irqchip/mips-gic: Replace open coded online CPU iterations

Several places in the MIPS GIC driver iterate over the online CPUs to
operate on the CPU's GIC local register block, accessed via the GIC's
other/redirect register block.

Abstract the process of iterating over online CPUs & configuring the
other/redirect region to access their registers through a new
for_each_online_cpu_gic() macro and convert all usage sites over.

Signed-off-by: Paul Burton <paulburton@kernel.org>
Signed-off-by: Chao-ying Fu <cfu@wavecomp.com>
Signed-off-by: Dragan Mladjenovic <dragan.mladjenovic@syrmia.com>
Signed-off-by: Aleksandar Rikalo <arikalo@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Serge Semin <fancer.lancer@gmail.com>
Tested-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Link: https://lore.kernel.org/all/20241028175935.51250-2-arikalo@gmail.com

Author: paulburton

drivers/irqchip/irq-mips-gic.c

@@ -66,6 +66,44 @@ static struct gic_all_vpes_chip_data {
 	bool	mask;
 } gic_all_vpes_chip_data[GIC_NUM_LOCAL_INTRS];
 
+static int __gic_with_next_online_cpu(int prev)
+{
+	unsigned int cpu;
+
+	/* Discover the next online CPU */
+	cpu = cpumask_next(prev, cpu_online_mask);
+
+	/* If there isn't one, we're done */
+	if (cpu >= nr_cpu_ids)
+		return cpu;
+
+	/*
+	 * Move the access lock to the next CPU's GIC local register block.
+	 *
+	 * Set GIC_VL_OTHER. Since the caller holds gic_lock nothing can
+	 * clobber the written value.
+	 */
+	write_gic_vl_other(mips_cm_vp_id(cpu));
+
+	return cpu;
+}
+
+/**
+ * for_each_online_cpu_gic() - Iterate over online CPUs, access local registers
+ * @cpu: An integer variable to hold the current CPU number
+ * @gic_lock: A pointer to raw spin lock used as a guard
+ *
+ * Iterate over online CPUs & configure the other/redirect register region to
+ * access each CPUs GIC local register block, which can be accessed from the
+ * loop body using read_gic_vo_*() or write_gic_vo_*() accessor functions or
+ * their derivatives.
+ */
+#define for_each_online_cpu_gic(cpu, gic_lock)		\
+	guard(raw_spinlock_irqsave)(gic_lock);		\
+	for ((cpu) = __gic_with_next_online_cpu(-1);	\
+	     (cpu) < nr_cpu_ids;			\
+	     (cpu) = __gic_with_next_online_cpu(cpu))
+
 static void gic_clear_pcpu_masks(unsigned int intr)
 {
 	unsigned int i;
@@ -350,37 +388,27 @@ static struct irq_chip gic_local_irq_controller = {
 static void gic_mask_local_irq_all_vpes(struct irq_data *d)
 {
 	struct gic_all_vpes_chip_data *cd;
-	unsigned long flags;
 	int intr, cpu;
 
 	intr = GIC_HWIRQ_TO_LOCAL(d->hwirq);
 	cd = irq_data_get_irq_chip_data(d);
 	cd->mask = false;
 
-	raw_spin_lock_irqsave(&gic_lock, flags);
-	for_each_online_cpu(cpu) {
-		write_gic_vl_other(mips_cm_vp_id(cpu));
+	for_each_online_cpu_gic(cpu, &gic_lock)
 		write_gic_vo_rmask(BIT(intr));
-	}
-	raw_spin_unlock_irqrestore(&gic_lock, flags);
 }
 
 static void gic_unmask_local_irq_all_vpes(struct irq_data *d)
 {
 	struct gic_all_vpes_chip_data *cd;
-	unsigned long flags;
 	int intr, cpu;
 
 	intr = GIC_HWIRQ_TO_LOCAL(d->hwirq);
 	cd = irq_data_get_irq_chip_data(d);
 	cd->mask = true;
 
-	raw_spin_lock_irqsave(&gic_lock, flags);
-	for_each_online_cpu(cpu) {
-		write_gic_vl_other(mips_cm_vp_id(cpu));
+	for_each_online_cpu_gic(cpu, &gic_lock)
 		write_gic_vo_smask(BIT(intr));
-	}
-	raw_spin_unlock_irqrestore(&gic_lock, flags);
 }
 
 static void gic_all_vpes_irq_cpu_online(void)
@@ -469,7 +497,6 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int virq,
 			      irq_hw_number_t hwirq)
 {
 	struct gic_all_vpes_chip_data *cd;
-	unsigned long flags;
 	unsigned int intr;
 	int err, cpu;
 	u32 map;
@@ -533,12 +560,8 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int virq,
 	if (!gic_local_irq_is_routable(intr))
 		return -EPERM;
 
-	raw_spin_lock_irqsave(&gic_lock, flags);
-	for_each_online_cpu(cpu) {
-		write_gic_vl_other(mips_cm_vp_id(cpu));
+	for_each_online_cpu_gic(cpu, &gic_lock)
 		write_gic_vo_map(mips_gic_vx_map_reg(intr), map);
-	}
-	raw_spin_unlock_irqrestore(&gic_lock, flags);
 
 	return 0;
 }