1 /* drivers/rtc/rtc-max6902.c
2 *
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
16 * Converted to rtc_device and uses the SPI layer.
17 *
18 * ??-???-2005: Someone at Compulab
19 * - Initial driver creation.
20 */
21
22 #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
45 struct 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
52 static 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 '' to write */
59 buf[0] = address & 0x7f;
60 buf[1] = data;
61
62 spi_write(spi, buf, 2);
63 }
64
65 static 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
93 if (status == 0)
94 *data = chip->rx_buf[1];
95 return status;
96 }
97
98 static int max6902_get_datetime(struct device *dev, struct rtc_time *dt)
99 {
100 unsigned char tmp;
101 int century;
102 int err;
103 struct spi_device *spi = to_spi_device(dev);
104 struct max6902 *chip = dev_get_drvdata(dev);
105 struct spi_message message;
106 struct spi_transfer xfer;
107 int status;
108
109 err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp);
110 if (err)
111 return err;
112
113 /* build the message */
114 spi_message_init(&message);
115 memset(&xfer, 0, sizeof(xfer));
116 xfer.len = 1 + 7; /* Burst read command + 7 registers */
117 xfer.tx_buf = chip->buf;
118 xfer.rx_buf = chip->buf;
119 chip->buf[0] = 0xbf; /* Burst read */
120 spi_message_add_tail(&xfer, &message);
121
122 /* do the i/o */
123 status = spi_sync(spi, &message);
124 if (status)
125 return status;
126
127 /* The chip sends data in this order:
128 * Seconds, Minutes, Hours, Date, Month, Day, Year */
129 dt->tm_sec = BCD2BIN(chip->buf[1]);
130 dt->tm_min = BCD2BIN(chip->buf[2]);
131 dt->tm_hour = BCD2BIN(chip->buf[3]);
132 dt->tm_mday = BCD2BIN(chip->buf[4]);
133 dt->tm_mon = BCD2BIN(chip->buf[5]) - 1;
134 dt->tm_wday = BCD2BIN(chip->buf[6]);
135 dt->tm_year = BCD2BIN(chip->buf[7]);
136
137 century = BCD2BIN(tmp) * 100;
138
139 dt->tm_year += century;
140 dt->tm_year -= 1900;
141
142 #ifdef MAX6902_DEBUG
143 printk("\n%s : Read RTC values\n",__FUNCTION__);
144 printk("tm_hour: %i\n",dt->tm_hour);
145 printk("tm_min : %i\n",dt->tm_min);
146 printk("tm_sec : %i\n",dt->tm_sec);
147 printk("tm_year: %i\n",dt->tm_year);
148 printk("tm_mon : %i\n",dt->tm_mon);
149 printk("tm_mday: %i\n",dt->tm_mday);
150 printk("tm_wday: %i\n",dt->tm_wday);
151 #endif
152
153 return 0;
154 }
155
156 static int max6902_set_datetime(struct device *dev, struct rtc_time *dt)
157 {
158 dt->tm_year = dt->tm_year+1900;
159
160 #ifdef MAX6902_DEBUG
161 printk("\n%s : Setting RTC values\n",__FUNCTION__);
162 printk("tm_sec : %i\n",dt->tm_sec);
163 printk("tm_min : %i\n",dt->tm_min);
164 printk("tm_hour: %i\n",dt->tm_hour);
165 printk("tm_mday: %i\n",dt->tm_mday);
166 printk("tm_wday: %i\n",dt->tm_wday);
167 printk("tm_year: %i\n",dt->tm_year);
168 #endif
169
170 /* Remove write protection */
171 max6902_set_reg(dev, 0xF, 0);
172
173 max6902_set_reg(dev, 0x01, BIN2BCD(dt->tm_sec));
174 max6902_set_reg(dev, 0x03, BIN2BCD(dt->tm_min));
175 max6902_set_reg(dev, 0x05, BIN2BCD(dt->tm_hour));
176
177 max6902_set_reg(dev, 0x07, BIN2BCD(dt->tm_mday));
178 max6902_set_reg(dev, 0x09, BIN2BCD(dt->tm_mon+1));
179 max6902_set_reg(dev, 0x0B, BIN2BCD(dt->tm_wday));
180 max6902_set_reg(dev, 0x0D, BIN2BCD(dt->tm_year%100));
181 max6902_set_reg(dev, 0x13, BIN2BCD(dt->tm_year/100));
182
183 /* Compulab used a delay here. However, the datasheet
184 * does not mention a delay being required anywhere... */
185 /* delay(2000); */
186
187 /* Write protect */
188 max6902_set_reg(dev, 0xF, 0x80);
189
190 return 0;
191 }
192
193 static int max6902_read_time(struct device *dev, struct rtc_time *tm)
194 {
195 return max6902_get_datetime(dev, tm);
196 }
197
198 static int max6902_set_time(struct device *dev, struct rtc_time *tm)
199 {
200 return max6902_set_datetime(dev, tm);
201 }
202
203 static const struct rtc_class_ops max6902_rtc_ops = {
204 .read_time = max6902_read_time,
205 .set_time = max6902_set_time,
206 };
207
208 static int __devinit max6902_probe(struct spi_device *spi)
209 {
210 struct rtc_device *rtc;
211 unsigned char tmp;
212 struct max6902 *chip;
213 int res;
214
215 rtc = rtc_device_register("max6902",
216 &spi->dev, &max6902_rtc_ops, THIS_MODULE);
217 if (IS_ERR(rtc))
218 return PTR_ERR(rtc);
219
220 spi->mode = SPI_MODE_3;
221 spi->bits_per_word = 8;
222 spi_setup(spi);
223
224 chip = kzalloc(sizeof *chip, GFP_KERNEL);
225 if (!chip) {
226 rtc_device_unregister(rtc);
227 return -ENOMEM;
228 }
229 chip->rtc = rtc;
230 dev_set_drvdata(&spi->dev, chip);
231
232 res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
233 if (res) {
234 rtc_device_unregister(rtc);
235 return res;
236 }
237
238 return 0;
239 }
240
241 static int __devexit max6902_remove(struct spi_device *spi)
242 {
243 struct max6902 *chip = platform_get_drvdata(spi);
244 struct rtc_device *rtc = chip->rtc;
245
246 if (rtc)
247 rtc_device_unregister(rtc);
248
249 kfree(chip);
250
251 return 0;
252 }
253
254 static struct spi_driver max6902_driver = {
255 .driver = {
256 .name = "rtc-max6902",
257 .bus = &spi_bus_type,
258 .owner = THIS_MODULE,
259 },
260 .probe = max6902_probe,
261 .remove = __devexit_p(max6902_remove),
262 };
263
264 static __init int max6902_init(void)
265 {
266 printk("max6902 spi driver\n");
267 return spi_register_driver(&max6902_driver);
268 }
269 module_init(max6902_init);
270
271 static __exit void max6902_exit(void)
272 {
273 spi_unregister_driver(&max6902_driver);
274 }
275 module_exit(max6902_exit);
276
277 MODULE_DESCRIPTION ("max6902 spi RTC driver");
278 MODULE_AUTHOR ("Raphael Assenat");
279 MODULE_LICENSE ("GPL");
280
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