xref: /openbmc/linux/drivers/rtc/rtc-bq32k.c (revision a20eefae) 
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  * http://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/errno.h>
17 #include <linux/bcd.h>
18 
19 #define BQ32K_SECONDS		0x00	/* Seconds register address */
20 #define BQ32K_SECONDS_MASK	0x7F	/* Mask over seconds value */
21 #define BQ32K_STOP		0x80	/* Oscillator Stop flat */
22 
23 #define BQ32K_MINUTES		0x01	/* Minutes register address */
24 #define BQ32K_MINUTES_MASK	0x7F	/* Mask over minutes value */
25 #define BQ32K_OF		0x80	/* Oscillator Failure flag */
26 
27 #define BQ32K_HOURS_MASK	0x3F	/* Mask over hours value */
28 #define BQ32K_CENT		0x40	/* Century flag */
29 #define BQ32K_CENT_EN		0x80	/* Century flag enable bit */
30 
31 #define BQ32K_CALIBRATION	0x07	/* CAL_CFG1, calibration and control */
32 #define BQ32K_TCH2		0x08	/* Trickle charge enable */
33 #define BQ32K_CFG2		0x09	/* Trickle charger control */
34 #define BQ32K_TCFE		BIT(6)	/* Trickle charge FET bypass */
35 
36 #define MAX_LEN			10	/* Maximum number of consecutive
37 					 * register for this particular RTC.
38 					 */
39 
40 struct bq32k_regs {
41 	uint8_t		seconds;
42 	uint8_t		minutes;
43 	uint8_t		cent_hours;
44 	uint8_t		day;
45 	uint8_t		date;
46 	uint8_t		month;
47 	uint8_t		years;
48 };
49 
50 static struct i2c_driver bq32k_driver;
51 
52 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
53 {
54 	struct i2c_client *client = to_i2c_client(dev);
55 	struct i2c_msg msgs[] = {
56 		{
57 			.addr = client->addr,
58 			.flags = 0,
59 			.len = 1,
60 			.buf = &off,
61 		}, {
62 			.addr = client->addr,
63 			.flags = I2C_M_RD,
64 			.len = len,
65 			.buf = data,
66 		}
67 	};
68 
69 	if (i2c_transfer(client->adapter, msgs, 2) == 2)
70 		return 0;
71 
72 	return -EIO;
73 }
74 
75 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
76 {
77 	struct i2c_client *client = to_i2c_client(dev);
78 	uint8_t buffer[MAX_LEN + 1];
79 
80 	buffer[0] = off;
81 	memcpy(&buffer[1], data, len);
82 
83 	if (i2c_master_send(client, buffer, len + 1) == len + 1)
84 		return 0;
85 
86 	return -EIO;
87 }
88 
89 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
90 {
91 	struct bq32k_regs regs;
92 	int error;
93 
94 	error = bq32k_read(dev, &regs, 0, sizeof(regs));
95 	if (error)
96 		return error;
97 
98 	/*
99 	 * In case of oscillator failure, the register contents should be
100 	 * considered invalid. The flag is cleared the next time the RTC is set.
101 	 */
102 	if (regs.minutes & BQ32K_OF)
103 		return -EINVAL;
104 
105 	tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
106 	tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK);
107 	tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
108 	tm->tm_mday = bcd2bin(regs.date);
109 	tm->tm_wday = bcd2bin(regs.day) - 1;
110 	tm->tm_mon = bcd2bin(regs.month) - 1;
111 	tm->tm_year = bcd2bin(regs.years) +
112 				((regs.cent_hours & BQ32K_CENT) ? 100 : 0);
113 
114 	return 0;
115 }
116 
117 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
118 {
119 	struct bq32k_regs regs;
120 
121 	regs.seconds = bin2bcd(tm->tm_sec);
122 	regs.minutes = bin2bcd(tm->tm_min);
123 	regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
124 	regs.day = bin2bcd(tm->tm_wday + 1);
125 	regs.date = bin2bcd(tm->tm_mday);
126 	regs.month = bin2bcd(tm->tm_mon + 1);
127 
128 	if (tm->tm_year >= 100) {
129 		regs.cent_hours |= BQ32K_CENT;
130 		regs.years = bin2bcd(tm->tm_year - 100);
131 	} else
132 		regs.years = bin2bcd(tm->tm_year);
133 
134 	return bq32k_write(dev, &regs, 0, sizeof(regs));
135 }
136 
137 static const struct rtc_class_ops bq32k_rtc_ops = {
138 	.read_time	= bq32k_rtc_read_time,
139 	.set_time	= bq32k_rtc_set_time,
140 };
141 
142 static int trickle_charger_of_init(struct device *dev, struct device_node *node)
143 {
144 	unsigned char reg;
145 	int error;
146 	u32 ohms = 0;
147 
148 	if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms))
149 		return 0;
150 
151 	switch (ohms) {
152 	case 180+940:
153 		/*
154 		 * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging
155 		 * over diode and 940ohm resistor)
156 		 */
157 
158 		if (of_property_read_bool(node, "trickle-diode-disable")) {
159 			dev_err(dev, "diode and resistor mismatch\n");
160 			return -EINVAL;
161 		}
162 		reg = 0x05;
163 		break;
164 
165 	case 180+20000:
166 		/* diode disabled */
167 
