aboutsummaryrefslogtreecommitdiff
path: root/drivers/rtc/rtc-bq32k.c
blob: 2235c968842db76c3a05a35ecdb859f4f9bb3713 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for TI BQ32000 RTC.
 *
 * Copyright (C) 2009 Semihalf.
 * Copyright (C) 2014 Pavel Machek <pavel@denx.de>
 *
 * You can get hardware description at
 * https://www.ti.com/lit/ds/symlink/bq32000.pdf
 */

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/rtc.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/bcd.h>

#define BQ32K_SECONDS		0x00	/* Seconds register address */
#define BQ32K_SECONDS_MASK	0x7F	/* Mask over seconds value */
#define BQ32K_STOP		0x80	/* Oscillator Stop flat */

#define BQ32K_MINUTES		0x01	/* Minutes register address */
#define BQ32K_MINUTES_MASK	0x7F	/* Mask over minutes value */
#define BQ32K_OF		0x80	/* Oscillator Failure flag */

#define BQ32K_HOURS_MASK	0x3F	/* Mask over hours value */
#define BQ32K_CENT		0x40	/* Century flag */
#define BQ32K_CENT_EN		0x80	/* Century flag enable bit */

#define BQ32K_CALIBRATION	0x07	/* CAL_CFG1, calibration and control */
#define BQ32K_TCH2		0x08	/* Trickle charge enable */
#define BQ32K_CFG2		0x09	/* Trickle charger control */
#define BQ32K_TCFE		BIT(6)	/* Trickle charge FET bypass */

#define MAX_LEN			10	/* Maximum number of consecutive
					 * register for this particular RTC.
					 */

struct bq32k_regs {
	uint8_t		seconds;
	uint8_t		minutes;
	uint8_t		cent_hours;
	uint8_t		day;
	uint8_t		date;
	uint8_t		month;
	uint8_t		years;
};

static struct i2c_driver bq32k_driver;

static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct i2c_msg msgs[] = {
		{
			.addr = client->addr,
			.flags = 0,
			.len = 1,
			.buf = &off,
		}, {
			.addr = client->addr,
			.flags = I2C_M_RD,
			.len = len,
			.buf = data,
		}
	};

	if (i2c_transfer(client->adapter, msgs, 2) == 2)
		return 0;

	return -EIO;
}

static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
{
	struct i2c_client *client = to_i2c_client(dev);
	uint8_t buffer[MAX_LEN + 1];

	buffer[0] = off;
	memcpy(&buffer[1], data, len);

	if (i2c_master_send(client, buffer, len + 1) == len + 1)
		return 0;

	return -EIO;
}

static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct bq32k_regs regs;
	int error;

	error = bq32k_read(dev, &regs, 0, sizeof(regs));
	if (error)
		return error;

	/*
	 * In case of oscillator failure, the register contents should be
	 * considered invalid. The flag is cleared the next time the RTC is set.
	 */
	if (regs.minutes & BQ32K_OF)
		return -EINVAL;

	tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
	tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK);
	tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
	tm->tm_mday = bcd2bin(regs.date);
	tm->tm_wday = bcd2bin(regs.day) - 1;
	tm->tm_mon = bcd2bin(regs.month) - 1;
	tm->tm_year = bcd2bin(regs.years) +
				((regs.cent_hours & BQ32K_CENT) ? 100 : 0);

	return 0;
}

static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct bq32k_regs regs;

	regs.seconds = bin2bcd(tm->tm_sec);
	regs.minutes = bin2bcd(tm->tm_min);
	regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
	regs.day = bin2bcd(tm->tm_wday + 1);
	regs.date = bin2bcd(tm->tm_mday);
	regs.month = bin2bcd(tm->tm_mon + 1);

	if (tm->tm_year >= 100) {
		regs.cent_hours |= BQ32K_CENT;
		regs.years = bin2bcd(tm->tm_year - 100);
	} else
		regs.years = bin2bcd(tm->tm_year);

	return bq32k_write(dev, &regs, 0, sizeof(regs));
}

static const struct rtc_class_ops bq32k_rtc_ops = {
	.read_time	= bq32k_rtc_read_time,
	.set_time	= bq32k_rtc_set_time,
};

static int trickle_charger_of_init(struct device *dev, struct device_node *node)
{
	unsigned char reg;
	int error;
	u32 ohms = 0;

	if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms))
		return 0;

