xref: /openbmc/linux/drivers/rtc/rtc-bq32k.c (revision 31b0cecb)
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 
20 #define BQ32K_SECONDS		0x00	/* Seconds register address */
21 #define BQ32K_SECONDS_MASK	0x7F	/* Mask over seconds value */
22 #define BQ32K_STOP		0x80	/* Oscillator Stop flat */
23 
24 #define BQ32K_MINUTES		0x01	/* Minutes register address */
25 #define BQ32K_MINUTES_MASK	0x7F	/* Mask over minutes value */
26 #define BQ32K_OF		0x80	/* Oscillator Failure flag */
27 
28 #define BQ32K_HOURS_MASK	0x3F	/* Mask over hours value */
29 #define BQ32K_CENT		0x40	/* Century flag */
30 #define BQ32K_CENT_EN		0x80	/* Century flag enable bit */
31 
32 #define BQ32K_CALIBRATION	0x07	/* CAL_CFG1, calibration and control */
33 #define BQ32K_TCH2		0x08	/* Trickle charge enable */
34 #define BQ32K_CFG2		0x09	/* Trickle charger control */
35 #define BQ32K_TCFE		BIT(6)	/* Trickle charge FET bypass */
36 
37 #define MAX_LEN			10	/* Maximum number of consecutive
38 					 * register for this particular RTC.
39 					 */
40 
41 struct bq32k_regs {
42 	uint8_t		seconds;
43 	uint8_t		minutes;
44 	uint8_t		cent_hours;
45 	uint8_t		day;
46 	uint8_t		date;
47 	uint8_t		month;
48 	uint8_t		years;
49 };
50 
51 static struct i2c_driver bq32k_driver;
52 
bq32k_read(struct device * dev,void * data,uint8_t off,uint8_t len)53 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
54 {
55 	struct i2c_client *client = to_i2c_client(dev);
56 	struct i2c_msg msgs[] = {
57 		{
58 			.addr = client->addr,
59 			.flags = 0,
60 			.len = 1,
61 			.buf = &off,
62 		}, {
63 			.addr = client->addr,
64 			.flags = I2C_M_RD,
65 			.len = len,
66 			.buf = data,
67 		}
68 	};
69 
70 	if (i2c_transfer(client->adapter, msgs, 2) == 2)
71 		return 0;
72 
73 	return -EIO;
74 }
75 
bq32k_write(struct device * dev,void * data,uint8_t off,uint8_t len)76 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
77 {
78 	struct i2c_client *client = to_i2c_client(dev);
79 	uint8_t buffer[MAX_LEN + 1];
80 
81 	buffer[0] = off;
82 	memcpy(&buffer[1], data, len);
83 
84 	if (i2c_master_send(client, buffer, len + 1) == len + 1)
85 		return 0;
86 
87 	return -EIO;
88 }
89 
bq32k_rtc_read_time(struct device * dev,struct rtc_time * tm)90 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
91 {
92 	struct bq32k_regs regs;
93 	int error;
94 
95 	error = bq32k_read(dev, &regs, 0, sizeof(regs));
96 	if (error)
97 		return error;
98 
99 	/*
100 	 * In case of oscillator failure, the register contents should be
101 	 * considered invalid. The flag is cleared the next time the RTC is set.
102 	 */
103 	if (regs.minutes & BQ32K_OF)
104 		return -EINVAL;
105 
106 	tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
107 	tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK);
108 	tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
109 	tm->tm_mday = bcd2bin(regs.date);
110 	tm->tm_wday = bcd2bin(regs.day) - 1;
111 	tm->tm_mon = bcd2bin(regs.month) - 1;
112 	tm->tm_year = bcd2bin(regs.years) +
113 				((regs.cent_hours & BQ32K_CENT) ? 100 : 0);
114 
115 	return 0;
116 }
117 
bq32k_rtc_set_time(struct device * dev,struct rtc_time * tm)118 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
119 {
120 	struct bq32k_regs regs;
121 
122 	regs.seconds = bin2bcd(tm->tm_sec);
123 	regs.minutes = bin2bcd(tm->tm_min);
124 	regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
125 	regs.day = bin2bcd(tm->tm_wday + 1);
126 	regs.date = bin2bcd(tm->tm_mday);
127 	regs.month = bin2bcd(tm->tm_mon + 1);
128 
129 	if (tm->tm_year >= 100) {
130 		regs.cent_hours |= BQ32K_CENT;
131 		regs.years = bin2bcd(tm->tm_year - 100);
132 	} else
133 		regs.years = bin2bcd(tm->tm_year);
134 
135 	return bq32k_write(dev, &regs, 0, sizeof(regs));
136 }
137 
138 static const struct rtc_class_ops bq32k_rtc_ops = {
139 	.read_time	= bq32k_rtc_read_time,
140 	.set_time	= bq32k_rtc_set_time,
141 };
142 
trickle_charger_of_init(struct device * dev,struct device_node * node)143 static int trickle_charger_of_init(struct device *dev, struct device_node *node)
144 {
145 	unsigned char reg;
