sbs-charger.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright (c) 2016, Prodys S.L.
  4 *
  5 * This adds support for sbs-charger compilant chips as defined here:
  6 * http://sbs-forum.org/specs/sbc110.pdf
  7 *
  8 * Implemetation based on sbs-battery.c
  9 */
 10
 11#include <linux/init.h>
 12#include <linux/module.h>
 13#include <linux/kernel.h>
 14#include <linux/err.h>
 15#include <linux/power_supply.h>
 16#include <linux/i2c.h>
 17#include <linux/slab.h>
 18#include <linux/interrupt.h>
 19#include <linux/regmap.h>
 20#include <linux/bitops.h>
 21#include <linux/devm-helpers.h>
 22
 23#define SBS_CHARGER_REG_SPEC_INFO		0x11
 24#define SBS_CHARGER_REG_STATUS			0x13
 25#define SBS_CHARGER_REG_ALARM_WARNING		0x16
 26
 27#define SBS_CHARGER_STATUS_CHARGE_INHIBITED	BIT(0)
 28#define SBS_CHARGER_STATUS_RES_COLD		BIT(9)
 29#define SBS_CHARGER_STATUS_RES_HOT		BIT(10)
 30#define SBS_CHARGER_STATUS_BATTERY_PRESENT	BIT(14)
 31#define SBS_CHARGER_STATUS_AC_PRESENT		BIT(15)
 32
 33#define SBS_CHARGER_POLL_TIME			500
 34
 35struct sbs_info {
 36	struct i2c_client		*client;
 37	struct power_supply		*power_supply;
 38	struct regmap			*regmap;
 39	struct delayed_work		work;
 40	unsigned int			last_state;
 41};
 42
 43static int sbs_get_property(struct power_supply *psy,
 44			    enum power_supply_property psp,
 45			    union power_supply_propval *val)
 46{
 47	struct sbs_info *chip = power_supply_get_drvdata(psy);
 48	unsigned int reg;
 49
 50	reg = chip->last_state;
 51
 52	switch (psp) {
 53	case POWER_SUPPLY_PROP_PRESENT:
 54		val->intval = !!(reg & SBS_CHARGER_STATUS_BATTERY_PRESENT);
 55		break;
 56
 57	case POWER_SUPPLY_PROP_ONLINE:
 58		val->intval = !!(reg & SBS_CHARGER_STATUS_AC_PRESENT);
 59		break;
 60
 61	case POWER_SUPPLY_PROP_STATUS:
 62		val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
 63
 64		if (!(reg & SBS_CHARGER_STATUS_BATTERY_PRESENT))
 65			val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
 66		else if (reg & SBS_CHARGER_STATUS_AC_PRESENT &&
 67			 !(reg & SBS_CHARGER_STATUS_CHARGE_INHIBITED))
 68			val->intval = POWER_SUPPLY_STATUS_CHARGING;
 69		else
 70			val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
 71
 72		break;
 73
 74	case POWER_SUPPLY_PROP_HEALTH:
 75		if (reg & SBS_CHARGER_STATUS_RES_COLD)
 76			val->intval = POWER_SUPPLY_HEALTH_COLD;
 77		if (reg & SBS_CHARGER_STATUS_RES_HOT)
 78			val->intval = POWER_SUPPLY_HEALTH_OVERHEAT;
 79		else
 80			val->intval = POWER_SUPPLY_HEALTH_GOOD;
 81
 82		break;
 83
 84	default:
 85		return -EINVAL;
 86	}
 87
 88	return 0;
 89}
 90
 91static int sbs_check_state(struct sbs_info *chip)
 92{
 93	unsigned int reg;
 94	int ret;
 95
 96	ret = regmap_read(chip->regmap, SBS_CHARGER_REG_STATUS, &reg);
 97	if (!ret && reg != chip->last_state) {
 98		chip->last_state = reg;
 99		power_supply_changed(chip->power_supply);
100		return 1;
101	}
102
103	return 0;
104}
105
106static void sbs_delayed_work(struct work_struct *work)
107{
108	struct sbs_info *chip = container_of(work, struct sbs_info, work.work);
109
110	sbs_check_state(chip);
111
112	schedule_delayed_work(&chip->work,
113			      msecs_to_jiffies(SBS_CHARGER_POLL_TIME));
114}
115
116static irqreturn_t sbs_irq_thread(int irq, void *data)
117{
118	struct sbs_info *chip = data;
119	int ret;
120
121	ret = sbs_check_state(chip);
122
123	return ret ? IRQ_HANDLED : IRQ_NONE;
124}
125
126static enum power_supply_property sbs_properties[] = {
127	POWER_SUPPLY_PROP_STATUS,
128	POWER_SUPPLY_PROP_PRESENT,
129	POWER_SUPPLY_PROP_ONLINE,
130	POWER_SUPPLY_PROP_HEALTH,
131};
132
133static bool sbs_readable_reg(struct device *dev, unsigned int reg)
134{
135	return reg >= SBS_CHARGER_REG_SPEC_INFO;
136}
137
138static bool sbs_volatile_reg(struct device *dev, unsigned int reg)
