This patch bring in a documentation for UltraSoc SMB drivers. It simple descripts the device, sysfs interface and the firmware bindings.
Signed-off-by: Qi Liu liuqi115@huawei.com --- .../trace/coresight/ultrasoc-smb.rst | 80 +++++++++++++++++++ 1 file changed, 80 insertions(+) create mode 100644 Documentation/trace/coresight/ultrasoc-smb.rst
diff --git a/Documentation/trace/coresight/ultrasoc-smb.rst b/Documentation/trace/coresight/ultrasoc-smb.rst new file mode 100644 index 000000000000..b4cfea82deb8 --- /dev/null +++ b/Documentation/trace/coresight/ultrasoc-smb.rst @@ -0,0 +1,80 @@ +.. SPDX-License-Identifier: GPL-2.0 + +====================================== +UltraSoc - HW Assisted Tracing on SoC +====================================== + :Author: Qi Liu liuqi115@huawei.com + :Date: March 2022 + +Introduction +------------ + +UltraSoc SMB is a per SCCL(Super CPU Cluster) hardware, and it provides a way to buffer and store +CPU trace messages in a region of shared system memory. SMB is plugged as +a coresight sink device and the corresponding trace generators (ETM) are +plugged in as source devices. + +Sysfs files and directories +--------------------------- + +The SMB devices appear on the existing coresight bus alongside the other +coresight devices:: + + $# ls /sys/bus/coresight/devices/ + ultra_smb0 ultra_smb1 ultra_smb2 ultra_smb3 + +The ``ultra_smb<N>`` named SMB associated with SCCL.:: + + $# ls /sys/bus/coresight/devices/ultra_smb0 + enable_sink mgmt + $# ls /sys/bus/coresight/devices/ultra_smb0/mgmt + buf_size buf_status read_pos write_pos + +*Key file items are:-* + * ``read_pos``: Shows the value held by UltraSoc SMB Read Pointer register. + * ``write_pos``: Shows the value held by UltraSoc SMB Write Pointer register. + * ``buf_status``: Shows the value held by UltraSoc SMB status register. + BIT(0) is zero means buffer is empty. + * ``buf_size``: Shows the buffer size of each UltraSoc SMB device. + +Firmware Bindings +--------------------------- + +Firmware binding of SMB device describes SMB device indentifier, resource +information and graph structure. + +SMB is platform device and device id is "HISI03A1", resource of device is +declared using the _CRS method. Each SMB must present two base address, +the first one is the configuration base address of SMB device, the second +one is the base address of shared system memory. + +examples:: + + Device(USMB) { \ + Name(_HID, "HISI03A1") \ + Name(_CRS, ResourceTemplate() { \ + MEM_RESRC(0x95100000, 0x951FFFFF, 0x100000) \ + MEM_RESRC(0x50000000, 0x53FFFFFF, 0x4000000) \ + }) \ + Name(_DSD, Package() { \ + ToUUID("ab02a46b-74c7-45a2-bd68-f7d344ef2153"), \ + /* Use CoreSight Graph ACPI bindings to describe connections topology */ + Package() { \ + 0, \ + 1, \ + Package() { \ + 1, \ + ToUUID("3ecbc8b6-1d0e-4fb3-8107-e627f805c6cd"), \ + 8, \ + Package() {0x8, 0, _SB.S00.SL11.CL28.F008, 0}, \ + Package() {0x9, 0, _SB.S00.SL11.CL29.F009, 0}, \ + Package() {0xa, 0, _SB.S00.SL11.CL2A.F010, 0}, \ + Package() {0xb, 0, _SB.S00.SL11.CL2B.F011, 0}, \ + Package() {0xc, 0, _SB.S00.SL11.CL2C.F012, 0}, \ + Package() {0xd, 0, _SB.S00.SL11.CL2D.F013, 0}, \ + Package() {0xe, 0, _SB.S00.SL11.CL2E.F014, 0}, \ + Package() {0xf, 0, _SB.S00.SL11.CL2F.F015, 0}, \ + } \ + } \ + }) \ + }