rtc-r9701.c
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/*
* Driver for Epson RTC-9701JE
*
* Copyright (C) 2008 Magnus Damm
*
* Based on rtc-max6902.c
*
* Copyright (C) 2006 8D Technologies inc.
* Copyright (C) 2004 Compulab Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#define RSECCNT 0x00 /* Second Counter */
#define RMINCNT 0x01 /* Minute Counter */
#define RHRCNT 0x02 /* Hour Counter */
#define RWKCNT 0x03 /* Week Counter */
#define RDAYCNT 0x04 /* Day Counter */
#define RMONCNT 0x05 /* Month Counter */
#define RYRCNT 0x06 /* Year Counter */
#define R100CNT 0x07 /* Y100 Counter */
#define RMINAR 0x08 /* Minute Alarm */
#define RHRAR 0x09 /* Hour Alarm */
#define RWKAR 0x0a /* Week/Day Alarm */
#define RTIMCNT 0x0c /* Interval Timer */
#define REXT 0x0d /* Extension Register */
#define RFLAG 0x0e /* RTC Flag Register */
#define RCR 0x0f /* RTC Control Register */
static int write_reg(struct device *dev, int address, unsigned char data)
{
struct spi_device *spi = to_spi_device(dev);
unsigned char buf[2];
buf[0] = address & 0x7f;
buf[1] = data;
return spi_write(spi, buf, ARRAY_SIZE(buf));
}
static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
{
struct spi_device *spi = to_spi_device(dev);
u8 txbuf[1], rxbuf[1];
int k, ret;
ret = 0;
for (k = 0; ret == 0 && k < no_regs; k++) {
txbuf[0] = 0x80 | regs[k];
ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
regs[k] = rxbuf[0];
}
return ret;
}
static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
{
int ret;
unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
RDAYCNT, RMONCNT, RYRCNT };
ret = read_regs(dev, buf, ARRAY_SIZE(buf));
if (ret)
return ret;
memset(dt, 0, sizeof(*dt));
dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */
dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */
dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */
dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */
dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */
dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */
/* the rtc device may contain illegal values on power up
* according to the data sheet. make sure they are valid.
*/
return rtc_valid_tm(dt);
}
static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
{
int ret, year;
year = dt->tm_year + 1900;
if (year >= 2100 || year < 2000)
return -EINVAL;
ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour));
ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min));
ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday));
ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1));
ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100));
ret = ret ? ret : write_reg(dev, RWKCNT, 1 << dt->tm_wday);
return ret;
}
static const struct rtc_class_ops r9701_rtc_ops = {
.read_time = r9701_get_datetime,
.set_time = r9701_set_datetime,
};
static int r9701_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
struct rtc_time dt;
unsigned char tmp;
int res;
tmp = R100CNT;
res = read_regs(&spi->dev, &tmp, 1);
if (res || tmp != 0x20) {
dev_err(&spi->dev, "cannot read RTC register\n");
return -ENODEV;
}
/*
* The device seems to be present. Now check if the registers
* contain invalid values. If so, try to write a default date:
* 2000/1/1 00:00:00
*/
if (r9701_get_datetime(&spi->dev, &dt)) {
dev_info(&spi->dev, "trying to repair invalid date/time\n");
dt.tm_sec = 0;
dt.tm_min = 0;
dt.tm_hour = 0;
dt.tm_mday = 1;
dt.tm_mon = 0;
dt.tm_year = 100;
if (r9701_set_datetime(&spi->dev, &dt) ||
r9701_get_datetime(&spi->dev, &dt)) {
dev_err(&spi->dev, "cannot repair RTC register\n");
return -ENODEV;
}
}
rtc = devm_rtc_device_register(&spi->dev, "r9701",
&r9701_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
spi_set_drvdata(spi, rtc);
return 0;
}
static int r9701_remove(struct spi_device *spi)
{
return 0;
}
static struct spi_driver r9701_driver = {
.driver = {
.name = "rtc-r9701",
.owner = THIS_MODULE,
},
.probe = r9701_probe,
.remove = r9701_remove,
};
module_spi_driver(r9701_driver);
MODULE_DESCRIPTION("r9701 spi RTC driver");
MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:rtc-r9701");