1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Driver for Epson RTC-9701JE
  4 *
  5 * Copyright (C) 2008 Magnus Damm
  6 *
  7 * Based on rtc-max6902.c
  8 *
  9 * Copyright (C) 2006 8D Technologies inc.
 10 * Copyright (C) 2004 Compulab Ltd.
 11 */
 12
 13#include <linux/module.h>
 14#include <linux/kernel.h>
 15#include <linux/platform_device.h>
 16#include <linux/device.h>
 17#include <linux/init.h>
 18#include <linux/rtc.h>
 19#include <linux/spi/spi.h>
 20#include <linux/bcd.h>
 21#include <linux/delay.h>
 22#include <linux/bitops.h>
 23
 24#define RSECCNT	0x00	/* Second Counter */
 25#define RMINCNT	0x01	/* Minute Counter */
 26#define RHRCNT	0x02	/* Hour Counter */
 27#define RWKCNT	0x03	/* Week Counter */
 28#define RDAYCNT	0x04	/* Day Counter */
 29#define RMONCNT	0x05	/* Month Counter */
 30#define RYRCNT	0x06	/* Year Counter */
 31#define R100CNT	0x07	/* Y100 Counter */
 32#define RMINAR	0x08	/* Minute Alarm */
 33#define RHRAR	0x09	/* Hour Alarm */
 34#define RWKAR	0x0a	/* Week/Day Alarm */
 35#define RTIMCNT	0x0c	/* Interval Timer */
 36#define REXT	0x0d	/* Extension Register */
 37#define RFLAG	0x0e	/* RTC Flag Register */
 38#define RCR	0x0f	/* RTC Control Register */
 39
 40static int write_reg(struct device *dev, int address, unsigned char data)
 41{
 42	struct spi_device *spi = to_spi_device(dev);
 43	unsigned char buf[2];
 44
 45	buf[0] = address & 0x7f;
 46	buf[1] = data;
 47
 48	return spi_write(spi, buf, ARRAY_SIZE(buf));
 49}
 50
 51static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
 52{
 53	struct spi_device *spi = to_spi_device(dev);
 54	u8 txbuf[1], rxbuf[1];
 55	int k, ret;
 56
 57	ret = 0;
 58
 59	for (k = 0; ret == 0 && k < no_regs; k++) {
 60		txbuf[0] = 0x80 | regs[k];
 61		ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
 62		regs[k] = rxbuf[0];
 63	}
 64
 65	return ret;
 66}
 67
 68static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
 69{
 70	int ret;
 71	unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
 72				RDAYCNT, RMONCNT, RYRCNT };
 73
 74	ret = read_regs(dev, buf, ARRAY_SIZE(buf));
 75	if (ret)
 76		return ret;
 77
 78	dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */
 79	dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */
 80	dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */
 81
 82	dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */
 83	dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */
 84	dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */
 85
 86	return 0;
 87}
 88
 89static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
 90{
 91	int ret;
 92
 93	ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour));
 94	ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min));
 95	ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
 96	ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday));
 97	ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1));
 98	ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100));
 99
100	return ret;
101}
102
103static const struct rtc_class_ops r9701_rtc_ops = {
104	.read_time	= r9701_get_datetime,
105	.set_time	= r9701_set_datetime,
106};
107
108static int r9701_probe(struct spi_device *spi)
109{
110	struct rtc_device *rtc;
111	unsigned char tmp;
112	int res;
113
114	tmp = R100CNT;
115	res = read_regs(&spi->dev, &tmp, 1);
116	if (res || tmp != 0x20) {
117		dev_err(&spi->dev, "cannot read RTC register\n");
118		return -ENODEV;
119	}
120
121	rtc = devm_rtc_allocate_device(&spi->dev);
122	if (IS_ERR(rtc))
123		return PTR_ERR(rtc);
124
125	spi_set_drvdata(spi, rtc);
126	rtc->ops = &r9701_rtc_ops;
127	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
128	rtc->range_max = RTC_TIMESTAMP_END_2099;
129
130	return devm_rtc_register_device(rtc);
131}
132
133static struct spi_driver r9701_driver = {
134	.driver = {
135		.name	= "rtc-r9701",
136	},
137	.probe	= r9701_probe,
138};
139
140module_spi_driver(r9701_driver);
141
142MODULE_DESCRIPTION("r9701 spi RTC driver");
143MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
144MODULE_LICENSE("GPL");
145MODULE_ALIAS("spi:rtc-r9701");