xref: /linux/drivers/rtc/rtc-rx8581.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * An I2C driver for the Epson RX8581 RTC
4  *
5  * Author: Martyn Welch <martyn.welch@ge.com>
6  * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
7  *
8  * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
9  * Copyright 2005-06 Tower Technologies
10  */
11 
12 #include <linux/module.h>
13 #include <linux/i2c.h>
14 #include <linux/bcd.h>
15 #include <linux/of.h>
16 #include <linux/regmap.h>
17 #include <linux/rtc.h>
18 #include <linux/log2.h>
19 
20 #define RX8581_REG_SC		0x00 /* Second in BCD */
21 #define RX8581_REG_MN		0x01 /* Minute in BCD */
22 #define RX8581_REG_HR		0x02 /* Hour in BCD */
23 #define RX8581_REG_DW		0x03 /* Day of Week */
24 #define RX8581_REG_DM		0x04 /* Day of Month in BCD */
25 #define RX8581_REG_MO		0x05 /* Month in BCD */
26 #define RX8581_REG_YR		0x06 /* Year in BCD */
27 #define RX8581_REG_RAM		0x07 /* RAM */
28 #define RX8581_REG_AMN		0x08 /* Alarm Min in BCD*/
29 #define RX8581_REG_AHR		0x09 /* Alarm Hour in BCD */
30 #define RX8581_REG_ADM		0x0A
31 #define RX8581_REG_ADW		0x0A
32 #define RX8581_REG_TMR0		0x0B
33 #define RX8581_REG_TMR1		0x0C
34 #define RX8581_REG_EXT		0x0D /* Extension Register */
35 #define RX8581_REG_FLAG		0x0E /* Flag Register */
36 #define RX8581_REG_CTRL		0x0F /* Control Register */
37 
38 
39 /* Flag Register bit definitions */
40 #define RX8581_FLAG_UF		0x20 /* Update */
41 #define RX8581_FLAG_TF		0x10 /* Timer */
42 #define RX8581_FLAG_AF		0x08 /* Alarm */
43 #define RX8581_FLAG_VLF		0x02 /* Voltage Low */
44 
45 /* Control Register bit definitions */
46 #define RX8581_CTRL_UIE		0x20 /* Update Interrupt Enable */
47 #define RX8581_CTRL_TIE		0x10 /* Timer Interrupt Enable */
48 #define RX8581_CTRL_AIE		0x08 /* Alarm Interrupt Enable */
49 #define RX8581_CTRL_STOP	0x02 /* STOP bit */
50 #define RX8581_CTRL_RESET	0x01 /* RESET bit */
51 
52 #define RX8571_USER_RAM		0x10
53 #define RX8571_NVRAM_SIZE	0x10
54 
55 struct rx8581 {
56 	struct regmap		*regmap;
57 	struct rtc_device	*rtc;
58 };
59 
60 struct rx85x1_config {
61 	struct regmap_config regmap;
62 	unsigned int num_nvram;
63 };
64 
65 /*
66  * In the routines that deal directly with the rx8581 hardware, we use
67  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
68  */
rx8581_rtc_read_time(struct device * dev,struct rtc_time * tm)69 static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
70 {
71 	struct i2c_client *client = to_i2c_client(dev);
72 	unsigned char date[7];
73 	unsigned int data;
74 	int err;
75 	struct rx8581 *rx8581 = i2c_get_clientdata(client);
76 
77 	/* First we ensure that the "update flag" is not set, we read the
78 	 * time and date then re-read the "update flag". If the update flag
79 	 * has been set, we know that the time has changed during the read so
80 	 * we repeat the whole process again.
