[RFC PATCH v4 1/8] RISC-V: Enable CPU_IDLE drivers

From: Anup Patel
Date: Mon May 17 2021 - 09:09:40 EST


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@xxxxxxx>
---
arch/riscv/Kconfig | 7 +++++++
arch/riscv/configs/defconfig | 12 +++++-------
arch/riscv/configs/rv32_defconfig | 5 ++---
arch/riscv/include/asm/cpuidle.h | 24 ++++++++++++++++++++++++
arch/riscv/kernel/process.c | 3 ++-
5 files changed, 40 insertions(+), 11 deletions(-)
create mode 100644 arch/riscv/include/asm/cpuidle.h

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 195c6d319ab8..f607fd33014f 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -42,6 +42,7 @@ 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
@@ -555,4 +556,10 @@ source "kernel/power/Kconfig"

endmenu

+menu "CPU Power Management"
+
+source "drivers/cpuidle/Kconfig"
+
+endmenu
+
source "drivers/firmware/Kconfig"
diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
index 1f2be234b11c..57a24d40d43f 100644
--- a/arch/riscv/configs/defconfig
+++ b/arch/riscv/configs/defconfig
@@ -13,12 +13,14 @@ CONFIG_USER_NS=y
CONFIG_CHECKPOINT_RESTORE=y
CONFIG_BLK_DEV_INITRD=y
CONFIG_EXPERT=y
+# CONFIG_SYSFS_SYSCALL is not set
CONFIG_BPF_SYSCALL=y
+CONFIG_SOC_MICROCHIP_POLARFIRE=y
CONFIG_SOC_SIFIVE=y
CONFIG_SOC_VIRT=y
-CONFIG_SOC_MICROCHIP_POLARFIRE=y
CONFIG_SMP=y
CONFIG_HOTPLUG_CPU=y
+CONFIG_CPU_IDLE=y
CONFIG_JUMP_LABEL=y
CONFIG_MODULES=y
CONFIG_MODULE_UNLOAD=y
@@ -66,10 +68,9 @@ CONFIG_HW_RANDOM=y
CONFIG_HW_RANDOM_VIRTIO=y
CONFIG_SPI=y
CONFIG_SPI_SIFIVE=y
+# CONFIG_PTP_1588_CLOCK is not set
CONFIG_GPIOLIB=y
CONFIG_GPIO_SIFIVE=y
-# CONFIG_PTP_1588_CLOCK is not set
-CONFIG_POWER_RESET=y
CONFIG_DRM=y
CONFIG_DRM_RADEON=y
CONFIG_DRM_VIRTIO_GPU=y
@@ -83,10 +84,10 @@ CONFIG_USB_OHCI_HCD=y
CONFIG_USB_OHCI_HCD_PLATFORM=y
CONFIG_USB_STORAGE=y
CONFIG_USB_UAS=y
+CONFIG_MMC=y
CONFIG_MMC_SDHCI=y
CONFIG_MMC_SDHCI_PLTFM=y
CONFIG_MMC_SDHCI_CADENCE=y
-CONFIG_MMC=y
CONFIG_MMC_SPI=y
CONFIG_RTC_CLASS=y
CONFIG_VIRTIO_PCI=y
@@ -135,6 +136,3 @@ CONFIG_RCU_EQS_DEBUG=y
CONFIG_DEBUG_BLOCK_EXT_DEVT=y
# CONFIG_FTRACE is not set
# CONFIG_RUNTIME_TESTING_MENU is not set
-CONFIG_MEMTEST=y
-# CONFIG_SYSFS_SYSCALL is not set
-CONFIG_EFI=y
diff --git a/arch/riscv/configs/rv32_defconfig b/arch/riscv/configs/rv32_defconfig
index 8dd02b842fef..97d899df2445 100644
--- a/arch/riscv/configs/rv32_defconfig
+++ b/arch/riscv/configs/rv32_defconfig
@@ -13,12 +13,14 @@ CONFIG_USER_NS=y
CONFIG_CHECKPOINT_RESTORE=y
CONFIG_BLK_DEV_INITRD=y
CONFIG_EXPERT=y
+# CONFIG_SYSFS_SYSCALL is not set
CONFIG_BPF_SYSCALL=y
CONFIG_SOC_SIFIVE=y
CONFIG_SOC_VIRT=y
CONFIG_ARCH_RV32I=y
CONFIG_SMP=y
CONFIG_HOTPLUG_CPU=y
+CONFIG_CPU_IDLE=y
CONFIG_JUMP_LABEL=y
CONFIG_MODULES=y
CONFIG_MODULE_UNLOAD=y
@@ -67,7 +69,6 @@ CONFIG_HW_RANDOM_VIRTIO=y
CONFIG_SPI=y
CONFIG_SPI_SIFIVE=y
# CONFIG_PTP_1588_CLOCK is not set
-CONFIG_POWER_RESET=y
CONFIG_DRM=y
CONFIG_DRM_RADEON=y
CONFIG_DRM_VIRTIO_GPU=y
@@ -130,5 +131,3 @@ CONFIG_RCU_EQS_DEBUG=y
CONFIG_DEBUG_BLOCK_EXT_DEVT=y
# CONFIG_FTRACE is not set
# CONFIG_RUNTIME_TESTING_MENU is not set
-CONFIG_MEMTEST=y
-# CONFIG_SYSFS_SYSCALL is not set
diff --git a/arch/riscv/include/asm/cpuidle.h b/arch/riscv/include/asm/cpuidle.h
new file mode 100644
index 000000000000..71fdc607d4bc
--- /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 f9cd57c9c67d..461520222589 100644
--- 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();
}

--
2.25.1