MIPS: Alchemy: devboards: remove unneeded BCSR IRQ reg acc

Initially I had to write to both the MASK and ENABLE registers, otherwise
the CPLD would generate tons of spurious interrupts.  With the change to
the demux handler to disable the muxed line, it is now sufficient to
disable the interrupt by writing either the enable or mask register.
Signed-off-by: Manuel Lauss <manuel.lauss@googlemail.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2865/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/alchemy/devboards/bcsr.c

@@ -97,14 +97,9 @@ static void bcsr_csc_handler(unsigned int irq, struct irq_desc *d)
 	enable_irq(irq);
 }
 
-/* NOTE: both the enable and mask bits must be cleared, otherwise the
- * CPLD generates tons of spurious interrupts (at least on my DB1200).
- *	-- mlau
- */
 static void bcsr_irq_mask(struct irq_data *d)
 {
 	unsigned short v = 1 << (d->irq - bcsr_csc_base);
-	__raw_writew(v, bcsr_virt + BCSR_REG_INTCLR);
 	__raw_writew(v, bcsr_virt + BCSR_REG_MASKCLR);
 	wmb();
 }
@@ -112,7 +107,6 @@ static void bcsr_irq_mask(struct irq_data *d)
 static void bcsr_irq_maskack(struct irq_data *d)
 {
 	unsigned short v = 1 << (d->irq - bcsr_csc_base);
-	__raw_writew(v, bcsr_virt + BCSR_REG_INTCLR);
 	__raw_writew(v, bcsr_virt + BCSR_REG_MASKCLR);
 	__raw_writew(v, bcsr_virt + BCSR_REG_INTSTAT);	/* ack */
 	wmb();
@@ -121,7 +115,6 @@ static void bcsr_irq_maskack(struct irq_data *d)
 static void bcsr_irq_unmask(struct irq_data *d)
 {
 	unsigned short v = 1 << (d->irq - bcsr_csc_base);
-	__raw_writew(v, bcsr_virt + BCSR_REG_INTSET);
 	__raw_writew(v, bcsr_virt + BCSR_REG_MASKSET);
 	wmb();
 }
@@ -137,9 +130,9 @@ void __init bcsr_init_irq(int csc_start, int csc_end, int hook_irq)
 {
 	unsigned int irq;
 
-	/* mask & disable & ack all */
-	__raw_writew(0xffff, bcsr_virt + BCSR_REG_INTCLR);
+	/* mask & enable & ack all */
 	__raw_writew(0xffff, bcsr_virt + BCSR_REG_MASKCLR);
+	__raw_writew(0xffff, bcsr_virt + BCSR_REG_INTSET);
 	__raw_writew(0xffff, bcsr_virt + BCSR_REG_INTSTAT);
 	wmb();