charger: max14577: Configure battery-dependent settings from DTS and sysfs

Remove hard-coded values for:
- Fast Charge current,
- End Of Charge current,
- Fast Charge timer,
- Overvoltage Protection Threshold,
- Battery Constant Voltage,
and use DTS or sysfs to configure them. This allows using the max14577 charger
driver with different batteries.

Now the charger driver requires valid configuration data from DTS. In
case of wrong configuration data it fails during probe.

The fast charge timer is configured through sysfs entry.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Andrew Morton <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/power/Kconfig

···
 config CHARGER_MAX14577
 	tristate "Maxim MAX14577/77836 battery charger driver"
 	depends on MFD_MAX14577
+	select SYSFS
 	help
 	  Say Y to enable support for the battery charger control sysfs and
 	  platform data of MAX14577/77836 MUICs.

drivers/power/max14577_charger.c

···
 #include <linux/platform_device.h>
 #include <linux/power_supply.h>
 #include <linux/mfd/max14577-private.h>
+#include <linux/mfd/max14577.h>
 
 struct max14577_charger {
 	struct device *dev;
···
 
 	unsigned int		charging_state;
 	unsigned int		battery_state;
+
+	struct max14577_charger_platform_data	*pdata;
 };
 
 /*
···
 	return 1;
 }
 
+static int max14577_set_fast_charge_timer(struct max14577_charger *chg,
+		unsigned long hours)
+{
+	u8 reg_data;
+
+	switch (hours) {
+	case 5 ... 7:
+		reg_data = hours - 3;
+		break;
+	case 0:
+		/* Disable */
+		reg_data = 0x7;
+		break;
+	default:
+		dev_err(chg->dev, "Wrong value for Fast-Charge Timer: %lu\n",
+				hours);
+		return -EINVAL;
+	}
+	reg_data <<= CHGCTRL1_TCHW_SHIFT;
+
+	return max14577_update_reg(chg->max14577->regmap,
+			MAX14577_REG_CHGCTRL1, CHGCTRL1_TCHW_MASK, reg_data);
+}
+
+static int max14577_init_constant_voltage(struct max14577_charger *chg,
+		unsigned int uvolt)
+{
+	u8 reg_data;
+
+	if (uvolt < MAXIM_CHARGER_CONSTANT_VOLTAGE_MIN ||
+			uvolt > MAXIM_CHARGER_CONSTANT_VOLTAGE_MAX)
+		return -EINVAL;
+
+	if (uvolt == 4200000)
+		reg_data = 0x0;
+	else if (uvolt == MAXIM_CHARGER_CONSTANT_VOLTAGE_MAX)
+		reg_data = 0x1f;
+	else if (uvolt <= 4280000) {
+		unsigned int val = uvolt;
+
+		val -= MAXIM_CHARGER_CONSTANT_VOLTAGE_MIN;
+		val /= MAXIM_CHARGER_CONSTANT_VOLTAGE_STEP;
+		if (uvolt <= 4180000)
+			reg_data = 0x1 + val;
+		else
+			reg_data = val; /* Fix for gap between 4.18V and 4.22V */
+	} else
+		return -EINVAL;
+
+	reg_data <<= CHGCTRL3_MBCCVWRC_SHIFT;
+
+	return max14577_write_reg(chg->max14577->regmap,
+			MAX14577_CHG_REG_CHG_CTRL3, reg_data);
+}
+
+static int max14577_init_eoc(struct max14577_charger *chg,
+		unsigned int uamp)
+{
+	unsigned int current_bits = 0xf;
+	u8 reg_data;
+
+	switch (chg->max14577->dev_type) {
+	case MAXIM_DEVICE_TYPE_MAX77836:
+		if (uamp < 5000)
+			return -EINVAL; /* Requested current is too low */
+
+		if (uamp >= 7500 && uamp < 10000)
+			current_bits = 0x0;
+		else if (uamp <= 50000) {
+			/* <5000, 7499> and <10000, 50000> */
+			current_bits = uamp / 5000;
+		} else {
+			uamp = min(uamp, 100000U) - 50000U;
+			current_bits = 0xa + uamp / 10000;
+		}
+		break;
+
+	case MAXIM_DEVICE_TYPE_MAX14577:
+	default:
+		if (uamp < MAX14577_CHARGER_EOC_CURRENT_LIMIT_MIN)
+			return -EINVAL; /* Requested current is too low */
+
+		uamp = min(uamp, MAX14577_CHARGER_EOC_CURRENT_LIMIT_MAX);
+		uamp -= MAX14577_CHARGER_EOC_CURRENT_LIMIT_MIN;
+		current_bits = uamp / MAX14577_CHARGER_EOC_CURRENT_LIMIT_STEP;
+		break;
+	}
+
+	reg_data = current_bits << CHGCTRL5_EOCS_SHIFT;
+
+	return max14577_update_reg(chg->max14577->regmap,
+			MAX14577_CHG_REG_CHG_CTRL5, CHGCTRL5_EOCS_MASK,
+			reg_data);
+}
+
+static int max14577_init_fast_charge(struct max14577_charger *chg,
+		unsigned int uamp)
+{
+	u8 reg_data;
+	int ret;
+	const struct maxim_charger_current *limits =
+		&maxim_charger_currents[chg->max14577->dev_type];
+
+	ret = maxim_charger_calc_reg_current(limits, uamp, uamp, &reg_data);
+	if (ret) {
+		dev_err(chg->dev, "Wrong value for fast charge: %u\n", uamp);
+		return ret;
+	}
+
+	return max14577_update_reg(chg->max14577->regmap,
+			MAX14577_CHG_REG_CHG_CTRL4,
+			CHGCTRL4_MBCICHWRCL_MASK | CHGCTRL4_MBCICHWRCH_MASK,
+			reg_data);
+}
+
 /*
  * Sets charger registers to proper and safe default values.
  * Some of these values are equal to defaults in MAX14577E
  * data sheet but there are minor differences.
  */
-static void max14577_charger_reg_init(struct max14577_charger *chg)
+static int max14577_charger_reg_init(struct max14577_charger *chg)
 {
 	struct regmap *rmap = chg->max14577->regmap;
 	u8 reg_data;
+	int ret;
 
