Enable ADC charger current monitor for Slippy

The IOUT pin of the smart battery charger can be used to monitor the AC
adapter current (default) or the battery charging current.

BUG=none
BRANCH=none
TEST=manual

Discharge the battery a bit, and connect to the EC console. With the AC
power plugged in, the "battery" command should show charging status,
including current.

The "adc" command will display the A-D converters, including the current
measurement. For example:

  > battery
    Temp:      0x0b88 = 295.2 K (22.1 C)
    Manuf:     SMP-COS20
    Device:    OC2
    Chem:      LION
    Serial:    0x0005
    V:         0x4130 = 16688 mV
    V-desired: 0x41a0 = 16800 mV
    V-design:  0x39d0 = 14800 mV
    I:         0x008e = 142 mA(CHG)
    I-desired: 0x0080 = 128 mA
    Mode:      0x6001
    Charge:    98 %
      Abs:     94 %
    Remaining: 1871 mAh
    Cap-full:  1923 mAh
      Design:  2000 mAh
    Time-full: 0h:23
      Empty:   0h:0
  >
  > adc
  ADC channel "ECTemp" = 317
  ADC channel "ChargerCurrent" = 455
  >

That current is significantly higher than the "I:" reported by the "battery"
command. But look at the charger options:

  > sbc 0x12
  0x7904 (30980)
  >

Bit 5 controls the IOUT Selection. When clear, it monitors the current from
the AC adapter. Set bit 5 to monitor the current provided to the battery:

  > sbc 0x12 0x7924
  > adc
  ADC channel "ECTemp" = 318
  ADC channel "ChargerCurrent" = 128
  >

That matches what the smart battery sees.

Change-Id: I2fe351304421dfb22d83ef13d416aa44c9f56e8a
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/57940
Reviewed-by: Randall Spangler <rspangler@chromium.org>

3 files changed, 7 insertions, 8 deletions

diff --git a/board/slippy/board.c b/board/slippy/board.c
index 3bfd0ef6e3..ff37bc82f1 100644
--- a/board/slippy/board.c
+++ b/board/slippy/board.c
@@ -125,11 +125,13 @@ const struct adc_t adc_channels[ADC_CH_COUNT] = {
 	{"ECTemp", LM4_ADC_SEQ0, -225, ADC_READ_MAX, 420,
 	 LM4_AIN_NONE, 0x0e /* TS0 | IE0 | END0 */, 0, 0},
 
-	/* HEY: need different equation for Slippy */
-	/* Charger current is mapped from 0~4000mA to 0~1.6V.
-	 * And ADC maps 0~3.3V to ADC_READ_MAX.
+	/* IOUT == ICMNT is on PE3/AIN0 */
+	/* We have 0.01-ohm resistors, and IOUT is 20X the differential
+	 * voltage, so 1000mA ==> 200mV.
+	 * ADC returns 0x000-0xFFF, which maps to 0.0-3.3V (as configured).
+	 * mA = 1000 * ADC_VALUE / ADC_READ_MAX * 3300 / 200
 	 */
-	{"ChargerCurrent", LM4_ADC_SEQ1, 33 * 4000, ADC_READ_MAX * 16, 0,
+	{"ChargerCurrent", LM4_ADC_SEQ1, 33000, ADC_READ_MAX * 2, 0,
 	 LM4_AIN(0), 0x06 /* IE0 | END0 */, LM4_GPIO_E, (1<<3)},
 };
 
diff --git a/chip/lm4/clock.c b/chip/lm4/clock.c
index c0a5558cdb..02f955776e 100644
--- a/chip/lm4/clock.c
+++ b/chip/lm4/clock.c
@@ -27,7 +27,6 @@ static int freq;
  */
 static void disable_pll(void)
 {
-#ifdef BOARD_link			       /* FIXME: crosbug.com/p/19366 */
 	/* Switch to 16MHz internal oscillator and power down the PLL */
 	LM4_SYSTEM_RCC = LM4_SYSTEM_RCC_SYSDIV(0) |
 		LM4_SYSTEM_RCC_BYPASS |
@@ -35,7 +34,6 @@ static void disable_pll(void)
 		LM4_SYSTEM_RCC_OSCSRC(1) |
 		LM4_SYSTEM_RCC_MOSCDIS;
 	LM4_SYSTEM_RCC2 &= ~LM4_SYSTEM_RCC2_USERCC2;
-#endif
 
 	freq = INTERNAL_CLOCK;
 }
@@ -48,7 +46,6 @@ static void enable_pll(void)
 	/* Disable the PLL so we can reconfigure it */
 	disable_pll();
 
-#ifdef BOARD_link			       /* FIXME: crosbug.com/p/19366 */
 	/*
 	 * Enable the PLL (PWRDN is no longer set) and set divider.  PLL is
 	 * still bypassed, since it hasn't locked yet.
@@ -66,7 +63,6 @@ static void enable_pll(void)
 
 	/* Remove bypass on PLL */
 	LM4_SYSTEM_RCC &= ~LM4_SYSTEM_RCC_BYPASS;
-#endif
 	freq = PLL_CLOCK;
 }
 
diff --git a/common/charger_bq24707a.c b/common/charger_bq24707a.c
index 8c8aefccb9..35ca469ed1 100644
--- a/common/charger_bq24707a.c
+++ b/common/charger_bq24707a.c
@@ -180,6 +180,7 @@ int charger_post_init(void)
 	 *	input current limit = ~1/2 maximum setting
 	 *	charging voltage    = 0 mV
 	 *	charging current    = 0 mA
+	 *      IOUT                = 20x adapter current sense
 	 */
 
 	/* Set charger input current limit */