rtc: add support for ST M41T94 SPI RTC

This patch adds kernel driver for M41T94 RTC chip connected via SPI.
I've tested it on two different AT91-based hardwares.

This is third revision of the patch: some comments made by
Alessandro Zummo fixed.

Revision two added support for century bit and fixes.

Signed-off-by: Kim B. Heino <Kim.Heino@bluegiga.com>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kim B. Heino 2008-07-23 21:30:34 -07:00 коммит произвёл Linus Torvalds
Родитель 5ad31a5751
Коммит 8fc2c767b0
3 изменённых файлов: 183 добавлений и 0 удалений

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@ -273,6 +273,15 @@ comment "SPI RTC drivers"
if SPI_MASTER
config RTC_DRV_M41T94
tristate "ST M41T94"
help
If you say yes here you will get support for the
ST M41T94 SPI RTC chip.
This driver can also be built as a module. If so, the module
will be called rtc-m41t94.
config RTC_DRV_MAX6902
tristate "Maxim MAX6902"
help

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@ -34,6 +34,7 @@ obj-$(CONFIG_RTC_DRV_EP93XX) += rtc-ep93xx.o
obj-$(CONFIG_RTC_DRV_FM3130) += rtc-fm3130.o
obj-$(CONFIG_RTC_DRV_ISL1208) += rtc-isl1208.o
obj-$(CONFIG_RTC_DRV_M41T80) += rtc-m41t80.o
obj-$(CONFIG_RTC_DRV_M41T94) += rtc-m41t94.o
obj-$(CONFIG_RTC_DRV_M48T59) += rtc-m48t59.o
obj-$(CONFIG_RTC_DRV_M48T86) += rtc-m48t86.o
obj-$(CONFIG_RTC_DRV_MAX6900) += rtc-max6900.o

173
drivers/rtc/rtc-m41t94.c Normal file
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@ -0,0 +1,173 @@
/*
* Driver for ST M41T94 SPI RTC
*
* Copyright (C) 2008 Kim B. Heino
*
* 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/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#define M41T94_REG_SECONDS 0x01
#define M41T94_REG_MINUTES 0x02
#define M41T94_REG_HOURS 0x03
#define M41T94_REG_WDAY 0x04
#define M41T94_REG_DAY 0x05
#define M41T94_REG_MONTH 0x06
#define M41T94_REG_YEAR 0x07
#define M41T94_REG_HT 0x0c
#define M41T94_BIT_HALT 0x40
#define M41T94_BIT_STOP 0x80
#define M41T94_BIT_CB 0x40
#define M41T94_BIT_CEB 0x80
static int m41t94_set_time(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
u8 buf[8]; /* write cmd + 7 registers */
dev_dbg(dev, "%s secs=%d, mins=%d, "
"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
"write", tm->tm_sec, tm->tm_min,
tm->tm_hour, tm->tm_mday,
tm->tm_mon, tm->tm_year, tm->tm_wday);
buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */
buf[M41T94_REG_SECONDS] = BIN2BCD(tm->tm_sec);
buf[M41T94_REG_MINUTES] = BIN2BCD(tm->tm_min);
buf[M41T94_REG_HOURS] = BIN2BCD(tm->tm_hour);
buf[M41T94_REG_WDAY] = BIN2BCD(tm->tm_wday + 1);
buf[M41T94_REG_DAY] = BIN2BCD(tm->tm_mday);
buf[M41T94_REG_MONTH] = BIN2BCD(tm->tm_mon + 1);
buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB;
if (tm->tm_year >= 100)
buf[M41T94_REG_HOURS] |= M41T94_BIT_CB;
buf[M41T94_REG_YEAR] = BIN2BCD(tm->tm_year % 100);
return spi_write(spi, buf, 8);
}
static int m41t94_read_time(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
u8 buf[2];
int ret, hour;
/* clear halt update bit */
ret = spi_w8r8(spi, M41T94_REG_HT);
if (ret < 0)
return ret;
if (ret & M41T94_BIT_HALT) {
buf[0] = 0x80 | M41T94_REG_HT;
buf[1] = ret & ~M41T94_BIT_HALT;
spi_write(spi, buf, 2);
}
/* clear stop bit */
ret = spi_w8r8(spi, M41T94_REG_SECONDS);
if (ret < 0)
return ret;
if (ret & M41T94_BIT_STOP) {
buf[0] = 0x80 | M41T94_REG_SECONDS;
buf[1] = ret & ~M41T94_BIT_STOP;
spi_write(spi, buf, 2);
}
tm->tm_sec = BCD2BIN(spi_w8r8(spi, M41T94_REG_SECONDS));
tm->tm_min = BCD2BIN(spi_w8r8(spi, M41T94_REG_MINUTES));
hour = spi_w8r8(spi, M41T94_REG_HOURS);
tm->tm_hour = BCD2BIN(hour & 0x3f);
tm->tm_wday = BCD2BIN(spi_w8r8(spi, M41T94_REG_WDAY)) - 1;
tm->tm_mday = BCD2BIN(spi_w8r8(spi, M41T94_REG_DAY));
tm->tm_mon = BCD2BIN(spi_w8r8(spi, M41T94_REG_MONTH)) - 1;
tm->tm_year = BCD2BIN(spi_w8r8(spi, M41T94_REG_YEAR));
if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB))
tm->tm_year += 100;
dev_dbg(dev, "%s secs=%d, mins=%d, "
"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
"read", tm->tm_sec, tm->tm_min,
tm->tm_hour, tm->tm_mday,
tm->tm_mon, tm->tm_year, tm->tm_wday);
/* initial clock setting can be undefined */
return rtc_valid_tm(tm);
}
static const struct rtc_class_ops m41t94_rtc_ops = {
.read_time = m41t94_read_time,
.set_time = m41t94_set_time,
};
static struct spi_driver m41t94_driver;
static int __devinit m41t94_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
int res;
spi->bits_per_word = 8;
spi_setup(spi);
res = spi_w8r8(spi, M41T94_REG_SECONDS);
if (res < 0) {
dev_err(&spi->dev, "not found.\n");
return res;
}
rtc = rtc_device_register(m41t94_driver.driver.name,
&spi->dev, &m41t94_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
dev_set_drvdata(&spi->dev, rtc);
return 0;
}
static int __devexit m41t94_remove(struct spi_device *spi)
{
struct rtc_device *rtc = platform_get_drvdata(spi);
if (rtc)
rtc_device_unregister(rtc);
return 0;
}
static struct spi_driver m41t94_driver = {
.driver = {
.name = "rtc-m41t94",
.bus = &spi_bus_type,
.owner = THIS_MODULE,
},
.probe = m41t94_probe,
.remove = __devexit_p(m41t94_remove),
};
static __init int m41t94_init(void)
{
return spi_register_driver(&m41t94_driver);
}
module_init(m41t94_init);
static __exit void m41t94_exit(void)
{
spi_unregister_driver(&m41t94_driver);
}
module_exit(m41t94_exit);
MODULE_AUTHOR("Kim B. Heino <Kim.Heino@bluegiga.com>");
MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC");
MODULE_LICENSE("GPL");