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// SPDX-License-Identifier: GPL-2.0-only
/*
* An rtc driver for the Dallas DS1742
*
* Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
*
* Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk>
* - nvram size determined from resource
* - this ds1742 driver now supports ds1743.
*/
#include <linux/bcd.h>
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/rtc.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/module.h>
#define RTC_SIZE 8
#define RTC_CONTROL 0
#define RTC_CENTURY 0
#define RTC_SECONDS 1
#define RTC_MINUTES 2
#define RTC_HOURS 3
#define RTC_DAY 4
#define RTC_DATE 5
#define RTC_MONTH 6
#define RTC_YEAR 7
#define RTC_CENTURY_MASK 0x3f
#define RTC_SECONDS_MASK 0x7f
#define RTC_DAY_MASK 0x07
/* Bits in the Control/Century register */
#define RTC_WRITE 0x80
#define RTC_READ 0x40
/* Bits in the Seconds register */
#define RTC_STOP 0x80
/* Bits in the Day register */
#define RTC_BATT_FLAG 0x80
struct rtc_plat_data {
void __iomem *ioaddr_nvram;
void __iomem *ioaddr_rtc;
unsigned long last_jiffies;
};
static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct rtc_plat_data *pdata = dev_get_drvdata(dev);
void __iomem *ioaddr = pdata->ioaddr_rtc;
u8 century;
century = bin2bcd((tm->tm_year + 1900) / 100);
writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
/* RTC_CENTURY and RTC_CONTROL share same register */
writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
return 0;
}
static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct rtc_plat_data *pdata = dev_get_drvdata(dev);
void __iomem *ioaddr = pdata->ioaddr_rtc;
unsigned int year, month, day, hour, minute, second, week;
unsigned int century;
/* give enough time to update RTC in case of continuous read */
if (pdata->last_jiffies == jiffies)
msleep(1);
pdata->last_jiffies = jiffies;
writeb(RTC_READ, ioaddr + RTC_CONTROL);
second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
minute = readb(ioaddr + RTC_MINUTES);
hour = readb(ioaddr + RTC_HOURS);
day = readb(ioaddr + RTC_DATE);
week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
month = readb(ioaddr + RTC_MONTH);
year = readb(ioaddr + RTC_YEAR);
century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
writeb(0, ioaddr + RTC_CONTROL);
tm->tm_sec = bcd2bin(second);
tm->tm_min = bcd2bin(minute);
tm->tm_hour = bcd2bin(hour);
tm->tm_mday = bcd2bin(day);
tm->tm_wday = bcd2bin(week);
tm->tm_mon = bcd2bin(month) - 1;
/* year is 1900 + tm->tm_year */
tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
return 0;
}
static const struct rtc_class_ops ds1742_rtc_ops = {
.read_time = ds1742_rtc_read_time,
.set_time = ds1742_rtc_set_time,
};
static int ds1742_nvram_read(void *priv, unsigned int pos, void *val,
size_t bytes)
{
struct rtc_plat_data *pdata = priv;
void __iomem *ioaddr = pdata->ioaddr_nvram;
u8 *buf = val;
for (; bytes; bytes--)
*buf++ = readb(ioaddr + pos++);
return 0;
}
static int ds1742_nvram_write(void *priv, unsigned int pos, void *val,
size_t bytes)
{
struct rtc_plat_data *pdata = priv;
void __iomem *ioaddr = pdata->ioaddr_nvram;
u8 *buf = val;
for (; bytes; bytes--)
writeb(*buf++, ioaddr + pos++);
return 0;
}
static int ds1742_rtc_probe(struct platform_device *pdev)
{
struct rtc_device *rtc;
struct resource *res;
unsigned int cen, sec;
struct rtc_plat_data *pdata;
void __iomem *ioaddr;
int ret = 0;
struct nvmem_config nvmem_cfg = {
.name = "ds1742_nvram",
.reg_read = ds1742_nvram_read,
.reg_write = ds1742_nvram_write,
};
pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return -ENOMEM;
ioaddr = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
if (IS_ERR(ioaddr))
return PTR_ERR(ioaddr);
pdata->ioaddr_nvram = ioaddr;
pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE;
nvmem_cfg.size = resource_size(res) - RTC_SIZE;
nvmem_cfg.priv = pdata;
/* turn RTC on if it was not on */
ioaddr = pdata->ioaddr_rtc;
sec = readb(ioaddr + RTC_SECONDS);
if (sec & RTC_STOP) {
sec &= RTC_SECONDS_MASK;
cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
writeb(sec, ioaddr + RTC_SECONDS);
writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
}
if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
dev_warn(&pdev->dev, "voltage-low detected.\n");
pdata->last_jiffies = jiffies;
platform_set_drvdata(pdev, pdata);
rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
rtc->ops = &ds1742_rtc_ops;
ret = devm_rtc_register_device(rtc);
if (ret)
return ret;
devm_rtc_nvmem_register(rtc, &nvmem_cfg);
return 0;
}
static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {
{ .compatible = "maxim,ds1742", },
{ }
};
MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);
static struct platform_driver ds1742_rtc_driver = {
.probe = ds1742_rtc_probe,
.driver = {
.name = "rtc-ds1742",
.of_match_table = of_match_ptr(ds1742_rtc_of_match),
},
};
module_platform_driver(ds1742_rtc_driver);
MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rtc-ds1742");
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