irqchip/loongson-pch-pic: Improve edge triggered interrupt support

Edge-triggered mode and level-triggered mode need different handlers,
and edge-triggered mode need a specific ack operation. So improve it.

Fixes: ef8c01eb64 ("irqchip: Add Loongson PCH PIC controller")
Signed-off-by: Chen Zhu <zhuchen@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210805132216.3539007-1-chenhuacai@loongson.cn

drivers/irqchip/irq-loongson-pch-pic.c

@@ -92,18 +92,22 @@ static int pch_pic_set_type(struct irq_data *d, unsigned int type)
 	case IRQ_TYPE_EDGE_RISING:
 		pch_pic_bitset(priv, PCH_PIC_EDGE, d->hwirq);
 		pch_pic_bitclr(priv, PCH_PIC_POL, d->hwirq);
+		irq_set_handler_locked(d, handle_edge_irq);
 		break;
 	case IRQ_TYPE_EDGE_FALLING:
 		pch_pic_bitset(priv, PCH_PIC_EDGE, d->hwirq);
 		pch_pic_bitset(priv, PCH_PIC_POL, d->hwirq);
+		irq_set_handler_locked(d, handle_edge_irq);
 		break;
 	case IRQ_TYPE_LEVEL_HIGH:
 		pch_pic_bitclr(priv, PCH_PIC_EDGE, d->hwirq);
 		pch_pic_bitclr(priv, PCH_PIC_POL, d->hwirq);
+		irq_set_handler_locked(d, handle_level_irq);
 		break;
 	case IRQ_TYPE_LEVEL_LOW:
 		pch_pic_bitclr(priv, PCH_PIC_EDGE, d->hwirq);
 		pch_pic_bitset(priv, PCH_PIC_POL, d->hwirq);
+		irq_set_handler_locked(d, handle_level_irq);
 		break;
 	default:
 		ret = -EINVAL;
@@ -113,11 +117,24 @@ static int pch_pic_set_type(struct irq_data *d, unsigned int type)
 	return ret;
 }
 
+static void pch_pic_ack_irq(struct irq_data *d)
+{
+	unsigned int reg;
+	struct pch_pic *priv = irq_data_get_irq_chip_data(d);
+
+	reg = readl(priv->base + PCH_PIC_EDGE + PIC_REG_IDX(d->hwirq) * 4);
+	if (reg & BIT(PIC_REG_BIT(d->hwirq))) {
+		writel(BIT(PIC_REG_BIT(d->hwirq)),
+			priv->base + PCH_PIC_CLR + PIC_REG_IDX(d->hwirq) * 4);
+	}
+	irq_chip_ack_parent(d);
+}
+
 static struct irq_chip pch_pic_irq_chip = {
 	.name			= "PCH PIC",
 	.irq_mask		= pch_pic_mask_irq,
 	.irq_unmask		= pch_pic_unmask_irq,
-	.irq_ack		= irq_chip_ack_parent,
+	.irq_ack		= pch_pic_ack_irq,
 	.irq_set_affinity	= irq_chip_set_affinity_parent,
 	.irq_set_type		= pch_pic_set_type,
 };