From 90dd2f84a9174c38dbfb07d582ec6ee7697b1939 Mon Sep 17 00:00:00 2001
From: Aidan MacDonald <amachronic@protonmail.com>
Date: Mon, 27 Dec 2021 12:26:59 +0000
Subject: [PATCH] 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
---
 .../erosqnative/power-erosqnative.c           | 24 +++++++++++++++++--
 .../ingenic_x1000/fiiom3k/power-fiiom3k.c     | 21 +++++++++++++++-
 .../shanlingq1/power-shanlingq1.c             | 23 ++++++++++++++++--
 3 files changed, 63 insertions(+), 5 deletions(-)

diff --git a/firmware/target/mips/ingenic_x1000/erosqnative/power-erosqnative.c b/firmware/target/mips/ingenic_x1000/erosqnative/power-erosqnative.c
index 17cdb4d645..7ad9479a96 100644
--- a/firmware/target/mips/ingenic_x1000/erosqnative/power-erosqnative.c
+++ b/firmware/target/mips/ingenic_x1000/erosqnative/power-erosqnative.c
@@ -62,7 +62,8 @@ void power_init(void)
     /* FIXME: Copy paste from M3K. Probably not necessary */
     axp_modify(AXP_REG_DCDCMODE, 0, 0xc0);
 
-    /* Power on required supplies */
+    /* Power on required supplies
+     * TODO: This should be checked, though likely all but EXTEN are needed */
     axp_set_enabled_supplies(
         (1 << AXP_SUPPLY_EXTEN) |
         (1 << AXP_SUPPLY_DCDC1) |
@@ -81,6 +82,10 @@ 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 outputs time to stabilize.
      * With the power thread delay, this can apparently go as low as 50,
      * Keeping a higher value here just to ensure the bootloader works
@@ -91,7 +96,22 @@ 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
 
diff --git a/firmware/target/mips/ingenic_x1000/fiiom3k/power-fiiom3k.c b/firmware/target/mips/ingenic_x1000/fiiom3k/power-fiiom3k.c
index 53451ffa6c..c8498c4dbc 100644
--- a/firmware/target/mips/ingenic_x1000/fiiom3k/power-fiiom3k.c
+++ b/firmware/target/mips/ingenic_x1000/fiiom3k/power-fiiom3k.c
@@ -78,6 +78,10 @@ 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);
+
     /* Short delay to give power outputs time to stabilize */
     mdelay(200);
 }
@@ -85,7 +89,22 @@ 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
 
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