GNSS change only: option for uDeviceClose() to call uGnssPwrOffBackup().

When uDeviceClose() is called with powerOff set to true on a GNSS device, the function uGnssPwrOff() is internally called to power the GNSS device down.  This switches off the positioning engine but does not put the device into the lowest power state; the reason for this is that the mechanism through which the GNSS device is restored from back-up mode may require additional pins to be connected; e.g. toggling the I2C pins of the GNSS device will NOT cause it to return to normal operation (toggling the SPI or UART lines will).

With this commit the application _can_ now set a Boolean flag, powerOffToBackup, in uDeviceCfgGnss_t; this will cause the device layer to call uGnssPwrOffBackup() instead of uGnssPwrOff().  It is up to the application to know how to restore the GNSS device to normal operation afterwards, e.g. it may be necessary to toggle RESET_N or connect a separate GPIO line; please refer to the section of the integration manual for your GNSS device that covers backup modes for details.

common/device/api/u_device.h

@@ -427,6 +427,27 @@ typedef struct {
                                       the GNSS device is using is NOT the default
                                       #U_GNSS_I2C_ADDRESS; otherwise let the
                                       compiler initialise this to 0. */
+    bool powerOffToBackup;       /**< Normally the GNSS device will be powered
+                                      off by the device layer with a call to
+                                      uGnssPwrOff(), however this only stops
+                                      GNSS; for least power consumption the
+                                      device should be powered off to back-up
+                                      mode with a call to uGnssPwrOffBackup();
+                                      setting this item to true will cause
+                                      uGnssPwrOffBackup() to be called instead
+                                      of uGnssPwrOff().  HOWEVER note that the
+                                      mechanism through which the GNSS device
+                                      is restored from back-up mode may require
+                                      additional pins to be connected; e.g.
+                                      toggling the I2C pins of the GNSS device
+                                      will NOT cause it to return to normal
+                                      operation (toggling the SPI and UART
+                                      lines will).  Instead, for this case
+                                      the application must toggle the RESET_N
+                                      line or a chosen GPIO line.  For more
+                                      details refer to the section of the
+                                      integration manual for your GNSS device
+                                      that covers backup modes. */
     /* Add any new version 0 structure items to the end here.
      *
      * IMPORTANT IMPORTANT IMPORTANT IMPORTANT IMPORTANT IMPORTANT:

common/device/src/u_device_private_gnss.c

@@ -91,7 +91,8 @@ const uGnssTransportType_t gDeviceToGnssTransportType[] = {
 // Populate the GNSS device context
 static void populateContext(uDeviceGnssInstance_t *pContext,
                             uGnssTransportHandle_t gnssTransportHandle,
-                            uDeviceTransportType_t deviceTransportType)
+                            uDeviceTransportType_t deviceTransportType,
+                            bool powerOffToBackup)
 {
     switch (deviceTransportType) {
         case U_DEVICE_TRANSPORT_TYPE_UART:
@@ -114,6 +115,7 @@ static void populateContext(uDeviceGnssInstance_t *pContext,
             break;
     }
     pContext->deviceTransportType = deviceTransportType;
+    pContext->powerOffToBackup = powerOffToBackup;
 }
 
 // Do all the leg-work to remove a GNSS device.
@@ -125,7 +127,11 @@ static int32_t removeDevice(uDeviceHandle_t devHandle, bool powerOff)
     if (pContext != NULL) {
         errorCode = (int32_t) U_ERROR_COMMON_SUCCESS;
         if (powerOff) {
-            errorCode = uGnssPwrOff(devHandle);
+            if (pContext->powerOffToBackup) {
+                errorCode = uGnssPwrOffBackup(devHandle);
+            } else {
+                errorCode = uGnssPwrOff(devHandle);
+            }
             if (errorCode == 0) {
                 // This will destroy the instance
                 uGnssRemove(devHandle);
@@ -160,7 +166,8 @@ static int32_t addDevice(uGnssTransportHandle_t gnssTransportHandle,
     pContext = (uDeviceGnssInstance_t *) pUPortMalloc(sizeof(uDeviceGnssInstance_t));
     if (pContext != NULL) {
         memset(pContext, 0, sizeof(*pContext));
-        populateContext(pContext, gnssTransportHandle, deviceTransportType);
+        populateContext(pContext, gnssTransportHandle, deviceTransportType,
+                        pCfgGnss->powerOffToBackup);
         // Add the GNSS instance, which actually creates pDeviceHandle
         errorCode = uGnssAdd((uGnssModuleType_t) pCfgGnss->moduleType,
                              gnssTransportType, gnssTransportHandle,

common/device/src/u_device_shared_gnss.h

@@ -53,6 +53,7 @@ typedef union {
 typedef struct {
     uDeviceGnssTransportHandle_t transportHandle;
     uDeviceTransportType_t deviceTransportType;
+    bool powerOffToBackup;
 } uDeviceGnssInstance_t;
 
