power: qpnp-fg-gen3: Add support to clamp ESR

If ESR value goes to 0 because of some hardware issue, there is
no way to recover it back from that state. This causes incorrect
SOC reporting leading to a bad user experience. Hence add support
to clamp ESR value based on user defined DT property so that ESR
can be clamped to this value once it is found to go below it.

Since this change modifies ESR value in SRAM, having FG_SRAM_ESR
property would make encode and decode the value easier. Hence
remove fg_get_battery_esr() and get it from FG_SRAM_ESR property.

CRs-Fixed: 2011200
Change-Id: I96250b44f52d6208f3c64fb9e61f70ea41f54f4e
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>

3 files changed, 62 insertions, 29 deletions

diff --git a/Documentation/devicetree/bindings/power/supply/qcom/qpnp-fg-gen3.txt b/Documentation/devicetree/bindings/power/supply/qcom/qpnp-fg-gen3.txt
index af80de7f5f1f..9638888ebc9e 100644
--- a/Documentation/devicetree/bindings/power/supply/qcom/qpnp-fg-gen3.txt
+++ b/Documentation/devicetree/bindings/power/supply/qcom/qpnp-fg-gen3.txt
@@ -278,6 +278,14 @@ First Level Node - FG Gen3 device
 		    is specified, then ESR to Rslow scaling factors will be
 		    updated to account it for an accurate ESR.
 
+- qcom,fg-esr-clamp-mohms
+	Usage:      optional
+	Value type: <u32>
+	Definition: Equivalent series resistance (ESR) in milliohms. If this
+		    is specified, then ESR will be clamped to this value when
+		    ESR is found to be dropping below this. Default value is
+		    20.
+
 - qcom,fg-esr-filter-switch-temp
 	Usage:      optional
 	Value type: <u32>
diff --git a/drivers/power/supply/qcom/fg-core.h b/drivers/power/supply/qcom/fg-core.h
index c146654e438b..32a25b4e2c7b 100644
--- a/drivers/power/supply/qcom/fg-core.h
+++ b/drivers/power/supply/qcom/fg-core.h
@@ -143,6 +143,7 @@ enum fg_sram_param_id {
 	FG_SRAM_FULL_SOC,
 	FG_SRAM_VOLTAGE_PRED,
 	FG_SRAM_OCV,
+	FG_SRAM_ESR,
 	FG_SRAM_RSLOW,
 	FG_SRAM_ALG_FLAGS,
 	FG_SRAM_CC_SOC,
@@ -233,6 +234,7 @@ struct fg_dt_props {
 	int	esr_timer_awake;
 	int	esr_timer_asleep;
 	int	rconn_mohms;
+	int	esr_clamp_mohms;
 	int	cl_start_soc;
 	int	cl_max_temp;
 	int	cl_min_temp;
diff --git a/drivers/power/supply/qcom/qpnp-fg-gen3.c b/drivers/power/supply/qcom/qpnp-fg-gen3.c
index 1fd092c550f3..39afc235fbc3 100644
--- a/drivers/power/supply/qcom/qpnp-fg-gen3.c
+++ b/drivers/power/supply/qcom/qpnp-fg-gen3.c
@@ -99,6 +99,8 @@
 #define VOLTAGE_PRED_OFFSET		0
 #define OCV_WORD			97
 #define OCV_OFFSET			2
+#define ESR_WORD			99
+#define ESR_OFFSET			0
 #define RSLOW_WORD			101
 #define RSLOW_OFFSET			0
 #define ACT_BATT_CAP_WORD		117
@@ -173,6 +175,8 @@ static struct fg_sram_param pmi8998_v1_sram_params[] = {
 		244141, 0, NULL, fg_decode_voltage_15b),
 	PARAM(OCV, OCV_WORD, OCV_OFFSET, 2, 1000, 244141, 0, NULL,
 		fg_decode_voltage_15b),
+	PARAM(ESR, ESR_WORD, ESR_OFFSET, 2, 1000, 244141, 0, fg_encode_default,
+		fg_decode_value_16b),
 	PARAM(RSLOW, RSLOW_WORD, RSLOW_OFFSET, 2, 1000, 244141, 0, NULL,
 		fg_decode_value_16b),
 	PARAM(ALG_FLAGS, ALG_FLAGS_WORD, ALG_FLAGS_OFFSET, 1, 1, 1, 0, NULL,
@@ -235,6 +239,8 @@ static struct fg_sram_param pmi8998_v2_sram_params[] = {
 		244141, 0, NULL, fg_decode_voltage_15b),
 	PARAM(OCV, OCV_WORD, OCV_OFFSET, 2, 1000, 244141, 0, NULL,
 		fg_decode_voltage_15b),
+	PARAM(ESR, ESR_WORD, ESR_OFFSET, 2, 1000, 244141, 0, fg_encode_default,
+		fg_decode_value_16b),
 	PARAM(RSLOW, RSLOW_WORD, RSLOW_OFFSET, 2, 1000, 244141, 0, NULL,
 		fg_decode_value_16b),
 	PARAM(ALG_FLAGS, ALG_FLAGS_WORD, ALG_FLAGS_OFFSET, 1, 1, 1, 0, NULL,
@@ -571,38 +577,11 @@ static int fg_get_battery_temp(struct fg_chip *chip, int *val)
 	return 0;
 }
 
