[PATCH 2/3] firmware: zynqmp: Add sysfs entry for runtime features

[Ronak Jain]

Create sysfs entry for runtime feature configuration. Here the support
 is added for an over temperature and external watchdog feature.

The below listed path is used for runtime features configuration:
/sys/devices/platform/firmware\:zynqmp-firmware/*

Here there are two files to configure features at runtime.
1. feature_config_id
2. feature_config_value

In order to configure an over temperature or external watchdog
 features, first the user need to select the valid config id and then
 the user can configure the value for selected feature config id.

Signed-off-by: Ronak Jain <ronak.jain at xilinx.com>
---
 .../ABI/stable/sysfs-driver-firmware-zynqmp   | 84 +++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/Documentation/ABI/stable/sysfs-driver-firmware-zynqmp b/Documentation/ABI/stable/sysfs-driver-firmware-zynqmp
index f5724bb5b462..2fde354715a5 100644
--- a/Documentation/ABI/stable/sysfs-driver-firmware-zynqmp
+++ b/Documentation/ABI/stable/sysfs-driver-firmware-zynqmp
@@ -113,3 +113,87 @@ Description:
                    # echo 0 > /sys/devices/platform/firmware\:zynqmp-firmware/health_status

 Users:         Xilinx
+
+What:          /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_*
+Date:          Aug 2021
+KernelVersion: 5.14
+Contact:       "Ronak Jain" <ronak.jain at xilinx.com>
+Description:
+               This sysfs interface allows to configure features at runtime.
+               The user can enable or disable features running at firmware.
+               Also, the user can configure the parameters of the features
+               at runtime. The supported features are over temperature and
+               external watchdog. Here, the external watchdog is completely
+               different than the /dev/watchdog as the external watchdog is
+               running on the firmware and it is used to monitor the health
+               of firmware not APU(Linux). Also, the external watchdog is
+               interfaced outside of the zynqmp soc.
+
+               By default the features are disabled in the firmware. The user
+               can enable features by querying appropriate config id of the
+               features.
+
+               The default limit for the over temperature is 90 Degree Celsius.
+               The default timer interval for the external watchdog is 570ms.
+
+               The supported config ids are for the feature configuration is,
+               1. PM_FEATURE_OVERTEMP_STATUS = 1, the user can enable or
+               disable the over temperature feature.
+               2. PM_FEATURE_OVERTEMP_VALUE = 2, the user can configure the
+               over temperature limit in Degree Celsius.
+               3. PM_FEATURE_EXTWDT_STATUS = 3, the user can enable or disable
+               the external watchdog feature.
+               4. PM_FEATURE_EXTWDT_VALUE = 4, the user can configure the
+               external watchdog feature.
+
+               Usage:
+
+               Enable over temperature feature
+               # echo 1 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_id
+               # echo 1 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+
+               Check whether the over temperature feature is enabled or not
+               # cat /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+               The expected result is 1.
+
+               Disable over temperature feature
+               # echo 1 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_id
+               # echo 0 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+
+               Check whether the over temperature feature is disabled or not
+               # cat /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+               The expected result is 0.
+
+               Configure over temperature limit to 50 Degree Celsius
+               # echo 2 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_id
+               # echo 50 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+
+               Check whether the over temperature limit is configured or not
+               # cat /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+               The expected result is 50.
+
+               Enable external watchdog feature
+               # echo 3 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_id
+               # echo 1 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+
+               Check whether the external watchdog feature is enabled or not
+               # cat /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+               The expected result is 1.
+
+               Disable external watchdog feature
+               # echo 3 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_id
+               # echo 0 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+
+               Check whether the external watchdog feature is disabled or not
+               # cat /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+               The expected result is 0.
+
+               Configure external watchdog timer interval to 500ms
+               # echo 4 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_id
+               # echo 500 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+
+               Check whether the external watchdog timer interval is configured or not
+               # cat /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
+               The expected result is 500.
+
+Users:         Xilinx
--
2.32.0.93.g670b81a

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