[PATCH v3 3/3] documentation: misc: intel_sysid: Add the system id sysfs documentation for Altera(Intel) FPGA platform

[kah.jing.lee@intel.com]

From: Kah Jing Lee <kah.jing.lee@intel.com>

This sysfs documentation is created for Altera(Intel) FPGA platform
System ID soft IP. The Altera(Intel) Sysid component is generally
part of an FPGA design.
The component can be hotplugged when the FPGA is reconfigured.

Based on an initial contribution from Ley Foon Tan at Altera
Signed-off-by: Kah Jing Lee <kah.jing.lee@intel.com>
Reviewed-by: Zhou Furong <furong.zhou@intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

---
v2->v3:
- Updated kernel version & date
- Added format for sysid & builtime output
---
---
 .../testing/sysfs-devices-platform-soc-sysid  | 41 +++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-platform-soc-sysid

diff --git a/Documentation/ABI/testing/sysfs-devices-platform-soc-sysid b/Documentation/ABI/testing/sysfs-devices-platform-soc-sysid
new file mode 100644
index 000000000000..6e40d154601f
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-platform-soc-sysid
@@ -0,0 +1,41 @@
+What:		/sys/devices/platform/soc@X/soc:base_fpga_region/
+soc:base_fpga_region:fpga_pr_region0/XXXXXXXX.sysid/
+Date:		July 2022
+KernelVersion:	v5.20
+Contact:	Kah Jing Lee <kah.jing.lee@intel.com>
+Description:
+		The soc@X/soc:base_fpga_region/soc:base_fpga_region:fpga_pr_region0/
+		XXXXXXXX.sysid/ directory contains read-only attributes exposing
+		information about an System ID soft IP device. The X values could vary,
+		based on the FPGA platform System ID soft IP register address.
+
+What:		.../XXXXXXX.sysid/sysid
+Date:		July 2022
+KernelVersion:	v5.20
+Contact:	Kah Jing Lee <kah.jing.lee@intel.com>
+Description:
+		The .../XXXXXXX.sysid/sysid file contains the System ID for the FPGA
+		platform which is unique for the platform type and can be used for
+		checking the platform type for software download purposes. Sysid value
+		reported is in numerical format, and can also be printed in hex format
+		for human-readable string.
+		E.g:
+			root@agilex:~# cat /sys/bus/platform/drivers/altera_sysid/
+				f9000900.sysid/sysid/id
+			4207856382
+			root@agilex:~# cat /sys/bus/platform/drivers/altera_sysid/
+				f9000900.sysid/sysid/id | xargs printf "0x%08x\n"
+			0xfacecafe
+
+What:		.../XXXXXXX.sysid/buildtime
+Date:		July 2022
+KernelVersion:	v5.20
+Contact:	Kah Jing Lee <kah.jing.lee@intel.com>
+Description:
+		The .../XXXXXXX.sysid/buildtime file contains the buildtime for the
+		FPGA board file generation. Buildtime value reported in
+		<Unix timestamp> (YYYY-mm-dd HH:MM:SS UTC) format.
+		E.g:
+			root@agilex:~# cat /sys/bus/platform/drivers/altera_sysid/
+				f9000900.sysid/sysid/timestamp
+			1637751409 (2021-11-24 10:56:49 UTC)
-- 
2.25.1