139{
140	switch (reg) {
141	case SBS_CHARGER_REG_STATUS:
142		return true;
143	}
144
145	return false;
146}
147
148static const struct regmap_config sbs_regmap = {
149	.reg_bits	= 8,
150	.val_bits	= 16,
151	.max_register	= SBS_CHARGER_REG_ALARM_WARNING,
152	.readable_reg	= sbs_readable_reg,
153	.volatile_reg	= sbs_volatile_reg,
154	.val_format_endian = REGMAP_ENDIAN_LITTLE, /* since based on SMBus */
155};
156
157static const struct power_supply_desc sbs_default_desc = {
158	.type = POWER_SUPPLY_TYPE_MAINS,
159	.properties = sbs_properties,
160	.num_properties = ARRAY_SIZE(sbs_properties),
161	.get_property = sbs_get_property,
162};
163
164static int sbs_probe(struct i2c_client *client)
165{
166	struct power_supply_config psy_cfg = {};
167	struct power_supply_desc *sbs_desc;
168	struct sbs_info *chip;
169	int ret, val;
170
171	sbs_desc = devm_kmemdup(&client->dev, &sbs_default_desc,
172				sizeof(*sbs_desc), GFP_KERNEL);
173	if (!sbs_desc)
174		return -ENOMEM;
175
176	sbs_desc->name = devm_kasprintf(&client->dev, GFP_KERNEL, "sbs-%s",
177					dev_name(&client->dev));
178	if (!sbs_desc->name)
179		return -ENOMEM;
180
181	chip = devm_kzalloc(&client->dev, sizeof(struct sbs_info), GFP_KERNEL);
182	if (!chip)
183		return -ENOMEM;
184
185	chip->client = client;
186	psy_cfg.fwnode = dev_fwnode(&client->dev);
187	psy_cfg.drv_data = chip;
188
189	i2c_set_clientdata(client, chip);
190
191	chip->regmap = devm_regmap_init_i2c(client, &sbs_regmap);
192	if (IS_ERR(chip->regmap))
193		return PTR_ERR(chip->regmap);
194
195	/*
196	 * Before we register, we need to make sure we can actually talk
197	 * to the battery.
198	 */
199	ret = regmap_read(chip->regmap, SBS_CHARGER_REG_STATUS, &val);
200	if (ret)
201		return dev_err_probe(&client->dev, ret, "Failed to get device status\n");
202	chip->last_state = val;
203
204	chip->power_supply = devm_power_supply_register(&client->dev, sbs_desc, &psy_cfg);
205	if (IS_ERR(chip->power_supply))
206		return dev_err_probe(&client->dev, PTR_ERR(chip->power_supply),
207				     "Failed to register power supply\n");
208
209	/*
210	 * The sbs-charger spec doesn't impose the use of an interrupt. So in
211	 * the case it wasn't provided we use polling in order get the charger's
212	 * status.
213	 */
214	if (client->irq) {
215		ret = devm_request_threaded_irq(&client->dev, client->irq,
216					NULL, sbs_irq_thread,
217					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
218					dev_name(&client->dev), chip);
219		if (ret)
220			return dev_err_probe(&client->dev, ret, "Failed to request irq\n");
221	} else {
222		ret = devm_delayed_work_autocancel(&client->dev, &chip->work,
223						   sbs_delayed_work);
224		if (ret)
225			return dev_err_probe(&client->dev, ret,
226					     "Failed to init work for polling\n");
227
228		schedule_delayed_work(&chip->work,
229				      msecs_to_jiffies(SBS_CHARGER_POLL_TIME));
230	}
231
232	dev_info(&client->dev,
233		 "%s: smart charger device registered\n", client->name);
234
235	return 0;
236}
237
238#ifdef CONFIG_OF
239static const struct of_device_id sbs_dt_ids[] = {
240	{ .compatible = "sbs,sbs-charger" },
241	{ },
242};
243MODULE_DEVICE_TABLE(of, sbs_dt_ids);
244#endif
245
246static const struct i2c_device_id sbs_id[] = {
247	{ "sbs-charger" },
248	{ }
249};
250MODULE_DEVICE_TABLE(i2c, sbs_id);
251
252static struct i2c_driver sbs_driver = {
253	.probe		= sbs_probe,
254	.id_table	= sbs_id,
255	.driver = {
256		.name	= "sbs-charger",
257		.of_match_table = of_match_ptr(sbs_dt_ids),
258	},
259};
260module_i2c_driver(sbs_driver);
261
262MODULE_AUTHOR("Nicolas Saenz Julienne <nicolassaenzj@gmail.com>");
263MODULE_DESCRIPTION("SBS smart charger driver");
264MODULE_LICENSE("GPL v2");