drm/radeon: add get_allowed_info_register for r6xx/r7xx

Registers that can be fetched from the info ioctl.

Tested-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index 2fcad34..8f6d862 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -109,6 +109,32 @@
 extern void rv770_set_clk_bypass_mode(struct radeon_device *rdev);
 
 /**
+ * r600_get_allowed_info_register - fetch the register for the info ioctl
+ *
+ * @rdev: radeon_device pointer
+ * @reg: register offset in bytes
+ * @val: register value
+ *
+ * Returns 0 for success or -EINVAL for an invalid register
+ *
+ */
+int r600_get_allowed_info_register(struct radeon_device *rdev,
+				   u32 reg, u32 *val)
+{
+	switch (reg) {
+	case GRBM_STATUS:
+	case GRBM_STATUS2:
+	case R_000E50_SRBM_STATUS:
+	case DMA_STATUS_REG:
+	case UVD_STATUS:
+		*val = RREG32(reg);
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+/**
  * r600_get_xclk - get the xclk
  *
  * @rdev: radeon_device pointer