Re: [PATCH v6 06/21] PM / devfreq: Add new passive governor

Re: [PATCH v6 06/21] PM / devfreq: Add new passive governor

[MyungJoo Ham]

[]
> Suggested-by: Myungjoo Ham <myungjoo.ham@samsung.com>
> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
> [tjakobi: Reported RCU locking issue and cw00.choi fix it.]
> Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> [m.reichl and linux.amoon: Tested it on exynos4412-odroidu3 board]
> Tested-by: Markus Reichl <m.reichl@fivetechno.de>
> Tested-by: Anand Moon <linux.amoon@gmail.com>
> ---
>  drivers/devfreq/Kconfig            |   7 ++
>  drivers/devfreq/Makefile           |   1 +
>  drivers/devfreq/devfreq.c          |  17 ++++
>  drivers/devfreq/governor.h         |  15 +++
>  drivers/devfreq/governor_passive.c | 192 +++++++++++++++++++++++++++++++++++++
>  include/linux/devfreq.h            |   3 +
>  6 files changed, 235 insertions(+)
>  create mode 100644 drivers/devfreq/governor_passive.c
> 
> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig

[]

> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
> index 8af8aaf922a8..2633087d5c63 100644
> --- a/drivers/devfreq/Makefile
> +++ b/drivers/devfreq/Makefile
> @@ -4,6 +4,7 @@ obj-$(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)	+= governor_simpleondemand.o
>  obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE)	+= governor_performance.o
>  obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE)	+= governor_powersave.o
>  obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)	+= governor_userspace.o
> +obj-$(CONFIG_DEVFREQ_GOV_PASSIVE)	+= governor_passive.o
>  
>  # DEVFREQ Drivers
>  obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ)	+= exynos-bus.o
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 1d6c803804d5..9f84bbc2994c 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -478,7 +478,13 @@ static void _remove_devfreq(struct devfreq *devfreq)
>  		dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
>  		return;
>  	}
> +
> +	if (devfreq->governor->type == DEVFREQ_GOV_PASSIVE)
> +		devfreq_passive_unregister_notifier(devfreq);
> +
>  	list_del(&devfreq->node);
> +	list_del_init(&devfreq->passive_node);
> +

Let's do this inside governor_passive.c, you already have
the DEVFREQ_GOV_STOP signal. This may be called more frequently
because the START-STOP pair has wider usage than add-remove pair.
However, still, it's ok to be detached during the "STOP"ed but not
removed state.

>  	mutex_unlock(&devfreq_list_lock);
>  
>  	if (devfreq->governor)
> @@ -598,6 +604,17 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  		goto err_init;
>  	}
>  
> +	if (devfreq->governor->type == DEVFREQ_GOV_PASSIVE) {
> +		struct devfreq *parent_devfreq = (struct devfreq *)data;
> +		list_add(&devfreq->passive_node, &parent_devfreq->passive_node);
> +
> +		err = devfreq_passive_register_notifier(devfreq);
> +		if (err <0)
> +			goto err_init;
> +	} else {
> +		INIT_LIST_HEAD(&devfreq->passive_node);
> +	}
> +

Same as above. We can reuse DEVFREQ_GOV_START for this.
With DEVFREQ_GOV_START/STOP, we can entirely remove any modifications
in the devfreq.c, governor.h, devfreq.h.

Besides, such an approach removed the need for the patch 05/21.
We no longer (or yet) need "governor type".

>  	return devfreq;
>  
>  err_init:
> diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
> index cf19b923c362..64d1dffcdb43 100644
> --- a/drivers/devfreq/governor.h
> +++ b/drivers/devfreq/governor.h

as mentioned above, we don't need to modify this file.

> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> new file mode 100644
> index 000000000000..521e93b68c11
> --- /dev/null
> +++ b/drivers/devfreq/governor_passive.c
> @@ -0,0 +1,192 @@
> +/*
> + * linux/drivers/devfreq/governor_passive.c
> + *
> + * Copyright (C) 2016 Samsung Electronics
> + * Author: Chanwoo Choi <cw00.choi@samsung.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.
> + */
> +
> +#include <linux/devfreq.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/devfreq.h>

Doubly included

> +#include "governor.h"
> +

[]

> +static int devfreq_passive_event_handler(struct devfreq *devfreq,
> +				unsigned int event, void *data)
> +{
> +	return 0;

Let's handle DEVFREQ_GOV_START/STOP event here.

