Re: [PATCH v4 12/13] cpuidle: mvebu: Add initial CPU idle support for Armada 370/XP SoC

[Gregory CLEMENT <gregory.clement@free-electrons.com>]

On 17/02/2014 09:49, Daniel Lezcano wrote:
> On 02/13/2014 06:33 PM, Gregory CLEMENT wrote:
>> Add the wfi, cpu idle and cpu deep idle power states support for the
>> Armada XP SoCs.
>>
>> All the latencies and the power consumption values used at the
>> "armada_370_xp_idle_driver" structure are preliminary and will be
>> modified in the future after running some measurements and analysis.
>>
>> Based on the work of Nadav Haklai.
>>
>> Signed-off-by: Nadav Haklai <nadavh@marvell.com>
>> Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
>> ---
>>   drivers/cpuidle/Kconfig.arm             |   5 ++
>>   drivers/cpuidle/Makefile                |   1 +
>>   drivers/cpuidle/cpuidle-armada-370-xp.c | 120 ++++++++++++++++++++++++++++++++
>>   3 files changed, 126 insertions(+)
>>   create mode 100644 drivers/cpuidle/cpuidle-armada-370-xp.c
>>
>> diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
>> index d988948a89a0..f377eb0840e3 100644
>> --- a/drivers/cpuidle/Kconfig.arm
>> +++ b/drivers/cpuidle/Kconfig.arm
>> @@ -1,6 +1,11 @@
>>   #
>>   # ARM CPU Idle drivers
>>   #
>> +config ARM_ARMADA_370_XP_CPUIDLE
>> +	bool "CPU Idle Driver for Armada 370/XP family processors"
>> +	depends on ARCH_MVEBU
>> +	help
>> +	  Select this to enable cpuidle on Armada 370/XP processors.
>>
>>   config ARM_BIG_LITTLE_CPUIDLE
>>   	bool "Support for ARM big.LITTLE processors"
>> diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
>> index f71ae1b373c5..9902d052bd87 100644
>> --- a/drivers/cpuidle/Makefile
>> +++ b/drivers/cpuidle/Makefile
>> @@ -7,6 +7,7 @@ obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
>>
>>   ##################################################################################
>>   # ARM SoC drivers
>> +obj-$(CONFIG_ARM_ARMADA_370_XP_CPUIDLE) += cpuidle-armada-370-xp.o
>>   obj-$(CONFIG_ARM_BIG_LITTLE_CPUIDLE)	+= cpuidle-big_little.o
>>   obj-$(CONFIG_ARM_HIGHBANK_CPUIDLE)	+= cpuidle-calxeda.o
>>   obj-$(CONFIG_ARM_KIRKWOOD_CPUIDLE)	+= cpuidle-kirkwood.o
>> diff --git a/drivers/cpuidle/cpuidle-armada-370-xp.c b/drivers/cpuidle/cpuidle-armada-370-xp.c
>> new file mode 100644
>> index 000000000000..57c69812e79d
>> --- /dev/null
>> +++ b/drivers/cpuidle/cpuidle-armada-370-xp.c
>> @@ -0,0 +1,120 @@
>> +/*
>> + * Marvell Armada 370 and Armada XP SoC cpuidle driver
>> + *
>> + * Copyright (C) 2013 Marvell
>> + *
>> + * Nadav Haklai <nadavh@marvell.com>
>> + * Gregory CLEMENT <gregory.clement@free-electrons.com>
>> + *
>> + * This file is licensed under the terms of the GNU General Public
>> + * License version 2.  This program is licensed "as is" without any
>> + * warranty of any kind, whether express or implied.
>> + *
>> + * Maintainer: Gregory CLEMENT <gregory.clement@free-electrons.com>
>> + */
> 
> Hi Gregory,
> 
>> +#include <linux/cpu_pm.h>
>> +#include <linux/cpuidle.h>
>> +#include <linux/module.h>
>> +#include <linux/io.h>
>> +#include <linux/of.h>
>> +#include <linux/suspend.h>
>> +#include <asm/suspend.h>
>> +#include <linux/smp.h>
>> +#include <asm/cpuidle.h>
>> +#include <asm/smp_plat.h>
>> +#include <linux/platform_device.h>
>> +#include <asm/cp15.h>
>> +#include <asm/cacheflush.h>
> 
> the convention for the drivers inside this directory is to not include 
> <asm/*>.

