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Message-ID: <51F35A2A.1080408@linaro.org>
Date: Sat, 27 Jul 2013 07:27:06 +0200
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>
CC: linuxppc-dev@...ts.ozlabs.org, linux-pm@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org
Subject: Re: [linux-pm] [PATCH 1/3] cpuidle/powernv: cpuidle backend driver
for powernv
On 07/23/2013 11:01 AM, Deepthi Dharwar wrote:
> This patch implements a back-end cpuidle driver for
> powernv calling power7_nap and snooze idle states.
> This can be extended by adding more idle states
> in the future to the existing framework.
>
> Signed-off-by: Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>
> ---
> arch/powerpc/platforms/powernv/Kconfig | 9 +
> arch/powerpc/platforms/powernv/Makefile | 1
> arch/powerpc/platforms/powernv/processor_idle.c | 239 +++++++++++++++++++++++
> 3 files changed, 249 insertions(+)
> create mode 100644 arch/powerpc/platforms/powernv/processor_idle.c
>
> diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
> index c24684c..ace2d22 100644
> --- a/arch/powerpc/platforms/powernv/Kconfig
> +++ b/arch/powerpc/platforms/powernv/Kconfig
> @@ -20,3 +20,12 @@ config PPC_POWERNV_RTAS
> default y
> select PPC_ICS_RTAS
> select PPC_RTAS
> +
> +config POWERNV_IDLE
> + bool "CPUIdle driver for powernv platform"
> + depends on CPU_IDLE
> + depends on PPC_POWERNV
> + default y
> + help
> + Select this option to enable processor idle state management
> + through cpuidle subsystem.
> diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
> index 7fe5951..c0e44eb 100644
> --- a/arch/powerpc/platforms/powernv/Makefile
> +++ b/arch/powerpc/platforms/powernv/Makefile
> @@ -4,3 +4,4 @@ obj-y += opal-rtc.o opal-nvram.o
> obj-$(CONFIG_SMP) += smp.o
> obj-$(CONFIG_PCI) += pci.o pci-p5ioc2.o pci-ioda.o
> obj-$(CONFIG_EEH) += eeh-ioda.o eeh-powernv.o
> +obj-$(CONFIG_POWERNV_IDLE) += processor_idle.o
> diff --git a/arch/powerpc/platforms/powernv/processor_idle.c b/arch/powerpc/platforms/powernv/processor_idle.c
> new file mode 100644
> index 0000000..f43ad91a
> --- /dev/null
> +++ b/arch/powerpc/platforms/powernv/processor_idle.c
> @@ -0,0 +1,239 @@
> +/*
> + * processor_idle - idle state cpuidle driver.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/moduleparam.h>
> +#include <linux/cpuidle.h>
> +#include <linux/cpu.h>
> +#include <linux/notifier.h>
> +
> +#include <asm/machdep.h>
> +#include <asm/runlatch.h>
> +
> +struct cpuidle_driver powernv_idle_driver = {
> + .name = "powernv_idle",
> + .owner = THIS_MODULE,
> +};
> +
> +#define MAX_IDLE_STATE_COUNT 2
> +
> +static int max_idle_state = MAX_IDLE_STATE_COUNT - 1;
> +static struct cpuidle_device __percpu *powernv_cpuidle_devices;
> +static struct cpuidle_state *cpuidle_state_table;
> +
> +static int snooze_loop(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv,
> + int index)
> +{
> + int cpu = dev->cpu;
> +
> + local_irq_enable();
> + set_thread_flag(TIF_POLLING_NRFLAG);
> +
> + while ((!need_resched()) && cpu_online(cpu)) {
> + ppc64_runlatch_off();
> + HMT_very_low();
> + }
Why are you using the cpu_online test here ?
> +
> + HMT_medium();
> + clear_thread_flag(TIF_POLLING_NRFLAG);
> + smp_mb();
> + return index;
> +}
> +
> +
> +static int nap_loop(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv,
> + int index)
> +{
> + ppc64_runlatch_off();
> + power7_idle();
> + return index;
> +}
> +
> +/*
> + * States for dedicated partition case.
> + */
> +static struct cpuidle_state powernv_states[MAX_IDLE_STATE_COUNT] = {
> + { /* Snooze */
> + .name = "snooze",
> + .desc = "snooze",
> + .flags = CPUIDLE_FLAG_TIME_VALID,
> + .exit_latency = 0,
> + .target_residency = 0,
> + .enter = &snooze_loop },
> + { /* Nap */
> + .name = "Nap",
> + .desc = "Nap",
> + .flags = CPUIDLE_FLAG_TIME_VALID,
> + .exit_latency = 10,
> + .target_residency = 100,
> + .enter = &nap_loop },
> +};
> +
> +static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
> + unsigned long action, void *hcpu)
> +{
> + int hotcpu = (unsigned long)hcpu;
> + struct cpuidle_device *dev =
> + per_cpu_ptr(powernv_cpuidle_devices, hotcpu);
> +
> + if (dev && cpuidle_get_driver()) {
> + switch (action) {
> + case CPU_ONLINE:
> + case CPU_ONLINE_FROZEN:
> + cpuidle_pause_and_lock();
> + cpuidle_enable_device(dev);
> + cpuidle_resume_and_unlock();
> + break;
> +
> + case CPU_DEAD:
> + case CPU_DEAD_FROZEN:
> + cpuidle_pause_and_lock();
> + cpuidle_disable_device(dev);
> + cpuidle_resume_and_unlock();
> + break;
> +
> + default:
> + return NOTIFY_DONE;
> + }
> + }
> + return NOTIFY_OK;
> +}
> +
> +static struct notifier_block setup_hotplug_notifier = {
> + .notifier_call = powernv_cpuidle_add_cpu_notifier,
> +};
This is duplicated code with the pseries cpuidle driver and IMHO it
should be moved to the cpuidle framework.
