[PATCH v3 04/10] power: supply: max77693: Set charge current limits during init

[Artur Weber <aweber.kernel@gmail.com>]

There are two charger current limit registers:

- Fast charge current limit (which controls current going from the
  charger to the battery);
- CHGIN input current limit (which controls current going into the
  charger through the cable).

Add functions for setting both of the values, and set them to a
safe default value of 500mA at initialization.

The value for the fast charge current limit can be modified by setting
the constant-charge-current-max-ua DT property of the battery node
specified in the monitored-battery charger DT property; the CHGIN input
current limit will be set up later in the charger detection mechanism
(in the future, the INPUT_CURRENT_LIMIT property could also be made
writeable for userspace control of the current limit, while keeping
the actual current limit from the charger to the battery intact
so that users don't accidentally blow up their batteries with a bad
value).

Signed-off-by: Artur Weber <aweber.kernel@gmail.com>
---
Changes in v3:
- Dropped CHARGER reg in favor of managing the registers directly

Changes in v2:
- Squashed mfd include register additions into this commit
- Changed from custom fast charge current property to monitored-battery
  (devm_power_supply_register call has been moved up as it is needed by
  the DT init function now)
- Changed to adapt to both current limit values being managed by the
  CHARGER regulator
---
 drivers/power/supply/max77693_charger.c | 82 ++++++++++++++++++++++++++++-----
 include/linux/mfd/max77693-private.h    |  2 +
 2 files changed, 73 insertions(+), 11 deletions(-)

diff --git a/drivers/power/supply/max77693_charger.c b/drivers/power/supply/max77693_charger.c
index 4caac142c428..17975ec69a6a 100644
--- a/drivers/power/supply/max77693_charger.c
+++ b/drivers/power/supply/max77693_charger.c
@@ -26,6 +26,7 @@ struct max77693_charger {
 	u32 min_system_volt;
 	u32 thermal_regulation_temp;
 	u32 batttery_overcurrent;
+	u32 fast_charge_current;
 	u32 charge_input_threshold_volt;
 };
 
@@ -596,6 +597,48 @@ static int max77693_set_batttery_overcurrent(struct max77693_charger *chg,
 			CHG_CNFG_12_B2SOVRC_MASK, data);
 }
 
+static int max77693_set_input_current_limit(struct max77693_charger *chg,
+		unsigned int uamp)
+{
+	unsigned int data;
+
+	if (uamp < 60000 || uamp > 2540000) {
+		dev_err(chg->dev, "Wrong value for input current limit");
+		return -EINVAL;
+	};
+
+	data = uamp / 20000; /* 20mA steps */
+
+	data <<= CHG_CNFG_09_CHGIN_ILIM_SHIFT;
+
+	dev_dbg(chg->dev, "Input current limit: %u (0x%x)\n", uamp, data);
+
+	return regmap_update_bits(chg->max77693->regmap,
+			MAX77693_CHG_REG_CHG_CNFG_09,
+			CHG_CNFG_09_CHGIN_ILIM_MASK, data);
+}
+
+static int max77693_set_fast_charge_current(struct max77693_charger *chg,
+		unsigned int uamp)
+{
+	unsigned int data;
+
+	if (uamp > 2100000) {
+		dev_err(chg->dev, "Wrong value for fast charge current\n");
+		return -EINVAL;
+	}
+
+	data = uamp / 33300; /* 0.1A/3 steps */
+
+	data <<= CHG_CNFG_02_CC_SHIFT;
+
+	dev_dbg(chg->dev, "Fast charge current: %u (0x%x)\n", uamp, data);
+
+	return regmap_update_bits(chg->max77693->regmap,
+			MAX77693_CHG_REG_CHG_CNFG_02,
+			CHG_CNFG_02_CC_MASK, data);
+}
+
 static int max77693_set_charge_input_threshold_volt(struct max77693_charger *chg,
 		unsigned int uvolt)
 {
@@ -673,6 +716,15 @@ static int max77693_reg_init(struct max77693_charger *chg)
 	if (ret)
 		return ret;
 
