pbio/drv/charger: Move charge enable logic.

The charger module should be in charge of charging, not the battery module.

This ensures that the battery status getter is synchronized with the actual battery state. Before this commit, the battery could be charging before it was reflected in the charging state.

This will also give us more control to disable charging under certain charger error state conditions in the next commit.

Author: laurensvalk

lib/pbio/drv/charger/charger_mp2639a.c

@@ -22,12 +22,9 @@
 #include <pbdrv/adc.h>
 #include <pbdrv/charger.h>
 #include <pbdrv/gpio.h>
-#if PBDRV_CONFIG_CHARGER_MP2639A_MODE_PWM | PBDRV_CONFIG_CHARGER_MP2639A_ISET_PWM
 #include <pbdrv/pwm.h>
-#endif
-#if PBDRV_CONFIG_CHARGER_MP2639A_CHG_RESISTOR_LADDER
 #include <pbdrv/resistor_ladder.h>
-#endif
+#include <pbdrv/usb.h>
 #include <pbio/error.h>
 #include <pbio/util.h>
 
@@ -70,7 +67,13 @@ pbdrv_charger_status_t pbdrv_charger_get_status(void) {
     return pbdrv_charger_status;
 }
 
-void pbdrv_charger_enable(bool enable, pbdrv_charger_limit_t limit) {
+/**
+ * Enables or disables the charger.
+ *
+ * @param enable    True to enable the charger, false to disable.
+ * @param limit     The current limit to set. Only used on some platforms.
+ */
+static void pbdrv_charger_enable(bool enable, pbdrv_charger_limit_t limit) {
     #if PBDRV_CONFIG_CHARGER_MP2639A_ISET_PWM
 
     // Set the current limit (ISET) based on the type of charger attached.
@@ -116,6 +119,32 @@ void pbdrv_charger_enable(bool enable, pbdrv_charger_limit_t limit) {
     mode_pin_is_low = enable;
 }
 
+/**
+ * Enables the charger if USB is connected, otherwise disables charger.
+ */
+static void pbdrv_charger_enable_if_usb_connected(void) {
+    pbdrv_usb_bcd_t bcd = pbdrv_usb_get_bcd();
+    bool enable = bcd != PBDRV_USB_BCD_NONE;
+    pbdrv_charger_limit_t limit;
+
+    // This battery charger chip will automatically monitor VBUS and
+    // limit the current if the VBUS voltage starts to drop, so these limits
+    // are a bit looser than they could be.
+    switch (bcd) {
+        case PBDRV_USB_BCD_NONE:
+            limit = PBDRV_CHARGER_LIMIT_NONE;
+            break;
+        case PBDRV_USB_BCD_STANDARD_DOWNSTREAM:
+            limit = PBDRV_CHARGER_LIMIT_STD_MAX;
+            break;
+        default:
+            limit = PBDRV_CHARGER_LIMIT_CHARGING;
+            break;
+    }
+
+    pbdrv_charger_enable(enable, limit);
+}
+
 /**
  * Gets the current CHG signal status (inverted compared to /CHG pin state).
  */
@@ -174,6 +203,11 @@ PROCESS_THREAD(pbdrv_charger_mp2639a_process, ev, data) {
         PROCESS_WAIT_EVENT_UNTIL(ev == PROCESS_EVENT_TIMER && etimer_expired(&timer));
         etimer_restart(&timer);
 
+        // Enable charger chip based on USB state. We don't need to disable it
+        // on charger fault since the chip will automatically disable itself.
+        // If we disable it here we can't detect the fault condition.
+        pbdrv_charger_enable_if_usb_connected();
+
         chg_samples[chg_index] = read_chg();
 
         if (mode_pin_is_low) {

lib/pbio/include/pbdrv/charger.h

@@ -72,13 +72,6 @@ pbio_error_t pbdrv_charger_get_current_now(uint16_t *current);
  */
 pbdrv_charger_status_t pbdrv_charger_get_status(void);
 
-/**
- * Enables or disables charging.
- * @param [in]  enable  True to enable charging or false for discharging.
- * @param [in]  limit   The current limit for the charging rate.
- */
-void pbdrv_charger_enable(bool enable, pbdrv_charger_limit_t limit);
-
 #else
 
 static inline pbio_error_t pbdrv_charger_get_current_now(uint16_t *current) {
@@ -90,9 +83,6 @@ static inline pbdrv_charger_status_t pbdrv_charger_get_status(void) {
     return PBDRV_CHARGER_STATUS_FAULT;
 }
 
-static inline void pbdrv_charger_enable(bool enable, pbdrv_charger_limit_t limit) {
-}
-
 #endif
 
 #endif // _PBDRV_CHARGER_H_

lib/pbio/sys/battery.c

@@ -99,32 +99,6 @@ void pbsys_battery_poll(void) {
     } else if (avg_battery_voltage >= battery_ok_mv) {
         pbsys_status_clear(PBIO_PYBRICKS_STATUS_BATTERY_LOW_VOLTAGE_WARNING);
     }
-
-    // REVISIT: we should be able to make this event driven rather than polled
-    #if PBDRV_CONFIG_CHARGER
-
-    pbdrv_usb_bcd_t bcd = pbdrv_usb_get_bcd();
-    bool enable = bcd != PBDRV_USB_BCD_NONE;
-    pbdrv_charger_limit_t limit;
-
-    // REVISIT: The only current battery charger chip will automatically monitor
-    // VBUS and limit the current if the VBUS voltage starts to drop, so these
-    // limits are a bit looser than they could be.
-    switch (bcd) {
-        case PBDRV_USB_BCD_NONE:
-            limit = PBDRV_CHARGER_LIMIT_NONE;
-            break;
-        case PBDRV_USB_BCD_STANDARD_DOWNSTREAM:
-            limit = PBDRV_CHARGER_LIMIT_STD_MAX;
-            break;
-        default:
-            limit = PBDRV_CHARGER_LIMIT_CHARGING;
-            break;
-    }
-
-    pbdrv_charger_enable(enable, limit);
-
-    #endif // PBDRV_CONFIG_CHARGER
 }
 
 /**