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[76.210.143.223]) by smtp.gmail.com with ESMTPSA id l9sm10244020pgg.29.2020.09.14.15.08.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Sep 2020 15:08:35 -0700 (PDT) Date: Mon, 14 Sep 2020 15:08:35 -0700 (PDT) X-Google-Original-Date: Mon, 14 Sep 2020 15:08:31 PDT (-0700) Subject: Re: [PATCH] cpuidle: add riscv cpuidle driver In-Reply-To: <1600048323-2964-1-git-send-email-liush@allwinnertech.com> CC: Paul Walmsley , aou@eecs.berkeley.edu, rjw@rjwysocki.net, daniel.lezcano@linaro.org, Anup Patel , Atish Patra , Damien Le Moal , wangkefeng.wang@huawei.com, kernel@esmil.dk, zong.li@sifive.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, liush@allwinnertech.com From: Palmer Dabbelt To: liush@allwinnertech.com Message-ID: Mime-Version: 1.0 (MHng) Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Sun, 13 Sep 2020 18:52:03 PDT (-0700), liush@allwinnertech.com wrote: > This patch adds a cpuidle driver for systems based RISCV architecture. > This patch supports state WFI. Other states will be supported in the > future. > > Signed-off-by: liush > --- > arch/riscv/Kconfig | 7 +++++ > arch/riscv/include/asm/cpuidle.h | 7 +++++ > arch/riscv/kernel/Makefile | 1 + > arch/riscv/kernel/cpuidle.c | 8 ++++++ > drivers/cpuidle/Kconfig | 5 ++++ > drivers/cpuidle/Kconfig.riscv | 11 ++++++++ > drivers/cpuidle/Makefile | 4 +++ > drivers/cpuidle/cpuidle-riscv.c | 55 ++++++++++++++++++++++++++++++++++++++++ > 8 files changed, 98 insertions(+) > create mode 100644 arch/riscv/include/asm/cpuidle.h > create mode 100644 arch/riscv/kernel/cpuidle.c > create mode 100644 drivers/cpuidle/Kconfig.riscv > create mode 100644 drivers/cpuidle/cpuidle-riscv.c > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index df18372..c7ddb9d 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -86,6 +86,7 @@ config RISCV > select SPARSE_IRQ > select SYSCTL_EXCEPTION_TRACE > select THREAD_INFO_IN_TASK > + select CPU_IDLE > > config ARCH_MMAP_RND_BITS_MIN > default 18 if 64BIT > @@ -407,6 +408,12 @@ config BUILTIN_DTB > depends on RISCV_M_MODE > depends on OF > > +menu "CPU Power Management" > + > +source "drivers/cpuidle/Kconfig" > + > +endmenu > + > menu "Power management options" > > source "kernel/power/Kconfig" > diff --git a/arch/riscv/include/asm/cpuidle.h b/arch/riscv/include/asm/cpuidle.h > new file mode 100644 > index 00000000..2599d2f > --- /dev/null > +++ b/arch/riscv/include/asm/cpuidle.h > @@ -0,0 +1,7 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef __RISCV_CPUIDLE_H > +#define __RISCV_CPUIDLE_H > + > +extern void cpu_do_idle(void); > + > +#endif > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile > index dc93710..396ba9c 100644 > --- a/arch/riscv/kernel/Makefile > +++ b/arch/riscv/kernel/Makefile > @@ -29,6 +29,7 @@ obj-y += riscv_ksyms.o > obj-y += stacktrace.o > obj-y += cacheinfo.o > obj-y += patch.o > +obj-y += cpuidle.o Presumably we want this to be a Kconfig option, if only to avoid excess size on the smaller systems? > obj-$(CONFIG_MMU) += vdso.o vdso/ > > obj-$(CONFIG_RISCV_M_MODE) += traps_misaligned.o > diff --git a/arch/riscv/kernel/cpuidle.c b/arch/riscv/kernel/cpuidle.c > new file mode 100644 > index 00000000..a3289e7 > --- /dev/null > +++ b/arch/riscv/kernel/cpuidle.c > @@ -0,0 +1,8 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#include > + > +void cpu_do_idle(void) > +{ > + __asm__ __volatile__ ("wfi"); > + We have wait_for_interrupt() that