xref: /openbmc/linux/drivers/rtc/rtc-bq32k.c (revision e3b9f1e8) 
1 /*
2  * Driver for TI BQ32000 RTC.
3  *
4  * Copyright (C) 2009 Semihalf.
5  * Copyright (C) 2014 Pavel Machek <pavel@denx.de>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  * You can get hardware description at
12  * http://www.ti.com/lit/ds/symlink/bq32000.pdf
13  */
14 
15 #include <linux/module.h>
16 #include <linux/i2c.h>
17 #include <linux/rtc.h>
18 #include <linux/init.h>
19 #include <linux/errno.h>
20 #include <linux/bcd.h>
21 
22 #define BQ32K_SECONDS		0x00	/* Seconds register address */
23 #define BQ32K_SECONDS_MASK	0x7F	/* Mask over seconds value */
24 #define BQ32K_STOP		0x80	/* Oscillator Stop flat */
25 
26 #define BQ32K_MINUTES		0x01	/* Minutes register address */
27 #define BQ32K_MINUTES_MASK	0x7F	/* Mask over minutes value */
28 #define BQ32K_OF		0x80	/* Oscillator Failure flag */
29 
30 #define BQ32K_HOURS_MASK	0x3F	/* Mask over hours value */
31 #define BQ32K_CENT		0x40	/* Century flag */
32 #define BQ32K_CENT_EN		0x80	/* Century flag enable bit */
33 
34 #define BQ32K_CALIBRATION	0x07	/* CAL_CFG1, calibration and control */
35 #define BQ32K_TCH2		0x08	/* Trickle charge enable */
36 #define BQ32K_CFG2		0x09	/* Trickle charger control */
37 #define BQ32K_TCFE		BIT(6)	/* Trickle charge FET bypass */
38 
39 struct bq32k_regs {
40 	uint8_t		seconds;
41 	uint8_t		minutes;
42 	uint8_t		cent_hours;
43 	uint8_t		day;
44 	uint8_t		date;
45 	uint8_t		month;
46 	uint8_t		years;
47 };
48 
49 static struct i2c_driver bq32k_driver;
50 
51 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
52 {
53 	struct i2c_client *client = to_i2c_client(dev);
54 	struct i2c_msg msgs[] = {
55 		{
56 			.addr = client->addr,
57 			.flags = 0,
58 			.len = 1,
59 			.buf = &off,
60 		}, {
61 			.addr = client->addr,
62 			.flags = I2C_M_RD,
63 			.len = len,
64 			.buf = data,
65 		}
66 	};
67 
68 	if (i2c_transfer(client->adapter, msgs, 2) == 2)
69 		return 0;
70 
71 	return -EIO;
72 }
73 
74 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
75 {
76 	struct i2c_client *client = to_i2c_client(dev);
77 	uint8_t buffer[len + 1];
78 
79 	buffer[0] = off;
80 	memcpy(&buffer[1], data, len);
81 
82 	if (i2c_master_send(client, buffer, len + 1) == len + 1)
83 		return 0;
84 
85 	return -EIO;
86 }
87 
88 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
89 {
90 	struct bq32k_regs regs;
91 	int error;
92 
93 	error = bq32k_read(dev, &regs, 0, sizeof(regs));
94 	if (error)
95 		return error;
96 
97 	/*
98 	 * In case of oscillator failure, the register contents should be
99 	 * considered invalid. The flag is cleared the next time the RTC is set.
100 	 */
101 	if (regs.minutes & BQ32K_OF)
102 		return -EINVAL;
103 
104 	tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
105 	tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK);
106 	tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
107 	tm->tm_mday = bcd2bin(regs.date);
108 	tm->tm_wday = bcd2bin(regs.day) - 1;
109 	tm->tm_mon = bcd2bin(regs.month) - 1;
110 	tm->tm_year = bcd2bin(regs.years) +
111 				((regs.cent_hours & BQ32K_CENT) ? 100 : 0);
112 
113 	return rtc_valid_tm(tm);
114 }
115 
116 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
117 {
118 	struct bq32k_regs regs;
119 
120 	regs.seconds = bin2bcd(tm->tm_sec);
121 	regs.minutes = bin2bcd(tm->tm_min);
122 	regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
123 	regs.day = bin2bcd(tm->tm_wday + 1);
124 	regs.date = bin2bcd(tm->tm_mday);
125 	regs.month = bin2bcd(tm->tm_mon + 1);
126 
127 	if (tm->tm_year >= 100) {
128 		regs.cent_hours |= BQ32K_CENT;
129 		regs.years = bin2bcd(tm->tm_year - 100);
130 	} else
131 		regs.years = bin2bcd(tm->tm_year);
132 
133 	return bq32k_write(dev, &regs, 0, sizeof(regs));
134 }
135 
136 static const struct rtc_class_ops bq32k_rtc_ops = {
137 	.read_time	= bq32k_rtc_read_time,
138 	.set_time	= bq32k_rtc_set_time,
139 };
140 
141 static int trickle_charger_of_init(struct device *dev, struct device_node *node)
142 {
143 	unsigned char reg;
144 	int error;
145 	u32 ohms = 0;
146 
147 	if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms))
148 		return 0;
149 
150 	switch (ohms) {
151 	case 180+940:
152 		/*
153 		 * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging
154 		 * over diode and 940ohm resistor)
155 		 */
156 
157 		if (of_property_read_bool(node, "trickle-diode-disable")) {
158 			dev_err(dev, "diode and resistor mismatch\n");
159 			return -EINVAL;
160 		}
161 		reg = 0x05;
