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linux/drivers/rtc/rtc-at91rm9200.c
Nicolas Ferre 0ef1594c01 drivers/rtc/rtc-at91rm9200.c: use a variable for storing IMR 
On some revisions of AT91 SoCs, the RTC IMR register is not working.
Instead of elaborating a workaround for that specific SoC or IP version,
we simply use a software variable to store the Interrupt Mask Register
and modify it for each enabling/disabling of an interrupt.  The overhead
of this is negligible anyway.

The interrupt mask register (IMR) for the RTC is broken on the AT91SAM9x5
sub-family of SoCs (good overview of the members here:
http://www.eewiki.net/display/linuxonarm/AT91SAM9x5 ).  The "user visible
effect" is the RTC doesn't work.

That sub-family is less than two years old and only has devicetree (DT)
support and came online circa lk 3.7 .  The dust is yet to settle on the
DT stuff at least for AT91 SoCs (translation: lots of stuff is still
broken, so much that it is hard to know where to start).

The fix in the patch is pretty simple: just shadow the silicon IMR
register with a variable in the driver.  Some older SoCs (pre-DT) use the
the rtc-at91rm9200 driver (e.g.  obviously the AT91RM9200) and they should
not be impacted by the change.  There shouldn't be a large volume of
interrupts associated with a RTC.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Reported-by: Douglas Gilbert <dgilbert@interlog.com>
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Ludovic Desroches <ludovic.desroches@atmel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-03-22 16:41:20 -07:00

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/*
* Real Time Clock interface for Linux on Atmel AT91RM9200
*
* Copyright (C) 2002 Rick Bronson
*
* Converted to RTC class model by Andrew Victor
*
* Ported to Linux 2.6 by Steven Scholz
* Based on s3c2410-rtc.c Simtec Electronics
*
* Based on sa1100-rtc.c by Nils Faerber
* Based on rtc.c by Paul Gortmaker
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/time.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/interrupt.h>
#include <linux/ioctl.h>
#include <linux/completion.h>
#include <linux/io.h>
#include <asm/uaccess.h>
#include "rtc-at91rm9200.h"
#define at91_rtc_read(field) \
__raw_readl(at91_rtc_regs + field)
#define at91_rtc_write(field, val) \
__raw_writel((val), at91_rtc_regs + field)
#define AT91_RTC_EPOCH 1900UL /* just like arch/arm/common/rtctime.c */
static DECLARE_COMPLETION(at91_rtc_updated);
static unsigned int at91_alarm_year = AT91_RTC_EPOCH;
static void __iomem *at91_rtc_regs;
static int irq;
static u32 at91_rtc_imr;
/*
* Decode time/date into rtc_time structure
*/
static void at91_rtc_decodetime(unsigned int timereg, unsigned int calreg,
struct rtc_time *tm)
{
unsigned int time, date;
/* must read twice in case it changes */
do {
time = at91_rtc_read(timereg);
date = at91_rtc_read(calreg);
} while ((time != at91_rtc_read(timereg)) ||
(date != at91_rtc_read(calreg)));
tm->tm_sec = bcd2bin((time & AT91_RTC_SEC) >> 0);
tm->tm_min = bcd2bin((time & AT91_RTC_MIN) >> 8);
tm->tm_hour = bcd2bin((time & AT91_RTC_HOUR) >> 16);
/*
* The Calendar Alarm register does not have a field for
* the year - so these will return an invalid value. When an
* alarm is set, at91_alarm_year will store the current year.
