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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
*
* Copyright (C) 2000 Silicon Graphics, Inc.
* Written by Ulf Carlsson (ulfc@engr.sgi.com)
*
* Copyright (C) 2008 Thomas Bogendoerfer
*
* Based on code written by Paul Gortmaker.
*/
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/bcd.h>
#include <linux/io.h>
#include <linux/err.h>
struct m48t35_rtc {
u8 pad[0x7ff8]; /* starts at 0x7ff8 */
u8 control;
u8 sec;
u8 min;
u8 hour;
u8 day;
u8 date;
u8 month;
u8 year;
};
#define M48T35_RTC_SET 0x80
#define M48T35_RTC_READ 0x40
struct m48t35_priv {
struct rtc_device *rtc;
struct m48t35_rtc __iomem *reg;
size_t size;
unsigned long baseaddr;
spinlock_t lock;
};
static int m48t35_read_time(struct device *dev, struct rtc_time *tm)
{
struct m48t35_priv *priv = dev_get_drvdata(dev);
u8 control;
/*
* Only the values that we read from the RTC are set. We leave
* tm_wday, tm_yday and tm_isdst untouched. Even though the
* RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
* by the RTC when initially set to a non-zero value.
*/
spin_lock_irq(&priv->lock);
control = readb(&priv->reg->control);
writeb(control | M48T35_RTC_READ, &priv->reg->control);
tm->tm_sec = readb(&priv->reg->sec);
tm->tm_min = readb(&priv->reg->min);
tm->tm_hour = readb(&priv->reg->hour);
tm->tm_mday = readb(&priv->reg->date);
tm->tm_mon = readb(&priv->reg->month);
tm->tm_year = readb(&priv->reg->year);
writeb(control, &priv->reg->control);
spin_unlock_irq(&priv->lock);
tm->tm_sec = bcd2bin(tm->tm_sec);
tm->tm_min = bcd2bin(tm->tm_min);
tm->tm_hour = bcd2bin(tm->tm_hour);
tm->tm_mday = bcd2bin(tm->tm_mday);
tm->tm_mon = bcd2bin(tm->tm_mon);
tm->tm_year = bcd2bin(tm->tm_year);
/*
* Account for differences between how the RTC uses the values
* and how they are defined in a struct rtc_time;
*/
tm->tm_year += 70;
if (tm->tm_year <= 69)
tm->tm_year += 100;
tm->tm_mon--;
return 0;
}
static int m48t35_set_time(struct device *dev, struct rtc_time *tm)
{
struct m48t35_priv *priv = dev_get_drvdata(dev);
unsigned char mon, day, hrs, min, sec;
unsigned int yrs;
u8 control;
yrs = tm->tm_year + 1900;
mon = tm->tm_mon + 1; /* tm_mon starts at zero */
day = tm->tm_mday;
hrs = tm->tm_hour;
min = tm->tm_min;
sec = tm->tm_sec;
if (yrs < 1970)
return -EINVAL;
yrs -= 1970;
if (yrs > 255) /* They are unsigned */
return -EINVAL;
if (yrs > 169)
return -EINVAL;
if (yrs >= 100)
yrs -= 100;
sec = bin2bcd(sec);
min = bin2bcd(min);
hrs = bin2bcd(hrs);
day = bin2bcd(day);
mon = bin2bcd(mon);
yrs = bin2bcd(yrs);
spin_lock_irq(&priv->lock);
control = readb(&priv->reg->control);
writeb(control | M48T35_RTC_SET, &priv->reg->control);
writeb(yrs, &priv->reg->year);
writeb(mon, &priv->reg->month);
writeb(day, &priv->reg->date);
writeb(hrs, &priv->reg->hour);
writeb(min, &priv->reg->min);
writeb(sec, &priv->reg->sec);
writeb(control, &priv->reg->control);
spin_unlock_irq(&priv->lock);
return 0;
}
static const struct rtc_class_ops m48t35_ops = {
.read_time = m48t35_read_time,
.set_time = m48t35_set_time,
};
static int m48t35_probe(struct platform_device *pdev)
{
struct resource *res;
struct m48t35_priv *priv;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
priv = devm_kzalloc(&pdev->dev, sizeof(struct m48t35_priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->size = resource_size(res);
/*
* kludge: remove the #ifndef after ioc3 resource
* conflicts are resolved
*/
#ifndef CONFIG_SGI_IP27
if (!devm_request_mem_region(&pdev->dev, res->start, priv->size,
pdev->name))
return -EBUSY;
#endif
priv->baseaddr = res->start;
priv->reg = devm_ioremap(&pdev->dev, priv->baseaddr, priv->size);
if (!priv->reg)
return -ENOMEM;
spin_lock_init(&priv->lock);
platform_set_drvdata(pdev, priv);
priv->rtc = devm_rtc_device_register(&pdev->dev, "m48t35",
&m48t35_ops, THIS_MODULE);
return PTR_ERR_OR_ZERO(priv->rtc);
}
static struct platform_driver m48t35_platform_driver = {
.driver = {
.name = "rtc-m48t35",
},
.probe = m48t35_probe,
};
module_platform_driver(m48t35_platform_driver);
MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
MODULE_DESCRIPTION("M48T35 RTC driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rtc-m48t35");
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