168 		if (!of_property_read_bool(node, "trickle-diode-disable")) {
169 			dev_err(dev, "bq32k: diode and resistor mismatch\n");
170 			return -EINVAL;
171 		}
172 		reg = 0x45;
173 		break;
174 
175 	default:
176 		dev_err(dev, "invalid resistor value (%d)\n", ohms);
177 		return -EINVAL;
178 	}
179 
180 	error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
181 	if (error)
182 		return error;
183 
184 	reg = 0x20;
185 	error = bq32k_write(dev, &reg, BQ32K_TCH2, 1);
186 	if (error)
187 		return error;
188 
189 	dev_info(dev, "Enabled trickle RTC battery charge.\n");
190 	return 0;
191 }
192 
193 static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev,
194 					       struct device_attribute *attr,
195 					       char *buf)
196 {
197 	int reg, error;
198 
199 	error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
200 	if (error)
201 		return error;
202 
203 	return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0);
204 }
205 
206 static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev,
207 						struct device_attribute *attr,
208 						const char *buf, size_t count)
209 {
210 	int reg, enable, error;
211 
212 	if (kstrtoint(buf, 0, &enable))
213 		return -EINVAL;
214 
215 	error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
216 	if (error)
217 		return error;
218 
219 	if (enable) {
220 		reg |= BQ32K_TCFE;
221 		error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
222 		if (error)
223 			return error;
224 
225 		dev_info(dev, "Enabled trickle charge FET bypass.\n");
226 	} else {
227 		reg &= ~BQ32K_TCFE;
228 		error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
229 		if (error)
230 			return error;
231 
232 		dev_info(dev, "Disabled trickle charge FET bypass.\n");
233 	}
234 
235 	return count;
236 }
237 
238 static DEVICE_ATTR(trickle_charge_bypass, 0644,
239 		   bq32k_sysfs_show_tricklecharge_bypass,
240 		   bq32k_sysfs_store_tricklecharge_bypass);
241 
242 static int bq32k_sysfs_register(struct device *dev)
243 {
244 	return device_create_file(dev, &dev_attr_trickle_charge_bypass);
245 }
246 
247 static void bq32k_sysfs_unregister(struct device *dev)
248 {
249 	device_remove_file(dev, &dev_attr_trickle_charge_bypass);
250 }
251 
252 static int bq32k_probe(struct i2c_client *client,
253 				const struct i2c_device_id *id)
254 {
255 	struct device *dev = &client->dev;
256 	struct rtc_device *rtc;
257 	uint8_t reg;
258 	int error;
259 
260 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
261 		return -ENODEV;
262 
263 	/* Check Oscillator Stop flag */
264 	error = bq32k_read(dev, &reg, BQ32K_SECONDS, 1);
265 	if (!error && (reg & BQ32K_STOP)) {
266 		dev_warn(dev, "Oscillator was halted. Restarting...\n");
267 		reg &= ~BQ32K_STOP;
268 		error = bq32k_write(dev, &reg, BQ32K_SECONDS, 1);
269 	}
270 	if (error)
271 		return error;
272 
273 	/* Check Oscillator Failure flag */
274 	error = bq32k_read(dev, &reg, BQ32K_MINUTES, 1);
275 	if (error)
276 		return error;
277 	if (reg & BQ32K_OF)
278 		dev_warn(dev, "Oscillator Failure. Check RTC battery.\n");
279 
280 	if (client->dev.of_node)
281 		trickle_charger_of_init(dev, client->dev.of_node);
282 
283 	rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,
284 						&bq32k_rtc_ops, THIS_MODULE);
285 	if (IS_ERR(rtc))
286 		return PTR_ERR(rtc);
287 
288 	error = bq32k_sysfs_register(&client->dev);
289 	if (error) {
290 		dev_err(&client->dev,
291 			"Unable to create sysfs entries for rtc bq32000\n");
292 		return error;
293 	}
294 
295 
296 	i2c_set_clientdata(client, rtc);
297 
298 	return 0;
299 }
300 
301 static int bq32k_remove(struct i2c_client *client)
302 {
303 	bq32k_sysfs_unregister(&client->dev);
304 
305 	return 0;
306 }
307 
308 static const struct i2c_device_id bq32k_id[] = {
309 	{ "bq32000", 0 },
310 	{ }
311 };
312 MODULE_DEVICE_TABLE(i2c, bq32k_id);
313 
314 static const struct of_device_id bq32k_of_match[] = {
315 	{ .compatible = "ti,bq32000" },
316 	{ }
317 };
318 MODULE_DEVICE_TABLE(of, bq32k_of_match);
319 
320 static struct i2c_driver bq32k_driver = {
321 	.driver = {
322 		.name	= "bq32k",
323 		.of_match_table = of_match_ptr(bq32k_of_match),
324 	},
325 	.probe		= bq32k_probe,
326 	.remove		= bq32k_remove,
327 	.id_table	= bq32k_id,
328 };
329 
330 module_i2c_driver(bq32k_driver);
331 
332 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
333 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
334 MODULE_LICENSE("GPL");
335