memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
-                       uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP),
-                       xctrl->size);
-
+        kfree(data);
         mutex_unlock(&chain->ctrl_mutex);
         return ret;
 }
diff --git a/drivers/media/video/uvc/uvc_v4l2.c b/drivers/media/video/uvc/uvc_v4l2.c
index 9005a8d9d5f8..74323362c8e6 100644
--- a/drivers/media/video/uvc/uvc_v4l2.c
+++ b/drivers/media/video/uvc/uvc_v4l2.c
@@ -1029,10 +1029,23 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
                                           cmd == UVCIOC_CTRL_MAP_OLD);
 
         case UVCIOC_CTRL_GET:
-                return uvc_xu_ctrl_query(chain, arg, 0);
-
         case UVCIOC_CTRL_SET:
-                return uvc_xu_ctrl_query(chain, arg, 1);
+        {
+                struct uvc_xu_control *xctrl = arg;
+                struct uvc_xu_control_query xqry = {
+                        .unit           = xctrl->unit,
+                        .selector       = xctrl->selector,
+                        .query          = cmd == UVCIOC_CTRL_GET
+                                        ? UVC_GET_CUR : UVC_SET_CUR,
+                        .size           = xctrl->size,
+                        .data           = xctrl->data,
+                };
+
+                return uvc_xu_ctrl_query(chain, &xqry);
+        }
+
+        case UVCIOC_CTRL_QUERY:
+                return uvc_xu_ctrl_query(chain, arg);
 
         default:
                 uvc_trace(UVC_TRACE_IOCTL, "Unknown ioctl 0x%08x\n", cmd);
diff --git a/drivers/media/video/uvc/uvcvideo.h b/drivers/media/video/uvc/uvcvideo.h
index 45f01e7e13d2..a3f4d308358a 100644
--- a/drivers/media/video/uvc/uvcvideo.h
+++ b/drivers/media/video/uvc/uvcvideo.h
@@ -57,7 +57,7 @@ struct uvc_xu_control_mapping {
 
         __u8 size;
         __u8 offset;
-        enum v4l2_ctrl_type v4l2_type;
+        __u32 v4l2_type;
         __u32 data_type;
 
         struct uvc_menu_info __user *menu_info;
@@ -73,11 +73,20 @@ struct uvc_xu_control {
         __u8 __user *data;
 };
 
+struct uvc_xu_control_query {
+        __u8 unit;
+        __u8 selector;
+        __u8 query;
+        __u16 size;
+        __u8 __user *data;
+};
+
 #define UVCIOC_CTRL_ADD         _IOW('U', 1, struct uvc_xu_control_info)
 #define UVCIOC_CTRL_MAP_OLD     _IOWR('U', 2, struct uvc_xu_control_mapping_old)
 #define UVCIOC_CTRL_MAP         _IOWR('U', 2, struct uvc_xu_control_mapping)
 #define UVCIOC_CTRL_GET         _IOWR('U', 3, struct uvc_xu_control)
 #define UVCIOC_CTRL_SET         _IOW('U', 4, struct uvc_xu_control)
+#define UVCIOC_CTRL_QUERY       _IOWR('U', 5, struct uvc_xu_control_query)
 
 #ifdef __KERNEL__
 
@@ -638,7 +647,7 @@ extern int uvc_ctrl_set(struct uvc_video_chain *chain,
                 struct v4l2_ext_control *xctrl);
 
 extern int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
-                struct uvc_xu_control *ctrl, int set);
+                struct uvc_xu_control_query *xqry);
 
 /* Utility functions */
 extern void uvc_simplify_fraction(uint32_t *numerator, uint32_t *denominator,