146 	int error;
147 	u32 ohms = 0;
148 
149 	if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms))
150 		return 0;
151 
152 	switch (ohms) {
153 	case 180+940:
154 		/*
155 		 * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging
156 		 * over diode and 940ohm resistor)
157 		 */
158 
159 		if (of_property_read_bool(node, "trickle-diode-disable")) {
160 			dev_err(dev, "diode and resistor mismatch\n");
161 			return -EINVAL;
162 		}
163 		reg = 0x05;
164 		break;
165 
166 	case 180+20000:
167 		/* diode disabled */
168 
169 		if (!of_property_read_bool(node, "trickle-diode-disable")) {
170 			dev_err(dev, "bq32k: diode and resistor mismatch\n");
171 			return -EINVAL;
172 		}
173 		reg = 0x45;
174 		break;
175 
176 	default:
177 		dev_err(dev, "invalid resistor value (%d)\n", ohms);
178 		return -EINVAL;
179 	}
180 
181 	error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
182 	if (error)
183 		return error;
184 
185 	reg = 0x20;
186 	error = bq32k_write(dev, &reg, BQ32K_TCH2, 1);
187 	if (error)
188 		return error;
189 
190 	dev_info(dev, "Enabled trickle RTC battery charge.\n");
191 	return 0;
192 }
193 
bq32k_sysfs_show_tricklecharge_bypass(struct device * dev,struct device_attribute * attr,char * buf)194 static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev,
195 					       struct device_attribute *attr,
196 					       char *buf)
197 {
198 	int reg, error;
199 
200 	error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
201 	if (error)
202 		return error;
203 
204 	return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0);
205 }
206 
bq32k_sysfs_store_tricklecharge_bypass(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)207 static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev,
208 						struct device_attribute *attr,
209 						const char *buf, size_t count)
210 {
211 	int reg, enable, error;
212 
213 	if (kstrtoint(buf, 0, &enable))
214 		return -EINVAL;
215 
216 	error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
217 	if (error)
218 		return error;
219 
220 	if (enable) {
221 		reg |= BQ32K_TCFE;
222 		error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
223 		if (error)
224 			return error;
225 
226 		dev_info(dev, "Enabled trickle charge FET bypass.\n");
227 	} else {
228 		reg &= ~BQ32K_TCFE;
229 		error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
230 		if (error)
231 			return error;
232 
233 		dev_info(dev, "Disabled trickle charge FET bypass.\n");
234 	}
235 
236 	return count;
237 }
238 
239 static DEVICE_ATTR(trickle_charge_bypass, 0644,
240 		   bq32k_sysfs_show_tricklecharge_bypass,
241 		   bq32k_sysfs_store_tricklecharge_bypass);
242 
bq32k_sysfs_register(struct device * dev)243 static int bq32k_sysfs_register(struct device *dev)
244 {
245 	return device_create_file(dev, &dev_attr_trickle_charge_bypass);
246 }
247 
bq32k_sysfs_unregister(struct device * dev)248 static void bq32k_sysfs_unregister(struct device *dev)
249 {
250 	device_remove_file(dev, &dev_attr_trickle_charge_bypass);
251 }
252 
bq32k_probe(struct i2c_client * client)253 static int bq32k_probe(struct i2c_client *client)
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 
bq32k_remove(struct i2c_client * client)301 static void bq32k_remove(struct i2c_client *client)
302 {
303 	bq32k_sysfs_unregister(&client->dev);
304 }
305 
306 static const struct i2c_device_id bq32k_id[] = {
307 	{ "bq32000", 0 },
308 	{ }
309 };
310 MODULE_DEVICE_TABLE(i2c, bq32k_id);
311 
312 static const __maybe_unused struct of_device_id bq32k_of_match[] = {
313 	{ .compatible = "ti,bq32000" },
314 	{ }
315 };
316 MODULE_DEVICE_TABLE(of, bq32k_of_match);
317 
318 static struct i2c_driver bq32k_driver = {
319 	.driver = {
320 		.name	= "bq32k",
321 		.of_match_table = of_match_ptr(bq32k_of_match),
322 	},
323 	.probe		= bq32k_probe,
324 	.remove		= bq32k_remove,
325 	.id_table	= bq32k_id,
326 };
327 
328 module_i2c_driver(bq32k_driver);
329 
330 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
331 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
332 MODULE_LICENSE("GPL");
333