[PATCH 3/3] power: supply: max17040: Set rcomp value

[Jonathan Bakker]

According to the datasheet (1), the rcomp parameter can
vary based on the typical operating temperature and the
battery chemistry.  If provided, make sure we set it after
we reset the chip on boot.

1) https://datasheets.maximintegrated.com/en/ds/MAX17040-MAX17041.pdf

Signed-off-by: Jonathan Bakker <xc-racer2@xxxxxxx>
---
 drivers/power/supply/max17040_battery.c | 33 +++++++++++++++++++++----
 1 file changed, 28 insertions(+), 5 deletions(-)

diff --git a/drivers/power/supply/max17040_battery.c b/drivers/power/supply/max17040_battery.c
index 48aa44665e2f..f66e2fdc0a8a 100644
--- a/drivers/power/supply/max17040_battery.c
+++ b/drivers/power/supply/max17040_battery.c
@@ -10,6 +10,7 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/mutex.h>
+#include <linux/property.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/delay.h>
@@ -31,6 +32,8 @@
 
 #define MAX17040_ATHD_MASK		0xFFC0
 #define MAX17040_ATHD_DEFAULT_POWER_UP	4
+#define MAX17040_RCOMP_MASK		0xFF
+#define MAX17040_RCOMP_DEFAULT_POWER_UP	0x97
 
 struct max17040_chip {
 	struct i2c_client		*client;
@@ -48,6 +51,8 @@ struct max17040_chip {
 	int status;
 	/* Low alert threshold from 32% to 1% of the State of Charge */
 	u32 low_soc_alert;
+	/* Optimization for specific chemistries */
+	u8 rcomp_value;
 };
 
 static int max17040_get_property(struct power_supply *psy,
@@ -119,6 +124,20 @@ static int max17040_set_low_soc_alert(struct i2c_client *client, u32 level)
 	return ret;
 }
 
+static int max17040_set_rcomp(struct i2c_client *client, u32 val)
+{
+	int ret;
+	u16 data;
+
+	data = max17040_read_reg(client, MAX17040_RCOMP);
+	/* clear the rcomp val and set MSb 8 bits */
+	data &= MAX17040_RCOMP_MASK;
+	data |= val << 8;
+	ret = max17040_write_reg(client, MAX17040_RCOMP, data);
+
+	return ret;
+}
+
 static void max17040_get_vcell(struct i2c_client *client)
 {
 	struct max17040_chip *chip = i2c_get_clientdata(client);
@@ -190,8 +209,14 @@ static int max17040_get_of_data(struct max17040_chip *chip)
 				 "maxim,alert-low-soc-level",
 				 &chip->low_soc_alert);
 
-	if (chip->low_soc_alert <= 0 || chip->low_soc_alert >= 33)
+	if (chip->low_soc_alert <= 0 || chip->low_soc_alert >= 33) {
+		dev_err(&client->dev,
+			"failed: low SOC alert OF data out of bounds\n");
 		return -EINVAL;
+	}
+
+	chip->rcomp_value = MAX17040_RCOMP_DEFAULT_POWER_UP;
+	device_property_read_u8(dev, "maxim,rcomp-value", &chip->rcomp_value);
 
 	return 0;
 }
@@ -289,11 +314,8 @@ static int max17040_probe(struct i2c_client *client,
 	chip->client = client;
 	chip->pdata = client->dev.platform_data;
 	ret = max17040_get_of_data(chip);
-	if (ret) {
-		dev_err(&client->dev,
-			"failed: low SOC alert OF data out of bounds\n");
+	if (ret)
 		return ret;
-	}
 
 	i2c_set_clientdata(client, chip);
 	psy_cfg.drv_data = chip;
@@ -307,6 +329,7 @@ static int max17040_probe(struct i2c_client *client,
 
 	max17040_reset(client);
 	max17040_get_version(client);
+	max17040_set_rcomp(client, chip->rcomp_value);
 
 	/* check interrupt */
 	if (client->irq && of_device_is_compatible(client->dev.of_node,
-- 
2.20.1