 #ifdef __cplusplus

port/platform/zephyr/dts/bindings/u-blox,ubxlib-device-gnss.yaml

@@ -103,4 +103,8 @@ properties:
     gnss-uart2:
         type: boolean
         description: "Specify this flag if your UART connection is to the _second_ serial port of a GNSS device."
+# request that the device layer powers the GNSS device off to back-up state
+    power-off-to-backup:
+        type: boolean
+        description: "Specify this flag if you want uDeviceClose(), when called with powerOff true, to call uGnssPwrOffBackup() instead of just uGnssPwrOff(); refer to the integration manual for your GNSS device, the backup or power section, for what the application must do to restore the GNSS device to normal operation afterwards."
 # Note: there is no associated network configuration for the GNSS case

port/platform/zephyr/runner/boards/ubx_evkninab3_nrf52840.overlay

@@ -39,6 +39,7 @@
         module-type = "U_GNSS_MODULE_TYPE_M9";
         pin-enable-power = <1>;
         pin-data-ready = <36>;
+        power-off-to-backup;
     };
     cfg-device-gnss-1 {
         compatible = "u-blox,ubxlib-device-gnss";

port/platform/zephyr/src/u_port_board_cfg.c

@@ -713,6 +713,16 @@ static const int32_t gDeviceCfgGnssPinDataReady[] = {
                                  pin_data_ready)
 };
 
+/** Get whether the "power-off-to-backup" property is set
+ * for each ubxlib-device-gnss compatible device, in the
+ * order they appear in the device tree.
+ */
+static const bool gDeviceCfgGnssPowerOffToBackup[] = {
+    DT_FOREACH_STATUS_OKAY_VARGS(u_blox_ubxlib_device_gnss,
+                                 U_PORT_BOARD_CFG_GET_BOOLEAN,
+                                 power_off_to_backup)
+};
+
 #endif // #if DT_HAS_COMPAT_STATUS_OKAY(u_blox_ubxlib_device_gnss)
 
 /* ----------------------------------------------------------------
@@ -1166,11 +1176,14 @@ static void cfgGnss(uDeviceCfg_t *pCfg, int32_t index)
     pCfgGnss->pinEnablePower = gDeviceCfgGnssPinEnablePower[index];
     pCfgGnss->pinDataReady = gDeviceCfgGnssPinDataReady[index];
     pCfgGnss->i2cAddress = -1;
+    pCfgGnss->powerOffToBackup = gDeviceCfgGnssPowerOffToBackup[index];
     uPortLog("U_PORT_BOARD_CFG: using GNSS device \"%s\" from the device tree,"
-             " module-type %d with pin-enable-power %d (0x%02x), pin-data-ready %d (0x%02x)...\n",
+             " module-type %d with pin-enable-power %d (0x%02x),"
+             " pin-data-ready %d (0x%02x)%s...\n",
              gpCfgGnssDeviceName[index], pCfgGnss->moduleType,
              pCfgGnss->pinEnablePower, pCfgGnss->pinEnablePower,
-             pCfgGnss->pinDataReady, pCfgGnss->pinDataReady);
+             pCfgGnss->pinDataReady, pCfgGnss->pinDataReady,
+             pCfgGnss->powerOffToBackup ? ", power-off-to-backup" : "");
     // Don't need to check for NULL here as transport is a required field for GNSS
     x = getPort(gpDeviceCfgGnssTransportType[index], &(pCfg->transportType));
     switch (pCfg->transportType) {

port/platform/zephyr/test/u_zephyr_port_board_cfg_test.c

@@ -419,6 +419,7 @@ U_PORT_TEST_FUNCTION("[zephyrPortBoardCfg]", "zephyrPortBoardCfgBasic")
     U_PORT_TEST_ASSERT(pCfgGnss->i2cAddress == 0x43);
     U_PORT_TEST_ASSERT(pCfgGnss->pinEnablePower == 1);
     U_PORT_TEST_ASSERT(pCfgGnss->pinDataReady == 36);
+    U_PORT_TEST_ASSERT(pCfgGnss->powerOffToBackup);
     // Set the second valid configuration
     setDeviceCfg(&deviceCfg, &instance, U_DEVICE_TYPE_GNSS, "cfg-device-gnss-1");
     U_PORT_TEST_ASSERT(uPortBoardCfgDevice(&deviceCfg) == 0);
@@ -448,6 +449,7 @@ U_PORT_TEST_FUNCTION("[zephyrPortBoardCfg]", "zephyrPortBoardCfgBasic")
     U_PORT_TEST_ASSERT(pCfgGnss->moduleType == U_GNSS_MODULE_TYPE_M8);
     U_PORT_TEST_ASSERT(pCfgGnss->pinEnablePower == 2);
     U_PORT_TEST_ASSERT(pCfgGnss->pinDataReady == 37);
+    U_PORT_TEST_ASSERT(!pCfgGnss->powerOffToBackup);
     // Set the final valid configuration
     setDeviceCfg(&deviceCfg, &instance, U_DEVICE_TYPE_GNSS, "cfg-device-gnss-2");
     U_PORT_TEST_ASSERT(uPortBoardCfgDevice(&deviceCfg) == 0);
@@ -468,6 +470,7 @@ U_PORT_TEST_FUNCTION("[zephyrPortBoardCfg]", "zephyrPortBoardCfgBasic")
     U_PORT_TEST_ASSERT(pCfgGnss->moduleType == U_GNSS_MODULE_TYPE_ANY);
     U_PORT_TEST_ASSERT(pCfgGnss->pinEnablePower == -1);
     U_PORT_TEST_ASSERT(pCfgGnss->pinDataReady == -1);
+    U_PORT_TEST_ASSERT(!pCfgGnss->powerOffToBackup);
 
     // Let debug printing catch up
     uPortTaskBlock(100);