does this already, but it's one line so it doesn't really matter. Either way, there's an extra newline here. Additionally, we have arch_cpu_idle() which is calling cpu_do_idle() on other platforms. Presumably we should be doing something similar, under the assumption that we will eventually have cpu_do_idle() hook into CPU idle drivers here? > +} > diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig > index c0aeedd..f6be0fd 100644 > --- a/drivers/cpuidle/Kconfig > +++ b/drivers/cpuidle/Kconfig > @@ -62,6 +62,11 @@ depends on PPC > source "drivers/cpuidle/Kconfig.powerpc" > endmenu > > +menu "RISCV CPU Idle Drivers" > +depends on RISCV > +source "drivers/cpuidle/Kconfig.riscv" > +endmenu > + > config HALTPOLL_CPUIDLE > tristate "Halt poll cpuidle driver" > depends on X86 && KVM_GUEST > diff --git a/drivers/cpuidle/Kconfig.riscv b/drivers/cpuidle/Kconfig.riscv > new file mode 100644 > index 00000000..e86d36b > --- /dev/null > +++ b/drivers/cpuidle/Kconfig.riscv > @@ -0,0 +1,11 @@ > +# SPDX-License-Identifier: GPL-2.0-only > +# > +# RISCV CPU Idle drivers > +# > +config RISCV_CPUIDLE > + bool "Generic RISCV CPU idle Driver" > + select DT_IDLE_STATES > + select CPU_IDLE_MULTIPLE_DRIVERS Looks like there's some space/tab issues here. IIRC checkpatch will catch this sort of thing. > + help > + Select this option to enable generic cpuidle driver for RISCV. > + Now only support C0 State. > diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile > index 26bbc5e..4c83c4e 100644 > --- a/drivers/cpuidle/Makefile > +++ b/drivers/cpuidle/Makefile > @@ -34,3 +34,7 @@ obj-$(CONFIG_MIPS_CPS_CPUIDLE) += cpuidle-cps.o > # POWERPC drivers > obj-$(CONFIG_PSERIES_CPUIDLE) += cpuidle-pseries.o > obj-$(CONFIG_POWERNV_CPUIDLE) += cpuidle-powernv.o > + > +############################################################################### > +# RISCV drivers > +obj-$(CONFIG_RISCV_CPUIDLE) += cpuidle-riscv.o > diff --git a/drivers/cpuidle/cpuidle-riscv.c b/drivers/cpuidle/cpuidle-riscv.c > new file mode 100644 > index 00000000..5dddcfa > --- /dev/null > +++ b/drivers/cpuidle/cpuidle-riscv.c > @@ -0,0 +1,55 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * RISC-V CPU idle driver. > + * > + * Copyright (C) 2020-2022 Allwinner Ltd > + * > + * Based on code - driver/cpuidle/cpuidle-at91.c > + * > + */ > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define MAX_IDLE_STATES 1 > + > +/* TODO: Implement deeper idle states */ > +static int riscv_low_level_suspend_enter(int state) > +{ > + return 0; As far as I can tell, this driver just doesn't do anything? Assuming that's the case, it's probably best to just drop everything but cpu_do_idle() until we have something to exercise this. > +} > + > +/* Actual code that puts the SoC in different idle states */ > +static int riscv_enter_idle(struct cpuidle_device *dev, > + struct cpuidle_driver *drv, > + int index) > +{ > + return CPU_PM_CPU_IDLE_ENTER_PARAM(riscv_low_level_suspend_enter, > + index, 0); > +} > + > +static struct cpuidle_driver riscv_idle_driver = { > + .name = "riscv_idle", > + .owner = THIS_MODULE, > + .states[0] = { > + .enter = riscv_enter_idle, > + .exit_latency = 1, > + .target_residency = 1, > + .name = "WFI", > + .desc = "RISCV WFI", > + }, > + .state_count = MAX_IDLE_STATES, > +}; > + > +static int __init riscv_cpuidle_init(void) > +{ > + return cpuidle_register(&riscv_idle_driver, NULL); > +} > + > +device_initcall(riscv_cpuidle_init);