[PATCH 2/6] irqchip: sunxi: Add irq controller driver

On 11/15/2012 11:46 PM, Maxime Ripard wrote:

<snip>

Are you sure that you need to touch all those 23registers to ack the
interrupt? I know that the original code provided by Allwinner does
exactly this. My tests have shown though, that writing to the pending
reg is enough.

+}
+
+static void sunxi_irq_mask(struct irq_data *irqd)
+{
+	unsigned int irq = irqd_to_hwirq(irqd);
+	unsigned int irq_off = irq % 32;
+	int reg = irq / 32;
+	u32 val;
+
+	val = readl(sunxi_irq_base + SUNXI_IRQ_ENABLE_REG(reg));
+	writel(val & ~(1 << irq_off),
+	       sunxi_irq_base + SUNXI_IRQ_ENABLE_REG(reg));
+
+	val = readl(sunxi_irq_base + SUNXI_IRQ_MASK_REG(reg));
+	writel(val | (1 << irq_off),
+	       sunxi_irq_base + SUNXI_IRQ_MASK_REG(reg));

I unmasked all interrupts in the mask register in the init function.
Then only using the enable register for masking/unmasking seems to be
enough. What do you think?

+}
+
+static void sunxi_irq_unmask(struct irq_data *irqd)
+{
+	unsigned int irq = irqd_to_hwirq(irqd);
+	unsigned int irq_off = irq % 32;
+	int reg = irq / 32;
+	u32 val;
+
+	val = readl(sunxi_irq_base + SUNXI_IRQ_ENABLE_REG(reg));
+	writel(val | (1 << irq_off),
+	       sunxi_irq_base + SUNXI_IRQ_ENABLE_REG(reg));
+
+	val = readl(sunxi_irq_base + SUNXI_IRQ_MASK_REG(reg));
+	writel(val & ~(1 << irq_off),
+	       sunxi_irq_base + SUNXI_IRQ_MASK_REG(reg));
+
+	/* Must clear pending bit when enabled */
+	if (irq == 0)
+		writel(1, sunxi_irq_base + SUNXI_IRQ_PENDING_REG(0));

Again. Might be that one register is enough here.

+}
+
+static struct irq_chip sunxi_irq_chip = {
+	.name		= "sunxi_irq",
+	.irq_ack	= sunxi_irq_ack,
+	.irq_mask	= sunxi_irq_mask,
+	.irq_unmask	= sunxi_irq_unmask,
+};
+
+static int sunxi_irq_map(struct irq_domain *d, unsigned int virq,
+			 irq_hw_number_t hw)
+{
+	irq_set_chip(virq, &sunxi_irq_chip);
+	irq_set_handler(virq, handle_level_irq);

irq_set_chip_and_handler()

+	set_irq_flags(virq, IRQF_VALID | IRQF_PROBE);
+
+	return 0;
+}
+
+static struct irq_domain_ops sunxi_irq_ops = {
+	.map = sunxi_irq_map,
+	.xlate = irq_domain_xlate_onecell,
+};
+
+static int __init sunxi_of_init(struct device_node *node,
+				struct device_node *parent)
+{
+	sunxi_irq_base = of_iomap(node, 0);
+	if (!sunxi_irq_base)
+		panic("%s: unable to map IC registers\n",
+			node->full_name);
+
+	/* Disable all interrupts */
+	writel(0, sunxi_irq_base + SUNXI_IRQ_ENABLE_REG(0));
+	writel(0, sunxi_irq_base + SUNXI_IRQ_ENABLE_REG(1));
+	writel(0, sunxi_irq_base + SUNXI_IRQ_ENABLE_REG(2));
+
+	/* Mask all the interrupts */
+	writel(0xffffffff, sunxi_irq_base + SUNXI_IRQ_MASK_REG(0));
+	writel(0xffffffff, sunxi_irq_base + SUNXI_IRQ_MASK_REG(1));
+	writel(0xffffffff, sunxi_irq_base + SUNXI_IRQ_MASK_REG(2));

Here is where I wrote 0 to the mask registers.

+	/* Clear all the pending interrupts */
+	writel(0xffffffff, sunxi_irq_base + SUNXI_IRQ_PENDING_REG(0));
+	writel(0xffffffff, sunxi_irq_base + SUNXI_IRQ_PENDING_REG(1));
+	writel(0xffffffff, sunxi_irq_base + SUNXI_IRQ_PENDING_REG(2));
+
+	/* Enable protection mode */
+	writel(0x01, sunxi_irq_base + SUNXI_IRQ_PROTECTION_REG);
+
+	/* Configure the external interrupt source type */
+	writel(0x00, sunxi_irq_base + SUNXI_IRQ_NMI_CTRL_REG);
+
+	sunxi_irq_domain = irq_domain_add_linear(node, 3 * 32,
+						 &sunxi_irq_ops, NULL);
+	if (!sunxi_irq_domain)
+		panic("%s: unable to create IRQ domain\n", node->full_name);
+
+	return 0;
+}
+
+static struct of_device_id sunxi_irq_dt_ids[] __initconst = {
+	{ .compatible = "allwinner,sunxi-ic", .data = sunxi_of_init }
+};
+
+void __init sunxi_init_irq(void)
+{
+	of_irq_init(sunxi_irq_dt_ids);
+}
+
+asmlinkage void __exception_irq_entry sunxi_handle_irq(struct pt_regs *regs)
+{
+	u32 irq, reg;
+	int i;
+
+	for (i = 0; i < 3; i++) {
+		reg = readl(sunxi_irq_base + SUNXI_IRQ_PENDING_REG(i));
+		if (reg == 0)
+			continue;
+		irq = ilog2(reg);
+		break;
+	}
+	irq = irq_find_mapping(sunxi_irq_domain, irq);
+	handle_IRQ(irq, regs);

Why don't you use the interrupt-vector register to get the active
interrupt source? Here is my version:

asmlinkage void __exception_irq_entry sunxi_handle_irq(struct pt_regs *regs)
{
	u32 irq;

	irq = readl(int_base + SW_INT_VECTOR_REG) >> 2;
	irq = irq_find_mapping(sunxi_vic_domain, irq);
	handle_IRQ(irq, regs);
}

I suggest you give it a try.

Cheers,
Stefan