[PATCH v9 6/9] docs: misc-devices: (smpro-misc) Add documentation

[Quan Nguyen <quan@os.amperecomputing.com>]

Adds documentation for the Ampere(R)'s Altra(R) SMpro misc driver.

Signed-off-by: Thu Nguyen <thu@os.amperecomputing.com>
Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
---
Changes in v9:
  + Update SPDX licence                          [Greg]

Changes in v8:
  + Update to reflect single value per sysfs     [Quan]

Changes in v7:
  + None

Changes in v6:
  + First introduced in v6 [Quan]

 Documentation/misc-devices/index.rst      |  1 +
 Documentation/misc-devices/smpro-misc.rst | 82 +++++++++++++++++++++++
 2 files changed, 83 insertions(+)
 create mode 100644 Documentation/misc-devices/smpro-misc.rst

diff --git a/Documentation/misc-devices/index.rst b/Documentation/misc-devices/index.rst
index b74b3b34a235..b40cd1b402f7 100644
--- a/Documentation/misc-devices/index.rst
+++ b/Documentation/misc-devices/index.rst
@@ -28,6 +28,7 @@ fit into other categories.
    oxsemi-tornado
    pci-endpoint-test
    smpro-errmon
+   smpro-misc
    spear-pcie-gadget
    uacce
    xilinx_sdfec
diff --git a/Documentation/misc-devices/smpro-misc.rst b/Documentation/misc-devices/smpro-misc.rst
new file mode 100644
index 000000000000..d21be4a09e69
--- /dev/null
+++ b/Documentation/misc-devices/smpro-misc.rst
@@ -0,0 +1,82 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel driver Ampere(R) Altra(R) SMpro miscellaneous
+====================================================
+
+Supported chips:
+
+  * Ampere(R) Altra(R)
+
+    Prefix: 'smpro'
+
+    Reference: Altra SoC BMC Interface Specification
+
+Author: Thu Nguyen <thu@os.amperecomputing.com>
+
+Description
+-----------
+
+This driver support the monitoring and configuration of various miscellaneous
+data provided by Ampere(R) Altra(R) SMpro processor.
+At this time, these include:
+
+  * Reading Boot Progress information
+  * Configuring SoC Power Limit
+
+Sysfs entries
+-------------
+
+1) Boot progress
+
+SMpro misc driver creates the sysfs files ``boot_progress``.
+The format of ``boot_progress`` file is as below::
+
+<boot stage><boot status><boot progress>
+
+Where:
+
+* Boot stage::
+
+    0: SMpro firmware booting.
+    1: PMpro firmware booting.
+    2: ATF BL1 firmware booting.
+    3: DDR initialization.
+    4: DDR training report status.
+    5: ATF BL2 firmware booting.
+    6: ATF BL31 firmware booting.
+    7: ATF BL32 firmware booting.
+    8: UEFI firmware booting.
+    9: OS booting.
+
+* Boot status::
+
+    0: Not started.
+    1: Started.
+    2: Complete without error.
+    3: Failure.
+
+* boot progress: 32 bits boot progress code
+
+The sysfs ``boot_progress`` only reports the boot state when the host is booting.
+If the host is already booted, it returns latest state.
+
+Example::
+
+    #cat boot_progress
+    0102808454A8
+
+2) SoC Power Limit
+
+SMpro misc driver creates the sysfs file ``soc_power_limit`` to get/set the SoC Power Limit.
+
+Reading this sysfs return the current setting of SoC Power Limit (W) in decimal string.
+Writing the desired value in decimal string to set the SoC Power Limit in Watt (W).
+The range of SoC Power Limit is 90-500(W) and will be ignored if out of range.
+
+Example::
+
+    #cat soc_power_limit
+    90
+    #echo 95 > soc_power_limit
+    #cat soc_power_limit
+    95
-- 
2.35.1