imx233: speedup charging trickle phase

Per Freescale recommandation, we need to ramp up the 4.2V rail before enabling
charging. Ramping should be done at 1 step/10ms, but the old code did 1 step/1s
because the powermgmt_step() function is called once every second. Use a tick
task to ramp up much faster.

Change-Id: I9a52bdd0c2ba5426d83ed42db8db7ecce2fea1f7

firmware/target/arm/imx233/debug-imx233.c

@@ -407,7 +407,6 @@ bool dbg_hw_info_powermgmt(void)
             "<unknown>");
         lcd_putsf(0, 1, "charging tmo: %d", info.charging_timeout);
         lcd_putsf(0, 2, "topoff tmo: %d", info.topoff_timeout);
-        lcd_putsf(0, 3, "4p2ilimit tmo: %d", info.incr_4p2_ilimit_timeout);
 
         lcd_update();
         yield();

firmware/target/arm/imx233/powermgmt-imx233.c

@@ -39,7 +39,6 @@
 /* charger state is maintained in charge_state (see powermgmt.h) */
 static int timeout_charging; /* timeout before charging will be declared broken */
 static int timeout_topping_off; /* timeout before stopping charging after topping off */
-static int timeout_4p2_ilimit_increase; /* timeout before increasing 4p2 ilimit */
 
 /* Returns battery voltage from ADC [millivolts] */
 int _battery_voltage(void)
@@ -69,9 +68,24 @@ void imx233_powermgmt_init(void)
 #endif
 }
 
+#define MAX_4P2_ILIMIT  0x3f
+
+/* The code below assumes HZ = 100 so that it runs every 10ms */
+#if HZ != 100
+#warning The ramp_up_4p2_rail() tick task assumes HZ = 100, this may break charging
+#endif
+
+static void ramp_up_4p2_rail(void)
+{
+    /* only ramp up in the TRICKLE state and if we haven't reached the maximum yet */
+    if(charge_state == TRICKLE && BF_RD(POWER_5VCTRL, CHARGE_4P2_ILIMIT) < MAX_4P2_ILIMIT)
+        HW_POWER_5VCTRL += BF_POWER_5VCTRL_CHARGE_4P2_ILIMIT(1);
+}
+
 void powermgmt_init_target(void)
 {
     charge_state = DISCHARGING;
+    tick_add_task(&ramp_up_4p2_rail);
 }
 
 void charging_algorithm_step(void)
@@ -84,15 +98,15 @@ void charging_algorithm_step(void)
     {
         logf("pwrmgmt: * -> discharging");
         logf("pwrmgmt: disable charger and 4p2"); 
+        charge_state = DISCHARGING;
         /* 5V has been lost: disable 4p2 power rail */
         BF_SET(POWER_CHARGE, PWD_BATTCHRG);
 #if IMX233_SUBTARGET >= 3780
         BF_WR(POWER_DCDC4P2, ENABLE_DCDC(0));
         BF_WR(POWER_DCDC4P2, ENABLE_4P2(0));
-        BF_WR(POWER_5VCTRL, CHARGE_4P2_ILIMIT(1));
+        BF_WR(POWER_5VCTRL, CHARGE_4P2_ILIMIT(0));
         BF_SET(POWER_5VCTRL, PWD_CHARGE_4P2);
 #endif
-        charge_state = DISCHARGING;
     }
     /* battery -> 5v transition */
     else if(is_5v_present && charge_state == DISCHARGING)
@@ -108,26 +122,22 @@ void charging_algorithm_step(void)
          * limit on the 4P2 rail. */
         BF_WR(POWER_DCDC4P2, ENABLE_4P2(1));
         BF_SET(POWER_CHARGE, ENABLE_LOAD);
-        BF_WR(POWER_5VCTRL, CHARGE_4P2_ILIMIT(1)); /* start by drawing 10mA only */
+        BF_WR(POWER_5VCTRL, CHARGE_4P2_ILIMIT(0)); /* start by drawing 0mA */
         BF_CLR(POWER_5VCTRL, PWD_CHARGE_4P2);// FIXME: manual error ?
         BF_WR(POWER_DCDC4P2, ENABLE_DCDC(1));
+        /* the tick task will take care of slowly ramping up the current in the rail
+         * every 10ms (since it runs at HZ and HZ=100) */
 #endif
-        timeout_4p2_ilimit_increase = current_tick + HZ / 100;
         charge_state = TRICKLE;
     }
-    else if(charge_state == TRICKLE && TIME_AFTER(current_tick, timeout_4p2_ilimit_increase))
+    /* trickle -> charging transition */
+    else if(charge_state == TRICKLE)
     {
 #if IMX233_SUBTARGET >= 3780
-        /* if 4.2V current limit has not reached 780mA, increase it slowly to
+        /* If 4.2V current limit has not reached 780mA, don't do anything, the
-         * charge the 4.2V capacitance */
+         * DPC is still running */
-        if(BF_RD(POWER_5VCTRL, CHARGE_4P2_ILIMIT) != 0x3f)
+        /* If we've reached the maximum, take action */
-        {
+        if(BF_RD(POWER_5VCTRL, CHARGE_4P2_ILIMIT) == MAX_4P2_ILIMIT)
-            //logf("pwrmgmt: incr 4.2 ilimit");
-            HW_POWER_5VCTRL += BF_POWER_5VCTRL_CHARGE_4P2_ILIMIT(1);
-            timeout_4p2_ilimit_increase = current_tick + HZ / 100;
-        }
-        /* we've reached the maximum, take action */
-        else
 #endif
         {
             logf("pwrmgmt: enable dcdc and charger");
@@ -181,6 +191,7 @@ void charging_algorithm_step(void)
 
 void charging_algorithm_close(void)
 {
+    tick_remove_task(&ramp_up_4p2_rail);
 }
 
 struct imx233_powermgmt_info_t imx233_powermgmt_get_info(void)
@@ -192,7 +203,5 @@ struct imx233_powermgmt_info_t imx233_powermgmt_get_info(void)
         charge_state == CHARGING ? timeout_charging - current_tick : 0;
     info.topoff_timeout =
         charge_state == TOPOFF ? timeout_topping_off - current_tick : 0;
-    info.incr_4p2_ilimit_timeout =
-        charge_state == TRICKLE ? timeout_4p2_ilimit_increase - current_tick : 0;
     return info;
 }

firmware/target/arm/imx233/powermgmt-imx233.h

@@ -31,7 +31,6 @@ struct imx233_powermgmt_info_t
     enum charge_state_type state;
     int charging_timeout; /* time in tick before timeout, -1 if n/a */
     int topoff_timeout; /* ditto */
-    int incr_4p2_ilimit_timeout; /* ditto */
 };
 
 struct imx233_powermgmt_info_t imx233_powermgmt_get_info(void);