162 		break;
163 
164 	case 180+20000:
165 		/* diode disabled */
166 
167 		if (!of_property_read_bool(node, "trickle-diode-disable")) {
168 			dev_err(dev, "bq32k: diode and resistor mismatch\n");
169 			return -EINVAL;
170 		}
171 		reg = 0x45;
172 		break;
173 
174 	default:
175 		dev_err(dev, "invalid resistor value (%d)\n", ohms);
176 		return -EINVAL;
177 	}
178 
179 	error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
180 	if (error)
181 		return error;
182 
183 	reg = 0x20;
184 	error = bq32k_write(dev, &reg, BQ32K_TCH2, 1);
185 	if (error)
186 		return error;
187 
188 	dev_info(dev, "Enabled trickle RTC battery charge.\n");
189 	return 0;
190 }
191 
192 static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev,
193 					       struct device_attribute *attr,
194 					       char *buf)
195 {
196 	int reg, error;
197 
198 	error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
199 	if (error)
200 		return error;
201 
202 	return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0);
203 }
204 
205 static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev,
206 						struct device_attribute *attr,
207 						const char *buf, size_t count)
208 {
209 	int reg, enable, error;
210 
211 	if (kstrtoint(buf, 0, &enable))
212 		return -EINVAL;
213 
214 	error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
215 	if (error)
216 		return error;
217 
218 	if (enable) {
219 		reg |= BQ32K_TCFE;
220 		error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
221 		if (error)
222 			return error;
223 
224 		dev_info(dev, "Enabled trickle charge FET bypass.\n");
225 	} else {
226 		reg &= ~BQ32K_TCFE;
227 		error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
228 		if (error)
229 			return error;
230 
231 		dev_info(dev, "Disabled trickle charge FET bypass.\n");
232 	}
233 
234 	return count;
235 }
236 
237 static DEVICE_ATTR(trickle_charge_bypass, 0644,
238 		   bq32k_sysfs_show_tricklecharge_bypass,
239 		   bq32k_sysfs_store_tricklecharge_bypass);
240 
241 static int bq32k_sysfs_register(struct device *dev)
242 {
243 	return device_create_file(dev, &dev_attr_trickle_charge_bypass);
244 }
245 
246 static void bq32k_sysfs_unregister(struct device *dev)
247 {
248 	device_remove_file(dev, &dev_attr_trickle_charge_bypass);
249 }
250 
251 static int bq32k_probe(struct i2c_client *client,
252 				const struct i2c_device_id *id)
253 {
254 	struct device *dev = &client->dev;
255 	struct rtc_device *rtc;
256 	uint8_t reg;
257 	int error;
258 
259 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
260 		return -ENODEV;
261 
262 	/* Check Oscillator Stop flag */
263 	error = bq32k_read(dev, &reg, BQ32K_SECONDS, 1);
264 	if (!error && (reg & BQ32K_STOP)) {
265 		dev_warn(dev, "Oscillator was halted. Restarting...\n");
266 		reg &= ~BQ32K_STOP;
267 		error = bq32k_write(dev, &reg, BQ32K_SECONDS, 1);
268 	}
269 	if (error)
270 		return error;
271 
272 	/* Check Oscillator Failure flag */
273 	error = bq32k_read(dev, &reg, BQ32K_MINUTES, 1);
274 	if (error)
275 		return error;
276 	if (reg & BQ32K_OF)
277 		dev_warn(dev, "Oscillator Failure. Check RTC battery.\n");
278 
279 	if (client->dev.of_node)
280 		trickle_charger_of_init(dev, client->dev.of_node);
281 
282 	rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,
283 						&bq32k_rtc_ops, THIS_MODULE);
284 	if (IS_ERR(rtc))
285 		return PTR_ERR(rtc);
286 
287 	error = bq32k_sysfs_register(&client->dev);
288 	if (error) {
289 		dev_err(&client->dev,
290 			"Unable to create sysfs entries for rtc bq32000\n");
291 		return error;
292 	}
293 
294 
295 	i2c_set_clientdata(client, rtc);
296 
297 	return 0;
298 }
299 
300 static int bq32k_remove(struct i2c_client *client)
301 {
302 	bq32k_sysfs_unregister(&client->dev);
303 
304 	return 0;
305 }
306 
307 static const struct i2c_device_id bq32k_id[] = {
308 	{ "bq32000", 0 },
309 	{ }
310 };
311 MODULE_DEVICE_TABLE(i2c, bq32k_id);
312 
313 static const struct of_device_id bq32k_of_match[] = {
314 	{ .compatible = "ti,bq32000" },
315 	{ }
316 };
317 MODULE_DEVICE_TABLE(of, bq32k_of_match);
318 
319 static struct i2c_driver bq32k_driver = {
320 	.driver = {
321 		.name	= "bq32k",
322 		.of_match_table = of_match_ptr(bq32k_of_match),
323 	},
324 	.probe		= bq32k_probe,
325 	.remove		= bq32k_remove,
326 	.id_table	= bq32k_id,
327 };
328 
329 module_i2c_driver(bq32k_driver);
330 
331 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
332 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
333 MODULE_LICENSE("GPL");
334