1/*
  2 * Driver for Epson RTC-9701JE
  3 *
  4 * Copyright (C) 2008 Magnus Damm
  5 *
  6 * Based on 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
 16#include <linux/module.h>
 17#include <linux/kernel.h>
 18#include <linux/platform_device.h>
 19#include <linux/device.h>
 20#include <linux/init.h>
 21#include <linux/rtc.h>
 22#include <linux/spi/spi.h>
 23#include <linux/bcd.h>
 24#include <linux/delay.h>
 25#include <linux/bitops.h>
 26
 27#define RSECCNT	0x00	/* Second Counter */
 28#define RMINCNT	0x01	/* Minute Counter */
 29#define RHRCNT	0x02	/* Hour Counter */
 30#define RWKCNT	0x03	/* Week Counter */
 31#define RDAYCNT	0x04	/* Day Counter */
 32#define RMONCNT	0x05	/* Month Counter */
 33#define RYRCNT	0x06	/* Year Counter */
 34#define R100CNT	0x07	/* Y100 Counter */
 35#define RMINAR	0x08	/* Minute Alarm */
 36#define RHRAR	0x09	/* Hour Alarm */
 37#define RWKAR	0x0a	/* Week/Day Alarm */
 38#define RTIMCNT	0x0c	/* Interval Timer */
 39#define REXT	0x0d	/* Extension Register */
 40#define RFLAG	0x0e	/* RTC Flag Register */
 41#define RCR	0x0f	/* RTC Control Register */
 42
 43static int write_reg(struct device *dev, int address, unsigned char data)
 44{
 45	struct spi_device *spi = to_spi_device(dev);
 46	unsigned char buf[2];
 47
 48	buf[0] = address & 0x7f;
 49	buf[1] = data;
 50
 51	return spi_write(spi, buf, ARRAY_SIZE(buf));
 52}
 53
 54static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
 55{
 56	struct spi_device *spi = to_spi_device(dev);
 57	u8 txbuf[1], rxbuf[1];
 58	int k, ret;
 59
 60	ret = 0;
 61
 62	for (k = 0; ret == 0 && k < no_regs; k++) {
 63		txbuf[0] = 0x80 | regs[k];
 64		ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
 65		regs[k] = rxbuf[0];
 66	}
 67
 68	return ret;
 69}
 70
 71static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
 72{
 73	int ret;
 74	unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
 75				RDAYCNT, RMONCNT, RYRCNT };
 76
 77	ret = read_regs(dev, buf, ARRAY_SIZE(buf));
 78	if (ret)
 79		return ret;
 80
 81	memset(dt, 0, sizeof(*dt));
 82
 83	dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */
 84	dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */
 85	dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */
 86
 87	dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */
 88	dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */
 89	dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */
 90
 91	/* the rtc device may contain illegal values on power up
 92	 * according to the data sheet. make sure they are valid.
 93	 */
 94
 95	return rtc_valid_tm(dt);
 96}
 97
 98static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
 99{
100	int ret, year;
101
102	year = dt->tm_year + 1900;
103	if (year >= 2100 || year < 2000)
104		return -EINVAL;
105
106	ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour));
107	ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min));
108	ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
109	ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday));
110	ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1));
111	ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100));
112	ret = ret ? ret : write_reg(dev, RWKCNT, 1 << dt->tm_wday);
113
114	return ret;
115}
116
117static const struct rtc_class_ops r9701_rtc_ops = {
118	.read_time	= r9701_get_datetime,
119	.set_time	= r9701_set_datetime,
120};
121
122static int r9701_probe(struct spi_device *spi)
123{
124	struct rtc_device *rtc;
125	struct rtc_time dt;
126	unsigned char tmp;
127	int res;
128
129	tmp = R100CNT;
130	res = read_regs(&spi->dev, &tmp, 1);
131	if (res || tmp != 0x20) {
132		dev_err(&spi->dev, "cannot read RTC register\n");
133		return -ENODEV;
134	}
135
136	/*
137	 * The device seems to be present. Now check if the registers
138	 * contain invalid values. If so, try to write a default date:
139	 * 2000/1/1 00:00:00
140	 */
141	if (r9701_get_datetime(&spi->dev, &dt)) {
142		dev_info(&spi->dev, "trying to repair invalid date/time\n");
143		dt.tm_sec  = 0;
144		dt.tm_min  = 0;
145		dt.tm_hour = 0;
146		dt.tm_mday = 1;
147		dt.tm_mon  = 0;
148		dt.tm_year = 100;
149
150		if (r9701_set_datetime(&spi->dev, &dt) ||
151				r9701_get_datetime(&spi->dev, &dt)) {
152			dev_err(&spi->dev, "cannot repair RTC register\n");
153			return -ENODEV;
154		}
155	}
156
157	rtc = devm_rtc_device_register(&spi->dev, "r9701",
158				&r9701_rtc_ops, THIS_MODULE);
159	if (IS_ERR(rtc))
160		return PTR_ERR(rtc);
161
162	spi_set_drvdata(spi, rtc);
163
164	return 0;
165}
166
167static int r9701_remove(struct spi_device *spi)
168{
169	return 0;
170}
171
172static struct spi_driver r9701_driver = {
173	.driver = {
174		.name	= "rtc-r9701",
175		.owner	= THIS_MODULE,
176	},
177	.probe	= r9701_probe,
178	.remove = r9701_remove,
179};
180
181module_spi_driver(r9701_driver);
182
183MODULE_DESCRIPTION("r9701 spi RTC driver");
184MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
185MODULE_LICENSE("GPL");
186MODULE_ALIAS("spi:rtc-r9701");