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
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]);
139	dt->tm_mon	= BCD2BIN(chip->buf[5]) - 1;
140	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
209static const struct rtc_class_ops max6902_rtc_ops = {
210	.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 = {
262		.name 	= "max6902",
263		.bus	= &spi_bus_type,
264		.owner	= THIS_MODULE,
265	},
266	.probe 	= max6902_probe,
267	.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");
286