FS#13535: AXP2101: ADC / reporting improvements

Improve ADC behavior, add correct conversion
for die temperature, add readout of EGauge to debug screen.

Add delay to give ADC time to get a good reading. Initial reading
may still be 1-3% optimistic, which is probably ok.

EGauge appears to be pretty good, but no great need to convert
to using it either.

Change-Id: Iab9d50e2427f656ad0875f9a623b03545fc69881

firmware/drivers/axp-2101.c

@@ -57,17 +57,16 @@ struct axp_supply_info {
 };
 
 static const struct axp_adc_info axp_adc_info[AXP2101_NUM_ADC_CHANNELS] = {
-    // TODO: Datasheet ADC conversion table doesn't seem to make any sense...
+    // 0x000    0x001   0x002 ... 0x1FFF
-    // 0x000    0x001   0x002 ... 0xFFF
     // 0mV      1mV     2mV   ... 8.192V
     [AXP2101_ADC_VBAT_VOLTAGE]      = {AXP2101_REG_ADC_VBAT_H,  AXP2101_REG_ADCCHNENABLE, 1 << 0, 1, 1},
     // 0mV      1mV     2mV   ... 8.192V
     [AXP2101_ADC_VBUS_VOLTAGE]      = {AXP2101_REG_ADC_VBUS_H,  AXP2101_REG_ADCCHNENABLE, 1 << 2, 1, 1},
     // 0mV      1mV     2mV   ... 8.192V
     [AXP2101_ADC_VSYS_VOLTAGE]      = {AXP2101_REG_ADC_VSYS_H,  AXP2101_REG_ADCCHNENABLE, 1 << 3, 1, 1},
-    // 0mV      0.5mV   1mV   ... 4.096V
+    // 0mV      0.5mV   0.1mV   ... 4.096V
-    [AXP2101_ADC_TS_VOLTAGE]        = {AXP2101_REG_ADC_TS_H,    AXP2101_REG_ADCCHNENABLE, 1 << 1, 1, 1},
+    [AXP2101_ADC_TS_VOLTAGE]        = {AXP2101_REG_ADC_TS_H,    AXP2101_REG_ADCCHNENABLE, 1 << 1, 1, 2},
-    // 0mV      0.1mV   2mV   ... 0.8192V
+    // see axp2101_adc_conv_raw() for conversion
     [AXP2101_ADC_DIE_TEMPERATURE]   = {AXP2101_REG_ADC_TDIE_H,  AXP2101_REG_ADCCHNENABLE, 1 << 4, 1, 1},
 };
 
@@ -309,7 +308,7 @@ void axp2101_supply_set_voltage(int supply, int voltage)
     if(voltage > 0 && info->step_mV != 0) {
         if(voltage < info->min_mV)
             return;
-        
+
         int regval;
 
         // there's probably a more elegant way to do this...
@@ -446,11 +445,20 @@ int axp2101_adc_read_raw(int adc)
         return INT_MIN;
 
     /* Parse the value */
-    return ((buf[0] & 0x3f) << 8) | (buf[1] & 0xff);
+    return ((int)(buf[0] & 0x3f) << 8) | (buf[1] & 0xff);
 }
 
 int axp2101_adc_conv_raw(int adc, int value)
 {
+    if (adc == AXP2101_ADC_DIE_TEMPERATURE)
+        return 22 + ((7274 - value) / 20);
+
+    // seems to be a signed 14-bit value, but
+    // let's clamp it to zero. Seems to give sane results
+    // on v_bus and v_ts channels
+    if (value & 0x2000)
+        return 0;
+
     return axp_adc_info[adc].num * value / axp_adc_info[adc].den;
 }
 
@@ -472,12 +480,12 @@ void axp2101_adc_set_enabled(int adc_bits)
     i2c_reg_write(AXP_PMU_BUS, AXP_PMU_ADDR, AXP2101_REG_ADCCHNENABLE, 1, &xfer[0]);
 }
 