*/
tm->tm_year = bcd2bin(date & AT91_RTC_CENT) * 100; /* century */
tm->tm_year += bcd2bin((date & AT91_RTC_YEAR) >> 8); /* year */
tm->tm_wday = bcd2bin((date & AT91_RTC_DAY) >> 21) - 1; /* day of the week [0-6], Sunday=0 */
tm->tm_mon = bcd2bin((date & AT91_RTC_MONTH) >> 16) - 1;
tm->tm_mday = bcd2bin((date & AT91_RTC_DATE) >> 24);
}
/*
* Read current time and date in RTC
*/
static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
{
at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, tm);
tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
tm->tm_year = tm->tm_year - 1900;
dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
tm->tm_hour, tm->tm_min, tm->tm_sec);
return 0;
}
/*
* Set current time and date in RTC
*/
static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
{
unsigned long cr;
dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
tm->tm_hour, tm->tm_min, tm->tm_sec);
/* Stop Time/Calendar from counting */
cr = at91_rtc_read(AT91_RTC_CR);
at91_rtc_write(AT91_RTC_CR, cr | AT91_RTC_UPDCAL | AT91_RTC_UPDTIM);
at91_rtc_imr |= AT91_RTC_ACKUPD;
at91_rtc_write(AT91_RTC_IER, AT91_RTC_ACKUPD);
wait_for_completion(&at91_rtc_updated); /* wait for ACKUPD interrupt */
at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD);
at91_rtc_imr &= ~AT91_RTC_ACKUPD;
at91_rtc_write(AT91_RTC_TIMR,
bin2bcd(tm->tm_sec) << 0
| bin2bcd(tm->tm_min) << 8
| bin2bcd(tm->tm_hour) << 16);
at91_rtc_write(AT91_RTC_CALR,
bin2bcd((tm->tm_year + 1900) / 100) /* century */
| bin2bcd(tm->tm_year % 100) << 8 /* year */
| bin2bcd(tm->tm_mon + 1) << 16 /* tm_mon starts at zero */
| bin2bcd(tm->tm_wday + 1) << 21 /* day of the week [0-6], Sunday=0 */
| bin2bcd(tm->tm_mday) << 24);
/* Restart Time/Calendar */
cr = at91_rtc_read(AT91_RTC_CR);
at91_rtc_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL | AT91_RTC_UPDTIM));
return 0;
}
/*
* Read alarm time and date in RTC
*/
static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rtc_time *tm = &alrm->time;
at91_rtc_decodetime(AT91_RTC_TIMALR, AT91_RTC_CALALR, tm);
tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
tm->tm_year = at91_alarm_year - 1900;
alrm->enabled = (at91_rtc_imr & AT91_RTC_ALARM)
? 1 : 0;
dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
tm->tm_hour, tm->tm_min, tm->tm_sec);
return 0;
}
/*
* Set alarm time and date in RTC
*/
static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rtc_time tm;
at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, &tm);
at91_alarm_year = tm.tm_year;
tm.tm_hour = alrm->time.tm_hour;
tm.tm_min = alrm->time.tm_min;
tm.tm_sec = alrm->time.tm_sec;
at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ALARM);
at91_rtc_imr &= ~AT91_RTC_ALARM;
at91_rtc_write(AT91_RTC_TIMALR,
bin2bcd(tm.tm_sec) << 0
| bin2bcd(tm.tm_min) << 8
| bin2bcd(tm.tm_hour) << 16
| AT91_RTC_HOUREN | AT91_RTC_MINEN | AT91_RTC_SECEN);
at91_rtc_write(AT91_RTC_CALALR,
bin2bcd(tm.tm_mon + 1) << 16 /* tm_mon starts at zero */
| bin2bcd(tm.tm_mday) << 24
| AT91_RTC_DATEEN | AT91_RTC_MTHEN);
if (alrm->enabled) {
at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
at91_rtc_imr |= AT91_RTC_ALARM;
at91_rtc_write(AT91_RTC_IER, AT91_RTC_ALARM);
}
dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
at91_alarm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour,
tm.tm_min, tm.tm_sec);
return 0;
}
static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
dev_dbg(dev, "%s(): cmd=%08x\n", __func__, enabled);
if (enabled) {
at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
at91_rtc_imr |= AT91_RTC_ALARM;
at91_rtc_write(AT91_RTC_IER, AT91_RTC_ALARM);
} else {
at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ALARM);
at91_rtc_imr &= ~AT91_RTC_ALARM;
}
return 0;
}
/*
* Provide additional RTC information in /proc/driver/rtc
*/
static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
{
seq_printf(seq, "update_IRQ\t: %s\n",
(at91_rtc_imr & AT91_RTC_ACKUPD) ? "yes" : "no");
seq_printf(seq, "periodic_IRQ\t: %s\n",
(at91_rtc_imr & AT91_RTC_SECEV) ? "yes" : "no");
return 0;
}
/*
* IRQ handler for the RTC
*/
static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id)
{
struct platform_device *pdev = dev_id;
struct rtc_device *rtc = platform_get_drvdata(pdev);
