ingenic-battery.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Battery driver for the Ingenic JZ47xx SoCs
  4 * Copyright (c) 2019 Artur Rojek <contact@artur-rojek.eu>
  5 *
  6 * based on drivers/power/supply/jz4740-battery.c
  7 */
  8
  9#include <linux/iio/consumer.h>
 10#include <linux/module.h>
 11#include <linux/of.h>
 12#include <linux/platform_device.h>
 13#include <linux/power_supply.h>
 14#include <linux/property.h>
 15
 16struct ingenic_battery {
 17	struct device *dev;
 18	struct iio_channel *channel;
 19	struct power_supply_desc desc;
 20	struct power_supply *battery;
 21	struct power_supply_battery_info *info;
 22};
 23
 24static int ingenic_battery_get_property(struct power_supply *psy,
 25					enum power_supply_property psp,
 26					union power_supply_propval *val)
 27{
 28	struct ingenic_battery *bat = power_supply_get_drvdata(psy);
 29	struct power_supply_battery_info *info = bat->info;
 30	int ret;
 31
 32	switch (psp) {
 33	case POWER_SUPPLY_PROP_HEALTH:
 34		ret = iio_read_channel_processed_scale(bat->channel,
 35						       &val->intval,
 36						       1000);
 37		if (val->intval < info->voltage_min_design_uv)
 38			val->intval = POWER_SUPPLY_HEALTH_DEAD;
 39		else if (val->intval > info->voltage_max_design_uv)
 40			val->intval = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
 41		else
 42			val->intval = POWER_SUPPLY_HEALTH_GOOD;
 43		return ret;
 44	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 45		ret = iio_read_channel_processed_scale(bat->channel,
 46						       &val->intval,
 47						       1000);
 48		return ret;
 49	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
 50		val->intval = info->voltage_min_design_uv;
 51		return 0;
 52	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
 53		val->intval = info->voltage_max_design_uv;
 54		return 0;
 55	default:
 56		return -EINVAL;
 57	}
 58}
 59
 60/* Set the most appropriate IIO channel voltage reference scale
 61 * based on the battery's max voltage.
 62 */
 63static int ingenic_battery_set_scale(struct ingenic_battery *bat)
 64{
 65	const int *scale_raw;
 66	int scale_len, scale_type, best_idx = -1, best_mV, max_raw, i, ret;
 67	u64 max_mV;
 68
 69	ret = iio_read_max_channel_raw(bat->channel, &max_raw);
 70	if (ret) {
 71		dev_err(bat->dev, "Unable to read max raw channel value\n");
 72		return ret;
 73	}
 74
 75	ret = iio_read_avail_channel_attribute(bat->channel, &scale_raw,
 76					       &scale_type, &scale_len,
 77					       IIO_CHAN_INFO_SCALE);
 78	if (ret < 0) {
 79		dev_err(bat->dev, "Unable to read channel avail scale\n");
 80		return ret;
 81	}
 82	if (ret != IIO_AVAIL_LIST || scale_type != IIO_VAL_FRACTIONAL_LOG2)
 83		return -EINVAL;
 84
 85	max_mV = bat->info->voltage_max_design_uv / 1000;
 86
 87	for (i = 0; i < scale_len; i += 2) {
 88		u64 scale_mV = (max_raw * scale_raw[i]) >> scale_raw[i + 1];
 89
 90		if (scale_mV < max_mV)
 91			continue;
 92
 93		if (best_idx >= 0 && scale_mV > best_mV)
 94			continue;
 95
 96		best_mV = scale_mV;
 97		best_idx = i;
 98	}
 99
100	if (best_idx < 0) {
101		dev_err(bat->dev, "Unable to find matching voltage scale\n");
102		return -EINVAL;
103	}
104
105	/* Only set scale if there is more than one (fractional) entry */
106	if (scale_len > 2) {
107		ret = iio_write_channel_attribute(bat->channel,
108						  scale_raw[best_idx],
109						  scale_raw[best_idx + 1],
110						  IIO_CHAN_INFO_SCALE);
111		if (ret)
112			return ret;
113	}
114
115	return 0;
116}
117
118static enum power_supply_property ingenic_battery_properties[] = {
119	POWER_SUPPLY_PROP_HEALTH,
120	POWER_SUPPLY_PROP_VOLTAGE_NOW,
121	POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
122	POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
123};
124
125static int ingenic_battery_probe(struct platform_device *pdev)
126{
127	struct device *dev = &pdev->dev;
128	struct ingenic_battery *bat;
129	struct power_supply_config psy_cfg = {};
130	struct power_supply_desc *desc;
131	int ret;
132
133	bat = devm_kzalloc(dev, sizeof(*bat), GFP_KERNEL);
134	if (!bat)
135		return -ENOMEM;
136
137	bat->dev = dev;
138	bat->channel = devm_iio_channel_get(dev, "battery");
139	if (IS_ERR(bat->channel))
140		return PTR_ERR(bat->channel);
141
142	desc = &bat->desc;
143	desc->name = "jz-battery";
144	desc->type = POWER_SUPPLY_TYPE_BATTERY;
145	desc->properties = ingenic_battery_properties;
146	desc->num_properties = ARRAY_SIZE(ingenic_battery_properties);
147	desc->get_property = ingenic_battery_get_property;
148	psy_cfg.drv_data = bat;
149	psy_cfg.fwnode = dev_fwnode(dev);
150
151	bat->battery = devm_power_supply_register(dev, desc, &psy_cfg);
152	if (IS_ERR(bat->battery))
153		return dev_err_probe(dev, PTR_ERR(bat->battery),
154				     "Unable to register battery\n");
155
156	ret = power_supply_get_battery_info(bat->battery, &bat->info);
157	if (ret) {
158		dev_err(dev, "Unable to get battery info: %d\n", ret);
159		return ret;
160	}
161	if (bat->info->voltage_min_design_uv < 0) {
162		dev_err(dev, "Unable to get voltage min design\n");
163		return bat->info->voltage_min_design_uv;
164	}
165	if (bat->info->voltage_max_design_uv < 0) {
166		dev_err(dev, "Unable to get voltage max design\n");
167		return bat->info->voltage_max_design_uv;
168	}
169
170	return ingenic_battery_set_scale(bat);
171}
172
173#ifdef CONFIG_OF
174static const struct of_device_id ingenic_battery_of_match[] = {
175	{ .compatible = "ingenic,jz4740-battery", },
176	{ },
177};
178MODULE_DEVICE_TABLE(of, ingenic_battery_of_match);
179#endif
180
181static struct platform_driver ingenic_battery_driver = {
182	.driver = {
183		.name = "ingenic-battery",
184		.of_match_table = of_match_ptr(ingenic_battery_of_match),
185	},
186	.probe = ingenic_battery_probe,
187};
188module_platform_driver(ingenic_battery_driver);
189
190MODULE_DESCRIPTION("Battery driver for Ingenic JZ47xx SoCs");
191MODULE_AUTHOR("Artur Rojek <contact@artur-rojek.eu>");
192MODULE_LICENSE("GPL");