> +}
> +
> +static struct devfreq_governor devfreq_passive = {
> +	.name = "passive",
> +	.type = DEVFREQ_GOV_PASSIVE,

Let's not use .type enum, yet. We don't this this. At least for now.

> +	.get_target_freq = devfreq_passive_get_target_freq,
> +	.event_handler = devfreq_passive_event_handler,
> +};
> +

[]

> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h

As mentioned above, we don't need to modify this file.

Re: [PATCH v6 06/21] PM / devfreq: Add new passive governor

[Chanwoo Choi]

On 2016년 03월 28일 12:11, MyungJoo Ham wrote:
> []
>> Suggested-by: Myungjoo Ham <myungjoo.ham@samsung.com>
>> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
>> [tjakobi: Reported RCU locking issue and cw00.choi fix it.]
>> Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>> [m.reichl and linux.amoon: Tested it on exynos4412-odroidu3 board]
>> Tested-by: Markus Reichl <m.reichl@fivetechno.de>
>> Tested-by: Anand Moon <linux.amoon@gmail.com>
>> ---
>>  drivers/devfreq/Kconfig            |   7 ++
>>  drivers/devfreq/Makefile           |   1 +
>>  drivers/devfreq/devfreq.c          |  17 ++++
>>  drivers/devfreq/governor.h         |  15 +++
>>  drivers/devfreq/governor_passive.c | 192 +++++++++++++++++++++++++++++++++++++
>>  include/linux/devfreq.h            |   3 +
>>  6 files changed, 235 insertions(+)
>>  create mode 100644 drivers/devfreq/governor_passive.c
>>
>> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> 
> []
> 
>> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
>> index 8af8aaf922a8..2633087d5c63 100644
>> --- a/drivers/devfreq/Makefile
>> +++ b/drivers/devfreq/Makefile
>> @@ -4,6 +4,7 @@ obj-$(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)	+= governor_simpleondemand.o
>>  obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE)	+= governor_performance.o
>>  obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE)	+= governor_powersave.o
>>  obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)	+= governor_userspace.o
>> +obj-$(CONFIG_DEVFREQ_GOV_PASSIVE)	+= governor_passive.o
>>  
>>  # DEVFREQ Drivers
>>  obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ)	+= exynos-bus.o
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 1d6c803804d5..9f84bbc2994c 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -478,7 +478,13 @@ static void _remove_devfreq(struct devfreq *devfreq)
>>  		dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
>>  		return;
>>  	}
>> +
>> +	if (devfreq->governor->type == DEVFREQ_GOV_PASSIVE)
>> +		devfreq_passive_unregister_notifier(devfreq);
>> +
>>  	list_del(&devfreq->node);
>> +	list_del_init(&devfreq->passive_node);
>> +
> 
> Let's do this inside governor_passive.c, you already have
> the DEVFREQ_GOV_STOP signal. This may be called more frequently
> because the START-STOP pair has wider usage than add-remove pair.
> However, still, it's ok to be detached during the "STOP"ed but not
> removed state.

I agree the code about passive governor to drivers/devfreq/governor_passive.c.
It makes the code clear.

> 
>>  	mutex_unlock(&devfreq_list_lock);
>>  
>>  	if (devfreq->governor)
>> @@ -598,6 +604,17 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  		goto err_init;
>>  	}
>>  
>> +	if (devfreq->governor->type == DEVFREQ_GOV_PASSIVE) {
>> +		struct devfreq *parent_devfreq = (struct devfreq *)data;
>> +		list_add(&devfreq->passive_node, &parent_devfreq->passive_node);
>> +
>> +		err = devfreq_passive_register_notifier(devfreq);
>> +		if (err <0)
>> +			goto err_init;
>> +	} else {
>> +		INIT_LIST_HEAD(&devfreq->passive_node);
>> +	}
>> +
> 
> Same as above. We can reuse DEVFREQ_GOV_START for this.
> With DEVFREQ_GOV_START/STOP, we can entirely remove any modifications
> in the devfreq.c, governor.h, devfreq.h.

