acer_a500_battery.c

  1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Battery driver for Acer Iconia Tab A500.
  4 *
  5 * Copyright 2020 GRATE-driver project.
  6 *
  7 * Based on downstream driver from Acer Inc.
  8 * Based on NVIDIA Gas Gauge driver for SBS Compliant Batteries.
  9 *
 10 * Copyright (c) 2010, NVIDIA Corporation.
 11 */
 12
 13#include <linux/module.h>
 14#include <linux/platform_device.h>
 15#include <linux/power_supply.h>
 16#include <linux/regmap.h>
 17#include <linux/sched.h>
 18#include <linux/slab.h>
 19#include <linux/workqueue.h>
 20#include <linux/property.h>
 21
 22enum {
 23	REG_CAPACITY,
 24	REG_VOLTAGE,
 25	REG_CURRENT,
 26	REG_DESIGN_CAPACITY,
 27	REG_TEMPERATURE,
 28};
 29
 30#define EC_DATA(_reg, _psp) {			\
 31	.psp = POWER_SUPPLY_PROP_ ## _psp,	\
 32	.reg = _reg,				\
 33}
 34
 35static const struct battery_register {
 36	enum power_supply_property psp;
 37	unsigned int reg;
 38} ec_data[] = {
 39	[REG_CAPACITY]		= EC_DATA(0x00, CAPACITY),
 40	[REG_VOLTAGE]		= EC_DATA(0x01, VOLTAGE_NOW),
 41	[REG_CURRENT]		= EC_DATA(0x03, CURRENT_NOW),
 42	[REG_DESIGN_CAPACITY]	= EC_DATA(0x08, CHARGE_FULL_DESIGN),
 43	[REG_TEMPERATURE]	= EC_DATA(0x0a, TEMP),
 44};
 45
 46static const enum power_supply_property a500_battery_properties[] = {
 47	POWER_SUPPLY_PROP_CAPACITY,
 48	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
 49	POWER_SUPPLY_PROP_CURRENT_NOW,
 50	POWER_SUPPLY_PROP_PRESENT,
 51	POWER_SUPPLY_PROP_STATUS,
 52	POWER_SUPPLY_PROP_TECHNOLOGY,
 53	POWER_SUPPLY_PROP_TEMP,
 54	POWER_SUPPLY_PROP_VOLTAGE_NOW,
 55};
 56
 57struct a500_battery {
 58	struct delayed_work poll_work;
 59	struct power_supply *psy;
 60	struct regmap *regmap;
 61	unsigned int capacity;
 62};
 63
 64static bool a500_battery_update_capacity(struct a500_battery *bat)
 65{
 66	unsigned int capacity;
 67	int err;
 68
 69	err = regmap_read(bat->regmap, ec_data[REG_CAPACITY].reg, &capacity);
 70	if (err)
 71		return false;
 72
 73	/* capacity can be >100% even if max value is 100% */
 74	capacity = min(capacity, 100u);
 75
 76	if (bat->capacity != capacity) {
 77		bat->capacity = capacity;
 78		return true;
 79	}
 80
 81	return false;
 82}
 83
 84static int a500_battery_get_status(struct a500_battery *bat)
 85{
 86	if (bat->capacity < 100) {
 87		if (power_supply_am_i_supplied(bat->psy))
 88			return POWER_SUPPLY_STATUS_CHARGING;
 89		else
 90			return POWER_SUPPLY_STATUS_DISCHARGING;
 91	}
 92
 93	return POWER_SUPPLY_STATUS_FULL;
 94}
 95
 96static void a500_battery_unit_adjustment(struct device *dev,
 97					 enum power_supply_property psp,
 98					 union power_supply_propval *val)
 99{
100	const unsigned int base_unit_conversion = 1000;
101	const unsigned int temp_kelvin_to_celsius = 2731;
102
103	switch (psp) {
104	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
105	case POWER_SUPPLY_PROP_CURRENT_NOW:
106	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
107		val->intval *= base_unit_conversion;
108		break;
109
110	case POWER_SUPPLY_PROP_TEMP:
111		val->intval -= temp_kelvin_to_celsius;
112		break;
113
114	case POWER_SUPPLY_PROP_PRESENT:
115		val->intval = !!val->intval;
116		break;
117
118	default:
119		dev_dbg(dev,
120			"%s: no need for unit conversion %d\n", __func__, psp);
121	}
122}
123
124static int a500_battery_get_ec_data_index(struct device *dev,
125					  enum power_supply_property psp)
126{
127	unsigned int i;
128
129	/*
130	 * DESIGN_CAPACITY register always returns a non-zero value if
131	 * battery is connected and zero if disconnected, hence we'll use
132	 * it for judging the battery presence.
