[RFC PATCH 1/8] ARM: Add commonly used cpuidle init code
Rob Herring
robherring2 at gmail.com
Tue Dec 6 10:06:57 EST 2011
On 12/05/2011 10:38 PM, Robert Lee wrote:
> Add commonly used cpuidle init code to avoid unecessary duplication.
>
> Signed-off-by: Robert Lee <rob.lee at linaro.org>
> ---
> arch/arm/common/Makefile | 1 +
> arch/arm/common/cpuidle.c | 132 ++++++++++++++++++++++++++++++++++++++++
> arch/arm/include/asm/cpuidle.h | 25 ++++++++
Why not move cpuidle drivers to drivers/idle/ ?
> 3 files changed, 158 insertions(+), 0 deletions(-)
> create mode 100644 arch/arm/common/cpuidle.c
> create mode 100644 arch/arm/include/asm/cpuidle.h
>
> diff --git a/arch/arm/common/Makefile b/arch/arm/common/Makefile
> index 6ea9b6f..0865f69 100644
> --- a/arch/arm/common/Makefile
> +++ b/arch/arm/common/Makefile
> @@ -17,3 +17,4 @@ obj-$(CONFIG_ARCH_IXP2000) += uengine.o
> obj-$(CONFIG_ARCH_IXP23XX) += uengine.o
> obj-$(CONFIG_PCI_HOST_ITE8152) += it8152.o
> obj-$(CONFIG_ARM_TIMER_SP804) += timer-sp.o
> +obj-$(CONFIG_CPU_IDLE) += cpuidle.o
> diff --git a/arch/arm/common/cpuidle.c b/arch/arm/common/cpuidle.c
> new file mode 100644
> index 0000000..e9a46a3
> --- /dev/null
> +++ b/arch/arm/common/cpuidle.c
> @@ -0,0 +1,132 @@
> +/*
> + * Copyright 2011 Freescale Semiconductor, Inc.
> + * Copyright 2011 Linaro Ltd.
> + *
> + * The code contained herein is licensed under the GNU General Public
> + * License. You may obtain a copy of the GNU General Public License
> + * Version 2 or later at the following locations:
> + *
> + * http://www.opensource.org/licenses/gpl-license.html
> + * http://www.gnu.org/copyleft/gpl.html
> + */
> +
> +/*
> + * This code performs provides some commonly used cpuidle setup functionality
> + * used by many ARM SoC platforms. Providing this functionality here
> + * reduces the duplication of this code for each ARM platform that uses it.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/io.h>
> +#include <linux/cpuidle.h>
> +#include <linux/hrtimer.h>
> +#include <linux/err.h>
> +#include <asm/cpuidle.h>
> +#include <asm/proc-fns.h>
> +
> +static struct cpuidle_device __percpu * arm_cpuidle_devices;
> +
> +static int (*mach_cpuidle)(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv,
> + int index);
> +
> +static int arm_enter_idle(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv, int index)
I think how this works is backwards. This function is only called if
there is a NULL enter function for a state, but mach_cpuidle is global.
Ideally, I want to call this function for every state, but call a
different mach_cpuidle function for each state. Yes, you could select a
specific function for each state within the mach_cpuidle function, but
that seems silly to make the per state function global and then have to
select a per state function again. And if many users are doing that,
then it belongs in the common code.
> +{
> + ktime_t time_start, time_end;
> +
> + local_irq_disable();
> + local_fiq_disable();
> +
> + time_start = ktime_get();
> +
> + index = mach_cpuidle(dev, drv, index);
> +
> + time_end = ktime_get();
> +
> + local_fiq_enable();
> + local_irq_enable();
> +
> + dev->last_residency =
> + (int)ktime_to_us(ktime_sub(time_end, time_start));
> +
> + return index;
> +}
> +
> +void arm_cpuidle_devices_uninit(void)
> +{
> + int cpu_id;
> + struct cpuidle_device *dev;
> +
> + for_each_possible_cpu(cpu_id) {
> + dev = per_cpu_ptr(arm_cpuidle_devices, cpu_id);
> + cpuidle_unregister_device(dev);
> + }
> +
> + free_percpu(arm_cpuidle_devices);
> + return;
Don't need return statement.
> +}
> +
> +int __init arm_cpuidle_init(struct cpuidle_driver *drv,
> + int (*common_enter)(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv, int index),
> + void *driver_data[])
> +{
> + struct cpuidle_device *dev;
> + int i, cpu_id;
> +
> + if (drv == NULL) {
> + pr_err("%s: cpuidle_driver pointer NULL\n", __func__);
> + return -EINVAL;
> + }
> +
> + if (drv->state_count > CPUIDLE_STATE_MAX)
> + pr_err("%s: state count exceeds maximum\n", __func__);
return an error?
You can collapse these 2 parameter checks down to:
if (!drv || (drv->state_count > CPUIDLE_STATE_MAX))
> +
> + mach_cpuidle = common_enter;
> +
> + /* if state enter function not specified, use common_enter function */
> + for (i = 0; i < drv->state_count; i++) {
> + if (drv->states[i].enter == NULL) {
> + if (mach_cpuidle == NULL) {
Usually !mach_cpuidle is preferred for NULL checks. You can move this
check out of the loop.
> + pr_err("%s: 'enter' function pointer NULL\n",
> + __func__);
> + return -EINVAL;
> + } else
> + drv->states[i].enter = arm_enter_idle;
> + }
> + }
> +
> + if (cpuidle_register_driver(drv)) {
> + pr_err("%s: Failed to register cpuidle driver\n", __func__);
> + return -ENODEV;
> + }
> +
> + arm_cpuidle_devices = alloc_percpu(struct cpuidle_device);
> + if (arm_cpuidle_devices == NULL) {
> + cpuidle_unregister_driver(drv);
> + return -ENOMEM;
> + }
> +
> + /* initialize state data for each cpuidle_device */
> + for_each_possible_cpu(cpu_id) {
> +
> + dev = per_cpu_ptr(arm_cpuidle_devices, cpu_id);
> + dev->cpu = cpu_id;
> + dev->state_count = drv->state_count;
> +
> + if (driver_data)
> + for (i = 0; i < dev->state_count; i++) {
This would be more concise and less indentation:
for (i = 0; driver_data, i < dev->state_count; i++)
> + dev->states_usage[i].driver_data =
> + driver_data[i];
> + }
> +
> + if (cpuidle_register_device(dev)) {
> + pr_err("%s: Failed to register cpu %u\n",
> + __func__, cpu_id);
> + return -ENODEV;
Leaking memory here from alloc_percpu.
Also, need to unregister driver. It's usually cleaner to use goto's for
error clean-up.
Rob
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