I agree. I'll modify it.

> 
> Besides, such an approach removed the need for the patch 05/21.
> We no longer (or yet) need "governor type".
> 
>>  	return devfreq;
>>  
>>  err_init:
>> diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
>> index cf19b923c362..64d1dffcdb43 100644
>> --- a/drivers/devfreq/governor.h
>> +++ b/drivers/devfreq/governor.h
> 
> as mentioned above, we don't need to modify this file.

OK.

> 
>> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
>> new file mode 100644
>> index 000000000000..521e93b68c11
>> --- /dev/null
>> +++ b/drivers/devfreq/governor_passive.c
>> @@ -0,0 +1,192 @@
>> +/*
>> + * linux/drivers/devfreq/governor_passive.c
>> + *
>> + * Copyright (C) 2016 Samsung Electronics
>> + * Author: Chanwoo Choi <cw00.choi@samsung.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.
>> + */
>> +
>> +#include <linux/devfreq.h>
>> +#include <linux/module.h>
>> +#include <linux/device.h>
>> +#include <linux/devfreq.h>
> 
> Doubly included

I'll fix it.

> 
>> +#include "governor.h"
>> +
> 
> []
> 
>> +static int devfreq_passive_event_handler(struct devfreq *devfreq,
>> +				unsigned int event, void *data)
>> +{
>> +	return 0;
> 
> Let's handle DEVFREQ_GOV_START/STOP event here.

OK. I'll register/unregister the DEVFREQ_TRANSITION_NOTIFIER by using
DEVFREQ_GOV_START/STOP event.

> 
>> +}
>> +
>> +static struct devfreq_governor devfreq_passive = {
>> +	.name = "passive",
>> +	.type = DEVFREQ_GOV_PASSIVE,
> 
> Let's not use .type enum, yet. We don't this this. At least for now.

OK. I'll remove it.

> 
>> +	.get_target_freq = devfreq_passive_get_target_freq,
>> +	.event_handler = devfreq_passive_event_handler,
>> +};
>> +
> 
> []
> 
>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h


When the devfreq device using passive governor registers the notifier
to DEVFREQ_TRANSITION_NOTIFIER, the devfreq device need the one notifier block field
as following:

struct devfreq {
	...
	...
	struct notifier_block passive_nb;
}

static int devfreq_passive_event_handler(struct devfreq *devfreq,
                               unsigned int event, void *data)
{
       struct device *dev = devfreq->dev.parent;
       struct devfreq *parent = (struct devfreq *)devfreq->data;
       struct notifier_block *nb = &devfreq->passive_nb;
       int ret = 0;

       if (!parent)
               return -EPROBE_DEFER;

       switch (event) {
       case DEVFREQ_GOV_START:
               nb->notifier_call = devfreq_passive_notifier_call;
               ret = devm_devfreq_register_notifier(dev, parent, nb,
                                       DEVFREQ_TRANSITION_NOTIFIER);
               break;
       case DEVFREQ_GOV_STOP:
               devm_devfreq_unregister_notifier(dev, parent, nb,
                                       DEVFREQ_TRANSITION_NOTIFIER);
               break;
       default:
               break;
       }

       return ret;
}

Best Regards,
Chanwoo Choi

[PATCH v6 00/21] PM / devferq: Add generic exynos bus frequency driver and new passive governor

[Chanwoo Choi]

This patch-set includes the two features as following. The generic exynos bus
frequency driver is able to support almost Exynos SoCs for bus frequency
scaling. And the new passive governor is able to make the dependency on
between devices for frequency/voltage scaling. I had posted the patch-set[1]
with the similiar concept. This is is revised version for exynos bus frequency.
- Generic exynos bus frequency driver
- New passive governor of DEVFREQ framework
[1] https://lkml.org/lkml/2015/1/7/872
: [PATCHv3 0/8] devfreq: Add generic exynos memory-bus frequency driver


Changes from v5:
(https://lkml.org/lkml/2016/3/24/5)
- Rebase the patch-set on Linux v4.6-rc1
- Add Tested-by tag from Markus Reichl <m.reichl@fivetechno.de>
- Add Tested-by tag from Anand Moon <linux.amoon@gmail.com>

