linux-kernel - [PATCH 09/10] irqchip: irq-mips-cpu: Rework software IRQ handling flow

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Message-Id: <20240616-b4-mips-ipi-improvements-v1-9-e332687f1692@flygoat.com>
Date: Sun, 16 Jun 2024 22:03:13 +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 09/10] irqchip: irq-mips-cpu: Rework software IRQ handling
 flow

Remove unnecessary irq_chip hooks for software interrupts,
and don't mask them in ack hook to match kernel's expectation
on handling flow.

Create a irq_chip for regular (non-MT) mode software interrupts
so they will be acked as well.

Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
---
 drivers/irqchip/irq-mips-cpu.c | 57 +++++++++++++++++++++++++++++-------------
 1 file changed, 39 insertions(+), 18 deletions(-)

diff --git a/drivers/irqchip/irq-mips-cpu.c b/drivers/irqchip/irq-mips-cpu.c
index 7b3501485d95..4854c06ce652 100644
--- a/drivers/irqchip/irq-mips-cpu.c
+++ b/drivers/irqchip/irq-mips-cpu.c
@@ -49,7 +49,21 @@ static inline void mask_mips_irq(struct irq_data *d)
 	irq_disable_hazard();
 }
 
-static struct irq_chip mips_cpu_irq_controller = {
+static unsigned int mips_sw_irq_startup(struct irq_data *d)
+{
+	clear_c0_cause(C_SW0 << d->hwirq);
+	back_to_back_c0_hazard();
+	unmask_mips_irq(d);
+	return 0;
+}
+
+static void mips_sw_irq_ack(struct irq_data *d)
+{
+	clear_c0_cause(C_SW0 << d->hwirq);
+	back_to_back_c0_hazard();
+}
+
+static const struct irq_chip mips_cpu_irq_controller = {
 	.name		= "MIPS",
 	.irq_ack	= mask_mips_irq,
 	.irq_mask	= mask_mips_irq,
@@ -60,11 +74,19 @@ static struct irq_chip mips_cpu_irq_controller = {
 	.irq_enable	= unmask_mips_irq,
 };
 
+static const struct irq_chip mips_cpu_sw_irq_controller = {
+	.name		= "MIPS",
+	.irq_startup	= mips_sw_irq_startup,
+	.irq_ack	= mips_sw_irq_ack,
+	.irq_mask	= mask_mips_irq,
+	.irq_unmask	= unmask_mips_irq,
+};
+
+#ifdef CONFIG_MIPS_MT
 /*
  * Basically the same as above but taking care of all the MT stuff
  */
-
-static unsigned int mips_mt_cpu_irq_startup(struct irq_data *d)
+static unsigned int mips_mt_sw_irq_startup(struct irq_data *d)
 {
 	unsigned int vpflags = dvpe();
 
@@ -76,14 +98,14 @@ static unsigned int mips_mt_cpu_irq_startup(struct irq_data *d)
 
 /*
  * While we ack the interrupt interrupts are disabled and thus we don't need
- * to deal with concurrency issues.  Same for mips_cpu_irq_end.
+ * to deal with concurrency issues.
  */
-static void mips_mt_cpu_irq_ack(struct irq_data *d)
+static void mips_mt_sw_irq_ack(struct irq_data *d)
 {
 	unsigned int vpflags = dvpe();
+
 	clear_c0_cause(C_SW0 << d->hwirq);
 	evpe(vpflags);
-	mask_mips_irq(d);
 }
 
 #ifdef CONFIG_GENERIC_IRQ_IPI
@@ -108,21 +130,17 @@ static void mips_mt_send_ipi(struct irq_data *d, unsigned int cpu)
 }
 
 #endif /* CONFIG_GENERIC_IRQ_IPI */
-
-static struct irq_chip mips_mt_cpu_irq_controller = {
+static const struct irq_chip mips_mt_cpu_irq_controller = {
 	.name		= "MIPS",
-	.irq_startup	= mips_mt_cpu_irq_startup,
-	.irq_ack	= mips_mt_cpu_irq_ack,
+	.irq_startup	= mips_mt_sw_irq_startup,
+	.irq_ack	= mips_mt_sw_irq_ack,
 	.irq_mask	= mask_mips_irq,
-	.irq_mask_ack	= mips_mt_cpu_irq_ack,
 	.irq_unmask	= unmask_mips_irq,
-	.irq_eoi	= unmask_mips_irq,
-	.irq_disable	= mask_mips_irq,
-	.irq_enable	= unmask_mips_irq,
 #ifdef CONFIG_GENERIC_IRQ_IPI
 	.ipi_send_single = mips_mt_send_ipi,
 #endif
 };
+#endif
 
 asmlinkage void __weak plat_irq_dispatch(void)
 {
@@ -152,11 +170,14 @@ asmlinkage void __weak plat_irq_dispatch(void)
 static int mips_cpu_intc_map(struct irq_domain *d, unsigned int irq,
 			     irq_hw_number_t hw)
 {
-	struct irq_chip *chip;
+	const struct irq_chip *chip;
 
-	if (hw < 2 && cpu_has_mipsmt) {
-		/* Software interrupts are used for MT/CMT IPI */
-		chip = &mips_mt_cpu_irq_controller;
+	if (hw < 2) {
+		chip = &mips_cpu_sw_irq_controller;
+#ifdef CONFIG_MIPS_MT
+		if (cpu_has_mipsmt)
+			chip = &mips_mt_cpu_irq_controller;
+#endif
 	} else {
 		chip = &mips_cpu_irq_controller;
 	}

-- 
2.43.0