> +/*
> + * powernv_cpuidle_driver_init()
> + */
> +static int powernv_cpuidle_driver_init(void)
> +{
> + int idle_state;
> + struct cpuidle_driver *drv = &powernv_idle_driver;
> +
> + drv->state_count = 0;
> +
> + for (idle_state = 0; idle_state < MAX_IDLE_STATE_COUNT; ++idle_state) {
> +
> + if (idle_state > max_idle_state)
> + break;
> +
> + /* is the state not enabled? */
> + if (cpuidle_state_table[idle_state].enter == NULL)
> + continue;
> +
> + drv->states[drv->state_count] = /* structure copy */
> + cpuidle_state_table[idle_state];
> +
> + drv->state_count += 1;
> + }
> +
> + return 0;
> +}
Instead of doing struct copy, why don't you use the state's 'disable'
field of the driver and then enable the state in the routine ?
> +/* powernv_idle_devices_uninit(void)
> + * unregister cpuidle devices and de-allocate memory
> + */
> +static void powernv_idle_devices_uninit(void)
> +{
> + int i;
> + struct cpuidle_device *dev;
> +
> + for_each_possible_cpu(i) {
> + dev = per_cpu_ptr(powernv_cpuidle_devices, i);
> + cpuidle_unregister_device(dev);
> + }
> +
> + free_percpu(powernv_cpuidle_devices);
> + return;
> +}
> +
> +/* powernv_idle_devices_init()
> + * allocate, initialize and register cpuidle device
> + */
> +static int powernv_idle_devices_init(void)
> +{
> + int i;
> + struct cpuidle_driver *drv = &powernv_idle_driver;
> + struct cpuidle_device *dev;
> +
> + powernv_cpuidle_devices = alloc_percpu(struct cpuidle_device);
> + if (powernv_cpuidle_devices == NULL)
> + return -ENOMEM;
> +
> + for_each_possible_cpu(i) {
> + dev = per_cpu_ptr(powernv_cpuidle_devices, i);
> + dev->state_count = drv->state_count;
> + dev->cpu = i;
> + if (cpuidle_register_device(dev)) {
> + printk(KERN_DEBUG \
> + "cpuidle_register_device %d failed!\n", i);
> + return -EIO;
> + }
> + }
> + return 0;
There is now the cpuidle_register(struct cpuidle_driver *, cpumask *);
You can get rid of the cpuidle_device struct and this init routine.
> +}
> +
> +/*
> + * powernv_idle_probe()
> + * Choose state table for shared versus dedicated partition
> + */
> +static int powernv_idle_probe(void)
> +{
> +
> + if (cpuidle_disable != IDLE_NO_OVERRIDE)
> + return -ENODEV;
> +
> + cpuidle_state_table = powernv_states;
> + return 0;
> +}
> +
> +static int __init powernv_processor_idle_init(void)
> +{
> + int retval;
> +
> + retval = powernv_idle_probe();
> + if (retval)
> + return retval;
> +
> + powernv_cpuidle_driver_init();
> + retval = cpuidle_register_driver(&powernv_idle_driver);
> + if (retval) {
> + printk(KERN_DEBUG "Registration of powernv driver failed.\n");
> + return retval;
> + }
> +
> + retval = powernv_idle_devices_init();
> + if (retval) {
> + powernv_idle_devices_uninit();
> + cpuidle_unregister_driver(&powernv_idle_driver);
> + return retval;
> + }
> +
> + register_cpu_notifier(&setup_hotplug_notifier);
> + printk(KERN_DEBUG "powernv_idle_driver registered\n");
> +
> + return 0;
> +}
> +
> +static void __exit powernv_processor_idle_exit(void)
> +{
> +
> + unregister_cpu_notifier(&setup_hotplug_notifier);
> + powernv_idle_devices_uninit();
> + cpuidle_unregister_driver(&powernv_idle_driver);
> +
> + return;
> +}
> +
> +module_init(powernv_processor_idle_init);
> +module_exit(powernv_processor_idle_exit);
> +
> +MODULE_AUTHOR("Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>");
> +MODULE_DESCRIPTION("Cpuidle driver for POWERNV");
> +MODULE_LICENSE("GPL");
>
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