Well it is not the case yet:

git grep asm drivers/cpuidle/cpuidle-* | wc -l
25

Most of the time it was asm/cpuidle.h which was needed for using
ARM_CPUIDLE_WFI_STATE. However I try to remove most of the header from
asm/ by following your other advises.

> 
>> +#define ARMADA_370_XP_MAX_STATES	3
>> +#define ARMADA_370_XP_FLAG_DEEP_IDLE	0x10000
>> +extern void armada_370_xp_pmsu_idle_prepare(bool deepidle);
>> +extern void ll_clear_cpu_coherent(void);
>> +extern void ll_set_cpu_coherent(void);
> 
> Here you have to declare three low level functions which should not be 
> visible in this driver.
> 
> I think you can go one step more in the code encapsulation by doing like 
> the cpuidle-at91 driver:
> 	* Move armada_370_xp_cpu_suspend inside arch/arm/mach-mvebu/pm.c or 
> whereever you want
> 	* Assign the suspend function to the platform device data file
> 	* Get the suspend function as a callback for suspend from the field above

Ok I have done it in the 5th version.

> 
> 
>> +noinline static int armada_370_xp_cpu_suspend(unsigned long deepidle)
>> +{
>> +	armada_370_xp_pmsu_idle_prepare(deepidle);
>> +
>> +	v7_exit_coherency_flush(all);
>> +
>> +	ll_clear_cpu_coherent();
>> +
>> +	dsb();
>> +
>> +	wfi();
>> +
>> +	ll_set_cpu_coherent();
>> +
>> +	asm volatile(
>> +	"mrc	p15, 0, %0, c1, c0, 0 \n\t"
>> +	"tst	%0, #(1 << 2) \n\t"
>> +	"orreq	r0, %0, #(1 << 2) \n\t"
>> +	"mcreq	p15, 0, %0, c1, c0, 0 \n\t"
>> +	"isb	"
>> +	: : "r" (0));
>> +
>> +	return 0;
>> +}
>> +
>> +static int armada_370_xp_enter_idle(struct cpuidle_device *dev,
>> +				struct cpuidle_driver *drv,
>> +				int index)
>> +{
>> +	bool deepidle = false;
>> +	cpu_pm_enter();
>> +
>> +	if (drv->states[index].flags & ARMADA_370_XP_FLAG_DEEP_IDLE)
>> +		deepidle = true;
>> +
>> +	cpu_suspend(deepidle, armada_370_xp_cpu_suspend);
>> +
>> +	cpu_pm_exit();
>> +
>> +	return index;
>> +}
>> +
>> +static struct cpuidle_driver armada_370_xp_idle_driver = {
>> +	.name			= "armada_370_xp_idle",
>> +	.states[0]		= ARM_CPUIDLE_WFI_STATE,
>> +	.states[1]		= {
>> +		.enter			= armada_370_xp_enter_idle,
>> +		.exit_latency		= 10,
>> +		.power_usage		= 50,
>> +		.target_residency	= 100,
>> +		.flags			= CPUIDLE_FLAG_TIME_VALID,
>> +		.name			= "MV CPU IDLE",
>> +		.desc			= "CPU power down",
>> +	},
>> +	.states[2]		= {
>> +		.enter			= armada_370_xp_enter_idle,
>> +		.exit_latency		= 100,
>> +		.power_usage		= 5,
>> +		.target_residency	= 1000,
>> +		.flags			= CPUIDLE_FLAG_TIME_VALID |
>> +						ARMADA_370_XP_FLAG_DEEP_IDLE,
>> +		.name			= "MV CPU DEEP IDLE",
>> +		.desc			= "CPU and L2 Fabric power down",
>> +	},
>> +	.state_count = ARMADA_370_XP_MAX_STATES,
>> +};
>> +
>> +static int armada_370_xp_cpuidle_probe(struct platform_device *pdev)
>> +{
>> +	return cpuidle_register(&armada_370_xp_idle_driver, NULL);
>> +}
>> +
>> +static struct platform_driver armada_370_xp_cpuidle_plat_driver = {
>> +	.driver = {
>> +		.name = "cpuidle-armada-370-xp",
>> +		.owner = THIS_MODULE,
>> +	},
>> +	.probe = armada_370_xp_cpuidle_probe,
>> +};
>> +
>> +module_platform_driver(armada_370_xp_cpuidle_plat_driver);
>> +
>> +MODULE_AUTHOR("Gregory CLEMENT <gregory.clement@free-electrons.com>");
>> +MODULE_DESCRIPTION("Armada 370/XP cpu idle driver");
>> +MODULE_LICENSE("GPL");
>>
> 
> 


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com