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
21enum {
22	REG_CAPACITY,
23	REG_VOLTAGE,
24	REG_CURRENT,
25	REG_DESIGN_CAPACITY,
26	REG_TEMPERATURE,
27};
28
29#define EC_DATA(_reg, _psp) {			\
30	.psp = POWER_SUPPLY_PROP_ ## _psp,	\
31	.reg = _reg,				\
32}
33
34static const struct battery_register {
35	enum power_supply_property psp;
36	unsigned int reg;
37} ec_data[] = {
38	[REG_CAPACITY]		= EC_DATA(0x00, CAPACITY),
39	[REG_VOLTAGE]		= EC_DATA(0x01, VOLTAGE_NOW),
40	[REG_CURRENT]		= EC_DATA(0x03, CURRENT_NOW),
41	[REG_DESIGN_CAPACITY]	= EC_DATA(0x08, CHARGE_FULL_DESIGN),
42	[REG_TEMPERATURE]	= EC_DATA(0x0a, TEMP),
43};
44
45static const enum power_supply_property a500_battery_properties[] = {
46	POWER_SUPPLY_PROP_CAPACITY,
47	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
48	POWER_SUPPLY_PROP_CURRENT_NOW,
49	POWER_SUPPLY_PROP_PRESENT,
50	POWER_SUPPLY_PROP_STATUS,
51	POWER_SUPPLY_PROP_TECHNOLOGY,
52	POWER_SUPPLY_PROP_TEMP,
53	POWER_SUPPLY_PROP_VOLTAGE_NOW,
54};
55
56struct a500_battery {
57	struct delayed_work poll_work;
58	struct power_supply *psy;
59	struct regmap *regmap;
60	unsigned int capacity;
61};
62
63static bool a500_battery_update_capacity(struct a500_battery *bat)
64{
65	unsigned int capacity;
66	int err;
67
68	err = regmap_read(bat->regmap, ec_data[REG_CAPACITY].reg, &capacity);
69	if (err)
70		return false;
71
72	/* capacity can be >100% even if max value is 100% */
73	capacity = min(capacity, 100u);
74
75	if (bat->capacity != capacity) {
76		bat->capacity = capacity;
77		return true;
78	}
79
80	return false;
81}
82
83static int a500_battery_get_status(struct a500_battery *bat)
84{
85	if (bat->capacity < 100) {
86		if (power_supply_am_i_supplied(bat->psy))
87			return POWER_SUPPLY_STATUS_CHARGING;
88		else
89			return POWER_SUPPLY_STATUS_DISCHARGING;
90	}
91
92	return POWER_SUPPLY_STATUS_FULL;
93}
94
95static void a500_battery_unit_adjustment(struct device *dev,
96					 enum power_supply_property psp,
97					 union power_supply_propval *val)
98{
99	const unsigned int base_unit_conversion = 1000;
100	const unsigned int temp_kelvin_to_celsius = 2731;
101
102	switch (psp) {
103	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
104	case POWER_SUPPLY_PROP_CURRENT_NOW:
105	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
106		val->intval *= base_unit_conversion;
107		break;
108
109	case POWER_SUPPLY_PROP_TEMP:
110		val->intval -= temp_kelvin_to_celsius;
111		break;
112
113	case POWER_SUPPLY_PROP_PRESENT:
114		val->intval = !!val->intval;
115		break;
116
117	default:
118		dev_dbg(dev,
119			"%s: no need for unit conversion %d\n", __func__, psp);
120	}
121}
122
123static int a500_battery_get_ec_data_index(struct device *dev,
124					  enum power_supply_property psp)
125{
126	unsigned int i;
127
128	/*
129	 * DESIGN_CAPACITY register always returns a non-zero value if
130	 * battery is connected and zero if disconnected, hence we'll use
131	 * it for judging the battery presence.
