Remove AccessMethod option from watchdog thrift interface

Summary:
The BSP API specification is clear that watchdogs must be accessed via the chardev interface: https://www.internalfb.com/code/fbsource/[e4f6abca5b20ff588ff625c57d8425c2cb42d19f]/fbcode/fboss/docs/bsp_api_specification.md#2-2-7-fan-watchdog-watch

meaning all watchdogs will be accessed with sysfs paths. No need to have the `AccessMethod` for watchdog in the fan_service thrift interface.

Reviewed By: somasun

Differential Revision: D68866366

fbshipit-source-id: d37e1db5e4135f41ac0f54d874add72a84c8b16d

Author: Scott8440

fboss/platform/configs/montblanc/fan_service.json

@@ -7,10 +7,7 @@
   "pwmLowerThreshold": 25,
   "pwmUpperThreshold": 70,
   "watchdog": {
-    "access": {
-      "accessType": "ACCESS_TYPE_SYSFS",
-      "path": "/run/devmap/watchdogs/FAN_WATCHDOG"
-    },
+    "sysfsPath": "/run/devmap/watchdogs/FAN_WATCHDOG",
     "value": 0
   },
   "controlInterval": {

fboss/platform/fan_service/Bsp.cpp

@@ -126,30 +126,20 @@ void Bsp::closeWatchdog() {
 }
 
 bool Bsp::writeToWatchdog(const std::string& value) {
-  int rc = true;
   std::string cmdLine;
   if (!config_.watchdog().has_value()) {
-    return rc;
+    return false;
   }
-  AccessMethod access = *config_.watchdog()->access();
-  if (*access.accessType() == constants::ACCESS_TYPE_UTIL()) {
-    cmdLine = fmt::format("{} {}", *access.path(), value);
-    auto [exitStatus, standardOut] = PlatformUtils().execCommand(cmdLine);
-    rc = exitStatus;
-  } else if (*access.accessType() == constants::ACCESS_TYPE_SYSFS()) {
-    try {
-      if (!watchdogFd_.has_value()) {
-        watchdogFd_ = open(access.path()->c_str(), O_WRONLY);
-      }
-      rc = writeFd(watchdogFd_.value(), value);
-    } catch (std::exception& e) {
-      XLOG(ERR) << "Could not write to watchdog: " << e.what();
-      return false;
+  try {
+    auto sysfsPath = config_.watchdog()->sysfsPath()->c_str();
+    if (!watchdogFd_.has_value()) {
+      watchdogFd_ = open(sysfsPath, O_WRONLY);
     }
-  } else {
-    throw facebook::fboss::FbossError("Invalid watchdog access type!");
+    return writeFd(watchdogFd_.value(), value);
+  } catch (std::exception& e) {
+    XLOG(ERR) << "Could not write to watchdog: " << e.what();
+    return false;
   }
-  return rc;
 }
 
 std::vector<std::pair<std::string, float>> Bsp::processOpticEntries(

fboss/platform/fan_service/ConfigValidator.cpp

@@ -66,9 +66,8 @@ bool ConfigValidator::isValid(const FanServiceConfig& config) {
   }
 
   if (config.watchdog()) {
-    if (!accessMethodTypes.count(*config.watchdog()->access()->accessType())) {
-      XLOG(ERR) << "Invalid access method for watchdog config: "
-                << *config.watchdog()->access()->accessType();
+    if (!config.watchdog()->sysfsPath()->c_str()) {
+      XLOG(ERR) << "Watchdog sysfs path must have a non-empty value";
       return false;
     }
   }

fboss/platform/fan_service/if/fan_service_config.thrift

@@ -83,7 +83,7 @@ struct Fan {
 }
 
 struct Watchdog {
-  1: AccessMethod access;
+  1: string sysfsPath;
   2: i32 value;
 }