Anacapa: Platform: Add mdio configuration function

fboss/platform/platform_manager/ConfigValidator.cpp

@@ -36,7 +36,8 @@ constexpr auto kSymlinkDirs = {
     "gpiochips",
     "xcvrs",
     "flashes",
-    "watchdogs"};
+    "watchdogs",
+    "mdio-busses"};
 // Supported modalias - spidev +
 // https://github.com/torvalds/linux/blob/master/drivers/spi/spidev.c#L702
 constexpr auto kSpiDevModaliases = {
@@ -287,6 +288,9 @@ bool ConfigValidator::isValidPciDeviceConfig(
   for (const auto& config : *pciDeviceConfig.miscCtrlConfigs()) {
     fpgaIpBlockConfigs.push_back(config);
   }
+  for (const auto& config : *pciDeviceConfig.mdioBusConfigs()) {
+    fpgaIpBlockConfigs.push_back(config);
+  }
 
   std::set<std::string> uniqueNames{};
   for (const auto& config : fpgaIpBlockConfigs) {
@@ -455,7 +459,8 @@ bool ConfigValidator::isValidDeviceName(
               *pciDeviceConfig.gpioChipConfigs(),
               *pciDeviceConfig.watchdogConfigs(),
               *pciDeviceConfig.infoRomConfigs(),
-              *pciDeviceConfig.miscCtrlConfigs())) {
+              *pciDeviceConfig.miscCtrlConfigs(),
+              *pciDeviceConfig.mdioBusConfigs())) {
         return true;
       }
     }

fboss/platform/platform_manager/ExplorationSummary.h

@@ -26,6 +26,7 @@ enum class ExplorationErrorType {
   PCI_SUB_DEVICE_CREATE_XCVR_CTRL,
   PCI_SUB_DEVICE_CREATE_INFO_ROM,
   PCI_SUB_DEVICE_CREATE_MISC_CTRL,
+  PCI_SUB_DEVICE_CREATE_MDIO_BUS,
   IDPROM_READ,
   SLOT_PM_UNIT_ABSENCE,
   SLOT_PRESENCE_CHECK,
@@ -73,6 +74,8 @@ constexpr const char* toExplorationErrorTypeStr(
       return "pci_sub_device_create_info_rom";
     case ExplorationErrorType::PCI_SUB_DEVICE_CREATE_MISC_CTRL:
       return "pci_sub_device_create_misc_ctrl";
+    case ExplorationErrorType::PCI_SUB_DEVICE_CREATE_MDIO_BUS:
+      return "pci_sub_device_create_mdio_bus";
     case ExplorationErrorType::IDPROM_READ:
       return "idprom_read";
     case ExplorationErrorType::SLOT_PM_UNIT_ABSENCE:

fboss/platform/platform_manager/PciExplorer.cpp

@@ -289,6 +289,15 @@ std::string PciExplorer::createFanPwmCtrl(
       pciDevice, *fanPwmCtrlConfig.fpgaIpBlockConfig(), instanceId);
 }
 
+std::string PciExplorer::createMdioBus(
+    const PciDevice& pciDevice,
+    const FpgaIpBlockConfig& mdioBusConfig,
+    uint32_t instanceId) {
+  auto auxData = getAuxData(mdioBusConfig, instanceId);
+  create(pciDevice, mdioBusConfig, auxData);
+  return getMdioBusSysfsPath(pciDevice, mdioBusConfig, instanceId);
+}
+
 void PciExplorer::createFpgaIpBlock(
     const PciDevice& pciDevice,
     const FpgaIpBlockConfig& fpgaIpBlockConfig,
@@ -690,6 +699,25 @@ std::string PciExplorer::getXcvrCtrlSysfsPath(
       *fpgaIpBlockConfig.pmUnitScopedName());
 }
 
+std::string PciExplorer::getMdioBusSysfsPath(
+    const PciDevice& pciDevice,
+    const FpgaIpBlockConfig& fpgaIpBlockConfig,
+    uint32_t instanceId) {
+  std::string expectedEnding =
+      fmt::format(".{}.{}", *fpgaIpBlockConfig.deviceName(), instanceId);
+  for (const auto& dirEntry : fs::directory_iterator(pciDevice.sysfsPath())) {
+    if (dirEntry.path().string().ends_with(expectedEnding)) {
+      return Utils().resolveMdioBusCharDevPath(*fpgaIpBlockConfig.deviceName(), instanceId);
+    }
+  }
+  throw PciSubDeviceRuntimeError(
+      fmt::format(
+          "Couldn't find MdioBus {} under {}",
+          *fpgaIpBlockConfig.deviceName(),
+          pciDevice.sysfsPath()),
+      *fpgaIpBlockConfig.pmUnitScopedName());
+}
+
 bool PciExplorer::isPciSubDeviceReady(
     const PciDevice& pciDevice,
     const FpgaIpBlockConfig& fpgaIpBlockConfig,

fboss/platform/platform_manager/PciExplorer.h

@@ -121,6 +121,13 @@ class PciExplorer {
       const FanPwmCtrlConfig& fanPwmCtrlConfig,
       uint32_t instanceId);
 
