linux-kernel - [PATCH 04/12] irqchip: mips-gic: Support multi-cluster in gic_with_each_online

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Date:   Thu, 19 May 2022 20:51:17 +0200
From:   Dragan Mladjenovic <Dragan.Mladjenovic@...mia.com>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     Paul Burton <paulburton@...nel.org>,
        Serge Semin <fancer.lancer@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org, Chao-ying Fu <cfu@...ecomp.com>
Subject: [PATCH 04/12] irqchip: mips-gic: Support multi-cluster in gic_with_each_online_cpu()

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

Introduce support for multi-cluster GIC register access in
__gic_with_next_online_cpu(), and therefore in its user
gic_with_each_online_cpu(). We access registers in remote clusters using
the CM's GCR_CL_REDIRECT register, and so here we delegate to
mips_cm_lock_other() in order to configure this access.

With this done, users of gic_with_each_online_cpu() gain support for
multi-cluster with no further changes.

Signed-off-by: Paul Burton <paulburton@...nel.org>
Signed-off-by: Chao-ying Fu <cfu@...ecomp.com>

diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index 4872bebe24cf..89a3c6d04e09 100644
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c
@@ -69,6 +69,20 @@ static int __gic_with_next_online_cpu(int prev)
 {
 	unsigned int cpu;
 
+	/*
+	 * Unlock access to the previous CPU's GIC local register block.
+	 *
+	 * Delegate to the CM locking code in the multi-cluster case, since
+	 * other clusters can only be accessed using GCR_CL_REDIRECT.
+	 *
+	 * In the single cluster case we don't need to do anything; the caller
+	 * is responsible for maintaining gic_lock & nothing should be
+	 * expecting any particular value of GIC_VL_OTHER so we can leave it
+	 * as-is.
+	 */
+	if ((prev != -1) && mips_cps_multicluster_cpus())
+		mips_cm_unlock_other();
+
 	/* Discover the next online CPU */
 	cpu = cpumask_next(prev, cpu_online_mask);
 
@@ -79,10 +93,16 @@ static int __gic_with_next_online_cpu(int prev)
 	/*
 	 * Lock access to the next CPU's GIC local register block.
 	 *
+	 * Delegate to the CM locking code in the multi-cluster case, since
+	 * other clusters can only be accessed using GCR_CL_REDIRECT.
+	 *
 	 * In the single cluster case we simply set GIC_VL_OTHER. The caller
 	 * holds gic_lock so nothing can clobber the value we write.
 	 */
-	write_gic_vl_other(mips_cm_vp_id(cpu));
+	if (mips_cps_multicluster_cpus())
+		mips_cm_lock_other_cpu(cpu, CM_GCR_Cx_OTHER_BLOCK_LOCAL);
+	else
+		write_gic_vl_other(mips_cm_vp_id(cpu));
 
 	return cpu;
 }
-- 
2.17.1