	switch (ohms) {
	case 180+940:
		/*
		 * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging
		 * over diode and 940ohm resistor)
		 */

		if (of_property_read_bool(node, "trickle-diode-disable")) {
			dev_err(dev, "diode and resistor mismatch\n");
			return -EINVAL;
		}
		reg = 0x05;
		break;

	case 180+20000:
		/* diode disabled */

		if (!of_property_read_bool(node, "trickle-diode-disable")) {
			dev_err(dev, "bq32k: diode and resistor mismatch\n");
			return -EINVAL;
		}
		reg = 0x45;
		break;

	default:
		dev_err(dev, "invalid resistor value (%d)\n", ohms);
		return -EINVAL;
	}

	error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
	if (error)
		return error;

	reg = 0x20;
	error = bq32k_write(dev, &reg, BQ32K_TCH2, 1);
	if (error)
		return error;

	dev_info(dev, "Enabled trickle RTC battery charge.\n");
	return 0;
}

static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev,
					       struct device_attribute *attr,
					       char *buf)
{
	int reg, error;

	error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
	if (error)
		return error;

	return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0);
}

static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev,
						struct device_attribute *attr,
						const char *buf, size_t count)
{
	int reg, enable, error;

	if (kstrtoint(buf, 0, &enable))
		return -EINVAL;

	error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
	if (error)
		return error;

	if (enable) {
		reg |= BQ32K_TCFE;
		error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
		if (error)
			return error;

		dev_info(dev, "Enabled trickle charge FET bypass.\n");
	} else {
		reg &= ~BQ32K_TCFE;
		error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
		if (error)
			return error;

		dev_info(dev, "Disabled trickle charge FET bypass.\n");
	}

	return count;
}

static DEVICE_ATTR(trickle_charge_bypass, 0644,
		   bq32k_sysfs_show_tricklecharge_bypass,
		   bq32k_sysfs_store_tricklecharge_bypass);

static int bq32k_sysfs_register(struct device *dev)
{
	return device_create_file(dev, &dev_attr_trickle_charge_bypass);
}

static void bq32k_sysfs_unregister(struct device *dev)
{
	device_remove_file(dev, &dev_attr_trickle_charge_bypass);
}

static int bq32k_probe(struct i2c_client *client,
				const struct i2c_device_id *id)
{
	struct device *dev = &client->dev;
	struct rtc_device *rtc;
	uint8_t reg;
	int error;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
		return -ENODEV;

	/* Check Oscillator Stop flag */
	error = bq32k_read(dev, &reg, BQ32K_SECONDS, 1);
	if (!error && (reg & BQ32K_STOP)) {
		dev_warn(dev, "Oscillator was halted. Restarting...\n");
		reg &= ~BQ32K_STOP;
		error = bq32k_write(dev, &reg, BQ32K_SECONDS, 1);
	}
	if (error)
		return error;

	/* Check Oscillator Failure flag */
	error = bq32k_read(dev, &reg, BQ32K_MINUTES, 1);
	if (error)
		return error;
	if (reg & BQ32K_OF)
		dev_warn(dev, "Oscillator Failure. Check RTC battery.\n");

	if (client->dev.of_node)
		trickle_charger_of_init(dev, client->dev.of_node);

	rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,
						&bq32k_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc))
		return PTR_ERR(rtc);

	error = bq32k_sysfs_register(&client->dev);
	if (error) {
		dev_err(&client->dev,
			"Unable to create sysfs entries for rtc bq32000\n");
		return error;
	}


	i2c_set_clientdata(client, rtc);

	return 0;
}

static int bq32k_remove(struct i2c_client *client)
{
	bq32k_sysfs_unregister(&client->dev);

	return 0;
}

static const struct i2c_device_id bq32k_id[] = {
	{ "bq32000", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, bq32k_id);

static const __maybe_unused struct of_device_id bq32k_of_match[] = {
	{ .compatible = "ti,bq32000" },
	{ }
};
MODULE_DEVICE_TABLE(of, bq32k_of_match);

static struct i2c_driver bq32k_driver = {
	.driver = {
		.name	= "bq32k",
		.of_match_table = of_match_ptr(bq32k_of_match),
	},
	.probe		= bq32k_probe,
	.remove		= bq32k_remove,
	.id_table	= bq32k_id,
};

module_i2c_driver(bq32k_driver);

MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
MODULE_LICENSE("GPL");