irqchip: mips-cpu: Prepare for non-legacy IRQ domains

The various struct irq_chip callbacks in the MIPS CPU interrupt
controller driver have been calculating the hardware interrupt number by
subtracting MIPS_CPU_IRQ_BASE from the virq number. This presumes a
linear mapping beginning from MIPS_CPU_IRQ_BASE, and this will not hold
once an IPI IRQ domain is introduced. Switch to using the hwirq field of
struct irq_data which already contains the hardware interrupt number
instead of attempting to calculate it.

Similarly, plat_irq_dispatch calculated the virq number by adding
MIPS_CPU_IRQ_BASE to the hardware interrupt number. Ready this for the
introduction of an IPI IRQ domain by instead using irq_linear_revmap.

Signed-off-by: Paul Burton <[e-mail]>
Acked-by: Thomas Gleixner <[e-mail]>
Cc: Jason Cooper <[e-mail]>
Cc: Marc Zyngier <[e-mail]>
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/15835/
Signed-off-by: Ralf Baechle <[e-mail]>

drivers/irqchip/irq-mips-cpu.c

···
 #include <asm/mipsmtregs.h>
 #include <asm/setup.h>
 
+static struct irq_domain *irq_domain;
+
 static inline void unmask_mips_irq(struct irq_data *d)
 {
-	set_c0_status(IE_SW0 << (d->irq - MIPS_CPU_IRQ_BASE));
+	set_c0_status(IE_SW0 << d->hwirq);
 	irq_enable_hazard();
 }
 
 static inline void mask_mips_irq(struct irq_data *d)
 {
-	clear_c0_status(IE_SW0 << (d->irq - MIPS_CPU_IRQ_BASE));
+	clear_c0_status(IE_SW0 << d->hwirq);
 	irq_disable_hazard();
 }
 
···
 {
 	unsigned int vpflags = dvpe();
 
-	clear_c0_cause(C_SW0 << (d->irq - MIPS_CPU_IRQ_BASE));
+	clear_c0_cause(C_SW0 << d->hwirq);
 	evpe(vpflags);
 	unmask_mips_irq(d);
 	return 0;
···
 static void mips_mt_cpu_irq_ack(struct irq_data *d)
 {
 	unsigned int vpflags = dvpe();
-	clear_c0_cause(C_SW0 << (d->irq - MIPS_CPU_IRQ_BASE));
+	clear_c0_cause(C_SW0 << d->hwirq);
 	evpe(vpflags);
 	mask_mips_irq(d);
 }
···
 asmlinkage void __weak plat_irq_dispatch(void)
 {
 	unsigned long pending = read_c0_cause() & read_c0_status() & ST0_IM;
+	unsigned int virq;
 	int irq;
 
 	if (!pending) {
···
 	pending >>= CAUSEB_IP;
 	while (pending) {
 		irq = fls(pending) - 1;
-		do_IRQ(MIPS_CPU_IRQ_BASE + irq);
+		virq = irq_linear_revmap(irq_domain, irq);
+		do_IRQ(virq);
 		pending &= ~BIT(irq);
 	}
 }
···
 
 static void __init __mips_cpu_irq_init(struct device_node *of_node)
 {
-	struct irq_domain *domain;
-
 	/* Mask interrupts. */
 	clear_c0_status(ST0_IM);
 	clear_c0_cause(CAUSEF_IP);
 
-	domain = irq_domain_add_legacy(of_node, 8, MIPS_CPU_IRQ_BASE, 0,
-				       &mips_cpu_intc_irq_domain_ops, NULL);
-	if (!domain)
+	irq_domain = irq_domain_add_legacy(of_node, 8, MIPS_CPU_IRQ_BASE, 0,
+					   &mips_cpu_intc_irq_domain_ops,
+					   NULL);
+	if (!irq_domain)
 		panic("Failed to add irqdomain for MIPS CPU");
 }