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Uwe Zeisbergerf30c2262006-10-03 23:01:26 +02001/* drivers/rtc/rtc-max6902.c
Raphael Assenat8e12ecc2006-06-25 05:48:23 -07002 *
3 * Copyright (C) 2006 8D Technologies inc.
4 * Copyright (C) 2004 Compulab Ltd.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Driver for MAX6902 spi RTC
11 *
12 * Changelog:
13 *
14 * 24-May-2006: Raphael Assenat <raph@8d.com>
15 * - Major rework
David Brownell5c076fc2007-08-22 14:01:57 -070016 * Converted to rtc_device and uses the SPI layer.
Raphael Assenat8e12ecc2006-06-25 05:48:23 -070017 *
18 * ??-???-2005: Someone at Compulab
19 * - Initial driver creation.
20 */
21
Raphael Assenat8e12ecc2006-06-25 05:48:23 -070022#include <linux/module.h>
23#include <linux/version.h>
24
25#include <linux/kernel.h>
26#include <linux/platform_device.h>
27#include <linux/init.h>
28#include <linux/rtc.h>
29#include <linux/spi/spi.h>
30#include <linux/bcd.h>
31#include <linux/delay.h>
32
33#define MAX6902_REG_SECONDS 0x01
34#define MAX6902_REG_MINUTES 0x03
35#define MAX6902_REG_HOURS 0x05
36#define MAX6902_REG_DATE 0x07
37#define MAX6902_REG_MONTH 0x09
38#define MAX6902_REG_DAY 0x0B
39#define MAX6902_REG_YEAR 0x0D
40#define MAX6902_REG_CONTROL 0x0F
41#define MAX6902_REG_CENTURY 0x13
42
43#undef MAX6902_DEBUG
44
45struct max6902 {
46 struct rtc_device *rtc;
47 u8 buf[9]; /* Burst read cmd + 8 registers */
48 u8 tx_buf[2];
49 u8 rx_buf[2];
50};
51
52static void max6902_set_reg(struct device *dev, unsigned char address,
53 unsigned char data)
54{
55 struct spi_device *spi = to_spi_device(dev);
56 unsigned char buf[2];
57
58 /* MSB must be '0' to write */
59 buf[0] = address & 0x7f;
60 buf[1] = data;
61
62 spi_write(spi, buf, 2);
63}
64
65static int max6902_get_reg(struct device *dev, unsigned char address,
66 unsigned char *data)
67{
68 struct spi_device *spi = to_spi_device(dev);
69 struct max6902 *chip = dev_get_drvdata(dev);
70 struct spi_message message;
71 struct spi_transfer xfer;
72 int status;
73
74 if (!data)
75 return -EINVAL;
76
77 /* Build our spi message */
78 spi_message_init(&message);
79 memset(&xfer, 0, sizeof(xfer));
80 xfer.len = 2;
81 /* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */
82 xfer.tx_buf = chip->tx_buf;
83 xfer.rx_buf = chip->rx_buf;
84
85 /* Set MSB to indicate read */
86 chip->tx_buf[0] = address | 0x80;
87
88 spi_message_add_tail(&xfer, &message);
89
90 /* do the i/o */
91 status = spi_sync(spi, &message);
92 if (status == 0)
93 status = message.status;
94 else
95 return status;
96
97 *data = chip->rx_buf[1];
98
99 return status;
100}
101
102static int max6902_get_datetime(struct device *dev, struct rtc_time *dt)
103{
104 unsigned char tmp;
105 int century;
106 int err;
107 struct spi_device *spi = to_spi_device(dev);
108 struct max6902 *chip = dev_get_drvdata(dev);
109 struct spi_message message;
110 struct spi_transfer xfer;
111 int status;
112
113 err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp);
114 if (err)
115 return err;
116
117 /* build the message */
118 spi_message_init(&message);
119 memset(&xfer, 0, sizeof(xfer));
120 xfer.len = 1 + 7; /* Burst read command + 7 registers */
121 xfer.tx_buf = chip->buf;
122 xfer.rx_buf = chip->buf;
123 chip->buf[0] = 0xbf; /* Burst read */
124 spi_message_add_tail(&xfer, &message);
125
126 /* do the i/o */
127 status = spi_sync(spi, &message);
128 if (status == 0)
129 status = message.status;
130 else
131 return status;
132
133 /* The chip sends data in this order:
134 * Seconds, Minutes, Hours, Date, Month, Day, Year */
135 dt->tm_sec = BCD2BIN(chip->buf[1]);
136 dt->tm_min = BCD2BIN(chip->buf[2]);
137 dt->tm_hour = BCD2BIN(chip->buf[3]);
138 dt->tm_mday = BCD2BIN(chip->buf[4]);
Francisco Larramendic4301692006-10-17 00:09:53 -0700139 dt->tm_mon = BCD2BIN(chip->buf[5]) - 1;
Raphael Assenat8e12ecc2006-06-25 05:48:23 -0700140 dt->tm_wday = BCD2BIN(chip->buf[6]);
141 dt->tm_year = BCD2BIN(chip->buf[7]);
142
143 century = BCD2BIN(tmp) * 100;
