drivers/power/supply/lego_ev3_battery.c

Source file repositories/reference/linux-study-clean/drivers/power/supply/lego_ev3_battery.c

File Facts

System
Linux kernel
Corpus path
drivers/power/supply/lego_ev3_battery.c
Extension
.c
Size
6501 bytes
Lines
234
Domain
Driver Families
Bucket
drivers/power
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct lego_ev3_battery {
	struct iio_channel *iio_v;
	struct iio_channel *iio_i;
	struct gpio_desc *rechargeable_gpio;
	struct power_supply *psy;
	int technology;
	int v_max;
	int v_min;
};

static int lego_ev3_battery_get_property(struct power_supply *psy,
					 enum power_supply_property psp,
					 union power_supply_propval *val)
{
	struct lego_ev3_battery *batt = power_supply_get_drvdata(psy);
	int ret, val2;

	switch (psp) {
	case POWER_SUPPLY_PROP_TECHNOLOGY:
		val->intval = batt->technology;
		break;
	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
		/* battery voltage is iio channel * 2 + Vce of transistor */
		ret = iio_read_channel_processed(batt->iio_v, &val->intval);
		if (ret)
			return ret;

		val->intval *= 2000;
		val->intval += 50000;

		/* plus adjust for shunt resistor drop */
		ret = iio_read_channel_processed(batt->iio_i, &val2);
		if (ret)
			return ret;

		val2 *= 1000;
		val2 /= 15;
		val->intval += val2;
		break;
	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
		val->intval = batt->v_max;
		break;
	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
		val->intval = batt->v_min;
		break;
	case POWER_SUPPLY_PROP_CURRENT_NOW:
		/* battery current is iio channel / 15 / 0.05 ohms */
		ret = iio_read_channel_processed(batt->iio_i, &val->intval);
		if (ret)
			return ret;

		val->intval *= 20000;
		val->intval /= 15;
		break;
	case POWER_SUPPLY_PROP_SCOPE:
		val->intval = POWER_SUPPLY_SCOPE_SYSTEM;
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static int lego_ev3_battery_set_property(struct power_supply *psy,
					 enum power_supply_property psp,
					 const union power_supply_propval *val)
{
	struct lego_ev3_battery *batt = power_supply_get_drvdata(psy);

	switch (psp) {
	case POWER_SUPPLY_PROP_TECHNOLOGY:
		/*
		 * Only allow changing technology from Unknown to NiMH. Li-ion
		 * batteries are automatically detected and should not be
		 * overridden. Rechargeable AA batteries, on the other hand,
		 * cannot be automatically detected, and so must be manually
		 * specified. This should only be set once during system init,
		 * so there is no mechanism to go back to Unknown.
		 */
		if (batt->technology != POWER_SUPPLY_TECHNOLOGY_UNKNOWN)
			return -EINVAL;
		switch (val->intval) {
		case POWER_SUPPLY_TECHNOLOGY_NiMH:
			batt->technology = POWER_SUPPLY_TECHNOLOGY_NiMH;
			batt->v_max = 7800000;
			batt->v_min = 5400000;
			break;
		default:
			return -EINVAL;

Annotation

Implementation Notes