+	ret = max77693_set_fast_charge_current(chg, chg->fast_charge_current);
+	if (ret)
+		return ret;
+
+	ret = max77693_set_input_current_limit(chg,
+				DEFAULT_FAST_CHARGE_CURRENT);
+	if (ret)
+		return ret;
+
 	return max77693_set_charge_input_threshold_volt(chg,
 			chg->charge_input_threshold_volt);
 }
@@ -681,6 +733,7 @@ static int max77693_reg_init(struct max77693_charger *chg)
 static int max77693_dt_init(struct device *dev, struct max77693_charger *chg)
 {
 	struct device_node *np = dev->of_node;
+	struct power_supply_battery_info *battery_info;
 
 	if (!np) {
 		dev_err(dev, "no charger OF node\n");
@@ -708,11 +761,20 @@ static int max77693_dt_init(struct device *dev, struct max77693_charger *chg)
 		chg->charge_input_threshold_volt =
 			DEFAULT_CHARGER_INPUT_THRESHOLD_VOLT;
 
+	if (power_supply_get_battery_info(chg->charger, &battery_info) ||
+			!battery_info->constant_charge_current_max_ua)
+		chg->fast_charge_current = DEFAULT_FAST_CHARGE_CURRENT;
+	else
+		chg->fast_charge_current =
+			battery_info->constant_charge_current_max_ua;
+
 	return 0;
 }
 #else /* CONFIG_OF */
 static int max77693_dt_init(struct device *dev, struct max77693_charger *chg)
 {
+	chg->fast_charge_current = DEFAULT_FAST_CHARGE_CURRENT;
+
 	return 0;
 }
 #endif /* CONFIG_OF */
@@ -732,6 +794,15 @@ static int max77693_charger_probe(struct platform_device *pdev)
 	chg->dev = &pdev->dev;
 	chg->max77693 = max77693;
 
+	psy_cfg.drv_data = chg;
+
+	chg->charger = devm_power_supply_register(&pdev->dev,
+						  &max77693_charger_desc,
+						  &psy_cfg);
+	if (IS_ERR(chg->charger))
+		return dev_err_probe(&pdev->dev, PTR_ERR(chg->charger),
+				     "failed: power supply register\n");
+
 	ret = max77693_dt_init(&pdev->dev, chg);
 	if (ret)
 		return ret;
@@ -740,8 +811,6 @@ static int max77693_charger_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	psy_cfg.drv_data = chg;
-
 	ret = device_create_file(&pdev->dev, &dev_attr_fast_charge_timer);
 	if (ret) {
 		dev_err(&pdev->dev, "failed: create fast charge timer sysfs entry\n");
@@ -761,15 +830,6 @@ static int max77693_charger_probe(struct platform_device *pdev)
 		goto err;
 	}
 
-	chg->charger = devm_power_supply_register(&pdev->dev,
-						  &max77693_charger_desc,
-						  &psy_cfg);
-	if (IS_ERR(chg->charger)) {
-		dev_err(&pdev->dev, "failed: power supply register\n");
-		ret = PTR_ERR(chg->charger);
-		goto err;
-	}
-
 	return 0;
 
 err:
diff --git a/include/linux/mfd/max77693-private.h b/include/linux/mfd/max77693-private.h
index 20c5e02ed9da..0819cf0a4f5f 100644
--- a/include/linux/mfd/max77693-private.h
+++ b/include/linux/mfd/max77693-private.h
@@ -145,6 +145,8 @@ enum max77693_pmic_reg {
 #define DEFAULT_THERMAL_REGULATION_TEMP		100
 /* microamps */
 #define DEFAULT_BATTERY_OVERCURRENT		3500000
+/* microamps */
+#define DEFAULT_FAST_CHARGE_CURRENT		500000
 /* microvolts */
 #define DEFAULT_CHARGER_INPUT_THRESHOLD_VOLT	4300000
 

-- 
2.45.2