xref: /linux/drivers/rtc/rtc-bq32k.c (revision 7d8d6ad659c02ed5d2387777194c22e8e81dbb2b) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Driver for TI BQ32000 RTC.
4  *
5  * Copyright (C) 2009 Semihalf.
6  * Copyright (C) 2014 Pavel Machek <pavel@denx.de>
7  *
8  * You can get hardware description at
9  * https://www.ti.com/lit/ds/symlink/bq32000.pdf
10  */
11 
12 #include <linux/module.h>
13 #include <linux/i2c.h>
14 #include <linux/rtc.h>
15 #include <linux/init.h>
16 #include <linux/kstrtox.h>
17 #include <linux/errno.h>
18 #include <linux/bcd.h>
19 #include <linux/delay.h>
20 
21 #define BQ32K_SECONDS		0x00	/* Seconds register address */
22 #define BQ32K_SECONDS_MASK	0x7F	/* Mask over seconds value */
23 #define BQ32K_STOP		0x80	/* Oscillator Stop flat */
24 
25 #define BQ32K_MINUTES		0x01	/* Minutes register address */
26 #define BQ32K_MINUTES_MASK	0x7F	/* Mask over minutes value */
27 #define BQ32K_OF		0x80	/* Oscillator Failure flag */
28 
29 #define BQ32K_HOURS_MASK	0x3F	/* Mask over hours value */
30 #define BQ32K_CENT		0x40	/* Century flag */
31 #define BQ32K_CENT_EN		0x80	/* Century flag enable bit */
32 
33 #define BQ32K_CALIBRATION	0x07	/* CAL_CFG1, calibration and control */
34 #define BQ32K_TCH2		0x08	/* Trickle charge enable */
35 #define BQ32K_CFG2		0x09	/* Trickle charger control */
36 #define BQ32K_TCFE		BIT(6)	/* Trickle charge FET bypass */
37 
38 #define MAX_LEN			10	/* Maximum number of consecutive
39 					 * register for this particular RTC.
40 					 */
41 
42 struct bq32k_regs {
43 	uint8_t		seconds;
44 	uint8_t		minutes;
45 	uint8_t		cent_hours;
46 	uint8_t		day;
47 	uint8_t		date;
48 	uint8_t		month;
49 	uint8_t		years;
50 };
51 
52 static struct i2c_driver bq32k_driver;
53 
54 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
55 {
56 	struct i2c_client *client = to_i2c_client(dev);
57 	struct i2c_msg msgs[] = {
58 		{
59 			.addr = client->addr,
60 			.flags = 0,
61 			.len = 1,
62 			.buf = &off,
63 		}, {
64 			.addr = client->addr,
65 			.flags = I2C_M_RD,
66 			.len = len,
67 			.buf = data,
68 		}
69 	};
70 
71 	if (i2c_transfer(client->adapter, msgs, 2) == 2)
72 		return 0;
73 
74 	return -EIO;
75 }
76 
77 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
78 {
79 	struct i2c_client *client = to_i2c_client(dev);
80 	uint8_t buffer[MAX_LEN + 1];
81 
82 	buffer[0] = off;
83 	memcpy(&buffer[1], data, len);
84 
85 	if (i2c_master_send(client, buffer, len + 1) == len + 1)
86 		return 0;
87 
88 	return -EIO;
89 }
90 
91 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
92 {
93 	struct i2c_client *client = to_i2c_client(dev);
94 	struct bq32k_regs regs;
95 	int error;
96 
97 	/*
98 	 * When the device doesn't have the interrupt connected, prevent
99 	 * userpace from polling the RTC registers too frequently.
100 	 */
101 	if (client->irq <= 0)
102 		usleep_range(2000, 2500);
103 
104 	error = bq32k_read(dev, &regs, 0, sizeof(regs));
105 	if (error)
106 		return error;
107 
108 	/*
109 	 * In case of oscillator failure, the register contents should be
110 	 * considered invalid. The flag is cleared the next time the RTC is set.
