linux-kernel - [PATCH v6 1/9] irqchip/mips-gic: Introduce for_each_online_cpu

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Message-Id: <20240912093051.452172-2-arikalo@gmail.com>
Date: Thu, 12 Sep 2024 11:30:43 +0200
From: Aleksandar Rikalo <arikalo@...il.com>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: Aleksandar Rikalo <arikalo@...il.com>,
	Chao-ying Fu <cfu@...ecomp.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Greg Ungerer <gerg@...nel.org>,
	Hauke Mehrtens <hauke@...ke-m.de>,
	Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>,
	Jiaxun Yang <jiaxun.yang@...goat.com>,
	linux-kernel@...r.kernel.org,
	linux-mips@...r.kernel.org,
	Marc Zyngier <maz@...nel.org>,
	Paul Burton <paulburton@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Serge Semin <fancer.lancer@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tiezhu Yang <yangtiezhu@...ngson.cn>
Subject: [PATCH v6 1/9] irqchip/mips-gic: Introduce for_each_online_cpu_gic()

From: Paul Burton <paulburton@...nel.org>

Parts of code in the MIPS GIC driver operate on the GIC local register
block for each online CPU, accessing each 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.

Signed-off-by: Paul Burton <paulburton@...nel.org>
Signed-off-by: Chao-ying Fu <cfu@...ecomp.com>
Signed-off-by: Dragan Mladjenovic <dragan.mladjenovic@...mia.com>
Signed-off-by: Aleksandar Rikalo <arikalo@...il.com>
Tested-by: Serge Semin <fancer.lancer@...il.com>
---
 drivers/irqchip/irq-mips-gic.c | 59 +++++++++++++++++++++++-----------
 1 file changed, 41 insertions(+), 18 deletions(-)

diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index 76253e864f23..6c7a7d2f0438 100644
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/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;
 }
-- 
2.25.1