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