unsigned int rtsr;
unsigned long events = 0;
rtsr = at91_rtc_read(AT91_RTC_SR) & at91_rtc_imr;
if (rtsr) { /* this interrupt is shared! Is it ours? */
if (rtsr & AT91_RTC_ALARM)
events |= (RTC_AF | RTC_IRQF);
if (rtsr & AT91_RTC_SECEV)
events |= (RTC_UF | RTC_IRQF);
if (rtsr & AT91_RTC_ACKUPD)
complete(&at91_rtc_updated);
at91_rtc_write(AT91_RTC_SCCR, rtsr); /* clear status reg */
rtc_update_irq(rtc, 1, events);
dev_dbg(&pdev->dev, "%s(): num=%ld, events=0x%02lx\n", __func__,
events >> 8, events & 0x000000FF);
return IRQ_HANDLED;
}
return IRQ_NONE; /* not handled */
}
static const struct rtc_class_ops at91_rtc_ops = {
.read_time = at91_rtc_readtime,
.set_time = at91_rtc_settime,
.read_alarm = at91_rtc_readalarm,
.set_alarm = at91_rtc_setalarm,
.proc = at91_rtc_proc,
.alarm_irq_enable = at91_rtc_alarm_irq_enable,
};
/*
* Initialize and install RTC driver
*/
static int __init at91_rtc_probe(struct platform_device *pdev)
{
struct rtc_device *rtc;
struct resource *regs;
int ret = 0;
regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!regs) {
dev_err(&pdev->dev, "no mmio resource defined\n");
return -ENXIO;
}
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(&pdev->dev, "no irq resource defined\n");
return -ENXIO;
}
at91_rtc_regs = ioremap(regs->start, resource_size(regs));
if (!at91_rtc_regs) {
dev_err(&pdev->dev, "failed to map registers, aborting.\n");
return -ENOMEM;
}
at91_rtc_write(AT91_RTC_CR, 0);
at91_rtc_write(AT91_RTC_MR, 0); /* 24 hour mode */
/* Disable all interrupts */
at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM |
AT91_RTC_SECEV | AT91_RTC_TIMEV |
AT91_RTC_CALEV);
at91_rtc_imr = 0;
ret = request_irq(irq, at91_rtc_interrupt,
IRQF_SHARED,
"at91_rtc", pdev);
if (ret) {
dev_err(&pdev->dev, "IRQ %d already in use.\n", irq);
return ret;
}
/* cpu init code should really have flagged this device as
* being wake-capable; if it didn't, do that here.
*/
if (!device_can_wakeup(&pdev->dev))
device_init_wakeup(&pdev->dev, 1);
rtc = rtc_device_register(pdev->name, &pdev->dev,
&at91_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc)) {
free_irq(irq, pdev);
return PTR_ERR(rtc);
}
platform_set_drvdata(pdev, rtc);
dev_info(&pdev->dev, "AT91 Real Time Clock driver.\n");
return 0;
}
/*
* Disable and remove the RTC driver
*/
static int __exit at91_rtc_remove(struct platform_device *pdev)
{
struct rtc_device *rtc = platform_get_drvdata(pdev);
/* Disable all interrupts */
at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM |
AT91_RTC_SECEV | AT91_RTC_TIMEV |
AT91_RTC_CALEV);
at91_rtc_imr = 0;
free_irq(irq, pdev);
rtc_device_unregister(rtc);
platform_set_drvdata(pdev, NULL);
return 0;
}
#ifdef CONFIG_PM
/* AT91RM9200 RTC Power management control */
static u32 at91_rtc_bkpimr;
static int at91_rtc_suspend(struct device *dev)
{
/* this IRQ is shared with DBGU and other hardware which isn't
* necessarily doing PM like we are...
*/
at91_rtc_bkpimr = at91_rtc_imr & (AT91_RTC_ALARM|AT91_RTC_SECEV);
if (at91_rtc_bkpimr) {
if (device_may_wakeup(dev)) {
enable_irq_wake(irq);
} else {
at91_rtc_write(AT91_RTC_IDR, at91_rtc_bkpimr);
at91_rtc_imr &= ~at91_rtc_bkpimr;
}
}
return 0;
}
static int at91_rtc_resume(struct device *dev)
{
if (at91_rtc_bkpimr) {
if (device_may_wakeup(dev)) {
disable_irq_wake(irq);
} else {
at91_rtc_imr |= at91_rtc_bkpimr;
at91_rtc_write(AT91_RTC_IER, at91_rtc_bkpimr);
}
}
return 0;
}
static const struct dev_pm_ops at91_rtc_pm = {
.suspend = at91_rtc_suspend,
.resume = at91_rtc_resume,
};
#define at91_rtc_pm_ptr &at91_rtc_pm
#else
#define at91_rtc_pm_ptr NULL
#endif
static struct platform_driver at91_rtc_driver = {
.remove = __exit_p(at91_rtc_remove),
.driver = {
.name = "at91_rtc",
.owner = THIS_MODULE,
.pm = at91_rtc_pm_ptr,
},
};
static int __init at91_rtc_init(void)
{
return platform_driver_probe(&at91_rtc_driver, at91_rtc_probe);
}
static void __exit at91_rtc_exit(void)
{
platform_driver_unregister(&at91_rtc_driver);
}
module_init(at91_rtc_init);
module_exit(at91_rtc_exit);
MODULE_AUTHOR("Rick Bronson");
MODULE_DESCRIPTION("RTC driver for Atmel AT91RM9200");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:at91_rtc");
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