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linux/drivers/rtc/rtc-ds1553.c
Alexandre Belloni 7d1bd37ff0 rtc: ds1553: let the core handle invalid time 
Returning a valid time when the time is invalid is a bad practice, because
then userspace is not able to react on the information. Also, it doesn't
make sense to return epoch because it is already the default time.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2018-03-01 10:49:39 +01:00

344 lines
9.7 KiB
C
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/*
* An rtc driver for the Dallas DS1553
*
* Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
*
* 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/bcd.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/module.h>
#define RTC_REG_SIZE 0x2000
#define RTC_OFFSET 0x1ff0
#define RTC_FLAGS (RTC_OFFSET + 0)
#define RTC_SECONDS_ALARM (RTC_OFFSET + 2)
#define RTC_MINUTES_ALARM (RTC_OFFSET + 3)
#define RTC_HOURS_ALARM (RTC_OFFSET + 4)
#define RTC_DATE_ALARM (RTC_OFFSET + 5)
#define RTC_INTERRUPTS (RTC_OFFSET + 6)
#define RTC_WATCHDOG (RTC_OFFSET + 7)
#define RTC_CONTROL (RTC_OFFSET + 8)
#define RTC_CENTURY (RTC_OFFSET + 8)
#define RTC_SECONDS (RTC_OFFSET + 9)
#define RTC_MINUTES (RTC_OFFSET + 10)
#define RTC_HOURS (RTC_OFFSET + 11)
#define RTC_DAY (RTC_OFFSET + 12)
#define RTC_DATE (RTC_OFFSET + 13)
#define RTC_MONTH (RTC_OFFSET + 14)
#define RTC_YEAR (RTC_OFFSET + 15)
#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 Flags register */
#define RTC_FLAGS_AF 0x40
#define RTC_FLAGS_BLF 0x10
/* Bits in the Interrupts register */
#define RTC_INTS_AE 0x80
struct rtc_plat_data {
struct rtc_device *rtc;
void __iomem *ioaddr;
unsigned long last_jiffies;
int irq;
unsigned int irqen;
int alrm_sec;
int alrm_min;
int alrm_hour;
int alrm_mday;
spinlock_t lock;
};
static int ds1553_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
u8 century;
century = bin2bcd((tm->tm_year + 1900) / 100);
writeb(RTC_WRITE, pdata->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 ds1553_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
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 void ds1553_rtc_update_alarm(struct rtc_plat_data *pdata)
{
void __iomem *ioaddr = pdata->ioaddr;
unsigned long flags;
spin_lock_irqsave(&pdata->lock, flags);
writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
0x80 : bin2bcd(pdata->alrm_mday),
ioaddr + RTC_DATE_ALARM);
writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
0x80 : bin2bcd(pdata->alrm_hour),
ioaddr + RTC_HOURS_ALARM);
writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
0x80 : bin2bcd(pdata->alrm_min),
ioaddr + RTC_MINUTES_ALARM);
writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
0x80 : bin2bcd(pdata->alrm_sec),
ioaddr + RTC_SECONDS_ALARM);
writeb(pdata->irqen ? RTC_INTS_AE : 0, ioaddr + RTC_INTERRUPTS);
readb(ioaddr + RTC_FLAGS); /* clear interrupts */
spin_unlock_irqrestore(&pdata->lock, flags);
}
static int ds1553_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
if (pdata->irq <= 0)
return -EINVAL;
pdata->alrm_mday = alrm->time.tm_mday;
pdata->alrm_hour = alrm->time.tm_hour;
pdata->alrm_min = alrm->time.tm_min;
pdata->alrm_sec = alrm->time.tm_sec;
if (alrm->enabled)
pdata->irqen |= RTC_AF;
ds1553_rtc_update_alarm(pdata);
return 0;
}
static int ds1553_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
if (pdata->irq <= 0)
return -EINVAL;
alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
return 0;
}
static irqreturn_t ds1553_rtc_interrupt(int irq, void *dev_id)
{
struct platform_device *pdev = dev_id;
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
unsigned long events = 0;
spin_lock(&pdata->lock);
/* read and clear interrupt */
if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
events = RTC_IRQF;
if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
events |= RTC_UF;
else
events |= RTC_AF;
rtc_update_irq(pdata->rtc, 1, events);
}
spin_unlock(&pdata->lock);
return events ? IRQ_HANDLED : IRQ_NONE;
}
static int ds1553_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
if (pdata->irq <= 0)
return -EINVAL;
if (enabled)
pdata->irqen |= RTC_AF;
else
pdata->irqen &= ~RTC_AF;
ds1553_rtc_update_alarm(pdata);
return 0;
}
static const struct rtc_class_ops ds1553_rtc_ops = {
.read_time = ds1553_rtc_read_time,
.set_time = ds1553_rtc_set_time,
.read_alarm = ds1553_rtc_read_alarm,
.set_alarm = ds1553_rtc_set_alarm,
.alarm_irq_enable = ds1553_rtc_alarm_irq_enable,
};
static int ds1553_nvram_read(void *priv, unsigned int pos, void *val,
size_t bytes)
{
struct platform_device *pdev = priv;
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
u8 *buf = val;
for (; bytes; bytes--)
*buf++ = readb(ioaddr + pos++);
return 0;
}
static int ds1553_nvram_write(void *priv, unsigned int pos, void *val,
size_t bytes)
{
struct platform_device *pdev = priv;
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
u8 *buf = val;
for (; bytes; bytes--)
writeb(*buf++, ioaddr + pos++);
return 0;
}
static int ds1553_rtc_probe(struct platform_device *pdev)
{
struct resource *res;
unsigned int cen, sec;
struct rtc_plat_data *pdata;
void __iomem *ioaddr;
int ret = 0;
struct nvmem_config nvmem_cfg = {
.name = "ds1553_nvram",
.word_size = 1,
.stride = 1,
.size = RTC_OFFSET,
.reg_read = ds1553_nvram_read,
.reg_write = ds1553_nvram_write,
.priv = pdev,
};
pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
ioaddr = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(ioaddr))
return PTR_ERR(ioaddr);
pdata->ioaddr = ioaddr;
pdata->irq = platform_get_irq(pdev, 0);
/* turn RTC on if it was not on */
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_FLAGS) & RTC_FLAGS_BLF)
dev_warn(&pdev->dev, "voltage-low detected.\n");
spin_lock_init(&pdata->lock);
pdata->last_jiffies = jiffies;
platform_set_drvdata(pdev, pdata);
pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(pdata->rtc))
return PTR_ERR(pdata->rtc);
pdata->rtc->ops = &ds1553_rtc_ops;
pdata->rtc->nvram_old_abi = true;
ret = rtc_register_device(pdata->rtc);
if (ret)
return ret;
if (pdata->irq > 0) {
writeb(0, ioaddr + RTC_INTERRUPTS);
if (devm_request_irq(&pdev->dev, pdata->irq,
ds1553_rtc_interrupt,
0, pdev->name, pdev) < 0) {
dev_warn(&pdev->dev, "interrupt not available.\n");
pdata->irq = 0;
}
}
if (rtc_nvmem_register(pdata->rtc, &nvmem_cfg))
dev_err(&pdev->dev, "unable to register nvmem\n");
return 0;
}
/* work with hotplug and coldplug */
MODULE_ALIAS("platform:rtc-ds1553");
static struct platform_driver ds1553_rtc_driver = {
.probe = ds1553_rtc_probe,
.driver = {
.name = "rtc-ds1553",
},
};
module_platform_driver(ds1553_rtc_driver);
MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
MODULE_DESCRIPTION("Dallas DS1553 RTC driver");
MODULE_LICENSE("GPL");
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