1 /* drivers/rtc/rtc-rx4581.c
2  *
3  * written by Torben Hohn <torbenh@linutronix.de>
4  *
5  * Based on:
6  * drivers/rtc/rtc-max6902.c
7  *
8  * Copyright (C) 2006 8D Technologies inc.
9  * Copyright (C) 2004 Compulab Ltd.
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License version 2 as
13  * published by the Free Software Foundation.
14  *
15  * Driver for MAX6902 spi RTC
16  *
17  * and based on:
18  * drivers/rtc/rtc-rx8581.c
19  *
20  * An I2C driver for the Epson RX8581 RTC
21  *
22  * Author: Martyn Welch <martyn.welch@ge.com>
23  * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
24  *
25  * This program is free software; you can redistribute it and/or modify
26  * it under the terms of the GNU General Public License version 2 as
27  * published by the Free Software Foundation.
28  *
29  * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
30  * Copyright 2005-06 Tower Technologies
31  *
32  */
33 
34 #include <linux/module.h>
35 #include <linux/kernel.h>
36 #include <linux/platform_device.h>
37 #include <linux/init.h>
38 #include <linux/rtc.h>
39 #include <linux/spi/spi.h>
40 #include <linux/bcd.h>
41 
42 #define RX4581_REG_SC		0x00 /* Second in BCD */
43 #define RX4581_REG_MN		0x01 /* Minute in BCD */
44 #define RX4581_REG_HR		0x02 /* Hour in BCD */
45 #define RX4581_REG_DW		0x03 /* Day of Week */
46 #define RX4581_REG_DM		0x04 /* Day of Month in BCD */
47 #define RX4581_REG_MO		0x05 /* Month in BCD */
48 #define RX4581_REG_YR		0x06 /* Year in BCD */
49 #define RX4581_REG_RAM		0x07 /* RAM */
50 #define RX4581_REG_AMN		0x08 /* Alarm Min in BCD*/
51 #define RX4581_REG_AHR		0x09 /* Alarm Hour in BCD */
52 #define RX4581_REG_ADM		0x0A
53 #define RX4581_REG_ADW		0x0A
54 #define RX4581_REG_TMR0		0x0B
55 #define RX4581_REG_TMR1		0x0C
56 #define RX4581_REG_EXT		0x0D /* Extension Register */
57 #define RX4581_REG_FLAG		0x0E /* Flag Register */
58 #define RX4581_REG_CTRL		0x0F /* Control Register */
59 
60 
61 /* Flag Register bit definitions */
62 #define RX4581_FLAG_UF		0x20 /* Update */
63 #define RX4581_FLAG_TF		0x10 /* Timer */
64 #define RX4581_FLAG_AF		0x08 /* Alarm */
65 #define RX4581_FLAG_VLF		0x02 /* Voltage Low */
66 
67 /* Control Register bit definitions */
68 #define RX4581_CTRL_UIE		0x20 /* Update Interrupt Enable */
69 #define RX4581_CTRL_TIE		0x10 /* Timer Interrupt Enable */
70 #define RX4581_CTRL_AIE		0x08 /* Alarm Interrupt Enable */
71 #define RX4581_CTRL_STOP	0x02 /* STOP bit */
72 #define RX4581_CTRL_RESET	0x01 /* RESET bit */
73 
rx4581_set_reg(struct device * dev,unsigned char address,unsigned char data)74 static int rx4581_set_reg(struct device *dev, unsigned char address,
75 				unsigned char data)
76 {
77 	struct spi_device *spi = to_spi_device(dev);
78 	unsigned char buf[2];
79 
80 	/* high nibble must be '0' to write */
81 	buf[0] = address & 0x0f;
82 	buf[1] = data;
83 
84 	return spi_write_then_read(spi, buf, 2, NULL, 0);
85 }
86 
rx4581_get_reg(struct device * dev,unsigned char address,unsigned char * data)87 static int rx4581_get_reg(struct device *dev, unsigned char address,
88 				unsigned char *data)
89 {
90 	struct spi_device *spi = to_spi_device(dev);
91 
92 	/* Set MSB to indicate read */
93 	*data = address | 0x80;
94 
95 	return spi_write_then_read(spi, data, 1, data, 1);
96 }
97 
98 /*
99  * In the routines that deal directly with the rx8581 hardware, we use
100  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
101  */
rx4581_get_datetime(struct device * dev,struct rtc_time * tm)102 static int rx4581_get_datetime(struct device *dev, struct rtc_time *tm)
103 {
104 	struct spi_device *spi = to_spi_device(dev);
105 	unsigned char date[7];
106 	unsigned char data;
107 	int err;
108 
109 	/* First we ensure that the "update flag" is not set, we read the
110 	 * time and date then re-read the "update flag". If the update flag
111 	 * has been set, we know that the time has changed during the read so
112 	 * we repeat the whole process again.
