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