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
74static 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
87static 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 */
102static 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	err = rtc_valid_tm(tm);
176	if (err < 0)
177		dev_err(dev, "retrieved date/time is not valid.\n");
178
179	return err;
180}
181
182static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm)
183{
184	struct spi_device *spi = to_spi_device(dev);
185	int err;
186	unsigned char buf[8], data;
187
188	dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
189		"mday=%d, mon=%d, year=%d, wday=%d\n",
190		__func__,
191		tm->tm_sec, tm->tm_min, tm->tm_hour,
192		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
193
194	buf[0] = 0x00;
195	/* hours, minutes and seconds */
196	buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec);
197	buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min);
198	buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour);
199
200	buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday);
201
202	/* month, 1 - 12 */
203	buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1);
204
205	/* year and century */
206	buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100);
207	buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday);
208
209	/* Stop the clock */
210	err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
211	if (err != 0) {
212		dev_err(dev, "Unable to read control register\n");
213		return -EIO;
214	}
215
216	err = rx4581_set_reg(dev, RX4581_REG_CTRL,
217		(data | RX4581_CTRL_STOP));
218	if (err != 0) {
219		dev_err(dev, "Unable to write control register\n");
220		return -EIO;
221	}
222
223	/* write register's data */
224	err = spi_write_then_read(spi, buf, 8, NULL, 0);
225	if (err != 0) {
226		dev_err(dev, "Unable to write to date registers\n");
227		return -EIO;
228	}
229
230	/* get VLF and clear it */
231	err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
232	if (err != 0) {
233		dev_err(dev, "Unable to read flag register\n");
234		return -EIO;
235	}
236
237	err = rx4581_set_reg(dev, RX4581_REG_FLAG,
238		(data & ~(RX4581_FLAG_VLF)));
239	if (err != 0) {
240		dev_err(dev, "Unable to write flag register\n");
241		return -EIO;
242	}
243
244	/* Restart the clock */
245	err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
246	if (err != 0) {
247		dev_err(dev, "Unable to read control register\n");
248		return -EIO;
249	}
250
251	err = rx4581_set_reg(dev, RX4581_REG_CTRL,
252		(data & ~(RX4581_CTRL_STOP)));
253	if (err != 0) {
254		dev_err(dev, "Unable to write control register\n");
255		return -EIO;
256	}
257
258	return 0;
259}
260
261static const struct rtc_class_ops rx4581_rtc_ops = {
262	.read_time	= rx4581_get_datetime,
263	.set_time	= rx4581_set_datetime,
264};
265
266static int rx4581_probe(struct spi_device *spi)
267{
268	struct rtc_device *rtc;
269	unsigned char tmp;
270	int res;
271
272	res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp);
273	if (res != 0)
274		return res;
275
276	rtc = devm_rtc_device_register(&spi->dev, "rx4581",
277				&rx4581_rtc_ops, THIS_MODULE);
278	if (IS_ERR(rtc))
279		return PTR_ERR(rtc);
280
281	spi_set_drvdata(spi, rtc);
282	return 0;
283}
284
285static const struct spi_device_id rx4581_id[] = {
286	{ "rx4581", 0 },
287	{ }
288};
289MODULE_DEVICE_TABLE(spi, rx4581_id);
290
291static struct spi_driver rx4581_driver = {
292	.driver = {
293		.name	= "rtc-rx4581",
294		.owner	= THIS_MODULE,
295	},
296	.probe	= rx4581_probe,
297	.id_table = rx4581_id,
298};
299
300module_spi_driver(rx4581_driver);
301
302MODULE_DESCRIPTION("rx4581 spi RTC driver");
303MODULE_AUTHOR("Torben Hohn");
304MODULE_LICENSE("GPL");
305MODULE_ALIAS("spi:rtc-rx4581");
306