-#define BATT_ESR_NUMR		244141
-#define BATT_ESR_DENR		1000
-static int fg_get_battery_esr(struct fg_chip *chip, int *val)
-{
-	int rc = 0;
-	u16 temp = 0;
-	u8 buf[2];
-
-	rc = fg_read(chip, BATT_INFO_ESR_LSB(chip), buf, 2);
-	if (rc < 0) {
-		pr_err("failed to read addr=0x%04x, rc=%d\n",
-			BATT_INFO_ESR_LSB(chip), rc);
-		return rc;
-	}
-
-	if (chip->wa_flags & PMI8998_V1_REV_WA)
-		temp = ((buf[0] & ESR_MSB_MASK) << 8) |
-			(buf[1] & ESR_LSB_MASK);
-	else
-		temp = ((buf[1] & ESR_MSB_MASK) << 8) |
-			(buf[0] & ESR_LSB_MASK);
-
-	pr_debug("buf: %x %x temp: %x\n", buf[0], buf[1], temp);
-	*val = div_u64((u64)temp * BATT_ESR_NUMR, BATT_ESR_DENR);
-	return 0;
-}
-
 static int fg_get_battery_resistance(struct fg_chip *chip, int *val)
 {
 	int rc, esr_uohms, rslow_uohms;
 
-	rc = fg_get_battery_esr(chip, &esr_uohms);
+	rc = fg_get_sram_prop(chip, FG_SRAM_ESR, &esr_uohms);
 	if (rc < 0) {
 		pr_err("failed to get ESR, rc=%d\n", rc);
 		return rc;
@@ -1631,7 +1610,7 @@ static int fg_rconn_config(struct fg_chip *chip)
 		return 0;
 	}
 
-	rc = fg_get_battery_esr(chip, &esr_uohms);
+	rc = fg_get_sram_prop(chip, FG_SRAM_ESR, &esr_uohms);
 	if (rc < 0) {
 		pr_err("failed to get ESR, rc=%d\n", rc);
 		return rc;
@@ -2744,6 +2723,39 @@ out:
 	return rc;
 }
 
+static int fg_esr_validate(struct fg_chip *chip)
+{
+	int rc, esr_uohms;
+	u8 buf[2];
+
+	if (chip->dt.esr_clamp_mohms <= 0)
+		return 0;
+
+	rc = fg_get_sram_prop(chip, FG_SRAM_ESR, &esr_uohms);
+	if (rc < 0) {
+		pr_err("failed to get ESR, rc=%d\n", rc);
+		return rc;
+	}
+
+	if (esr_uohms >= chip->dt.esr_clamp_mohms * 1000) {
+		pr_debug("ESR %d is > ESR_clamp\n", esr_uohms);
+		return 0;
+	}
+
+	esr_uohms = chip->dt.esr_clamp_mohms * 1000;
+	fg_encode(chip->sp, FG_SRAM_ESR, esr_uohms, buf);
+	rc = fg_sram_write(chip, chip->sp[FG_SRAM_ESR].addr_word,
+			chip->sp[FG_SRAM_ESR].addr_byte, buf,
+			chip->sp[FG_SRAM_ESR].len, FG_IMA_DEFAULT);
+	if (rc < 0) {
+		pr_err("Error in writing ESR, rc=%d\n", rc);
+		return rc;
+	}
+
+	fg_dbg(chip, FG_STATUS, "ESR clamped to %duOhms\n", esr_uohms);
+	return 0;
+}
+
 /* PSY CALLBACKS STAY HERE */
 
 static int fg_psy_get_property(struct power_supply *psy,
@@ -3371,6 +3383,10 @@ static irqreturn_t fg_delta_msoc_irq_handler(int irq, void *data)
 	if (rc < 0)
 		pr_err("Error in updating maint_soc, rc=%d\n", rc);
 
+	rc = fg_esr_validate(chip);
+	if (rc < 0)
+		pr_err("Error in validating ESR, rc=%d\n", rc);
+
 	if (batt_psy_initialized(chip))
 		power_supply_changed(chip->batt_psy);
 
@@ -3659,6 +3675,7 @@ static int fg_parse_ki_coefficients(struct fg_chip *chip)
 #define DEFAULT_ESR_BROAD_FLT_UPCT	99610
 #define DEFAULT_ESR_TIGHT_LT_FLT_UPCT	48829
 #define DEFAULT_ESR_BROAD_LT_FLT_UPCT	148438
+#define DEFAULT_ESR_CLAMP_MOHMS		20
 static int fg_parse_dt(struct fg_chip *chip)
 {
 	struct device_node *child, *revid_node, *node = chip->dev->of_node;
@@ -3972,6 +3989,12 @@ static int fg_parse_dt(struct fg_chip *chip)
 	if (rc < 0)
 		pr_err("Error in parsing slope limit coeffs, rc=%d\n", rc);
 
+	rc = of_property_read_u32(node, "qcom,fg-esr-clamp-mohms", &temp);
+	if (rc < 0)
+		chip->dt.esr_clamp_mohms = DEFAULT_ESR_CLAMP_MOHMS;
+	else
+		chip->dt.esr_clamp_mohms = temp;
+
 	return 0;
 }