diff options
Diffstat (limited to 'drivers/rtc')
| -rw-r--r-- | drivers/rtc/rtc-at91rm9200.c | 39 |
1 files changed, 38 insertions, 1 deletions
diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c index 9592d08f3b11..811a102092d4 100644 --- a/drivers/rtc/rtc-at91rm9200.c +++ b/drivers/rtc/rtc-at91rm9200.c @@ -25,6 +25,7 @@ #include <linux/rtc.h> #include <linux/bcd.h> #include <linux/interrupt.h> +#include <linux/spinlock.h> #include <linux/ioctl.h> #include <linux/completion.h> #include <linux/io.h> @@ -43,6 +44,7 @@ #define AT91_RTC_EPOCH 1900UL /* just like arch/arm/common/rtctime.c */ struct at91_rtc_config { + bool use_shadow_imr; }; static const struct at91_rtc_config *at91_rtc_config; @@ -50,20 +52,55 @@ 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 DEFINE_SPINLOCK(at91_rtc_lock); +static u32 at91_rtc_shadow_imr; static void at91_rtc_write_ier(u32 mask) { + unsigned long flags; + + spin_lock_irqsave(&at91_rtc_lock, flags); + at91_rtc_shadow_imr |= mask; at91_rtc_write(AT91_RTC_IER, mask); + spin_unlock_irqrestore(&at91_rtc_lock, flags); } static void at91_rtc_write_idr(u32 mask) { + unsigned long flags; + + spin_lock_irqsave(&at91_rtc_lock, flags); at91_rtc_write(AT91_RTC_IDR, mask); + /* + * Register read back (of any RTC-register) needed to make sure + * IDR-register write has reached the peripheral before updating + * shadow mask. + * + * Note that there is still a possibility that the mask is updated + * before interrupts have actually been disabled in hardware. The only + * way to be certain would be to poll the IMR-register, which is is + * the very register we are trying to emulate. The register read back + * is a reasonable heuristic. + */ + at91_rtc_read(AT91_RTC_SR); + at91_rtc_shadow_imr &= ~mask; + spin_unlock_irqrestore(&at91_rtc_lock, flags); } static u32 at91_rtc_read_imr(void) { - return at91_rtc_read(AT91_RTC_IMR); + unsigned long flags; + u32 mask; + + if (at91_rtc_config->use_shadow_imr) { + spin_lock_irqsave(&at91_rtc_lock, flags); + mask = at91_rtc_shadow_imr; + spin_unlock_irqrestore(&at91_rtc_lock, flags); + } else { + mask = at91_rtc_read(AT91_RTC_IMR); + } + + return mask; } /* |