irqchip/mips-gic: Get rid of the reliance on irq_cpu_online()

The MIPS GIC driver uses irq_cpu_online() to go and program the
per-CPU interrupts. However, this method iterates over all IRQs
in the system, despite only 3 per-CPU interrupts being of interest.

Let's be terribly bold and do the iteration ourselves. To ensure
mutual exclusion, hold the gic_lock spinlock that is otherwise
taken while dealing with these interrupts.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Serge Semin <fancer.lancer@gmail.com>
Link: https://lore.kernel.org/r/20211021170414.3341522-3-maz@kernel.org

drivers/irqchip/irq-mips-gic.c

@@ -381,24 +381,35 @@ static void gic_unmask_local_irq_all_vpes(struct irq_data *d)
 	spin_unlock_irqrestore(&gic_lock, flags);
 }
 
-static void gic_all_vpes_irq_cpu_online(struct irq_data *d)
+static void gic_all_vpes_irq_cpu_online(void)
 {
-	struct gic_all_vpes_chip_data *cd;
-	unsigned int intr;
+	static const unsigned int local_intrs[] = {
+		GIC_LOCAL_INT_TIMER,
+		GIC_LOCAL_INT_PERFCTR,
+		GIC_LOCAL_INT_FDC,
+	};
+	unsigned long flags;
+	int i;
 
-	intr = GIC_HWIRQ_TO_LOCAL(d->hwirq);
-	cd = irq_data_get_irq_chip_data(d);
+	spin_lock_irqsave(&gic_lock, flags);
 
-	write_gic_vl_map(mips_gic_vx_map_reg(intr), cd->map);
-	if (cd->mask)
-		write_gic_vl_smask(BIT(intr));
+	for (i = 0; i < ARRAY_SIZE(local_intrs); i++) {
+		unsigned int intr = local_intrs[i];
+		struct gic_all_vpes_chip_data *cd;
+
+		cd = &gic_all_vpes_chip_data[intr];
+		write_gic_vl_map(mips_gic_vx_map_reg(intr), cd->map);
+		if (cd->mask)
+			write_gic_vl_smask(BIT(intr));
+	}
+
+	spin_unlock_irqrestore(&gic_lock, flags);
 }
 
 static struct irq_chip gic_all_vpes_local_irq_controller = {
 	.name			= "MIPS GIC Local",
 	.irq_mask		= gic_mask_local_irq_all_vpes,
 	.irq_unmask		= gic_unmask_local_irq_all_vpes,
-	.irq_cpu_online		= gic_all_vpes_irq_cpu_online,
 };
 
 static void __gic_irq_dispatch(void)
@@ -477,6 +488,10 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int virq,
 	intr = GIC_HWIRQ_TO_LOCAL(hwirq);
 	map = GIC_MAP_PIN_MAP_TO_PIN | gic_cpu_pin;
 
+	/*
+	 * If adding support for more per-cpu interrupts, keep the the
+	 * array in gic_all_vpes_irq_cpu_online() in sync.
+	 */
 	switch (intr) {
 	case GIC_LOCAL_INT_TIMER:
 		/* CONFIG_MIPS_CMP workaround (see __gic_init) */
@@ -663,8 +678,8 @@ static int gic_cpu_startup(unsigned int cpu)
 	/* Clear all local IRQ masks (ie. disable all local interrupts) */
 	write_gic_vl_rmask(~0);
 
-	/* Invoke irq_cpu_online callbacks to enable desired interrupts */
-	irq_cpu_online();
+	/* Enable desired interrupts */
+	gic_all_vpes_irq_cpu_online();
 
 	return 0;
 }