144
145 dt->tm_year += century;
146 dt->tm_year -= 1900;
147
148#ifdef MAX6902_DEBUG
149 printk("\n%s : Read RTC values\n",__FUNCTION__);
150 printk("tm_hour: %i\n",dt->tm_hour);
151 printk("tm_min : %i\n",dt->tm_min);
152 printk("tm_sec : %i\n",dt->tm_sec);
153 printk("tm_year: %i\n",dt->tm_year);
154 printk("tm_mon : %i\n",dt->tm_mon);
155 printk("tm_mday: %i\n",dt->tm_mday);
156 printk("tm_wday: %i\n",dt->tm_wday);
157#endif
158
159 return 0;
160}
161
162static int max6902_set_datetime(struct device *dev, struct rtc_time *dt)
163{
164 dt->tm_year = dt->tm_year+1900;
165
166#ifdef MAX6902_DEBUG
167 printk("\n%s : Setting RTC values\n",__FUNCTION__);
168 printk("tm_sec : %i\n",dt->tm_sec);
169 printk("tm_min : %i\n",dt->tm_min);
170 printk("tm_hour: %i\n",dt->tm_hour);
171 printk("tm_mday: %i\n",dt->tm_mday);
172 printk("tm_wday: %i\n",dt->tm_wday);
173 printk("tm_year: %i\n",dt->tm_year);
174#endif
175
176 /* Remove write protection */
177 max6902_set_reg(dev, 0xF, 0);
178
179 max6902_set_reg(dev, 0x01, BIN2BCD(dt->tm_sec));
180 max6902_set_reg(dev, 0x03, BIN2BCD(dt->tm_min));
181 max6902_set_reg(dev, 0x05, BIN2BCD(dt->tm_hour));
182
183 max6902_set_reg(dev, 0x07, BIN2BCD(dt->tm_mday));
184 max6902_set_reg(dev, 0x09, BIN2BCD(dt->tm_mon+1));
185 max6902_set_reg(dev, 0x0B, BIN2BCD(dt->tm_wday));
186 max6902_set_reg(dev, 0x0D, BIN2BCD(dt->tm_year%100));
187 max6902_set_reg(dev, 0x13, BIN2BCD(dt->tm_year/100));
188
189 /* Compulab used a delay here. However, the datasheet
190 * does not mention a delay being required anywhere... */
191 /* delay(2000); */
192
193 /* Write protect */
194 max6902_set_reg(dev, 0xF, 0x80);
195
196 return 0;
197}
198
199static int max6902_read_time(struct device *dev, struct rtc_time *tm)
200{
201 return max6902_get_datetime(dev, tm);
202}
203
204static int max6902_set_time(struct device *dev, struct rtc_time *tm)
205{
206 return max6902_set_datetime(dev, tm);
207}
208
David Brownellff8371a2006-09-30 23:28:17 -0700209static const struct rtc_class_ops max6902_rtc_ops = {
Raphael Assenat8e12ecc2006-06-25 05:48:23 -0700210 .read_time = max6902_read_time,
211 .set_time = max6902_set_time,
212};
213
214static int __devinit max6902_probe(struct spi_device *spi)
215{
216 struct rtc_device *rtc;
217 unsigned char tmp;
218 struct max6902 *chip;
219 int res;
220
221 rtc = rtc_device_register("max6902",
222 &spi->dev, &max6902_rtc_ops, THIS_MODULE);
223 if (IS_ERR(rtc))
224 return PTR_ERR(rtc);
225
226 spi->mode = SPI_MODE_3;
227 spi->bits_per_word = 8;
228 spi_setup(spi);
229
230 chip = kzalloc(sizeof *chip, GFP_KERNEL);
231 if (!chip) {
232 rtc_device_unregister(rtc);
233 return -ENOMEM;
234 }
235 chip->rtc = rtc;
236 dev_set_drvdata(&spi->dev, chip);
237
238 res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
239 if (res) {
240 rtc_device_unregister(rtc);
241 return res;
242 }
243
244 return 0;
245}
246
247static int __devexit max6902_remove(struct spi_device *spi)
248{
249 struct max6902 *chip = platform_get_drvdata(spi);
250 struct rtc_device *rtc = chip->rtc;
251
252 if (rtc)
253 rtc_device_unregister(rtc);
254
255 kfree(chip);
256
257 return 0;
258}
259
260static struct spi_driver max6902_driver = {
261 .driver = {
David Brownell5c076fc2007-08-22 14:01:57 -0700262 .name = "rtc-max6902",
Raphael Assenat8e12ecc2006-06-25 05:48:23 -0700263 .bus = &spi_bus_type,
264 .owner = THIS_MODULE,
265 },
David Brownell5c076fc2007-08-22 14:01:57 -0700266 .probe = max6902_probe,
Raphael Assenat8e12ecc2006-06-25 05:48:23 -0700267 .remove = __devexit_p(max6902_remove),
268};
269
270static __init int max6902_init(void)
271{
272 printk("max6902 spi driver\n");
273 return spi_register_driver(&max6902_driver);
274}
275module_init(max6902_init);
276
277static __exit void max6902_exit(void)
278{
279 spi_unregister_driver(&max6902_driver);
280}
281module_exit(max6902_exit);
282
283MODULE_DESCRIPTION ("max6902 spi RTC driver");
284MODULE_AUTHOR ("Raphael Assenat");
285MODULE_LICENSE ("GPL");