[PATCH v6 5/7] drivers: cpuidle: CPU idle ARM64 driver
Ashwin Chaugule
ashwin.chaugule at linaro.org
Wed Jul 23 09:34:57 PDT 2014
On 21 July 2014 12:06, Lorenzo Pieralisi <lorenzo.pieralisi at arm.com> 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 does save the CPU context and executes
> 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.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> ---
> drivers/cpuidle/Kconfig | 5 ++
> drivers/cpuidle/Kconfig.arm64 | 14 +++++
> drivers/cpuidle/Makefile | 4 ++
> drivers/cpuidle/cpuidle-arm64.c | 128 ++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 151 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 414e7a96..ebf0c2e 100644
> --- a/drivers/cpuidle/Kconfig
> +++ b/drivers/cpuidle/Kconfig
> @@ -43,6 +43,11 @@ 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 b27a062..706cb7f 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..1aeb426
> --- /dev/null
> +++ b/drivers/cpuidle/cpuidle-arm64.c
> @@ -0,0 +1,128 @@
> +/*
> + * ARM64 generic CPU idle driver.
> + *
> + * Copyright (C) 2014 ARM Ltd.
> + * Author: Lorenzo Pieralisi <lorenzo.pieralisi at 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)
> +{
> + int ret;
> +
> + if (!idx) {
> + cpu_do_idle();
> + return idx;
> + }
> +
> + ret = cpu_pm_enter();
> + if (!ret) {
> + /*
> + * Pass idle state index to cpu_suspend which in turn will
> + * call the CPU ops suspend protocol with idle index as a
> + * parameter.
> + */
> + ret = cpu_suspend(idx);
> +
> + cpu_pm_exit();
> + }
> +
> + return ret ? -1 : idx;
> +}
> +
> +struct cpuidle_driver arm64_idle_driver = {
> + .name = "arm64_idle",
> + .owner = THIS_MODULE,
> + /*
> + * State at index 0 is standby wfi and considered standard
> + * on all ARM platforms. If in some platforms simple wfi
> + * can't be used as "state 0", DT bindings must be implemented
> + * to work around this issue and allow installing a special
> + * handler for idle state index 0.
> + */
> + .states[0] = {
> + .enter = arm_enter_idle_state,
> + .exit_latency = 1,
> + .target_residency = 1,
> + .power_usage = UINT_MAX,
> + .flags = CPUIDLE_FLAG_TIME_VALID,
> + .name = "WFI",
> + .desc = "ARM64 WFI",
> + }
> +};
> +
> +/*
> + * arm64_idle_init
> + *
> + * Registers the arm64 specific cpuidle driver with the cpuidle
> + * framework. It relies on core code to parse the idle states
> + * and initialize them using driver data structures accordingly.
> + */
> +static int __init arm64_idle_init(void)
> +{
> + int i, ret;
> + struct cpuidle_driver *drv = &arm64_idle_driver;
> +
> + drv->cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
> + if (!drv->cpumask)
> + return -ENOMEM;
> +
> + cpumask_copy(drv->cpumask, cpu_possible_mask);
> + /*
> + * Start at index 1, request idle state nodes to be filled
> + */
> + ret = dt_init_idle_driver(drv, 1);
> + if (ret)
> + goto free_mem;
> + /*
> + * Call arch CPU operations in order to initialize
> + * idle states suspend back-end specific data
> + */
> + for_each_cpu(i, drv->cpumask) {
> + ret = cpu_init_idle(i);
> + if (ret)
> + goto free_mem;
> + }
> +
> + for (i = 1; i < drv->state_count; i++)
> + drv->states[i].enter = arm_enter_idle_state;
> +
> + ret = cpuidle_register(drv, NULL);
> + if (ret)
> + goto free_mem;
> +
> + return 0;
> +free_mem:
> + kfree(drv->cpumask);
> + return ret;
> +}
> +device_initcall(arm64_idle_init);
> --
> 1.9.1
>
>
>
Reviewed-by: Ashwin Chaugule <ashwin.chaugule at linaro.org>
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