diff mbox series

[v3,5/5] power: supply: sc27xx: Calibrate the resistance of coulomb counter

Message ID b45e604462cd20e9b06fceff3d698c9c4a53a1d4.1575863274.git.baolin.wang7@gmail.com (mailing list archive)
State Not Applicable, archived
Headers show
Series Improve the SC27XX fuel gauge controller | expand

Commit Message

Baolin Wang Dec. 9, 2019, 3:56 a.m. UTC 
From: Baolin Wang <baolin.wang@linaro.org>

There are some deviations between the real resistance and the ideal
resistance of coulomb counter, which will affect the accuracy of
the coulomb counter, thus calibrate the real resistance of coulomb
counter to improve the accuracy.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
---
 drivers/power/supply/sc27xx_fuel_gauge.c |   17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/power/supply/sc27xx_fuel_gauge.c b/drivers/power/supply/sc27xx_fuel_gauge.c
index 221b6fb..951d5d1 100644
--- a/drivers/power/supply/sc27xx_fuel_gauge.c
+++ b/drivers/power/supply/sc27xx_fuel_gauge.c
@@ -62,6 +62,8 @@ 
 
 #define SC27XX_FGU_CUR_BASIC_ADC	8192
 #define SC27XX_FGU_SAMPLE_HZ		2
+/* micro Ohms */
+#define SC27XX_FGU_IDEAL_RESISTANCE	20000
 
 /*
  * struct sc27xx_fgu_data: describe the FGU device
@@ -84,6 +86,7 @@ 
  * @resist_table_len: the resistance table length
  * @cur_1000ma_adc: ADC value corresponding to 1000 mA
  * @vol_1000mv_adc: ADC value corresponding to 1000 mV
+ * @calib_resist: the real resistance of coulomb counter chip in mOhm
  * @cap_table: capacity table with corresponding ocv
  * @resist_table: resistance percent table with corresponding temperature
  */
@@ -108,6 +111,7 @@  struct sc27xx_fgu_data {
 	int resist_table_len;
 	int cur_1000ma_adc;
 	int vol_1000mv_adc;
+	int calib_resist;
 	struct power_supply_battery_ocv_table *cap_table;
 	struct power_supply_resistance_temp_table *resist_table;
 };
@@ -900,7 +904,9 @@  static int sc27xx_fgu_calibration(struct sc27xx_fgu_data *data)
 	 */
 	cal_4200mv = (calib_data & 0x1ff) + 6963 - 4096 - 256;
 	data->vol_1000mv_adc = DIV_ROUND_CLOSEST(cal_4200mv * 10, 42);
-	data->cur_1000ma_adc = data->vol_1000mv_adc * 4;
+	data->cur_1000ma_adc =
+		DIV_ROUND_CLOSEST(data->vol_1000mv_adc * 4 * data->calib_resist,
+				  SC27XX_FGU_IDEAL_RESISTANCE);
 
 	kfree(buf);
 	return 0;
@@ -1079,6 +1085,15 @@  static int sc27xx_fgu_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	ret = device_property_read_u32(&pdev->dev,
+				       "sprd,calib-resistance-micro-ohms",
+				       &data->calib_resist);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"failed to get fgu calibration resistance\n");
+		return ret;
+	}
+
 	data->channel = devm_iio_channel_get(dev, "bat-temp");
 	if (IS_ERR(data->channel)) {
 		dev_err(dev, "failed to get IIO channel\n");