drm/amdgpu: add tmz feature parameter (v2)

This patch adds tmz parameter to enable/disable
the feature in the amdgpu kernel module. Nomally,
by default, it should be auto (rely on the
hardware capability).

But right now, it need to set "off" to avoid
breaking other developers' work because it's not
totally completed.

Will set "auto" till the feature is stable and
completely verified.

v2: add "auto" option for future use.
Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -189,6 +189,8 @@ extern int sched_policy;
 static const int sched_policy = KFD_SCHED_POLICY_HWS;
 #endif
 
+extern int amdgpu_tmz;
+
 #ifdef CONFIG_DRM_AMDGPU_SI
 extern int amdgpu_si_support;
 #endif

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

@@ -145,6 +145,7 @@ int amdgpu_discovery = -1;
 int amdgpu_mes = 0;
 int amdgpu_noretry;
 int amdgpu_force_asic_type = -1;
+int amdgpu_tmz = 0;
 
 struct amdgpu_mgpu_info mgpu_info = {
 	.mutex = __MUTEX_INITIALIZER(mgpu_info.mutex),
@@ -729,6 +730,16 @@ uint amdgpu_dm_abm_level = 0;
 MODULE_PARM_DESC(abmlevel, "ABM level (0 = off (default), 1-4 = backlight reduction level) ");
 module_param_named(abmlevel, amdgpu_dm_abm_level, uint, 0444);
 
+/**
+ * DOC: tmz (int)
+ * Trusted Memory Zone (TMZ) is a method to protect data being written
+ * to or read from memory.
+ *
+ * The default value: 0 (off).  TODO: change to auto till it is completed.
+ */
+MODULE_PARM_DESC(tmz, "Enable TMZ feature (-1 = auto, 0 = off (default), 1 = on)");
+module_param_named(tmz, amdgpu_tmz, int, 0444);
+
 static const struct pci_device_id pciidlist[] = {
 #ifdef  CONFIG_DRM_AMDGPU_SI
 	{0x1002, 0x6780, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TAHITI},