drm/amdgpu: Fix null pointer dereference

amdgpu_reg_state_sysfs_fini could be invoked at the
time when asic_func is even not initialized, i.e.,
amdgpu_discovery_init fails for some reason.

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amdgpu: Fix null pointer dereference

amdgpu_reg_state_sysfs_fini could be invoked at the
time when asic_func is even not initialized, i.e.,
amdgpu_discovery_init fails for some reason.

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drm/amdgpu: Add reg_state sysfs attribute

Add reg_state attribute to fetch the register snapshot of different
IPs like XGMI, WAFL,PCIE and USR. To get a snapshot for a particular IP
1) Open the sysfs file
2) Seek to the offset as defined in amdgpu_sysfs_reg_offset
3) Read

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amdgpu: add amdgpu_reg_state.h

This header defines the reg state structures exposed via
sysfs for umr debugging.

v2: add content type

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>