 	/*
 	 * Charger-Type Manual Detection, default off (set CHGTYPMAN to 0)
···
 			CDETCTRL1_CHGDETEN_MASK | CDETCTRL1_CHGTYPMAN_MASK,
 			reg_data);
 
-	/* Battery Fast-Charge Timer, set to: 6hrs */
-	reg_data = 0x3 << CHGCTRL1_TCHW_SHIFT;
-	max14577_write_reg(rmap, MAX14577_REG_CHGCTRL1, reg_data);
-
 	/*
 	 * Wall-Adapter Rapid Charge, default on
 	 * Battery-Charger, default on
···
 	reg_data |= 0x1 << CHGCTRL2_MBCHOSTEN_SHIFT;
 	max14577_write_reg(rmap, MAX14577_REG_CHGCTRL2, reg_data);
 
-	/* Battery-Charger Constant Voltage (CV) Mode, set to: 4.35V */
-	reg_data = 0xf << CHGCTRL3_MBCCVWRC_SHIFT;
-	max14577_write_reg(rmap, MAX14577_REG_CHGCTRL3, reg_data);
-
-	/*
-	 * Fast Battery-Charge Current Low,
-	 * default 200-950mA (max14577) / 100-475mA (max77836)
-	 *
-	 * Fast Battery-Charge Current High,
-	 * set to 450mA (max14577) / 225mA (max77836)
-	 */
-	reg_data = 0x1 << CHGCTRL4_MBCICHWRCL_SHIFT;
-	reg_data |= 0x5 << CHGCTRL4_MBCICHWRCH_SHIFT;
-	max14577_write_reg(rmap, MAX14577_REG_CHGCTRL4, reg_data);
-
-	/* End-of-Charge Current, set to 50mA (max14577) / 7.5mA (max77836) */
-	reg_data = 0x0 << CHGCTRL5_EOCS_SHIFT;
-	max14577_write_reg(rmap, MAX14577_REG_CHGCTRL5, reg_data);
-
 	/* Auto Charging Stop, default off */
 	reg_data = 0x0 << CHGCTRL6_AUTOSTOP_SHIFT;
 	max14577_write_reg(rmap, MAX14577_REG_CHGCTRL6, reg_data);
 