111 	 */
112 	if (regs.minutes & BQ32K_OF)
113 		return -EINVAL;
114 
115 	tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
116 	tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK);
117 	tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
118 	tm->tm_mday = bcd2bin(regs.date);
119 	tm->tm_wday = bcd2bin(regs.day) - 1;
120 	tm->tm_mon = bcd2bin(regs.month) - 1;
121 	tm->tm_year = bcd2bin(regs.years) +
122 				((regs.cent_hours & BQ32K_CENT) ? 100 : 0);
123 
124 	return 0;
125 }
126 
127 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
128 {
129 	struct bq32k_regs regs;
130 
131 	regs.seconds = bin2bcd(tm->tm_sec);
132 	regs.minutes = bin2bcd(tm->tm_min);
133 	regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
134 	regs.day = bin2bcd(tm->tm_wday + 1);
135 	regs.date = bin2bcd(tm->tm_mday);
136 	regs.month = bin2bcd(tm->tm_mon + 1);
137 
138 	if (tm->tm_year >= 100) {
139 		regs.cent_hours |= BQ32K_CENT;
140 		regs.years = bin2bcd(tm->tm_year - 100);
141 	} else
142 		regs.years = bin2bcd(tm->tm_year);
143 
144 	return bq32k_write(dev, &regs, 0, sizeof(regs));
145 }
146 
147 static const struct rtc_class_ops bq32k_rtc_ops = {
148 	.read_time	= bq32k_rtc_read_time,
149 	.set_time	= bq32k_rtc_set_time,
150 };
151 
152 static int trickle_charger_of_init(struct device *dev, struct device_node *node)
153 {
154 	unsigned char reg;
155 	int error;
156 	u32 ohms = 0;
157 
158 	if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms))
159 		return 0;
160 
161 	switch (ohms) {
162 	case 180+940:
163 		/*
164 		 * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging
165 		 * over diode and 940ohm resistor)
166 		 */
167 
168 		if (of_property_read_bool(node, "trickle-diode-disable")) {
169 			dev_err(dev, "diode and resistor mismatch\n");
170 			return -EINVAL;
171 		}
172 		reg = 0x05;
173 		break;
174 
175 	case 180+20000:
176 		/* diode disabled */
177 
178 		if (!of_property_read_bool(node, "trickle-diode-disable")) {
179 			dev_err(dev, "bq32k: diode and resistor mismatch\n");
180 			return -EINVAL;
181 		}
182 		reg = 0x45;
183 		break;
184 
185 	default:
186 		dev_err(dev, "invalid resistor value (%d)\n", ohms);
187 		return -EINVAL;
188 	}
189 
190 	error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
191 	if (error)
192 		return error;
193 
194 	reg = 0x20;
195 	error = bq32k_write(dev, &reg, BQ32K_TCH2, 1);
196 	if (error)
197 		return error;
198 
199 	dev_info(dev, "Enabled trickle RTC battery charge.\n");
200 	return 0;
201 }
202 
203 static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev,
204 					       struct device_attribute *attr,
205 					       char *buf)
206 {
207 	int reg, error;
208 
209 	error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
210 	if (error)
211 		return error;
212 
213 	return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0);
214 }
215 
216 static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev,
217 						struct device_attribute *attr,
218 						const char *buf, size_t count)
219 {
220 	int reg, enable, error;
221 
222 	if (kstrtoint(buf, 0, &enable))
223 		return -EINVAL;
224 
225 	error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
226 	if (error)
227 		return error;
228 
229 	if (enable) {
230 		reg |= BQ32K_TCFE;
231 		error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
232 		if (error)
233 			return error;
234 
235 		dev_info(dev, "Enabled trickle charge FET bypass.\n");
236 	} else {
237 		reg &= ~BQ32K_TCFE;
238 		error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
239 		if (error)
240 			return error;
241 
242 		dev_info(dev, "Disabled trickle charge FET bypass.\n");
243 	}
244 
245 	return count;
246 }
247 
248 static DEVICE_ATTR(trickle_charge_bypass, 0644,
249 		   bq32k_sysfs_show_tricklecharge_bypass,
250 		   bq32k_sysfs_store_tricklecharge_bypass);
251 
252 static int bq32k_sysfs_register(struct device *dev)
253 {
254 	return device_create_file(dev, &dev_attr_trickle_charge_bypass);
255 }
256 
257 static void bq32k_sysfs_unregister(struct device *dev)
258 {
259 	device_remove_file(dev, &dev_attr_trickle_charge_bypass);
260 }
261 
262 static int bq32k_probe(struct i2c_client *client)
263 {
264 	struct device *dev = &client->dev;
265 	struct rtc_device *rtc;
266 	uint8_t reg;
267 	int error;
268 
269 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
270 		return -ENODEV;
271 
272 	/* Check Oscillator Stop flag */
273 	error = bq32k_read(dev, &reg, BQ32K_SECONDS, 1);
274 	if (!error && (reg & BQ32K_STOP)) {
275 		dev_warn(dev, "Oscillator was halted. Restarting...\n");
276 		reg &= ~BQ32K_STOP;
277 		error = bq32k_write(dev, &reg, BQ32K_SECONDS, 1);
278 	}
279 	if (error)
280 		return error;
281 
282 	/* Check Oscillator Failure flag */
283 	error = bq32k_read(dev, &reg, BQ32K_MINUTES, 1);
284 	if (error)
285 		return error;
286 	if (reg & BQ32K_OF)
287 		dev_warn(dev, "Oscillator Failure. Check RTC battery.\n");
288 
289 	if (client->dev.of_node)
290 		trickle_charger_of_init(dev, client->dev.of_node);
291 
292 	rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,
293 						&bq32k_rtc_ops, THIS_MODULE);
294 	if (IS_ERR(rtc))
295 		return PTR_ERR(rtc);
296 
297 	error = bq32k_sysfs_register(&client->dev);
298 	if (error) {
299 		dev_err(&client->dev,
300 			"Unable to create sysfs entries for rtc bq32000\n");
301 		return error;
302 	}
303 
304 
305 	i2c_set_clientdata(client, rtc);
306 
307 	return 0;
308 }
309 
310 static void bq32k_remove(struct i2c_client *client)
311 {
312 	bq32k_sysfs_unregister(&client->dev);
313 }
314 
315 static const struct i2c_device_id bq32k_id[] = {
316 	{ .name = "bq32000" },
317 	{ }
318 };
319 MODULE_DEVICE_TABLE(i2c, bq32k_id);
320 
321 static const __maybe_unused struct of_device_id bq32k_of_match[] = {
322 	{ .compatible = "ti,bq32000" },
323 	{ }
324 };
325 MODULE_DEVICE_TABLE(of, bq32k_of_match);
326 
327 static struct i2c_driver bq32k_driver = {
328 	.driver = {
329 		.name	= "bq32k",
330 		.of_match_table = of_match_ptr(bq32k_of_match),
331 	},
332 	.probe		= bq32k_probe,
333 	.remove		= bq32k_remove,
334 	.id_table	= bq32k_id,
335 };
336 
337 module_i2c_driver(bq32k_driver);
338 
339 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
340 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
341 MODULE_LICENSE("GPL");
342