RISC-V: Enable CPU_IDLE drivers

We force select CPU_PM and provide asm/cpuidle.h so that we can
use CPU IDLE drivers for Linux RISC-V kernel.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Anup Patel <apatel@vetanamicro.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 5adcbd9..76976d1 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -46,6 +46,7 @@ config RISCV
        select CLONE_BACKWARDS
        select CLINT_TIMER if !MMU
        select COMMON_CLK
+       select CPU_PM if CPU_IDLE
        select EDAC_SUPPORT
        select GENERIC_ARCH_TOPOLOGY if SMP
        select GENERIC_ATOMIC64 if !64BIT
@@ -547,4 +548,10 @@ source "kernel/power/Kconfig"
 
 endmenu
 
+menu "CPU Power Management"
+
+source "drivers/cpuidle/Kconfig"
+
+endmenu
+
 source "arch/riscv/kvm/Kconfig"

diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
index f120fcc..a5e0482 100644 (file)
--- a/arch/riscv/configs/defconfig
+++ b/arch/riscv/configs/defconfig
@@ -20,6 +20,7 @@ CONFIG_SOC_SIFIVE=y
 CONFIG_SOC_VIRT=y
 CONFIG_SMP=y
 CONFIG_HOTPLUG_CPU=y
+CONFIG_CPU_IDLE=y
 CONFIG_VIRTUALIZATION=y
 CONFIG_KVM=m
 CONFIG_JUMP_LABEL=y

diff --git a/arch/riscv/configs/rv32_defconfig b/arch/riscv/configs/rv32_defconfig
index 8b56a7f..d1b87db 100644 (file)
--- a/arch/riscv/configs/rv32_defconfig
+++ b/arch/riscv/configs/rv32_defconfig
@@ -20,6 +20,7 @@ CONFIG_SOC_VIRT=y
 CONFIG_ARCH_RV32I=y
 CONFIG_SMP=y
 CONFIG_HOTPLUG_CPU=y
+CONFIG_CPU_IDLE=y
 CONFIG_VIRTUALIZATION=y
 CONFIG_KVM=m
 CONFIG_JUMP_LABEL=y

diff --git a/arch/riscv/include/asm/cpuidle.h b/arch/riscv/include/asm/cpuidle.h
new file mode 100644 (file)
index 0000000..71fdc60
--- /dev/null
+++ b/arch/riscv/include/asm/cpuidle.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2021 Allwinner Ltd
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ */
+
+#ifndef _ASM_RISCV_CPUIDLE_H
+#define _ASM_RISCV_CPUIDLE_H
+
+#include <asm/barrier.h>
+#include <asm/processor.h>
+
+static inline void cpu_do_idle(void)
+{
+       /*
+        * Add mb() here to ensure that all
+        * IO/MEM accesses are completed prior
+        * to entering WFI.
+        */
+       mb();
+       wait_for_interrupt();
+}
+
+#endif

diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 03ac3aa..504b496 100644 (file)
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -23,6 +23,7 @@
 #include <asm/string.h>
 #include <asm/switch_to.h>
 #include <asm/thread_info.h>
+#include <asm/cpuidle.h>
 
 register unsigned long gp_in_global __asm__("gp");
 
@@ -37,7 +38,7 @@ extern asmlinkage void ret_from_kernel_thread(void);
 
 void arch_cpu_idle(void)
 {
-       wait_for_interrupt();
+       cpu_do_idle();
        raw_local_irq_enable();
 }