driver/temp_sensor: Add support for BD99992GW

Add support for ADC / thermistor reads on the BD99992GW PMIC.

BUG=chrome-os-partner:42156
TEST=Manual on Glados with subsequent commit. Boot to S0, run "temps".
Verify that temperatures start around 28C and begin to increase after
system is powered-on for a long duration.
BRANCH=None

Change-Id: Ic15f41046130317a0e0c3bce4a923ba624328c0d
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/289935
Reviewed-by: Alec Berg <alecaberg@chromium.org>

1 files changed, 53 insertions, 0 deletions

diff --git a/test/thermal.c b/test/thermal.c
index 10662ffd7d..761dc9358d 100644
--- a/test/thermal.c
+++ b/test/thermal.c
@@ -480,6 +480,58 @@ static int test_several_limits(void)
 	return EC_SUCCESS;
 }
 
+/* Tests for bd99992gw temperature sensor ADC-to-temp calculation */
+#define LOW_ADC_TEST_VALUE	887 /* 0 C */
+#define HIGH_ADC_TEST_VALUE	100 /* > 100C */
+
+static int test_bd99992_adc_to_temp(void)
+{
+	int i;
+	uint8_t temp;
+	uint8_t new_temp;
+
+	/* ADC value to temperature table, data from datasheet */
+	struct {
+		int adc;
+		int temp;
+	} adc_temp_datapoints[] = {
+		{ 615, 30 },
+		{ 561, 35 },
+		{ 508, 40 },
+		{ 407, 50 },
+		{ 315, 60 },
+		{ 243, 70 },
+		{ 186, 80 },
+		{ 140, 90 },
+		{ 107, 100 },
+	};
+
+
+	/*
+	 * Verify that calculated temp is decreasing for entire ADC range,
+	 * and that a tick down in ADC value results in no more than 1C
+	 * decrease.
+	 */
+	i = LOW_ADC_TEST_VALUE;
+	temp = bd99992gw_get_temp(i);
+
+	while (--i > HIGH_ADC_TEST_VALUE) {
+		new_temp = bd99992gw_get_temp(i);
+		TEST_ASSERT(new_temp == temp ||
+			    new_temp == temp + 1);
+		temp = new_temp;
+	}
+
+	/* Verify several datapoints are within 1C accuracy */
+	for (i = 0; i < ARRAY_SIZE(adc_temp_datapoints); ++i) {
+		temp = bd99992gw_get_temp(adc_temp_datapoints[i].adc);
+		ASSERT(temp >= adc_temp_datapoints[i].temp - 1 &&
+		       temp <= adc_temp_datapoints[i].temp + 1);
+	}
+
+	return EC_SUCCESS;
+}
+
 
 void run_test(void)
 {
@@ -492,5 +544,6 @@ void run_test(void)
 	RUN_TEST(test_one_limit);
 	RUN_TEST(test_several_limits);
 
+	RUN_TEST(test_bd99992_adc_to_temp);
 	test_print_result();
 }