drm/radeon: add fault decode function for cayman/TN (v2)

Helpful for debugging GPUVM errors as we can see what
hw block and page generated the fault in the log.

v2: simplify fault decoding

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index e49059d..526e428 100644
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -139,6 +139,8 @@
 void evergreen_program_aspm(struct radeon_device *rdev);
 extern void cayman_cp_int_cntl_setup(struct radeon_device *rdev,
 				     int ring, u32 cp_int_cntl);
+extern void cayman_vm_decode_fault(struct radeon_device *rdev,
+				   u32 status, u32 addr);
 
 static const u32 evergreen_golden_registers[] =
 {
@@ -4586,6 +4588,7 @@
 	bool queue_hotplug = false;
 	bool queue_hdmi = false;
 	bool queue_thermal = false;
+	u32 status, addr;
 
 	if (!rdev->ih.enabled || rdev->shutdown)
 		return IRQ_NONE;
@@ -4872,11 +4875,14 @@
 			break;
 		case 146:
 		case 147:
+			addr = RREG32(VM_CONTEXT1_PROTECTION_FAULT_ADDR);
+			status = RREG32(VM_CONTEXT1_PROTECTION_FAULT_STATUS);
 			dev_err(rdev->dev, "GPU fault detected: %d 0x%08x\n", src_id, src_data);
 			dev_err(rdev->dev, "  VM_CONTEXT1_PROTECTION_FAULT_ADDR   0x%08X\n",
-				RREG32(VM_CONTEXT1_PROTECTION_FAULT_ADDR));
+				addr);
 			dev_err(rdev->dev, "  VM_CONTEXT1_PROTECTION_FAULT_STATUS 0x%08X\n",
-				RREG32(VM_CONTEXT1_PROTECTION_FAULT_STATUS));
+				status);
+			cayman_vm_decode_fault(rdev, status, addr);
 			/* reset addr and status */
 			WREG32_P(VM_CONTEXT1_CNTL2, 1, ~1);
 			break;