linux-kernel - [PATCH v4 02/10] MIPS: smp: Manage IPI interrupts as percpu

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Message-Id: <20240907-b4-mips-ipi-improvements-v4-2-ac288f9aff0b@flygoat.com>
Date: Sat, 07 Sep 2024 12:48:08 +0100
From: Jiaxun Yang <jiaxun.yang@...goat.com>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
 Florian Fainelli <florian.fainelli@...adcom.com>, 
 Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, 
 Huacai Chen <chenhuacai@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, 
 Serge Semin <fancer.lancer@...il.com>, Paul Burton <paulburton@...nel.org>
Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Jiaxun Yang <jiaxun.yang@...goat.com>
Subject: [PATCH v4 02/10] MIPS: smp: Manage IPI interrupts as percpu_devid
 interrupts

IPI interrupts need to be enabled when a new CPU coming up.

Manage them as percpu_devid interrupts and invoke enable/disable
functions at appropriate time to perform enabling as required,
similar to what RISC-V and Arm doing.

This is required by generic IPI-Mux and some IPI drivers.

Tested-by: Serge Semin <fancer.lancer@...il.com>
Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
---
 arch/mips/include/asm/ipi.h | 11 +++++++++++
 arch/mips/kernel/smp-cps.c  |  1 +
 arch/mips/kernel/smp.c      | 26 ++++++++++++++++++++++++--
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/arch/mips/include/asm/ipi.h b/arch/mips/include/asm/ipi.h
index df7a0ac4227a..88b507339f51 100644
--- a/arch/mips/include/asm/ipi.h
+++ b/arch/mips/include/asm/ipi.h
@@ -29,6 +29,17 @@ int mips_smp_ipi_allocate(const struct cpumask *mask);
  * Return 0 on success.
  */
 int mips_smp_ipi_free(const struct cpumask *mask);
+
+void mips_smp_ipi_enable(void);
+void mips_smp_ipi_disable(void);
+#else
+static inline void mips_smp_ipi_enable(void)
+{
+}
+
+static inline void mips_smp_ipi_disable(void)
+{
+}
 #endif /* CONFIG_GENERIC_IRQ_IPI */
 #endif /* CONFIG_SMP */
 #endif
diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
index b7bcbc4770f2..6845884086f4 100644
--- a/arch/mips/kernel/smp-cps.c
+++ b/arch/mips/kernel/smp-cps.c
@@ -555,6 +555,7 @@ static int cps_cpu_disable(void)
 	smp_mb__after_atomic();
 	set_cpu_online(cpu, false);
 	calculate_cpu_foreign_map();
+	mips_smp_ipi_disable();
 	irq_migrate_all_off_this_cpu();
 
 	return 0;
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 62be2ca9f990..9918bf341ffd 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -186,6 +186,7 @@ irq_handler_t ipi_handlers[IPI_MAX] __read_mostly = {
 };
 
 #ifdef CONFIG_GENERIC_IRQ_IPI
+static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev);
 static int ipi_virqs[IPI_MAX] __ro_after_init;
 static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly;
 
@@ -225,13 +226,29 @@ void mips_smp_send_ipi_mask(const struct cpumask *mask,
 	local_irq_restore(flags);
 }
 
+void mips_smp_ipi_enable(void)
+{
+	int i;
+
+	for (i = 0; i < IPI_MAX; i++)
+		enable_percpu_irq(ipi_virqs[i], IRQ_TYPE_NONE);
+}
+
+void mips_smp_ipi_disable(void)
+{
+	int i;
+
+	for (i = 0; i < IPI_MAX; i++)
+		disable_percpu_irq(ipi_virqs[i]);
+}
+
 static void smp_ipi_init_one(unsigned int virq, const char *name,
 			     irq_handler_t handler)
 {
 	int ret;
 
-	irq_set_handler(virq, handle_percpu_irq);
-	ret = request_irq(virq, handler, IRQF_PERCPU, name, NULL);
+	irq_set_percpu_devid(virq);
+	ret = request_percpu_irq(virq, handler, "IPI", &ipi_dummy_dev);
 	BUG_ON(ret);
 }
 
@@ -343,6 +360,9 @@ static int __init mips_smp_ipi_init(void)
 			return -ENODEV;
 	}
 
+	/* Enable IPI for Boot CPU */
+	mips_smp_ipi_enable();
+
 	return 0;
 }
 early_initcall(mips_smp_ipi_init);
@@ -383,6 +403,8 @@ asmlinkage void start_secondary(void)
 
 	synchronise_count_slave(cpu);
 
+	mips_smp_ipi_enable();
+
 	/* The CPU is running and counters synchronised, now mark it online */
 	set_cpu_online(cpu, true);
 

-- 
2.46.0