Re: [PATCH v7 6/8] drivers: cpuidle: CPU idle ARM64 driver

Lorenzo Pieralisi
2014-08-18T22:30:30Z

On Mon, Aug 18, 2014 at 03:21:43PM +0100, Catalin Marinas wrote:
> On Wed, Aug 13, 2014 at 04:52:05PM +0100, Lorenzo Pieralisi wrote:
> > This patch implements a generic CPU idle driver for ARM64 machines.
> >
> > It relies on the DT idle states infrastructure to initialize idle
> > states count and respective parameters. Current code assumes the driver
> > is managing idle states on all possible CPUs but can be easily
> > generalized to support heterogenous systems and build cpumasks at
> > runtime using MIDRs or DT cpu nodes compatible properties.
> >
> > The driver relies on the arm64 CPU operations to call the idle
> > initialization hook used to parse and save suspend back-end specific
> > idle states information upon probing.
> >
> > Idle state index 0 is always initialized as a simple wfi state, ie always
> > considered present and functional on all ARM64 platforms.
> >
> > Idle state indices higher than 0 trigger idle state entry by calling
> > the cpu_suspend function, that triggers the suspend operation through
> > the CPU operations suspend back-end hook. cpu_suspend passes the idle
> > state index as a parameter so that the CPU operations suspend back-end
> > can retrieve the required idle state data by using the idle state
> > index to execute a look-up on its internal data structures.
> >
> > Reviewed-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > ---
> > drivers/cpuidle/Kconfig | 5 ++
> > drivers/cpuidle/Kconfig.arm64 | 14 +++++
> > drivers/cpuidle/Makefile | 4 ++
> > drivers/cpuidle/cpuidle-arm64.c | 131 ++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 154 insertions(+)
> > create mode 100644 drivers/cpuidle/Kconfig.arm64
> > create mode 100644 drivers/cpuidle/cpuidle-arm64.c
> >
> > diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
> > index 8deb934..c5029c1 100644
> > --- a/drivers/cpuidle/Kconfig
> > +++ b/drivers/cpuidle/Kconfig
> > @@ -33,6 +33,11 @@ depends on ARM
> > source "drivers/cpuidle/Kconfig.arm"
> > endmenu
> >
> > +menu "ARM64 CPU Idle Drivers"
> > +depends on ARM64
> > +source "drivers/cpuidle/Kconfig.arm64"
> > +endmenu
> > +
> > menu "MIPS CPU Idle Drivers"
> > depends on MIPS
> > source "drivers/cpuidle/Kconfig.mips"
> > diff --git a/drivers/cpuidle/Kconfig.arm64 b/drivers/cpuidle/Kconfig.arm64
> > new file mode 100644
> > index 0000000..d0a08ed
> > --- /dev/null
> > +++ b/drivers/cpuidle/Kconfig.arm64
> > @@ -0,0 +1,14 @@
> > +#
> > +# ARM64 CPU Idle drivers
> > +#
> > +
> > +config ARM64_CPUIDLE
> > + bool "Generic ARM64 CPU idle Driver"
> > + select ARM64_CPU_SUSPEND
> > + select DT_IDLE_STATES
> > + help
> > + Select this to enable generic cpuidle driver for ARM64.
> > + It provides a generic idle driver whose idle states are configured
> > + at run-time through DT nodes. The CPUidle suspend backend is
> > + initialized by calling the CPU operations init idle hook
> > + provided by architecture code.
> > diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
> > index 002b653..4d177b9 100644
> > --- a/drivers/cpuidle/Makefile
> > +++ b/drivers/cpuidle/Makefile
> > @@ -23,6 +23,10 @@ obj-$(CONFIG_ARM_EXYNOS_CPUIDLE) += cpuidle-exynos.o
> > obj-$(CONFIG_MIPS_CPS_CPUIDLE) += cpuidle-cps.o
> >
> > ###############################################################################
> > +# ARM64 drivers
> > +obj-$(CONFIG_ARM64_CPUIDLE) += cpuidle-arm64.o
> > +
> > +###############################################################################
> > # POWERPC drivers
> > obj-$(CONFIG_PSERIES_CPUIDLE) += cpuidle-pseries.o
> > obj-$(CONFIG_POWERNV_CPUIDLE) += cpuidle-powernv.o
> > diff --git a/drivers/cpuidle/cpuidle-arm64.c b/drivers/cpuidle/cpuidle-arm64.c
> > new file mode 100644
> > index 0000000..25ec622
> > --- /dev/null
> > +++ b/drivers/cpuidle/cpuidle-arm64.c
> > @@ -0,0 +1,131 @@
> > +/*
> > + * ARM64 generic CPU idle driver.
> > + *
> > + * Copyright (C) 2014 ARM Ltd.
> > + * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + */
> > +
> > +#define pr_fmt(fmt) "CPUidle arm64: " fmt
> > +
> > +#include <linux/cpuidle.h>
> > +#include <linux/cpumask.h>
> > +#include <linux/cpu_pm.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/slab.h>
> > +
> > +#include <asm/cpuidle.h>
> > +#include <asm/suspend.h>
> > +
> > +#include "dt_idle_states.h"
> > +
> > +/*
> > + * arm_enter_idle_state - Programs CPU to enter the specified state
> > + *
> > + * dev: cpuidle device
> > + * drv: cpuidle driver
> > + * idx: state index
> > + *
> > + * Called from the CPUidle framework to program the device to the
> > + * specified target state selected by the governor.
> > + */
> > +static int arm_enter_idle_state(struct cpuidle_device *dev,
> > + struct cpuidle_driver *drv, int idx)
>
> Nitpick: for consistency, I would either prefix it arm64 or drop the
> prefix entirely (it's a static function anyway).

Yes, that's right I will prefix it with arm64.

> > +struct cpuidle_driver arm64_idle_driver = {
>
> Should this be static?

Yes it should, I missed that, thanks.

> Otherwise:
>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Thank you !
Lorenzo