-// TODO: See if we can figure out "optimum" battery chemistry-type settings
+int axp2101_egauge_read(void)
-// like constant-current charging, charge curves... that stuff is all configurable
+{
-// as far as I can tell! Probably important to at least figure out if the defaults
+    uint8_t buf;
-// are clearly wrong or not!
+    i2c_reg_read(AXP_PMU_BUS, AXP_PMU_ADDR, AXP2101_REG_BATT_PERCENTAGE, 1, &buf);
-
+    return (int)buf;
-// TODO: what are DATA_BUFFER 0-3 for????
+}
 
 // there are many current settings:
 // Reg 16: Input current limit control
@@ -534,6 +542,7 @@ enum {
     AXP_DEBUG_BATTERY_STATUS,
     AXP_DEBUG_INPUT_STATUS,
     AXP_DEBUG_CHARGE_CURRENT,
+    AXP_DEBUG_EGAUGE_VALUE,
     AXP_DEBUG_FIRST_ADC,
     AXP_DEBUG_FIRST_SUPPLY = AXP_DEBUG_FIRST_ADC + AXP2101_NUM_ADC_CHANNELS,
     AXP_DEBUG_NUM_ENTRIES = AXP_DEBUG_FIRST_SUPPLY + AXP2101_NUM_SUPPLIES,
@@ -555,11 +564,11 @@ static const char* axp2101_debug_menu_get_name(int item, void* data,
     (void)data;
 
     static const char* const adc_names[] = {
-        "V_bat", "V_bus", "V_sys", "V_ts", "V_die",
+        "V_bat", "V_bus", "V_sys", "V_ts", "T_die",
     };
 
     static const char* const adc_units[] = {
-        "mV", "mV", "mV", "mV", "C*100",
+        "mV", "mV", "mV", "mV", "C",
     };
 
     static const char* const supply_names[] = {
@@ -625,6 +634,12 @@ static const char* axp2101_debug_menu_get_name(int item, void* data,
         return buf;
     } break;
 
+    case AXP_DEBUG_EGAUGE_VALUE: {
+        int percent = axp2101_egauge_read();
+        snprintf(buf, buflen, "EGauge percent: %d", percent);
+        return buf;
+    } break;
+
     default:
         return "---";
     }

firmware/target/mips/ingenic_x1000/erosqnative/power-erosqnative.c

@@ -97,10 +97,6 @@ void power_init(void)
         }
         
         // These match the OF as far as I can discern
-        // TODO: These values are set in EFUSE apparently, could
-        // do a "check then set if necessary"...
-        // Also if we had a fresh device we could verify what
-        // the OF sets.
         axp2101_supply_set_voltage(AXP2101_SUPPLY_DCDC1, 3300);
         axp2101_supply_set_voltage(AXP2101_SUPPLY_DCDC2, 1200);
         axp2101_supply_set_voltage(AXP2101_SUPPLY_DCDC3, 2800);
@@ -123,6 +119,12 @@ void power_init(void)
         /* Set the default charging current. This is the same as the
         * OF's setting, although it's not strictly within the USB spec. */
         axp2101_set_charge_current(780);
+
+        /* delay to allow ADC to get a good sample -
+         * may give bogus (high) readings otherwise. */
+#ifndef BOOTLOADER
+        mdelay(150);
+#endif
     } else {
         axp_init();
         /* Set lowest sample rate */
@@ -138,7 +140,6 @@ void power_init(void)
             (1 << ADC_INTERNAL_TEMP) |
             (1 << ADC_APS_VOLTAGE));
         
-        /* TODO: Set Output Voltages! */
         i2c_reg_modify1(AXP_PMU_BUS, AXP_PMU_ADDR,
                         AXP_REG_PWROUTPUTCTRL2, 0, 0x5f, NULL);
         i2c_reg_modify1(AXP_PMU_BUS, AXP_PMU_ADDR,