81 	 */
82 	err = regmap_read(rx8581->regmap, RX8581_REG_FLAG, &data);
83 	if (err < 0)
84 		return err;
85 
86 	if (data & RX8581_FLAG_VLF) {
87 		dev_warn(dev,
88 			 "low voltage detected, date/time is not reliable.\n");
89 		return -EINVAL;
90 	}
91 
92 	do {
93 		/* If update flag set, clear it */
94 		if (data & RX8581_FLAG_UF) {
95 			err = regmap_write(rx8581->regmap, RX8581_REG_FLAG,
96 					  data & ~RX8581_FLAG_UF);
97 			if (err < 0)
98 				return err;
99 		}
100 
101 		/* Now read time and date */
102 		err = regmap_bulk_read(rx8581->regmap, RX8581_REG_SC, date,
103 				       sizeof(date));
104 		if (err < 0)
105 			return err;
106 
107 		/* Check flag register */
108 		err = regmap_read(rx8581->regmap, RX8581_REG_FLAG, &data);
109 		if (err < 0)
110 			return err;
111 	} while (data & RX8581_FLAG_UF);
112 
113 	dev_dbg(dev, "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
114 		"wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
115 		__func__,
116 		date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
117 
118 	tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
119 	tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
120 	tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
121 	tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
122 	tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
123 	tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
124 	tm->tm_year = bcd2bin(date[RX8581_REG_YR]) + 100;
125 
126 	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
127 		"mday=%d, mon=%d, year=%d, wday=%d\n",
128 		__func__,
129 		tm->tm_sec, tm->tm_min, tm->tm_hour,
130 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
131 
132 	return 0;
133 }
134 
rx8581_rtc_set_time(struct device * dev,struct rtc_time * tm)135 static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
136 {
137 	struct i2c_client *client = to_i2c_client(dev);
138 	int err;
139 	unsigned char buf[7];
140 	struct rx8581 *rx8581 = i2c_get_clientdata(client);
141 
142 	dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
143 		"mday=%d, mon=%d, year=%d, wday=%d\n",
144 		__func__,
145 		tm->tm_sec, tm->tm_min, tm->tm_hour,
146 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
147 
148 	/* hours, minutes and seconds */
149 	buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
150 	buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
151 	buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);
152 
153 	buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);
154 
155 	/* month, 1 - 12 */
156 	buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);
157 
158 	/* year and century */
159 	buf[RX8581_REG_YR] = bin2bcd(tm->tm_year - 100);
160 	buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);
161 
162 	/* Stop the clock */
163 	err = regmap_update_bits(rx8581->regmap, RX8581_REG_CTRL,
164 				 RX8581_CTRL_STOP, RX8581_CTRL_STOP);
165 	if (err < 0)
166 		return err;
167 
168 	/* write register's data */
169 	err = regmap_bulk_write(rx8581->regmap, RX8581_REG_SC,
170 				buf, sizeof(buf));
171 	if (err < 0)
172 		return err;
173 
174 	/* get VLF and clear it */
175 	err = regmap_update_bits(rx8581->regmap, RX8581_REG_FLAG,
176 				 RX8581_FLAG_VLF, 0);
177 	if (err < 0)
178 		return err;
179 
180 	/* Restart the clock */
181 	return regmap_update_bits(rx8581->regmap, RX8581_REG_CTRL,
182 				 RX8581_CTRL_STOP, 0);
183 }
184 
185 static const struct rtc_class_ops rx8581_rtc_ops = {
186 	.read_time	= rx8581_rtc_read_time,
187 	.set_time	= rx8581_rtc_set_time,
188 };
189 
rx8571_nvram_read(void * priv,unsigned int offset,void * val,size_t bytes)190 static int rx8571_nvram_read(void *priv, unsigned int offset, void *val,
191 			     size_t bytes)
192 {
193 	struct rx8581 *rx8581 = priv;
194 
195 	return regmap_bulk_read(rx8581->regmap, RX8571_USER_RAM + offset,
196 				val, bytes);
197 }
198 
rx8571_nvram_write(void * priv,unsigned int offset,void * val,size_t bytes)199 static int rx8571_nvram_write(void *priv, unsigned int offset, void *val,
