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// SPDX-License-Identifier: GPL-2.0-only
/*
* A RTC driver for the Simtek STK17TA8
*
* By Thomas Hommel <thomas.hommel@ge.com>
*
* Based on the DS1553 driver from
* Atsushi Nemoto <anemo@mba.ocn.ne.jp>
*/
#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 0x20000
#define RTC_OFFSET 0x1fff0
#define RTC_FLAGS (RTC_OFFSET + 0)
#define RTC_CENTURY (RTC_OFFSET + 1)
#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_CALIBRATION (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_SECONDS_MASK 0x7f
#define RTC_DAY_MASK 0x07
#define RTC_CAL_MASK 0x3f
/* Bits in the Calibration register */
#define RTC_STOP 0x80
/* Bits in the Flags register */
#define RTC_FLAGS_AF 0x40
#define RTC_FLAGS_PF 0x20
#define RTC_WRITE 0x02
#define RTC_READ 0x01
/* Bits in the Interrupts register */
#define RTC_INTS_AIE 0x40
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 stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct rtc_plat_data *pdata = dev_get_drvdata(dev);
void __iomem *ioaddr = pdata->ioaddr;
u8 flags;
flags = readb(pdata->ioaddr + RTC_FLAGS);
writeb(flags | RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
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);
writeb(bin2bcd((tm->tm_year + 1900) / 100), ioaddr + RTC_CENTURY);
writeb(flags & ~RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
return 0;
}
static int stk17ta8_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct rtc_plat_data *pdata = dev_get_drvdata(dev);
void __iomem *ioaddr = pdata->ioaddr;
unsigned int year, month, day, hour, minute, second, week;
unsigned int century;
u8 flags;
/* give enough time to update RTC in case of continuous read */
if (pdata->last_jiffies == jiffies)
msleep(1);
pdata->last_jiffies = jiffies;
flags = readb(pdata->ioaddr + RTC_FLAGS);
writeb(flags | RTC_READ, ioaddr + RTC_FLAGS);
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);
writeb(flags & ~RTC_READ, ioaddr + RTC_FLAGS);
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 stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata)
{
void __iomem *ioaddr = pdata->ioaddr;
unsigned long irqflags;
u8 flags;
spin_lock_irqsave(&pdata->lock, irqflags);
flags = readb(ioaddr + RTC_FLAGS);
writeb(flags | RTC_WRITE, ioaddr + RTC_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_AIE : 0, ioaddr + RTC_INTERRUPTS);
readb(ioaddr + RTC_FLAGS); /* clear interrupts */
writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
spin_unlock_irqrestore(&pdata->lock, irqflags);
}
static int stk17ta8_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rtc_plat_data *pdata = dev_get_drvdata(dev);
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;
stk17ta8_rtc_update_alarm(pdata);
return 0;
}
static int stk17ta8_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rtc_plat_data *pdata = dev_get_drvdata(dev);
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 stk17ta8_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 stk17ta8_rtc_alarm_irq_enable(struct device *dev,
unsigned int enabled)
{
struct rtc_plat_data *pdata = dev_get_drvdata(dev);
if (pdata->irq <= 0)
return -EINVAL;
if (enabled)
pdata->irqen |= RTC_AF;
else
pdata->irqen &= ~RTC_AF;
stk17ta8_rtc_update_alarm(pdata);
return 0;
}
static const struct rtc_class_ops stk17ta8_rtc_ops = {
.read_time = stk17ta8_rtc_read_time,
.set_time = stk17ta8_rtc_set_time,
.read_alarm = stk17ta8_rtc_read_alarm,
.set_alarm = stk17ta8_rtc_set_alarm,
.alarm_irq_enable = stk17ta8_rtc_alarm_irq_enable,
};
static int stk17ta8_nvram_read(void *priv, unsigned int pos, void *val,
size_t bytes)
{
struct rtc_plat_data *pdata = priv;
void __iomem *ioaddr = pdata->ioaddr;
u8 *buf = val;
for (; bytes; bytes--)
*buf++ = readb(ioaddr + pos++);
return 0;
}
static int stk17ta8_nvram_write(void *priv, unsigned int pos, void *val,
size_t bytes)
{
struct rtc_plat_data *pdata = priv;
void __iomem *ioaddr = pdata->ioaddr;
u8 *buf = val;
for (; bytes; bytes--)
writeb(*buf++, ioaddr + pos++);
return 0;
}
static int stk17ta8_rtc_probe(struct platform_device *pdev)
{
unsigned int cal;
unsigned int flags;
struct rtc_plat_data *pdata;
void __iomem *ioaddr;
int ret = 0;
struct nvmem_config nvmem_cfg = {
.name = "stk17ta8_nvram",
.word_size = 1,
.stride = 1,
.size = RTC_OFFSET,
.reg_read = stk17ta8_nvram_read,
.reg_write = stk17ta8_nvram_write,
};
pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return -ENOMEM;
ioaddr = devm_platform_ioremap_resource(pdev, 0);
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 */
cal = readb(ioaddr + RTC_CALIBRATION);
if (cal & RTC_STOP) {
cal &= RTC_CAL_MASK;
flags = readb(ioaddr + RTC_FLAGS);
writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
writeb(cal, ioaddr + RTC_CALIBRATION);
writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
}
if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_PF)
dev_warn(&pdev->dev, "voltage-low detected.\n");
spin_lock_init(&pdata->lock);
pdata->last_jiffies = jiffies;
platform_set_drvdata(pdev, pdata);
if (pdata->irq > 0) {
writeb(0, ioaddr + RTC_INTERRUPTS);
if (devm_request_irq(&pdev->dev, pdata->irq,
stk17ta8_rtc_interrupt,
IRQF_SHARED,
pdev->name, pdev) < 0) {
dev_warn(&pdev->dev, "interrupt not available.\n");
pdata->irq = 0;
}
}
pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(pdata->rtc))
return PTR_ERR(pdata->rtc);
pdata->rtc->ops = &stk17ta8_rtc_ops;
nvmem_cfg.priv = pdata;
ret = rtc_nvmem_register(pdata->rtc, &nvmem_cfg);
if (ret)
return ret;
return rtc_register_device(pdata->rtc);
}
/* work with hotplug and coldplug */
MODULE_ALIAS("platform:stk17ta8");
static struct platform_driver stk17ta8_rtc_driver = {
.probe = stk17ta8_rtc_probe,
.driver = {
.name = "stk17ta8",
},
};
module_platform_driver(stk17ta8_rtc_driver);
MODULE_AUTHOR("Thomas Hommel <thomas.hommel@ge.com>");
MODULE_DESCRIPTION("Simtek STK17TA8 RTC driver");
MODULE_LICENSE("GPL");
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