+  // Create the mdio_bus based on the given FpgaIpBlockConfig residing
+  // at the given PciDevice path. Throw std::runtime_error on failure.
+  std::string createMdioBus(
+      const PciDevice& pciDevice,
+      const FpgaIpBlockConfig& mdioBusConfig,
+      uint32_t instanceId);
+
   // Create the generic device block based on the given FpgaIpBlockConfig
   // residing at the given PciDevice. Throw std::runtime_error on failure.
   void createFpgaIpBlock(
@@ -169,6 +176,10 @@ class PciExplorer {
       const PciDevice& pciDevice,
       const FpgaIpBlockConfig& fpgaIpBlockConfig,
       uint32_t instanceId);
+  std::string getMdioBusSysfsPath(
+      const PciDevice& pciDevice,
+      const FpgaIpBlockConfig& fpgaIpBlockConfig,
+      uint32_t instanceId);
   bool isPciSubDeviceReady(
       const PciDevice& pciDevice,
       const FpgaIpBlockConfig& fpgaIpBlockConfig,

fboss/platform/platform_manager/PlatformExplorer.cpp

@@ -645,6 +645,18 @@ void PlatformExplorer::explorePciDevices(
         [&](const auto& miscCtrlConfig) {
           pciExplorer_.createFpgaIpBlock(pciDevice, miscCtrlConfig, instId++);
         });
+    createPciSubDevices(
+        slotPath,
+        *pciDeviceConfig.mdioBusConfigs(),
+        ExplorationErrorType::PCI_SUB_DEVICE_CREATE_MDIO_BUS,
+        [&](const auto& mdioBusConfig) {
+          auto mdioBusSysfsPath =
+              pciExplorer_.createMdioBus(pciDevice, mdioBusConfig, instId++);
+          dataStore_.updateCharDevPath(
+              Utils().createDevicePath(
+                  slotPath, *mdioBusConfig.pmUnitScopedName()),
+              mdioBusSysfsPath);
+        });
   }
 }
 
@@ -691,7 +703,8 @@ void PlatformExplorer::createDeviceSymLink(
     } else if (
         linkParentPath.string() == "/run/devmap/gpiochips" ||
         linkParentPath.string() == "/run/devmap/flashes" ||
-        linkParentPath.string() == "/run/devmap/watchdogs") {
+        linkParentPath.string() == "/run/devmap/watchdogs" ||
+        linkParentPath.string() == "/run/devmap/mdio-busses") {
       targetPath = devicePathResolver_.resolvePciSubDevCharDevPath(devicePath);
     } else if (linkParentPath.string() == "/run/devmap/xcvrs") {
       auto xcvrName = linkPath.substr(linkParentPath.string().length() + 1);

fboss/platform/platform_manager/Utils.cpp

@@ -114,6 +114,21 @@ std::string Utils::resolveWatchdogCharDevPath(const std::string& sysfsPath) {
   return charDevPath;
 }
 
+std::string Utils::resolveMdioBusCharDevPath(
+    std::string deviceName,
+    uint32_t instanceId) {
+  auto failMsg = "Failed to resolve mdio_bus CharDevPath";
+  auto charDevPath = fmt::format("/dev/ioc_{}.{}", deviceName, instanceId);
+  if (!fs::exists(charDevPath)) {
+    throw std::runtime_error(
+        fmt::format(
+            "{}. Reason: {} does not exist in the system",
+            failMsg,
+            charDevPath));
+  }
+  return charDevPath;
+}
+
 bool Utils::checkDeviceReadiness(
     std::function<bool()>&& isDeviceReadyFunc,
     const std::string& onWaitMsg,

fboss/platform/platform_manager/Utils.h

@@ -32,6 +32,12 @@ class Utils {
   // Throws an exception when it fails to resolve CharDevicePath
   std::string resolveWatchdogCharDevPath(const std::string& sysfsPath);
 
+  // Explore and resolve MdioBus's CharDevicePath for given SysfsPath.
+  // Throws an exception when it fails to resolve CharDevicePath
+  std::string resolveMdioBusCharDevPath(
+      std::string deviceName,
+      uint32_t instanceId);
+
   bool checkDeviceReadiness(
       std::function<bool()>&& isDeviceReadyFunc,
       const std::string& onWaitMsg,

fboss/platform/platform_manager/platform_manager_config.thrift

@@ -403,7 +403,8 @@ struct PciDeviceConfig {
   12: list<XcvrCtrlConfig> xcvrCtrlConfigs;
   13: list<FpgaIpBlockConfig> infoRomConfigs;
   14: list<FpgaIpBlockConfig> miscCtrlConfigs;
-  15: optional string desiredDriver;
+  15: list<FpgaIpBlockConfig> mdioBusConfigs;
+  16: optional string desiredDriver;
 }
 
 // These are the PmUnit slot types. Examples: "PIM_SLOT", "PSU_SLOT" and

fboss/platform/platform_manager/tests/ConfigValidatorTest.cpp

@@ -328,6 +328,7 @@ TEST(ConfigValidatorTest, Symlink) {
   EXPECT_TRUE(ConfigValidator().isValidSymlink("/run/devmap/eeproms/EEPROM"));
   EXPECT_TRUE(ConfigValidator().isValidSymlink("/run/devmap/sensors/sensor1"));
   EXPECT_TRUE(ConfigValidator().isValidSymlink("/run/devmap/i2c-busses/bus"));
+  EXPECT_TRUE(ConfigValidator().isValidSymlink("/run/devmap/mdio-busses/bus"));
 }
 
 TEST(ConfigValidatorTest, DevicePath) {