Improve SpiDevice error handling

Summary:
We have a confusing error because when SpiDevice fails, we treat that as its SpiMaster failed.
So if SpiDevice X fails, in error reporting it will be reported as that SpiMaster failed.

We create a symlink for each SpiDevice and it will fail if SpiDevice creation fails.
So without some context, kinda hard to grasp a reason for symlink failure because the SpiDevice creation failure would be reported under its SpiMaster device path.

Reviewed By: somasun

Differential Revision: D67031958

fbshipit-source-id: 0737a252786d3f1bfe4987c8075e2a78dd5f666a

fboss/platform/platform_manager/PciExplorer.cpp

@@ -499,45 +499,70 @@ std::map<std::string, std::string> PciExplorer::getSpiDeviceCharDevPaths(
       if (!re2::RE2::FullMatch(spiDevId, kSpiDevIdRe, &busNum, &chipSelect)) {
         continue;
       }
+      // Find corresponding SpiDeviceConfig
+      auto spiDeviceConfigItr = std::find_if(
+          spiMasterConfig.spiDeviceConfigs()->begin(),
+          spiMasterConfig.spiDeviceConfigs()->end(),
+          [chipSelect](auto spiDeviceConfig) {
+            return *spiDeviceConfig.chipSelect() == chipSelect;
+          });
+      if (spiDeviceConfigItr == spiMasterConfig.spiDeviceConfigs()->end()) {
+        throw PciSubDeviceRuntimeError(
+            fmt::format(
+                "Unexpected SpiDevice created at {}. \
+                No matching SpiDeviceConfig defined with ChipSelect {} for SpiDevice {}",
+                childDirEntry.path().string(),
+                chipSelect,
+                *spiDeviceConfigItr->pmUnitScopedName()),
+            *spiDeviceConfigItr->pmUnitScopedName());
+      }
       auto spiCharDevPath = fmt::format("/dev/spidev{}.{}", busNum, chipSelect);
       if (!fs::exists(spiCharDevPath)) {
         // For more details on the two commands:
         // https://github.com/torvalds/linux/blob/master/Documentation/spi/spidev.rst#device-creation-driver-binding
         // Overriding driver of the SpiDevice so spidev doesn't fail to probe.
-        PlatformUtils().execCommand(fmt::format(
-            "echo spidev > /sys/bus/spi/devices/{}/driver_override", spiDevId));
+        auto overrideDriver =
+            PlatformUtils()
+                .execCommand(fmt::format(
+                    "echo spidev > /sys/bus/spi/devices/{}/driver_override",
+                    spiDevId))
+                .first == 0;
+        if (!overrideDriver) {
+          throw PciSubDeviceRuntimeError(
+              fmt::format(
+                  "Failed overridng SpiDriver spidev to /sys/bus/spi/devices/{}/driver_override "
+                  "for SpiDevice {}",
+                  spiDevId,
+                  *spiDeviceConfigItr->pmUnitScopedName()),
+              *spiDeviceConfigItr->pmUnitScopedName());
+        }
         // Bind SpiDevice to spidev driver in order to create its char device.
-        PlatformUtils().execCommand(fmt::format(
-            "echo {} > /sys/bus/spi/drivers/spidev/bind", spiDevId));
+        auto bindSpiDev =
+            PlatformUtils()
+                .execCommand(fmt::format(
+                    "echo {} > /sys/bus/spi/drivers/spidev/bind", spiDevId))
+                .first == 0;
+        if (!bindSpiDev) {
+          throw PciSubDeviceRuntimeError(
+              fmt::format(
+                  "Failed binding SpiDevice {} to /sys/bus/spi/drivers/spidev/bind for SpiDevice {}",
+                  spiDevId,
+                  *spiDeviceConfigItr->pmUnitScopedName()),
+              *spiDeviceConfigItr->pmUnitScopedName());
+        }
         XLOG(INFO) << fmt::format(
-            "Completed binding SpiDevice {} to {} for SpiController {}",
+            "Completed initializing SpiDevice {} as {} for SpiDevice {}",
             spiDevId,
             spiCharDevPath,
-            *spiMasterConfig.fpgaIpBlockConfig()->pmUnitScopedName());
+            *spiDeviceConfigItr->pmUnitScopedName());
       } else {
         XLOG(INFO) << fmt::format(
-            "{} already exists. Skipping binding SpiDevice {} for SpiController {}",
+            "{} already exists. Skipping binding SpiDevice {} for SpiDevice {}",
             spiCharDevPath,
             spiDevId,
-            *spiMasterConfig.fpgaIpBlockConfig()->pmUnitScopedName());
-      }
-      auto itr = std::find_if(
-          spiMasterConfig.spiDeviceConfigs()->begin(),
-          spiMasterConfig.spiDeviceConfigs()->end(),
-          [chipSelect](auto spiDeviceConfig) {
-            return *spiDeviceConfig.chipSelect() == chipSelect;
-          });
-      if (itr == spiMasterConfig.spiDeviceConfigs()->end()) {
-        throw PciSubDeviceRuntimeError(
-            fmt::format(
-                "Unexpected SpiDevice created at {}. \
-                No matching SpiDeviceConfig defined with ChipSelect {} for SpiController {}",
-                childDirEntry.path().string(),
-                chipSelect,
-                *spiMasterConfig.fpgaIpBlockConfig()->pmUnitScopedName()),
-            *spiMasterConfig.fpgaIpBlockConfig()->pmUnitScopedName());
+            *spiDeviceConfigItr->pmUnitScopedName());
       }
-      spiCharDevPaths[*itr->pmUnitScopedName()] = spiCharDevPath;
+      spiCharDevPaths[*spiDeviceConfigItr->pmUnitScopedName()] = spiCharDevPath;
     }
   }
   return spiCharDevPaths;