[merged] rtc-at91rm9200-add-shadow-interrupt-mask.patch removed from -mm tree

[merged] rtc-at91rm9200-add-shadow-interrupt-mask.patch removed from -mm tree

[akpm]

Subject: [merged] rtc-at91rm9200-add-shadow-interrupt-mask.patch removed from -mm tree
To: jhovold@gmail.com,Robert.Nelson@digikey.com,dgilbert@interlog.com,ludovic.desroches@atmel.com,nicolas.ferre@atmel.com,plagnioj@jcrosoft.com,mm-commits@vger.kernel.org
From: akpm@linux-foundation.org
Date: Thu, 13 Jun 2013 11:57:54 -0700


The patch titled
     Subject: rtc-at91rm9200: add shadow interrupt mask
has been removed from the -mm tree.  Its filename was
     rtc-at91rm9200-add-shadow-interrupt-mask.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Johan Hovold <jhovold@gmail.com>
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@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Ludovic Desroches <ludovic.desroches@atmel.com>
Cc: Robert Nelson <Robert.Nelson@digikey.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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>
@@ -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_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@gmail.com are

origin.patch
linux-next.patch