113 	 */
114 	err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
115 	if (err != 0) {
116 		dev_err(dev, "Unable to read device flags\n");
117 		return -EIO;
118 	}
119 
120 	do {
121 		/* If update flag set, clear it */
122 		if (data & RX4581_FLAG_UF) {
123 			err = rx4581_set_reg(dev,
124 				RX4581_REG_FLAG, (data & ~RX4581_FLAG_UF));
125 			if (err != 0) {
126 				dev_err(dev, "Unable to write device "
127 					"flags\n");
128 				return -EIO;
129 			}
130 		}
131 
132 		/* Now read time and date */
133 		date[0] = 0x80;
134 		err = spi_write_then_read(spi, date, 1, date, 7);
135 		if (err < 0) {
136 			dev_err(dev, "Unable to read date\n");
137 			return -EIO;
138 		}
139 
140 		/* Check flag register */
141 		err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
142 		if (err != 0) {
143 			dev_err(dev, "Unable to read device flags\n");
144 			return -EIO;
145 		}
146 	} while (data & RX4581_FLAG_UF);
147 
148 	if (data & RX4581_FLAG_VLF)
149 		dev_info(dev,
150 			"low voltage detected, date/time is not reliable.\n");
151 
152 	dev_dbg(dev,
153 		"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
154 		"wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
155 		__func__,
156 		date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
157 
158 	tm->tm_sec = bcd2bin(date[RX4581_REG_SC] & 0x7F);
159 	tm->tm_min = bcd2bin(date[RX4581_REG_MN] & 0x7F);
160 	tm->tm_hour = bcd2bin(date[RX4581_REG_HR] & 0x3F); /* rtc hr 0-23 */
161 	tm->tm_wday = ilog2(date[RX4581_REG_DW] & 0x7F);
162 	tm->tm_mday = bcd2bin(date[RX4581_REG_DM] & 0x3F);
163 	tm->tm_mon = bcd2bin(date[RX4581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
164 	tm->tm_year = bcd2bin(date[RX4581_REG_YR]);
165 	if (tm->tm_year < 70)
166 		tm->tm_year += 100;	/* assume we are in 1970...2069 */
167 
168 
169 	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
170 		"mday=%d, mon=%d, year=%d, wday=%d\n",
171 		__func__,
172 		tm->tm_sec, tm->tm_min, tm->tm_hour,
173 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
174 
175 	return 0;
176 }
177 
rx4581_set_datetime(struct device * dev,struct rtc_time * tm)178 static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm)
179 {
180 	struct spi_device *spi = to_spi_device(dev);
181 	int err;
182 	unsigned char buf[8], data;
183 
184 	dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
185 		"mday=%d, mon=%d, year=%d, wday=%d\n",
186 		__func__,
187 		tm->tm_sec, tm->tm_min, tm->tm_hour,
188 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
189 
190 	buf[0] = 0x00;
191 	/* hours, minutes and seconds */
192 	buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec);
193 	buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min);
194 	buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour);
195 
196 	buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday);
197 
198 	/* month, 1 - 12 */
199 	buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1);
200 
201 	/* year and century */
202 	buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100);
203 	buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday);
204 
205 	/* Stop the clock */
206 	err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
207 	if (err != 0) {
208 		dev_err(dev, "Unable to read control register\n");
209 		return -EIO;
210 	}
211 
212 	err = rx4581_set_reg(dev, RX4581_REG_CTRL,
213 		(data | RX4581_CTRL_STOP));
214 	if (err != 0) {
215 		dev_err(dev, "Unable to write control register\n");
216 		return -EIO;
217 	}
218 
219 	/* write register's data */
220 	err = spi_write_then_read(spi, buf, 8, NULL, 0);
221 	if (err != 0) {
222 		dev_err(dev, "Unable to write to date registers\n");
223 		return -EIO;
224 	}
225 
226 	/* get VLF and clear it */
227 	err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
228 	if (err != 0) {
229 		dev_err(dev, "Unable to read flag register\n");
230 		return -EIO;
231 	}
232 
233 	err = rx4581_set_reg(dev, RX4581_REG_FLAG,
234 		(data & ~(RX4581_FLAG_VLF)));
235 	if (err != 0) {
236 		dev_err(dev, "Unable to write flag register\n");
237 		return -EIO;
238 	}
239 
240 	/* Restart the clock */
241 	err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
242 	if (err != 0) {
243 		dev_err(dev, "Unable to read control register\n");
244 		return -EIO;
245 	}
246 
247 	err = rx4581_set_reg(dev, RX4581_REG_CTRL,
248 		(data & ~(RX4581_CTRL_STOP)));
249 	if (err != 0) {
250 		dev_err(dev, "Unable to write control register\n");
251 		return -EIO;
252 	}
253 
254 	return 0;
255 }
256 
257 static const struct rtc_class_ops rx4581_rtc_ops = {
258 	.read_time	= rx4581_get_datetime,
259 	.set_time	= rx4581_set_datetime,
260 };
261 
rx4581_probe(struct spi_device * spi)262 static int rx4581_probe(struct spi_device *spi)
263 {
264 	struct rtc_device *rtc;
265 	unsigned char tmp;
266 	int res;
267 
268 	res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp);
269 	if (res != 0)
270 		return res;
271 
272 	rtc = devm_rtc_device_register(&spi->dev, "rx4581",
273 				&rx4581_rtc_ops, THIS_MODULE);
274 	if (IS_ERR(rtc))
275 		return PTR_ERR(rtc);
276 
277 	spi_set_drvdata(spi, rtc);
278 	return 0;
279 }
280 
281 static const struct spi_device_id rx4581_id[] = {
282 	{ "rx4581", 0 },
283 	{ }
284 };
285 MODULE_DEVICE_TABLE(spi, rx4581_id);
286 
287 static struct spi_driver rx4581_driver = {
288 	.driver = {
289 		.name	= "rtc-rx4581",
290 	},
291 	.probe	= rx4581_probe,
292 	.id_table = rx4581_id,
293 };
294 
295 module_spi_driver(rx4581_driver);
296 
297 MODULE_DESCRIPTION("rx4581 spi RTC driver");
298 MODULE_AUTHOR("Torben Hohn");
299 MODULE_LICENSE("GPL");
300 MODULE_ALIAS("spi:rtc-rx4581");
301