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// SPDX-License-Identifier: GPL-2.0-only
/*
* Dallas DS1216 RTC driver
*
* Copyright (c) 2007 Thomas Bogendoerfer
*
*/
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/bcd.h>
#include <linux/slab.h>
struct ds1216_regs {
u8 tsec;
u8 sec;
u8 min;
u8 hour;
u8 wday;
u8 mday;
u8 month;
u8 year;
};
#define DS1216_HOUR_1224 (1 << 7)
#define DS1216_HOUR_AMPM (1 << 5)
struct ds1216_priv {
struct rtc_device *rtc;
void __iomem *ioaddr;
};
static const u8 magic[] = {
0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c
};
/*
* Read the 64 bit we'd like to have - It a series
* of 64 bits showing up in the LSB of the base register.
*
*/
static void ds1216_read(u8 __iomem *ioaddr, u8 *buf)
{
unsigned char c;
int i, j;
for (i = 0; i < 8; i++) {
c = 0;
for (j = 0; j < 8; j++)
c |= (readb(ioaddr) & 0x1) << j;
buf[i] = c;
}
}
static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf)
{
unsigned char c;
int i, j;
for (i = 0; i < 8; i++) {
c = buf[i];
for (j = 0; j < 8; j++) {
writeb(c, ioaddr);
c = c >> 1;
}
}
}
static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr)
{
/* Reset magic pointer */
readb(ioaddr);
/* Write 64 bit magic to DS1216 */
ds1216_write(ioaddr, magic);
}
static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct ds1216_priv *priv = dev_get_drvdata(dev);
struct ds1216_regs regs;
ds1216_switch_ds_to_clock(priv->ioaddr);
ds1216_read(priv->ioaddr, (u8 *)®s);
tm->tm_sec = bcd2bin(regs.sec);
tm->tm_min = bcd2bin(regs.min);
if (regs.hour & DS1216_HOUR_1224) {
/* AM/PM mode */
tm->tm_hour = bcd2bin(regs.hour & 0x1f);
if (regs.hour & DS1216_HOUR_AMPM)
tm->tm_hour += 12;
} else
tm->tm_hour = bcd2bin(regs.hour & 0x3f);
tm->tm_wday = (regs.wday & 7) - 1;
tm->tm_mday = bcd2bin(regs.mday & 0x3f);
tm->tm_mon = bcd2bin(regs.month & 0x1f);
tm->tm_year = bcd2bin(regs.year);
if (tm->tm_year < 70)
tm->tm_year += 100;
return 0;
}
static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct ds1216_priv *priv = dev_get_drvdata(dev);
struct ds1216_regs regs;
ds1216_switch_ds_to_clock(priv->ioaddr);
ds1216_read(priv->ioaddr, (u8 *)®s);
regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
regs.sec = bin2bcd(tm->tm_sec);
regs.min = bin2bcd(tm->tm_min);
regs.hour &= DS1216_HOUR_1224;
if (regs.hour && tm->tm_hour > 12) {
regs.hour |= DS1216_HOUR_AMPM;
tm->tm_hour -= 12;
}
regs.hour |= bin2bcd(tm->tm_hour);
regs.wday &= ~7;
regs.wday |= tm->tm_wday;
regs.mday = bin2bcd(tm->tm_mday);
regs.month = bin2bcd(tm->tm_mon);
regs.year = bin2bcd(tm->tm_year % 100);
ds1216_switch_ds_to_clock(priv->ioaddr);
ds1216_write(priv->ioaddr, (u8 *)®s);
return 0;
}
static const struct rtc_class_ops ds1216_rtc_ops = {
.read_time = ds1216_rtc_read_time,
.set_time = ds1216_rtc_set_time,
};
static int __init ds1216_rtc_probe(struct platform_device *pdev)
{
struct resource *res;
struct ds1216_priv *priv;
u8 dummy[8];
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
platform_set_drvdata(pdev, priv);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
priv->ioaddr = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(priv->ioaddr))
return PTR_ERR(priv->ioaddr);
priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216",
&ds1216_rtc_ops, THIS_MODULE);
if (IS_ERR(priv->rtc))
return PTR_ERR(priv->rtc);
/* dummy read to get clock into a known state */
ds1216_read(priv->ioaddr, dummy);
return 0;
}
static struct platform_driver ds1216_rtc_platform_driver = {
.driver = {
.name = "rtc-ds1216",
},
};
module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe);
MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
MODULE_DESCRIPTION("DS1216 RTC driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rtc-ds1216");
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