[WiP] power: supply: add battery driver for NTX MSP430

Signed-off-by: Josua Mayer <josua.mayer@jm0.eu>

arch/arm/boot/dts/imx50-kobo-aura.dts

@@ -20,6 +20,15 @@
 		reg = <0x70000000 0x10000000>;
 	};
 
+	/* PR-285083 battery */
+	bat: battery {
+		compatible = "simple-battery";
+		voltage-min-design-microvolt = <3400000>;
+		voltage-max-design-microvolt = <4100000>;
+		energy-full-design-microwatt-hours = <5550000>;
+		charge-full-design-microamp-hours = <1500000>;
+	};
+
 	gpio-leds {
 		compatible = "gpio-leds";
 		pinctrl-names = "default";
@@ -140,6 +149,11 @@
 		reg = <0x43>;
 		compatible = "netronix,msp430-ec";
 		status = "okay";
+
+		ec_bat {
+			compatible = "netronix,msp430-ec-battery";
+			monitored-battery = <&bat>;
+		};
 	};
 };
 

drivers/power/supply/Kconfig

@@ -710,4 +710,10 @@ config CHARGER_WILCO
 	  information can be found in
 	  Documentation/ABI/testing/sysfs-class-power-wilco
 
+config BATTERY_NTX_MSP430
+	tristate "NTX MSP430 battery monitor driver"
+	depends on MFD_NTX_MSP430
+	help
+	  Say Y here to enable support for battery monitoring with NTX MSP430.
+
 endif # POWER_SUPPLY

drivers/power/supply/Makefile

@@ -92,3 +92,4 @@ obj-$(CONFIG_FUEL_GAUGE_SC27XX)	+= sc27xx_fuel_gauge.o
 obj-$(CONFIG_CHARGER_UCS1002)	+= ucs1002_power.o
 obj-$(CONFIG_CHARGER_BD70528)	+= bd70528-charger.o
 obj-$(CONFIG_CHARGER_WILCO)	+= wilco-charger.o
+obj-$(CONFIG_BATTERY_NTX_MSP430) += ntx-msp430-ec_battery.o

drivers/power/supply/ntx-msp430-ec_battery.c

@@ -0,0 +1,141 @@
+#include <linux/mfd/ntx_msp430.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/of_device.h>
+
+struct ntx_msp430_battery_device_info {
+	struct ntx_msp430 *mfd;
+	struct power_supply *bat;
+};
+
+static enum power_supply_property ntx_msp430_battery_props[] = {
+	POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
+	POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
+	POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,
+};
+
+static int ntx_msp430_battery_read_voltage(struct ntx_msp430_battery_device_info *di)
+{
+	int val;
+	int voltage;
+
+	// voltage at 0x41
+	val = ntx_msp430_read16(di->mfd, 0x41);
+	if (val < 0) {
+		//dev_err(di->dev, "Could not read ADC: %d\n", voltage);
+		return val;
+	}
+
+	/* value to uV
+	 * vendor kernel source suggests linear behaviour from 3V to 4.2V with readings 767 to 1023
+	 * this gives 4687,5uV per step
+	 * adjusted 3V value in favour of an exact result 4.2V result at 1023
+	 */
+	voltage = 2999872;
+	voltage += (val - 767) * 4688;
+
+	return voltage;
+}
+
+int ntx_msp430_battery_get_property(struct power_supply *psy, enum power_supply_property psp, union power_supply_propval *val) {
+	struct ntx_msp430_battery_device_info *di = power_supply_get_drvdata(psy);
+	struct power_supply_battery_info battery_info = {};
+	int r;
+
+	r = power_supply_get_battery_info(psy, &battery_info);
+	if(r) {
+		dev_warn(&psy->dev, "Could not get battery info: %d\n", r);
+	}
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
+		val->intval = battery_info.voltage_max_design_uv;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
+		val->intval = battery_info.voltage_min_design_uv;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		val->intval = ntx_msp430_battery_read_voltage(di);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+		val->intval = battery_info.charge_full_design_uah;
+		break;
+	case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:
+		val->intval = battery_info.energy_full_design_uwh;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int ntx_msp430_battery_probe(struct platform_device *pdev) {
+	struct ntx_msp430 *mfd;
+	struct ntx_msp430_battery_device_info *di;
+	struct power_supply_desc *psy_desc;
+	struct power_supply_config psy_cfg = {};
+
+	mfd = dev_get_drvdata(pdev->dev.parent);
+	if(!mfd) {
+		return -EPROBE_DEFER;
+	}
+
+	di = devm_kzalloc(&pdev->dev, sizeof(*di), GFP_KERNEL);
+	if (!di)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, di);
+
+	psy_desc = devm_kzalloc(&pdev->dev, sizeof(*psy_desc), GFP_KERNEL);
+	if (!psy_desc)
+		return -ENOMEM;
+
+	psy_cfg.drv_data = di;
+	psy_cfg.of_node = pdev->dev.of_node;
+
+	psy_desc->name = "ntx-msp430-ec-battery";
+	psy_desc->type = POWER_SUPPLY_TYPE_BATTERY;
+	psy_desc->properties = ntx_msp430_battery_props;
+	psy_desc->num_properties = ARRAY_SIZE(ntx_msp430_battery_props);
+	psy_desc->get_property = ntx_msp430_battery_get_property;
+
+	di->mfd = mfd;
+	di->bat = power_supply_register_no_ws(&pdev->dev, psy_desc, &psy_cfg);
+	if (IS_ERR(di->bat)) {
+		dev_err(&pdev->dev, "failed to register battery\n");
+		return PTR_ERR(di->bat);
+	}
+
+	return 0;
+}
+
+static int ntx_msp430_battery_remove(struct platform_device *pdev) {
+	struct ntx_msp430_battery_device_info *di = platform_get_drvdata(pdev);
+
+	power_supply_unregister(di->bat);
+
+	return 0;
+}
+
+static const struct of_device_id ntx_msp430_battery_of_match[] = {
+	{ .compatible = "netronix,msp430-ec-battery" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ntx_msp430_battery_of_match);
+
+static struct platform_driver ntx_msp430_battery_driver = {
+	.driver = {
+		.name = "ntx-msp430-pwm",
+		.of_match_table = ntx_msp430_battery_of_match,
+	},
+	.probe = ntx_msp430_battery_probe,
+	.remove = ntx_msp430_battery_remove,
+};
+module_platform_driver(ntx_msp430_battery_driver);
+
+MODULE_AUTHOR("Josua Mayer <josua.mayer@jm0.eu>");
+MODULE_DESCRIPTION("NTX MSP430 battery monitor driver");
+MODULE_LICENSE("GPL");