drm/i915: add register read IOCTL
The interface's immediate purpose is to do synchronous timestamp queries
as required by GL_TIMESTAMP. The GPU has a register for reading the
timestamp but because that would normally require root access through
libpciaccess, the IOCTL can provide this service instead.
Currently the implementation whitelists only the render ring timestamp
register, because that is the only thing we need to expose at this time.
v2: make size implicit based on the register offset
Add a generation check
Reviewed-by: Eric Anholt <eric@anholt.net>
Cc: Jacek Lawrynowicz <jacek.lawrynowicz@intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
[danvet: fixup the ioctl numerb:]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 627fe35..2c0d840 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1529,6 +1529,8 @@
extern int intel_enable_rc6(const struct drm_device *dev);
extern bool i915_semaphore_is_enabled(struct drm_device *dev);
+int i915_reg_read_ioctl(struct drm_device *dev, void *data,
+ struct drm_file *file);
/* overlay */
#ifdef CONFIG_DEBUG_FS