[PATCH] drm/core: add ioctl to query device/driver capabilities

[Ben Skeggs <skeggsb@xxxxxxxxx>]

From: Ben Skeggs <bskeggs@xxxxxxxxxx>

We're coming to see a need to have a set of generic capability checks in
the core DRM, in addition to the driver-specific ioctls that already
exist.

This patch defines an ioctl to do as such, but does not yet define any
capabilities.

Signed-off-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
---
 drivers/gpu/drm/drm_drv.c   |    1 +
 drivers/gpu/drm/drm_ioctl.c |   13 +++++++++++++
 include/drm/drm.h           |    7 +++++++
 include/drm/drmP.h          |    9 +++++++++
 4 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 271835a..ad86135 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -67,6 +67,7 @@ static struct drm_ioctl_desc drm_ioctls[] = {
 	DRM_IOCTL_DEF(DRM_IOCTL_GET_MAP, drm_getmap, 0),
 	DRM_IOCTL_DEF(DRM_IOCTL_GET_CLIENT, drm_getclient, 0),
 	DRM_IOCTL_DEF(DRM_IOCTL_GET_STATS, drm_getstats, 0),
+	DRM_IOCTL_DEF(DRM_IOCTL_GET_CAP, drm_getcap, 0),
 	DRM_IOCTL_DEF(DRM_IOCTL_SET_VERSION, drm_setversion, DRM_MASTER),
 
 	DRM_IOCTL_DEF(DRM_IOCTL_SET_UNIQUE, drm_setunique, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index 47db4df..15a244b 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -365,6 +365,19 @@ int drm_getstats(struct drm_device *dev, void *data,
 }
 
 /**
+ * Get device/driver capabilities
+ */
+int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
+{
+	struct drm_get_cap *req = data;
+
+	req->value = 0;
+	if (dev->driver->get_cap)
+		req->value = (*dev->driver->get_cap)(dev, req->capability);
+	return 0;
+}
+
+/**
  * Setversion ioctl.
  *
  * \param inode device inode.
diff --git a/include/drm/drm.h b/include/drm/drm.h
index e5f7061..7254f1a 100644
--- a/include/drm/drm.h
+++ b/include/drm/drm.h
@@ -608,6 +608,12 @@ struct drm_gem_open {
 	__u64 size;
 };
 
+/** DRM_IOCTL_GET_CAP ioctl argument type */
+struct drm_get_cap {
+	__u64 capability;
+	__u64 value;
+};
+
 #include "drm_mode.h"
 
 #define DRM_IOCTL_BASE			'd'
@@ -628,6 +634,7 @@ struct drm_gem_open {
 #define DRM_IOCTL_GEM_CLOSE		DRM_IOW (0x09, struct drm_gem_close)
 #define DRM_IOCTL_GEM_FLINK		DRM_IOWR(0x0a, struct drm_gem_flink)
 #define DRM_IOCTL_GEM_OPEN		DRM_IOWR(0x0b, struct drm_gem_open)
+#define DRM_IOCTL_GET_CAP		DRM_IOWR(0x0c, struct drm_get_cap)
 
 #define DRM_IOCTL_SET_UNIQUE		DRM_IOW( 0x10, struct drm_unique)
 #define DRM_IOCTL_AUTH_MAGIC		DRM_IOW( 0x11, struct drm_auth)
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index fe29aad..a3d5ce8 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -869,6 +869,13 @@ struct drm_driver {
 	void (*debugfs_cleanup)(struct drm_minor *minor);
 
 	/**
+	 * Driver-specific routine to query capabilities of device/driver.
+	 *
+	 * If not present, core drm will assume a return value of 0.
+	 */
+	u64 (*get_cap)(struct drm_device *dev, u64 cap);
+
+	/**
 	 * Driver-specific constructor for drm_gem_objects, to set up
 	 * obj->driver_private.
 	 *
@@ -1264,6 +1271,8 @@ extern int drm_getclient(struct drm_device *dev, void *data,
 			 struct drm_file *file_priv);
 extern int drm_getstats(struct drm_device *dev, void *data,
 			struct drm_file *file_priv);
+extern int drm_getcap(struct drm_device *dev, void *data,
+		      struct drm_file *file_priv);
 extern int drm_setversion(struct drm_device *dev, void *data,
 			  struct drm_file *file_priv);
 extern int drm_noop(struct drm_device *dev, void *data,
-- 
1.7.4

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