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rtc-m48t86.c
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rtc-m48t86.c
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/*
* ST M48T86 / Dallas DS12887 RTC driver
* Copyright (c) 2006 Tower Technologies
*
* Author: Alessandro Zummo <[email protected]>
*
* 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.
*
* This drivers only supports the clock running in BCD and 24H mode.
* If it will be ever adapted to binary and 12H mode, care must be taken
* to not introduce bugs.
*/
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/m48t86.h>
#include <linux/bcd.h>
#define M48T86_REG_SEC 0x00
#define M48T86_REG_SECALRM 0x01
#define M48T86_REG_MIN 0x02
#define M48T86_REG_MINALRM 0x03
#define M48T86_REG_HOUR 0x04
#define M48T86_REG_HOURALRM 0x05
#define M48T86_REG_DOW 0x06 /* 1 = sunday */
#define M48T86_REG_DOM 0x07
#define M48T86_REG_MONTH 0x08 /* 1 - 12 */
#define M48T86_REG_YEAR 0x09 /* 0 - 99 */
#define M48T86_REG_A 0x0A
#define M48T86_REG_B 0x0B
#define M48T86_REG_C 0x0C
#define M48T86_REG_D 0x0D
#define M48T86_REG_B_H24 (1 << 1)
#define M48T86_REG_B_DM (1 << 2)
#define M48T86_REG_B_SET (1 << 7)
#define M48T86_REG_D_VRT (1 << 7)
#define DRV_VERSION "0.1"
static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
unsigned char reg;
struct platform_device *pdev = to_platform_device(dev);
struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
reg = ops->readbyte(M48T86_REG_B);
if (reg & M48T86_REG_B_DM) {
/* data (binary) mode */
tm->tm_sec = ops->readbyte(M48T86_REG_SEC);
tm->tm_min = ops->readbyte(M48T86_REG_MIN);
tm->tm_hour = ops->readbyte(M48T86_REG_HOUR) & 0x3F;
tm->tm_mday = ops->readbyte(M48T86_REG_DOM);
/* tm_mon is 0-11 */
tm->tm_mon = ops->readbyte(M48T86_REG_MONTH) - 1;
tm->tm_year = ops->readbyte(M48T86_REG_YEAR) + 100;
tm->tm_wday = ops->readbyte(M48T86_REG_DOW);
} else {
/* bcd mode */
tm->tm_sec = bcd2bin(ops->readbyte(M48T86_REG_SEC));
tm->tm_min = bcd2bin(ops->readbyte(M48T86_REG_MIN));
tm->tm_hour = bcd2bin(ops->readbyte(M48T86_REG_HOUR) & 0x3F);
tm->tm_mday = bcd2bin(ops->readbyte(M48T86_REG_DOM));
/* tm_mon is 0-11 */
tm->tm_mon = bcd2bin(ops->readbyte(M48T86_REG_MONTH)) - 1;
tm->tm_year = bcd2bin(ops->readbyte(M48T86_REG_YEAR)) + 100;
tm->tm_wday = bcd2bin(ops->readbyte(M48T86_REG_DOW));
}
/* correct the hour if the clock is in 12h mode */
if (!(reg & M48T86_REG_B_H24))
if (ops->readbyte(M48T86_REG_HOUR) & 0x80)
tm->tm_hour += 12;
return rtc_valid_tm(tm);
}
static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
unsigned char reg;
struct platform_device *pdev = to_platform_device(dev);
struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
reg = ops->readbyte(M48T86_REG_B);
/* update flag and 24h mode */
reg |= M48T86_REG_B_SET | M48T86_REG_B_H24;
ops->writebyte(reg, M48T86_REG_B);
if (reg & M48T86_REG_B_DM) {
/* data (binary) mode */
ops->writebyte(tm->tm_sec, M48T86_REG_SEC);
ops->writebyte(tm->tm_min, M48T86_REG_MIN);
ops->writebyte(tm->tm_hour, M48T86_REG_HOUR);
ops->writebyte(tm->tm_mday, M48T86_REG_DOM);
ops->writebyte(tm->tm_mon + 1, M48T86_REG_MONTH);
ops->writebyte(tm->tm_year % 100, M48T86_REG_YEAR);
ops->writebyte(tm->tm_wday, M48T86_REG_DOW);
} else {
/* bcd mode */
ops->writebyte(bin2bcd(tm->tm_sec), M48T86_REG_SEC);
ops->writebyte(bin2bcd(tm->tm_min), M48T86_REG_MIN);
ops->writebyte(bin2bcd(tm->tm_hour), M48T86_REG_HOUR);
ops->writebyte(bin2bcd(tm->tm_mday), M48T86_REG_DOM);
ops->writebyte(bin2bcd(tm->tm_mon + 1), M48T86_REG_MONTH);
ops->writebyte(bin2bcd(tm->tm_year % 100), M48T86_REG_YEAR);
ops->writebyte(bin2bcd(tm->tm_wday), M48T86_REG_DOW);
}
/* update ended */
reg &= ~M48T86_REG_B_SET;
ops->writebyte(reg, M48T86_REG_B);
return 0;
}
static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
{
unsigned char reg;
struct platform_device *pdev = to_platform_device(dev);
struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
reg = ops->readbyte(M48T86_REG_B);
seq_printf(seq, "mode\t\t: %s\n",
(reg & M48T86_REG_B_DM) ? "binary" : "bcd");
reg = ops->readbyte(M48T86_REG_D);
seq_printf(seq, "battery\t\t: %s\n",
(reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
return 0;
}
static const struct rtc_class_ops m48t86_rtc_ops = {
.read_time = m48t86_rtc_read_time,
.set_time = m48t86_rtc_set_time,
.proc = m48t86_rtc_proc,
};
static int m48t86_rtc_probe(struct platform_device *dev)
{
unsigned char reg;
struct m48t86_ops *ops = dev_get_platdata(&dev->dev);
struct rtc_device *rtc;
rtc = devm_rtc_device_register(&dev->dev, "m48t86",
&m48t86_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
platform_set_drvdata(dev, rtc);
/* read battery status */
reg = ops->readbyte(M48T86_REG_D);
dev_info(&dev->dev, "battery %s\n",
(reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
return 0;
}
static struct platform_driver m48t86_rtc_platform_driver = {
.driver = {
.name = "rtc-m48t86",
},
.probe = m48t86_rtc_probe,
};
module_platform_driver(m48t86_rtc_platform_driver);
MODULE_AUTHOR("Alessandro Zummo <[email protected]>");
MODULE_DESCRIPTION("M48T86 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
MODULE_ALIAS("platform:rtc-m48t86");