-	/* Overvoltage-Protection Threshold, set to 6.5V */
-	reg_data = 0x2 << CHGCTRL7_OTPCGHCVS_SHIFT;
+	ret = max14577_init_constant_voltage(chg, chg->pdata->constant_uvolt);
+	if (ret)
+		return ret;
+
+	ret = max14577_init_eoc(chg, chg->pdata->eoc_uamp);
+	if (ret)
+		return ret;
+
+	ret = max14577_init_fast_charge(chg, chg->pdata->fast_charge_uamp);
+	if (ret)
+		return ret;
+
+	ret = max14577_set_fast_charge_timer(chg,
+			MAXIM_CHARGER_FAST_CHARGE_TIMER_DEFAULT);
+	if (ret)
+		return ret;
+
+	/* Initialize Overvoltage-Protection Threshold */
+	switch (chg->pdata->ovp_uvolt) {
+	case 7500000:
+		reg_data = 0x0;
+		break;
+	case 6000000:
+	case 6500000:
+	case 7000000:
+		reg_data = 0x1 + (chg->pdata->ovp_uvolt - 6000000) / 500000;
+		break;
+	default:
+		dev_err(chg->dev, "Wrong value for OVP: %u\n",
+				chg->pdata->ovp_uvolt);
+		return -EINVAL;
+	}
+	reg_data <<= CHGCTRL7_OTPCGHCVS_SHIFT;
 	max14577_write_reg(rmap, MAX14577_REG_CHGCTRL7, reg_data);
+
+	return 0;
 }
 
 /* Support property from charger */
···
 	return ret;
 }
 
+#ifdef CONFIG_OF
+static struct max14577_charger_platform_data *max14577_charger_dt_init(
+		struct platform_device *pdev)
+{
+	struct max14577_charger_platform_data *pdata;
+	struct device_node *np = pdev->dev.of_node;
+	int ret;
+
+	if (!np) {
+		dev_err(&pdev->dev, "No charger OF node\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return ERR_PTR(-ENOMEM);
+
+	ret = of_property_read_u32(np, "maxim,constant-uvolt",
+			&pdata->constant_uvolt);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot parse maxim,constant-uvolt field from DT\n");
+		return ERR_PTR(ret);
+	}
+
+	ret = of_property_read_u32(np, "maxim,fast-charge-uamp",
+			&pdata->fast_charge_uamp);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot parse maxim,fast-charge-uamp field from DT\n");
+		return ERR_PTR(ret);
+	}
+
+	ret = of_property_read_u32(np, "maxim,eoc-uamp", &pdata->eoc_uamp);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot parse maxim,eoc-uamp field from DT\n");
+		return ERR_PTR(ret);
+	}
+
+	ret = of_property_read_u32(np, "maxim,ovp-uvolt", &pdata->ovp_uvolt);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot parse maxim,ovp-uvolt field from DT\n");
+		return ERR_PTR(ret);
+	}
+
+	return pdata;
+}
+#else /* CONFIG_OF */
+static struct max14577_charger_platform_data *max14577_charger_dt_init(
+		struct platform_device *pdev)
+{
+	return NULL;
+}
+#endif /* CONFIG_OF */
+
+static ssize_t show_fast_charge_timer(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct max14577_charger *chg = dev_get_drvdata(dev);
+	u8 reg_data;
+	int ret;
+	unsigned int val;
+
+	ret = max14577_read_reg(chg->max14577->regmap, MAX14577_REG_CHGCTRL1,
+			&reg_data);
+	if (ret)
+		return ret;
+
+	reg_data &= CHGCTRL1_TCHW_MASK;
+	reg_data >>= CHGCTRL1_TCHW_SHIFT;
+	switch (reg_data) {
+	case 0x2 ... 0x4:
+		val = reg_data + 3;
+		break;
+	case 0x7:
+		val = 0;
+		break;
+	default:
+		val = 5;
+		break;
+	}
+
+	return scnprintf(buf, PAGE_SIZE, "%u\n", val);
+}
+
+static ssize_t store_fast_charge_timer(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct max14577_charger *chg = dev_get_drvdata(dev);
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	ret = max14577_set_fast_charge_timer(chg, val);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static DEVICE_ATTR(fast_charge_timer, S_IRUGO | S_IWUSR,
+		show_fast_charge_timer, store_fast_charge_timer);
+
 static int max14577_charger_probe(struct platform_device *pdev)
 {
 	struct max14577_charger *chg;
···
 	chg->dev = &pdev->dev;
 	chg->max14577 = max14577;
 