133	 */
134	if (psp == POWER_SUPPLY_PROP_PRESENT)
135		psp = POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN;
136
137	for (i = 0; i < ARRAY_SIZE(ec_data); i++)
138		if (psp == ec_data[i].psp)
139			return i;
140
141	dev_dbg(dev, "%s: invalid property %u\n", __func__, psp);
142
143	return -EINVAL;
144}
145
146static int a500_battery_get_property(struct power_supply *psy,
147				     enum power_supply_property psp,
148				     union power_supply_propval *val)
149{
150	struct a500_battery *bat = power_supply_get_drvdata(psy);
151	struct device *dev = psy->dev.parent;
152	int ret = 0;
153
154	switch (psp) {
155	case POWER_SUPPLY_PROP_STATUS:
156		val->intval = a500_battery_get_status(bat);
157		break;
158
159	case POWER_SUPPLY_PROP_TECHNOLOGY:
160		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
161		break;
162
163	case POWER_SUPPLY_PROP_CAPACITY:
164		a500_battery_update_capacity(bat);
165		val->intval = bat->capacity;
166		break;
167
168	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
169	case POWER_SUPPLY_PROP_CURRENT_NOW:
170	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
171	case POWER_SUPPLY_PROP_PRESENT:
172	case POWER_SUPPLY_PROP_TEMP:
173		ret = a500_battery_get_ec_data_index(dev, psp);
174		if (ret < 0)
175			break;
176
177		ret = regmap_read(bat->regmap, ec_data[ret].reg, &val->intval);
178		break;
179
180	default:
181		dev_err(dev, "%s: invalid property %u\n", __func__, psp);
182		return -EINVAL;
183	}
184
185	if (!ret) {
186		/* convert units to match requirements of power supply class */
187		a500_battery_unit_adjustment(dev, psp, val);
188	}
189
190	dev_dbg(dev, "%s: property = %d, value = %x\n",
191		__func__, psp, val->intval);
192
193	/* return NODATA for properties if battery not presents */
194	if (ret)
195		return -ENODATA;
196
197	return 0;
198}
199
200static void a500_battery_poll_work(struct work_struct *work)
201{
202	struct a500_battery *bat;
203	bool capacity_changed;
204
205	bat = container_of(work, struct a500_battery, poll_work.work);
206	capacity_changed = a500_battery_update_capacity(bat);
207
208	if (capacity_changed)
209		power_supply_changed(bat->psy);
210
211	/* continuously send uevent notification */
212	schedule_delayed_work(&bat->poll_work, 30 * HZ);
213}
214
215static const struct power_supply_desc a500_battery_desc = {
216	.name = "ec-battery",
217	.type = POWER_SUPPLY_TYPE_BATTERY,
218	.properties = a500_battery_properties,
219	.get_property = a500_battery_get_property,
220	.num_properties = ARRAY_SIZE(a500_battery_properties),
221	.external_power_changed = power_supply_changed,
222};
223
224static int a500_battery_probe(struct platform_device *pdev)
225{
226	struct power_supply_config psy_cfg = {};
227	struct a500_battery *bat;
228
229	bat = devm_kzalloc(&pdev->dev, sizeof(*bat), GFP_KERNEL);
230	if (!bat)
231		return -ENOMEM;
232
233	platform_set_drvdata(pdev, bat);
234
235	psy_cfg.fwnode = dev_fwnode(pdev->dev.parent);
236	psy_cfg.drv_data = bat;
237	psy_cfg.no_wakeup_source = true;
238
239	bat->regmap = dev_get_regmap(pdev->dev.parent, "KB930");
240	if (!bat->regmap)
241		return -EINVAL;
242
243	bat->psy = devm_power_supply_register(&pdev->dev,
244					      &a500_battery_desc,
245					      &psy_cfg);
246	if (IS_ERR(bat->psy))
247		return dev_err_probe(&pdev->dev, PTR_ERR(bat->psy),
248				     "failed to register battery\n");
249
250	INIT_DELAYED_WORK(&bat->poll_work, a500_battery_poll_work);
251	schedule_delayed_work(&bat->poll_work, HZ);
252
253	return 0;
254}
255
256static void a500_battery_remove(struct platform_device *pdev)
257{
258	struct a500_battery *bat = dev_get_drvdata(&pdev->dev);
259
260	cancel_delayed_work_sync(&bat->poll_work);
261}
262
263static int __maybe_unused a500_battery_suspend(struct device *dev)
264{
265	struct a500_battery *bat = dev_get_drvdata(dev);
266
267	cancel_delayed_work_sync(&bat->poll_work);
268
269	return 0;
270}
271
272static int __maybe_unused a500_battery_resume(struct device *dev)
273{
274	struct a500_battery *bat = dev_get_drvdata(dev);
275
276	schedule_delayed_work(&bat->poll_work, HZ);
277
278	return 0;
279}
280
281static SIMPLE_DEV_PM_OPS(a500_battery_pm_ops,
282			 a500_battery_suspend, a500_battery_resume);
283
284static struct platform_driver a500_battery_driver = {
285	.driver = {
286		.name = "acer-a500-iconia-battery",
287		.pm = &a500_battery_pm_ops,
288	},
289	.probe = a500_battery_probe,
290	.remove = a500_battery_remove,
291};
292module_platform_driver(a500_battery_driver);
293
294MODULE_DESCRIPTION("Battery gauge driver for Acer Iconia Tab A500");
295MODULE_AUTHOR("Dmitry Osipenko <digetx@gmail.com>");
296MODULE_ALIAS("platform:acer-a500-iconia-battery");
297MODULE_LICENSE("GPL");