[ARM] Orion: add a separate BRIDGE_INT_TIMER1_CLR define

Some Feroceon-based SoCs have an MBUS bridge interrupt controller
that requires writing a one instead of a zero to clear edge
interrupt sources such as timer expiry.

This patch adds a new BRIDGE_INT_TIMER1_CLR define, which platform
code can set to either ~BRIDGE_INT_TIMER1 (write-zero-to-clear) or
BRIDGE_INT_TIMER1 (write-one-to-clear) depending on the platform.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>

arch/arm/plat-orion/time.c

@@ -74,7 +74,7 @@ orion_clkevt_next_event(unsigned long delta, struct clock_event_device *dev)
 	/*
 	 * Clear and enable clockevent timer interrupt.
 	 */
-	writel(~BRIDGE_INT_TIMER1, BRIDGE_CAUSE);
+	writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 
 	u = readl(BRIDGE_MASK);
 	u |= BRIDGE_INT_TIMER1;
@@ -138,7 +138,7 @@ orion_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev)
 		/*
 		 * ACK pending timer interrupt.
 		 */
-		writel(~BRIDGE_INT_TIMER1, BRIDGE_CAUSE);
+		writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 
 	}
 	local_irq_restore(flags);
@@ -159,7 +159,7 @@ static irqreturn_t orion_timer_interrupt(int irq, void *dev_id)
 	/*
 	 * ACK timer interrupt and call event handler.
 	 */
-	writel(~BRIDGE_INT_TIMER1, BRIDGE_CAUSE);
+	writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 	orion_clkevt.event_handler(&orion_clkevt);
 
 	return IRQ_HANDLED;

include/asm-arm/arch-orion5x/orion5x.h

@@ -154,6 +154,7 @@
 #define BRIDGE_MASK		ORION5X_BRIDGE_REG(0x114)
 #define  BRIDGE_INT_TIMER0	0x0002
 #define  BRIDGE_INT_TIMER1	0x0004
+#define  BRIDGE_INT_TIMER1_CLR	(~0x0004)
 #define MAIN_IRQ_CAUSE		ORION5X_BRIDGE_REG(0x200)
 #define MAIN_IRQ_MASK		ORION5X_BRIDGE_REG(0x204)