-	max14577_charger_reg_init(chg);
+	chg->pdata = max14577_charger_dt_init(pdev);
+	if (IS_ERR_OR_NULL(chg->pdata))
+		return PTR_ERR(chg->pdata);
+
+	ret = max14577_charger_reg_init(chg);
+	if (ret)
+		return ret;
 
 	chg->charger.name = "max14577-charger",
 	chg->charger.type = POWER_SUPPLY_TYPE_BATTERY,
···
 	chg->charger.num_properties = ARRAY_SIZE(max14577_charger_props),
 	chg->charger.get_property = max14577_charger_get_property,
 
-	ret = power_supply_register(&pdev->dev, &chg->charger);
+	ret = device_create_file(&pdev->dev, &dev_attr_fast_charge_timer);
 	if (ret) {
-		dev_err(&pdev->dev, "failed: power supply register\n");
+		dev_err(&pdev->dev, "failed: create sysfs entry\n");
 		return ret;
 	}
 
+	ret = power_supply_register(&pdev->dev, &chg->charger);
+	if (ret) {
+		dev_err(&pdev->dev, "failed: power supply register\n");
+		goto err;
+	}
+
+	/* Check for valid values for charger */
+	BUILD_BUG_ON(MAX14577_CHARGER_EOC_CURRENT_LIMIT_MIN +
+			MAX14577_CHARGER_EOC_CURRENT_LIMIT_STEP * 0xf !=
+			MAX14577_CHARGER_EOC_CURRENT_LIMIT_MAX);
 	return 0;
+
+err:
+	device_remove_file(&pdev->dev, &dev_attr_fast_charge_timer);
+
+	return ret;
 }
 
 static int max14577_charger_remove(struct platform_device *pdev)
 {
 	struct max14577_charger *chg = platform_get_drvdata(pdev);
 
+	device_remove_file(&pdev->dev, &dev_attr_fast_charge_timer);
 	power_supply_unregister(&chg->charger);
 
 	return 0;

include/linux/mfd/max14577-private.h

···
 #define MAX77836_CHARGER_CURRENT_LIMIT_HIGH_STEP	 25000U
 #define MAX77836_CHARGER_CURRENT_LIMIT_MAX		475000U
 
+/*
+ * MAX14577 charger End-Of-Charge current limits
+ * (as in CHGCTRL5 register), uA
+ */
+#define MAX14577_CHARGER_EOC_CURRENT_LIMIT_MIN		50000U
+#define MAX14577_CHARGER_EOC_CURRENT_LIMIT_STEP		10000U
+#define MAX14577_CHARGER_EOC_CURRENT_LIMIT_MAX		200000U
+
+/*
+ * MAX14577/MAX77836 Battery Constant Voltage
+ * (as in CHGCTRL3 register), uV
+ */
+#define MAXIM_CHARGER_CONSTANT_VOLTAGE_MIN		4000000U
+#define MAXIM_CHARGER_CONSTANT_VOLTAGE_STEP		20000U
+#define MAXIM_CHARGER_CONSTANT_VOLTAGE_MAX		4350000U
+
+/* Default value for fast charge timer, in hours */
+#define MAXIM_CHARGER_FAST_CHARGE_TIMER_DEFAULT		5
+
 /* MAX14577 regulator SFOUT LDO voltage, fixed, uV */
 #define MAX14577_REGULATOR_SAFEOUT_VOLTAGE		4900000
 

include/linux/mfd/max14577.h

···
 	struct device_node *of_node;
 };
 
+struct max14577_charger_platform_data {
+	u32 constant_uvolt;
+	u32 fast_charge_uamp;
+	u32 eoc_uamp;
+	u32 ovp_uvolt;
+};
+
 /*
  * MAX14577 MFD platform data
  */