x1000: Correctly limit USB charging current

The way this was done before was wrong - limiting the charge
current is not enough since the device will draw additional
power to run. Use the AXP192's vbus current limit control to
stay compliant with the USB specification.

Change-Id: I91b84e3480a432e49bec53cf2a17e4e3444404a4

1 files changed, 21 insertions, 2 deletions

diff --git a/firmware/target/mips/ingenic_x1000/shanlingq1/power-shanlingq1.c b/firmware/target/mips/ingenic_x1000/shanlingq1/power-shanlingq1.c
index 65d1bc163f..9637ceef2f 100644
--- a/firmware/target/mips/ingenic_x1000/shanlingq1/power-shanlingq1.c
+++ b/firmware/target/mips/ingenic_x1000/shanlingq1/power-shanlingq1.c
@@ -86,7 +86,7 @@ void power_init(void)
         (1 << AXP_SUPPLY_DCDC2) | /* LCD (1.2 V) */
         (1 << AXP_SUPPLY_DCDC3) | /* CPU (1.8 V) */
         (1 << AXP_SUPPLY_LDO2) |  /* Touchscreen (3.3 V) */
-        (1 << AXP_SUPPLY_LDO3));  /* not sure (2.5 V) */
+        (1 << AXP_SUPPLY_LDO3));  /* USB analog (2.5 V) */
 
     /* Enable required ADCs */
     axp_set_enabled_adcs(
@@ -98,6 +98,10 @@ void power_init(void)
         (1 << AXP_ADC_INTERNAL_TEMP) |
         (1 << AXP_ADC_APS_VOLTAGE));
 
+    /* Configure USB charging */
+    axp_set_vhold_level(4400);
+    usb_charging_maxcurrent_change(100);
+
     /* Delay to give power output time to stabilize */
     mdelay(20);
 }
@@ -105,7 +109,22 @@ void power_init(void)
 #ifdef HAVE_USB_CHARGING_ENABLE
 void usb_charging_maxcurrent_change(int maxcurrent)
 {
-    axp_set_charge_current(maxcurrent);
+    int vbus_limit;
+    int charge_current;
+
+    /* Note that the charge current setting is a maximum: it will be
+     * reduced dynamically by the AXP192 so the combined load is less
+     * than the set VBUS current limit. */
+    if(maxcurrent <= 100) {
+        vbus_limit = AXP_VBUS_LIMIT_100mA;
+        charge_current = 550;
+    } else {
+        vbus_limit = AXP_VBUS_LIMIT_500mA;
+        charge_current = 550;
+    }
+
+    axp_set_vbus_limit(vbus_limit);
+    axp_set_charge_current(charge_current);
 }
 #endif