genirq: replace irq_gc_ack() with {set,clr}_bit variants (fwd)

This fixes a regression introduced by e59347a "arm: orion:
Use generic irq chip".

Depending on the device, interrupts acknowledgement is done by setting
or by clearing a dedicated register. Replace irq_gc_ack() with some
{set,clr}_bit variants allows to handle both cases.

Note that this patch affects the following SoCs: Davinci, Samsung and
Orion. Except for this last, the change is minor: irq_gc_ack() is just
renamed into irq_gc_ack_set_bit().

For the Orion SoCs, the edge GPIO interrupts support is currently
broken. irq_gc_ack() try to acknowledge a such interrupt by setting
the corresponding cause register bit. The Orion GPIO device expect the
opposite. To fix this issue, the irq_gc_ack_clr_bit() variant is used.

Tested on Network Space v2.

Reported-by: Joey Oravec <joravec@drewtech.com>
Signed-off-by: Simon Guinot <sguinot@lacie.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/kernel/irq/generic-chip.c b/kernel/irq/generic-chip.c
index 31a9db7..3a2cab4 100644
--- a/kernel/irq/generic-chip.c
+++ b/kernel/irq/generic-chip.c
@@ -101,10 +101,10 @@
 }
 
 /**
- * irq_gc_ack - Ack pending interrupt
+ * irq_gc_ack_set_bit - Ack pending interrupt via setting bit
  * @d: irq_data
  */
-void irq_gc_ack(struct irq_data *d)
+void irq_gc_ack_set_bit(struct irq_data *d)
 {
 	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
 	u32 mask = 1 << (d->irq - gc->irq_base);
@@ -115,6 +115,20 @@
 }
 
 /**
+ * irq_gc_ack_clr_bit - Ack pending interrupt via clearing bit
+ * @d: irq_data
+ */
+void irq_gc_ack_clr_bit(struct irq_data *d)
+{
+	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
+	u32 mask = ~(1 << (d->irq - gc->irq_base));
+
+	irq_gc_lock(gc);
+	irq_reg_writel(mask, gc->reg_base + cur_regs(d)->ack);
+	irq_gc_unlock(gc);
+}
+
+/**
  * irq_gc_mask_disable_reg_and_ack- Mask and ack pending interrupt
  * @d: irq_data
  */