drm/amdgpu: add HDP asic callbacks for SI

Needed to flush and invalidate the HDP block using the CPU.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Samuel Li <Samuel.Li@amd.com>

drivers/gpu/drm/amd/amdgpu/si.c

@@ -1230,6 +1230,18 @@ static void si_detect_hw_virtualization(struct amdgpu_device *adev)
 		adev->virt.caps |= AMDGPU_PASSTHROUGH_MODE;
 }
 
+static void si_flush_hdp(struct amdgpu_device *adev)
+{
+	WREG32(mmHDP_MEM_COHERENCY_FLUSH_CNTL, 1);
+	RREG32(mmHDP_MEM_COHERENCY_FLUSH_CNTL);
+}
+
+static void si_invalidate_hdp(struct amdgpu_device *adev)
+{
+	WREG32(mmHDP_DEBUG0, 1);
+	RREG32(mmHDP_DEBUG0);
+}
+
 static const struct amdgpu_asic_funcs si_asic_funcs =
 {
 	.read_disabled_bios = &si_read_disabled_bios,
@@ -1241,6 +1253,8 @@ static const struct amdgpu_asic_funcs si_asic_funcs =
 	.set_uvd_clocks = &si_set_uvd_clocks,
 	.set_vce_clocks = NULL,
 	.get_config_memsize = &si_get_config_memsize,
+	.flush_hdp = &si_flush_hdp,
+	.invalidate_hdp = &si_invalidate_hdp,
 };
 
 static uint32_t si_get_rev_id(struct amdgpu_device *adev)