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Commit 0ef1594c authored by Nicolas Ferre's avatar Nicolas Ferre Committed by Linus Torvalds
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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: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Reported-by: default avatarDouglas 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e66b0587

drivers/rtc/rtc-at91rm9200.c

+31 −19
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ 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
@@ -108,9 +109,11 @@ static int at91_rtc_settime(struct device *dev, struct rtc_time *tm) 
	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
@@ -142,7 +145,7 @@ static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm) 
	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_read(AT91_RTC_IMR) & AT91_RTC_ALARM)

	alrm->enabled = (at91_rtc_imr & AT91_RTC_ALARM)

			? 1 : 0;



	dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
@@ -168,6 +171,7 @@ static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) 
	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
@@ -180,6 +184,7 @@ static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) 


	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);

	}
@@ -196,9 +201,12 @@ static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int 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

	} else {

		at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ALARM);

		at91_rtc_imr &= ~AT91_RTC_ALARM;

	}



	return 0;

}
@@ -207,12 +215,10 @@ static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) 
 */

static int at91_rtc_proc(struct device *dev, struct seq_file *seq)

{

	unsigned long imr = at91_rtc_read(AT91_RTC_IMR);



	seq_printf(seq, "update_IRQ\t: %s\n",

			(imr & AT91_RTC_ACKUPD) ? "yes" : "no");

			(at91_rtc_imr & AT91_RTC_ACKUPD) ? "yes" : "no");

	seq_printf(seq, "periodic_IRQ\t: %s\n",

			(imr & AT91_RTC_SECEV) ? "yes" : "no");

			(at91_rtc_imr & AT91_RTC_SECEV) ? "yes" : "no");



	return 0;

}
@@ -227,7 +233,7 @@ static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id) 
	unsigned int rtsr;

	unsigned long events = 0;



	rtsr = at91_rtc_read(AT91_RTC_SR) & at91_rtc_read(AT91_RTC_IMR);

	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);
@@ -291,6 +297,7 @@ static int __init at91_rtc_probe(struct platform_device *pdev) 
	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,
@@ -329,6 +336,7 @@ static int __exit at91_rtc_remove(struct platform_device *pdev) 
	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);
@@ -341,31 +349,35 @@ static int __exit at91_rtc_remove(struct platform_device *pdev) 


/* AT91RM9200 RTC Power management control */



static u32 at91_rtc_imr;

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_imr = at91_rtc_read(AT91_RTC_IMR)

			& (AT91_RTC_ALARM|AT91_RTC_SECEV);

	if (at91_rtc_imr) {

		if (device_may_wakeup(dev))

	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_imr);

		} 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_imr) {

		if (device_may_wakeup(dev))

	if (at91_rtc_bkpimr) {

		if (device_may_wakeup(dev)) {

			disable_irq_wake(irq);

		else

			at91_rtc_write(AT91_RTC_IER, at91_rtc_imr);

		} else {

			at91_rtc_imr |= at91_rtc_bkpimr;

			at91_rtc_write(AT91_RTC_IER, at91_rtc_bkpimr);

		}

	}

	return 0;

}

drivers/rtc/rtc-at91rm9200.h

+0 −1
Original line number Diff line number Diff line
@@ -64,7 +64,6 @@ 
#define	AT91_RTC_SCCR		0x1c			/* Status Clear Command Register */

#define	AT91_RTC_IER		0x20			/* Interrupt Enable Register */

#define	AT91_RTC_IDR		0x24			/* Interrupt Disable Register */

#define	AT91_RTC_IMR		0x28			/* Interrupt Mask Register */



#define	AT91_RTC_VER		0x2c			/* Valid Entry Register */

#define		AT91_RTC_NVTIM		(1 <<  0)		/* Non valid Time */