200 			      size_t bytes)
201 {
202 	struct rx8581 *rx8581 = priv;
203 
204 	return regmap_bulk_write(rx8581->regmap, RX8571_USER_RAM + offset,
205 				 val, bytes);
206 }
207 
rx85x1_nvram_read(void * priv,unsigned int offset,void * val,size_t bytes)208 static int rx85x1_nvram_read(void *priv, unsigned int offset, void *val,
209 			     size_t bytes)
210 {
211 	struct rx8581 *rx8581 = priv;
212 	unsigned int tmp_val;
213 	int ret;
214 
215 	ret = regmap_read(rx8581->regmap, RX8581_REG_RAM, &tmp_val);
216 	(*(unsigned char *)val) = (unsigned char) tmp_val;
217 
218 	return ret;
219 }
220 
rx85x1_nvram_write(void * priv,unsigned int offset,void * val,size_t bytes)221 static int rx85x1_nvram_write(void *priv, unsigned int offset, void *val,
222 			      size_t bytes)
223 {
224 	struct rx8581 *rx8581 = priv;
225 	unsigned char tmp_val;
226 
227 	tmp_val = *((unsigned char *)val);
228 	return regmap_write(rx8581->regmap, RX8581_REG_RAM,
229 				(unsigned int)tmp_val);
230 }
231 
232 static const struct rx85x1_config rx8581_config = {
233 	.regmap = {
234 		.reg_bits = 8,
235 		.val_bits = 8,
236 		.max_register = 0xf,
237 	},
238 	.num_nvram = 1
239 };
240 
241 static const struct rx85x1_config rx8571_config = {
242 	.regmap = {
243 		.reg_bits = 8,
244 		.val_bits = 8,
245 		.max_register = 0x1f,
246 	},
247 	.num_nvram = 2
248 };
249 
rx8581_probe(struct i2c_client * client)250 static int rx8581_probe(struct i2c_client *client)
251 {
252 	struct rx8581 *rx8581;
253 	const struct rx85x1_config *config = &rx8581_config;
254 	const void *data = of_device_get_match_data(&client->dev);
255 	static struct nvmem_config nvmem_cfg[] = {
256 		{
257 			.name = "rx85x1-",
258 			.word_size = 1,
259 			.stride = 1,
260 			.size = 1,
261 			.reg_read = rx85x1_nvram_read,
262 			.reg_write = rx85x1_nvram_write,
263 		}, {
264 			.name = "rx8571-",
265 			.word_size = 1,
266 			.stride = 1,
267 			.size = RX8571_NVRAM_SIZE,
268 			.reg_read = rx8571_nvram_read,
269 			.reg_write = rx8571_nvram_write,
270 		},
271 	};
272 	int ret, i;
273 
274 	dev_dbg(&client->dev, "%s\n", __func__);
275 
276 	if (data)
277 		config = data;
278 
279 	rx8581 = devm_kzalloc(&client->dev, sizeof(struct rx8581), GFP_KERNEL);
280 	if (!rx8581)
281 		return -ENOMEM;
282 
283 	i2c_set_clientdata(client, rx8581);
284 
285 	rx8581->regmap = devm_regmap_init_i2c(client, &config->regmap);
286 	if (IS_ERR(rx8581->regmap))
287 		return PTR_ERR(rx8581->regmap);
288 
289 	rx8581->rtc = devm_rtc_allocate_device(&client->dev);
290 	if (IS_ERR(rx8581->rtc))
291 		return PTR_ERR(rx8581->rtc);
292 
293 	rx8581->rtc->ops = &rx8581_rtc_ops;
294 	rx8581->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
295 	rx8581->rtc->range_max = RTC_TIMESTAMP_END_2099;
296 	rx8581->rtc->start_secs = 0;
297 	rx8581->rtc->set_start_time = true;
298 
299 	ret = devm_rtc_register_device(rx8581->rtc);
300 
301 	for (i = 0; i < config->num_nvram; i++) {
302 		nvmem_cfg[i].priv = rx8581;
303 		devm_rtc_nvmem_register(rx8581->rtc, &nvmem_cfg[i]);
304 	}
305 
306 	return ret;
307 }
308 
309 static const struct i2c_device_id rx8581_id[] = {
310 	{ "rx8581" },
311 	{ }
312 };
313 MODULE_DEVICE_TABLE(i2c, rx8581_id);
314 
315 static const __maybe_unused struct of_device_id rx8581_of_match[] = {
316 	{ .compatible = "epson,rx8571", .data = &rx8571_config },
317 	{ .compatible = "epson,rx8581", .data = &rx8581_config },
318 	{ /* sentinel */ }
319 };
320 MODULE_DEVICE_TABLE(of, rx8581_of_match);
321 
322 static struct i2c_driver rx8581_driver = {
323 	.driver		= {
324 		.name	= "rtc-rx8581",
325 		.of_match_table = of_match_ptr(rx8581_of_match),
326 	},
327 	.probe		= rx8581_probe,
328 	.id_table	= rx8581_id,
329 };
330 
331 module_i2c_driver(rx8581_driver);
332 
333 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
334 MODULE_DESCRIPTION("Epson RX-8571/RX-8581 RTC driver");
335 MODULE_LICENSE("GPL");
336