drivers/at86rf215: implement Battery Monitor

drivers/at86rf215/Kconfig

@@ -12,6 +12,24 @@ menuconfig KCONFIG_USEMODULE_AT86RF215
 
 if KCONFIG_USEMODULE_AT86RF215
 
+menuconfig KCONFIG_USEMODULE_AT86RF215_BATMON
+    bool "AT86RF215 Battery Monitor"
+    depends on USEMODULE_AT86RF215
+    help
+        Configure the AT86RF215 battery monitor using Kconfig.
+
+config AT86RF215_BATMON_THRESHOLD
+    int "Treshold voltage (in mV) of the battery monitor"
+    range 1700 3675
+    default 1800
+    depends on KCONFIG_USEMODULE_AT86RF215_BATMON
+    help
+        If the supply voltage falls below the configured threshold
+        a SYS_BUS_POWER_EVENT_LOW_VOLTAGE event is generated on the
+        SYS_BUS_POWER bus.
+
+        Battery Monitoring is disabled when the device is in Deep Sleep.
+
 config AT86RF215_USE_CLOCK_OUTPUT
     bool "Enable clock output"
     help

drivers/at86rf215/Makefile.dep

@@ -9,6 +9,10 @@ ifeq (,$(filter at86rf215_subghz at86rf215_24ghz,$(USEMODULE)))
   DEFAULT_MODULE += at86rf215_24ghz
 endif
 
+ifneq (,$(filter at86rf215_batmon,$(USEMODULE)))
+  USEMODULE += sys_bus_power
+endif
+
 DEFAULT_MODULE += netdev_ieee802154_multimode
 
 DEFAULT_MODULE += netdev_ieee802154_oqpsk

drivers/at86rf215/at86rf215_getset.c

@@ -396,3 +396,49 @@ bool at86rf215_set_idle_from_rx(at86rf215_t *dev, uint8_t state)
 
     return false;
 }
+
+int at86rf215_enable_batmon(at86rf215_t *dev, unsigned voltage)
+{
+    uint8_t bmdvc;
+
+    /* only configure BATMON on one interface */
+    if (!is_subGHz(dev) && dev->sibling != NULL) {
+        dev = dev->sibling;
+    }
+
+    /* ensure valid range */
+    if (voltage < 1700 || voltage > 3675) {
+        return -ERANGE;
+    }
+
+    if (voltage > 2500) {
+        /* high range */
+        bmdvc = (voltage - 2550 + 37) / 75;
+        DEBUG("[at86rf215] BATMON set to %u mV\n", 2550 + 75 * bmdvc);
+
+        bmdvc |= BMDVC_BMHR_MASK;
+    } else {
+        /* low range */
+        bmdvc  = (voltage - 1700 + 25) / 50;
+        DEBUG("[at86rf215] BATMON set to %u mV\n", 1700 + 50 * bmdvc);
+    }
+
+    /* set batmon threshold */
+    at86rf215_reg_write(dev, RG_RF_BMDVC, bmdvc);
+
+    /* enable interrupt */
+    at86rf215_reg_or(dev, dev->RF->RG_IRQM, RF_IRQ_BATLOW);
+
+    return 0;
+}
+
+void at86rf215_disable_batmon(at86rf215_t *dev)
+{
+    /* only configure BATMON on one interface */
+    if (!is_subGHz(dev) && dev->sibling != NULL) {
+        dev = dev->sibling;
+    }
+
+    /* disable interrupt */
+    at86rf215_reg_and(dev, dev->RF->RG_IRQM, ~RF_IRQ_BATLOW);
+}

drivers/at86rf215/at86rf215_internal.c

@@ -69,6 +69,11 @@ int at86rf215_hardware_reset(at86rf215_t *dev)
         return -ENODEV;
     }
 
+    /* enable battery monitor */
+    if (IS_ACTIVE(MODULE_AT86RF215_BATMON)) {
+        at86rf215_enable_batmon(dev, CONFIG_AT86RF215_BATMON_THRESHOLD);
+    }
+
     /* clear interrupts */
     at86rf215_reg_read(dev, RG_RF09_IRQS);
     at86rf215_reg_read(dev, RG_RF24_IRQS);

drivers/at86rf215/at86rf215_netdev.c

@@ -30,6 +30,8 @@
 #include "net/netdev/ieee802154.h"
 #include "net/gnrc/netif/internal.h"
 
+#include "sys/bus.h"
+
 #include "at86rf215.h"
 #include "at86rf215_netdev.h"
 #include "at86rf215_internal.h"
@@ -551,6 +553,22 @@ static int _set(netdev_t *netdev, netopt_t opt, const void *val, size_t len)
             res = sizeof(netopt_enable_t);
             break;
 
+#ifdef MODULE_AT86RF215_BATMON
+        case NETOPT_BATMON:
+            assert(len <= sizeof(uint16_t));
+            {
+                uint16_t mV = *(const uint16_t *)val;
+                if (mV) {
+                    res = at86rf215_enable_batmon(dev, mV);
+                    res = (res == 0) ? (int)sizeof(uint16_t) : res;
+                } else {
+                    at86rf215_disable_batmon(dev);
+                    res = sizeof(uint16_t);
+                }
+            }
+            break;
+#endif
+
         case NETOPT_RETRANS:
             assert(len <= sizeof(uint8_t));
             dev->retries_max =  *((const uint8_t *)val);
@@ -1052,6 +1070,14 @@ static void _isr(netdev_t *netdev)
         }
     }
 
+    /* Handle Low Battery IRQ */
+#if MODULE_AT86RF215_BATMON
+    if ((rf_irq_mask & RF_IRQ_BATLOW)) {
+        msg_bus_t *bus = sys_bus_get(SYS_BUS_POWER);
+        msg_bus_post(bus, SYS_BUS_POWER_EVENT_LOW_VOLTAGE, NULL);
+    }
+#endif
+
     /* exit early if the interrupt was not for this interface */
     if (!((bb_irq_mask & bb_irqs_enabled) ||
           (rf_irq_mask & (RF_IRQ_EDC | RF_IRQ_TRXRDY)) || timeout)) {

drivers/include/at86rf215.h

@@ -123,6 +123,16 @@ enum {
 #endif
 /** @} */
 
+/**
+ * @name    Default Battery Monitor trigger threshold (in mV)
+ *          if battery monitoring is enabled
+ * @{
+ */
+#ifndef CONFIG_AT86RF215_BATMON_THRESHOLD
+#define CONFIG_AT86RF215_BATMON_THRESHOLD       (1800)
+#endif
+/** @} */
+
 /**
  * @name    Default PHY Mode
  * @{
@@ -591,6 +601,24 @@ void at86rf215_tx_done(at86rf215_t *dev);
  */
 bool at86rf215_cca(at86rf215_t *dev);
 
+/**
+ * @brief   Generate an interrupt if supply voltage drops below the configured
+ *          threshold.
+ *
+ * @param[in] dev           device to configure
+ * @param[in] voltage       Threshold voltage in mV
+ *
+ * @return                  0 on success, error otherwise
+ */
+int at86rf215_enable_batmon(at86rf215_t *dev, unsigned voltage);
+
+/**
+ * @brief   Disable the Battery Monitor interrupt.
+ *
+ * @param[in] dev           device to configure
+ */
+void at86rf215_disable_batmon(at86rf215_t *dev);
+
 #ifdef __cplusplus
 }
 #endif