132	 */
133	if (psp == POWER_SUPPLY_PROP_PRESENT)
134		psp = POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN;
135
136	for (i = 0; i < ARRAY_SIZE(ec_data); i++)
137		if (psp == ec_data[i].psp)
138			return i;
139
140	dev_dbg(dev, "%s: invalid property %u\n", __func__, psp);
141
142	return -EINVAL;
143}
144
145static int a500_battery_get_property(struct power_supply *psy,
146				     enum power_supply_property psp,
147				     union power_supply_propval *val)
148{
149	struct a500_battery *bat = power_supply_get_drvdata(psy);
150	struct device *dev = psy->dev.parent;
151	int ret = 0;
152
153	switch (psp) {
154	case POWER_SUPPLY_PROP_STATUS:
155		val->intval = a500_battery_get_status(bat);
156		break;
157
158	case POWER_SUPPLY_PROP_TECHNOLOGY:
159		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
160		break;
161
162	case POWER_SUPPLY_PROP_CAPACITY:
163		a500_battery_update_capacity(bat);
164		val->intval = bat->capacity;
165		break;
166
167	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
168	case POWER_SUPPLY_PROP_CURRENT_NOW:
169	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
170	case POWER_SUPPLY_PROP_PRESENT:
171	case POWER_SUPPLY_PROP_TEMP:
172		ret = a500_battery_get_ec_data_index(dev, psp);
173		if (ret < 0)
174			break;
175
176		ret = regmap_read(bat->regmap, ec_data[ret].reg, &val->intval);
177		break;
178
179	default:
180		dev_err(dev, "%s: invalid property %u\n", __func__, psp);
181		return -EINVAL;
182	}
183
184	if (!ret) {
185		/* convert units to match requirements of power supply class */
186		a500_battery_unit_adjustment(dev, psp, val);
187	}
188
189	dev_dbg(dev, "%s: property = %d, value = %x\n",
190		__func__, psp, val->intval);
191
192	/* return NODATA for properties if battery not presents */
193	if (ret)
194		return -ENODATA;
195
196	return 0;
197}
198
199static void a500_battery_poll_work(struct work_struct *work)
200{
201	struct a500_battery *bat;
202	bool capacity_changed;
203
204	bat = container_of(work, struct a500_battery, poll_work.work);
205	capacity_changed = a500_battery_update_capacity(bat);
206
207	if (capacity_changed)
208		power_supply_changed(bat->psy);
209
210	/* continuously send uevent notification */
211	schedule_delayed_work(&bat->poll_work, 30 * HZ);
212}
213
214static const struct power_supply_desc a500_battery_desc = {
215	.name = "ec-battery",
216	.type = POWER_SUPPLY_TYPE_BATTERY,
217	.properties = a500_battery_properties,
218	.get_property = a500_battery_get_property,
219	.num_properties = ARRAY_SIZE(a500_battery_properties),
220	.external_power_changed = power_supply_changed,
221};
222
223static int a500_battery_probe(struct platform_device *pdev)
224{
225	struct power_supply_config psy_cfg = {};
226	struct a500_battery *bat;
227
228	bat = devm_kzalloc(&pdev->dev, sizeof(*bat), GFP_KERNEL);
229	if (!bat)
230		return -ENOMEM;
231
232	platform_set_drvdata(pdev, bat);
233
234	psy_cfg.of_node = pdev->dev.parent->of_node;
235	psy_cfg.drv_data = bat;
236
237	bat->regmap = dev_get_regmap(pdev->dev.parent, "KB930");
238	if (!bat->regmap)
239		return -EINVAL;
240
241	bat->psy = devm_power_supply_register_no_ws(&pdev->dev,
242						    &a500_battery_desc,
243						    &psy_cfg);
244	if (IS_ERR(bat->psy))
245		return dev_err_probe(&pdev->dev, PTR_ERR(bat->psy),
246				     "failed to register battery\n");
247
248	INIT_DELAYED_WORK(&bat->poll_work, a500_battery_poll_work);
249	schedule_delayed_work(&bat->poll_work, HZ);
250
251	return 0;
252}
253
254static int a500_battery_remove(struct platform_device *pdev)
255{
256	struct a500_battery *bat = dev_get_drvdata(&pdev->dev);
257
258	cancel_delayed_work_sync(&bat->poll_work);
259
260	return 0;
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");
298