Subject: + rtc-at91rm9200-add-shadow-interrupt-mask.patch added to -mm tree To: jhovold@xxxxxxxxx,Robert.Nelson@xxxxxxxxxxx,dgilbert@xxxxxxxxxxxx,ludovic.desroches@xxxxxxxxx,nicolas.ferre@xxxxxxxxx,plagnioj@xxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Wed, 29 May 2013 13:34:02 -0700 The patch titled Subject: rtc-at91rm9200: add shadow interrupt mask has been added to the -mm tree. Its filename is rtc-at91rm9200-add-shadow-interrupt-mask.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Johan Hovold <jhovold@xxxxxxxxx> Subject: rtc-at91rm9200: add shadow interrupt mask Add shadow interrupt-mask register which can be used on SoCs where the actual hardware register is broken. Note that some care needs to be taken to make sure the shadow mask corresponds to the actual hardware state. The added overhead is not an issue for the non-broken SoCs due to the relatively infrequent interrupt-mask updates. We do, however, only use the shadow mask value as a fall-back when it actually needed as there is still a theoretical possibility that the mask is incorrect (see the code for details). Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx> Cc: Nicolas Ferre <nicolas.ferre@xxxxxxxxx> Cc: Douglas Gilbert <dgilbert@xxxxxxxxxxxx> Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@xxxxxxxxxxxx> Cc: Ludovic Desroches <ludovic.desroches@xxxxxxxxx> Cc: Robert Nelson <Robert.Nelson@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/rtc/rtc-at91rm9200.c | 39 ++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff -puN drivers/rtc/rtc-at91rm9200.c~rtc-at91rm9200-add-shadow-interrupt-mask drivers/rtc/rtc-at91rm9200.c --- a/drivers/rtc/rtc-at91rm9200.c~rtc-at91rm9200-add-shadow-interrupt-mask +++ a/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> @@ -42,6 +43,7 @@ #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; @@ -49,20 +51,55 @@ 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 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; } /* _ Patches currently in -mm which might be from jhovold@xxxxxxxxx are rtc-at91rm9200-add-match-table-compile-guard.patch rtc-at91rm9200-add-configuration-support.patch rtc-at91rm9200-refactor-interrupt-register-handling.patch rtc-at91rm9200-add-shadow-interrupt-mask.patch rtc-at91rm9200-use-shadow-imr-on-at91sam9x5.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html