[ 50/98] drivers/rtc/rtc-at91rm9200.c: use a variable for storing IMR

Greg Kroah-Hartman
2013-03-26T23:37:02Z

From: Nicolas Ferre <nicolas.ferre@atmel.com>

commit 0ef1594c017521ea89278e80fe3f80dafb17abde upstream.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/rtc/rtc-at91rm9200.c | 50 ++++++++++++++++++++++++++-----------------
drivers/rtc/rtc-at91rm9200.h | 1
2 files changed, 31 insertions(+), 20 deletions(-)

--- a/drivers/rtc/rtc-at91rm9200.c
+++ b/drivers/rtc/rtc-at91rm9200.c
@@ -44,6 +44,7 @@ static DECLARE_COMPLETION(at91_rtc_updat
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 devic
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 dev
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;

pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
@@ -168,6 +171,7 @@ static int at91_rtc_setalarm(struct devi
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 devi

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(str

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(str
*/
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(in
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
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,
@@ -330,6 +337,7 @@ static int __exit at91_rtc_remove(struct
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);
@@ -342,31 +350,35 @@ static int __exit at91_rtc_remove(struct

/* 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;
}
--- a/drivers/rtc/rtc-at91rm9200.h
+++ b/drivers/rtc/rtc-at91rm9200.h
@@ -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 */