linux-kernel - [PATCH 1/5] RISC-V: Add mechanism to provide custom IPI operations

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Date:   Thu, 21 May 2020 19:15:40 +0530
From:   Anup Patel <anup.patel@....com>
To:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Rob Herring <robh+dt@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Damien Le Moal <damien.lemoal@....com>,
        Atish Patra <atish.patra@....com>,
        Alistair Francis <Alistair.Francis@....com>,
        Anup Patel <anup@...infault.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, Anup Patel <anup.patel@....com>
Subject: [PATCH 1/5] RISC-V: Add mechanism to provide custom IPI operations

We add mechanism to set custom IPI operations so that CLINT driver
from drivers directory can provide custom IPI operations.

Signed-off-by: Anup Patel <anup.patel@....com>
---
 arch/riscv/include/asm/smp.h | 11 ++++++++
 arch/riscv/kernel/smp.c      | 52 ++++++++++++++++++++++++------------
 arch/riscv/kernel/smpboot.c  |  3 +--
 3 files changed, 47 insertions(+), 19 deletions(-)

diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
index 40bb1c15a731..ad0601260cb1 100644
--- a/arch/riscv/include/asm/smp.h
+++ b/arch/riscv/include/asm/smp.h
@@ -40,6 +40,17 @@ void arch_send_call_function_single_ipi(int cpu);
 int riscv_hartid_to_cpuid(int hartid);
 void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out);
 
+struct riscv_ipi_ops {
+	void (*ipi_inject)(const unsigned long *hart_mask);
+	void (*ipi_clear)(void);
+};
+
+/* Set custom IPI operations */
+void riscv_set_ipi_ops(struct riscv_ipi_ops *ops);
+
+/* Clear IPI for current CPU */
+void riscv_clear_ipi(void);
+
 /*
  * Obtains the hart ID of the currently executing task.  This relies on
  * THREAD_INFO_IN_TASK, but we define that unconditionally.
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index b1d4f452f843..8375cc5970f6 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -84,6 +84,35 @@ static void ipi_stop(void)
 		wait_for_interrupt();
 }
 
+#if IS_ENABLED(CONFIG_RISCV_SBI)
+static void clear_ipi(void)
+{
+	csr_clear(CSR_IP, IE_SIE);
+}
+
+static struct riscv_ipi_ops sbi_ipi_ops = {
+	.ipi_inject = sbi_send_ipi,
+	.ipi_clear = clear_ipi,
+};
+
+static struct riscv_ipi_ops *ipi_ops = &sbi_ipi_ops;
+#else
+static struct riscv_ipi_ops *ipi_ops;
+#endif
+
+void riscv_set_ipi_ops(struct riscv_ipi_ops *ops)
+{
+	ipi_ops = ops;
+}
+EXPORT_SYMBOL_GPL(riscv_set_ipi_ops);
+
+void riscv_clear_ipi(void)
+{
+	if (ipi_ops)
+		ipi_ops->ipi_clear();
+}
+EXPORT_SYMBOL_GPL(riscv_clear_ipi);
+
 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
 {
 	struct cpumask hartid_mask;
@@ -95,10 +124,9 @@ static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
 	smp_mb__after_atomic();
 
 	riscv_cpuid_to_hartid_mask(mask, &hartid_mask);
-	if (IS_ENABLED(CONFIG_RISCV_SBI))
-		sbi_send_ipi(cpumask_bits(&hartid_mask));
-	else
-		clint_send_ipi_mask(mask);
+
+	if (ipi_ops)
+		ipi_ops->ipi_inject(cpumask_bits(&hartid_mask));
 }
 
 static void send_ipi_single(int cpu, enum ipi_message_type op)
@@ -109,18 +137,8 @@ static void send_ipi_single(int cpu, enum ipi_message_type op)
 	set_bit(op, &ipi_data[cpu].bits);
 	smp_mb__after_atomic();
 
-	if (IS_ENABLED(CONFIG_RISCV_SBI))
-		sbi_send_ipi(cpumask_bits(cpumask_of(hartid)));
-	else
-		clint_send_ipi_single(hartid);
-}
-
-static inline void clear_ipi(void)
-{
-	if (IS_ENABLED(CONFIG_RISCV_SBI))
-		csr_clear(CSR_IP, IE_SIE);
-	else
-		clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
+	if (ipi_ops)
+		ipi_ops->ipi_inject(cpumask_bits(cpumask_of(hartid)));
 }
 
 void handle_IPI(struct pt_regs *regs)
@@ -131,7 +149,7 @@ void handle_IPI(struct pt_regs *regs)
 
 	irq_enter();
 
-	clear_ipi();
+	riscv_clear_ipi();
 
 	while (true) {
 		unsigned long ops;
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 4e9922790f6e..5fe849791bf0 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -147,8 +147,7 @@ asmlinkage __visible void smp_callin(void)
 {
 	struct mm_struct *mm = &init_mm;
 
-	if (!IS_ENABLED(CONFIG_RISCV_SBI))
-		clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
+	riscv_clear_ipi();
 
 	/* All kernel threads share the same mm context.  */
 	mmgrab(mm);
-- 
2.25.1