Changes from v4:
(https://lkml.org/lkml/2015/12/14/43)
- Add new DEVFREQ_TRANSITION_NOTIFIER notifier. The passive
  devfreq device recevie the changed frequency of parent
  devfreq device through DEVFREQ_TRANSITION_NOTIFIER.
- Add governor type to identify thme using the defined constant
- Modify the passive governor using the DEVFREQ_TRANSITION_NOTIFIER notifier.
- Fix the RCU locking probrlm (Reported-by: Tobias Jakobi)
- Fix the debugfs error during the kernel booting (Reported-by: Tobias Jakobi)
- The Device Tree patches have got Reviewed-by tag from Exynos SoC Maintainer
  (Krzysztof Kozlowski <k.kozlowski@samsung.com>)

Changes from v3:
(https://lkml.org/lkml/2015/12/11/75)
- Add the reviewed-by tag from Krzysztof Kozlowski (patch2/3/13/14/15/16/17)
- Fix typo of the description on patch14
- Modify the subject and description of patch17
- Reorder the 'bus_xxx' device tree node alphabetically in 
  both exynos3250-rinato/monk.dts and exynos4412-trats/odroidu3

Changes from v2:
(https://lkml.org/lkml/2015/12/8/869)
- Fix typo on documentation
- Modify the more appropriate sentence on patch description
- Add the detailed description about both parent and passive bus device
- Modify the DMC frequency for Exynos4x12 DMC bus (200MHz -> 267MHz)
- Modify the voltage of 200MHz was included in Exynos3250 DMC bus (800mV -> 825mV)
- Rename OPP nodes as 'opp@<opp-hz>'
- Delete the duplicate 'opp-microvolt' property of passive devfreq device
- Reorder the 'bus_xxx' device tree node alphabetically in exynos3250-rinato/monk.dts
- Reorder the 'bus_xxx' device tree node alphabetically in exynos4412-trats/odroidu3
- Add new exynos4412-ppmu-common.dtsi to remove the duplicate PPMU dt node
  on rinato/monk/trats2/odroid-u3 board
- Add the log message if bus device is registered to devfreq framework successfully
- Add the reviewed-by tag from Krzysztof Kozlowski
- Add the tested-by tag from Anand Moon on Odroid U3
- Add 'SAMSUNG BUS FREQUENCY DRIVER' entry to MAINTAINERS

Changes from v1:
(https://lkml.org/lkml/2015/11/26/260)
- Check whether the instance of regulator is NULL or not
  when executing regulator_disable() because of only parent
  devfreq device has the regulator instance. After fixing it,
  the wake-up from suspend state is well working. (patch1)
- Fix bug which checks 'bus-clk' instead of 'bus->regulator'
  after calling devm_clk_get() (on patch1)
- Update the documentation to remove the description about
  DEVFREQ-EVENT subsystem (on patch2)
- Add the full name of DMC (Dynamic Memory Controller) (on patch2)
- Modify the detailed correlation of buses for Exynos3250
  on documentation (patch2)
- Add the MFC bus node for Exynos3250 (on patch11, patch12)
- Fix the duplicate frequency of bus_display on Exynos4x12.dtsi
- Add the PPMU node for exynos4412-odroidu3
- Add the support of bus frequency for exynos4412-odroidu3


[Description]
Detailed descirption for patch-set:
1. Add generic exynos bus frequency driver
: This patch-set adds the generic exynos bus frequency driver for AXI bus
of sub-blocks in exynos SoC. The Samsung Exynos SoC have the common
architecture for bus between DRAM and sub-blocks in SoC.

 There are the different buses according to Exynos SoC because Exynos SoC
has the differnt sub-blocks and bus speed. In spite of this difference
among Exynos SoCs, this driver is able to support almost Exynos SoC by adding
unique data of each bus in the devicetree file.

 In devicetree, each bus node has a bus clock, regulator, operation-point
and devfreq-event devices which measure the utilization of each bus block.

For example,
- The bus of DMC block in exynos3250.dtsi are listed below:

	bus_dmc: bus_dmc {
		compatible = "samsung,exynos-bus";
		clocks = <&cmu_dmc CLK_DIV_DMC>;
		clock-names = "bus";
		operating-points-v2 = <&bus_dmc_opp_table>;
		status = "disabled";
	};

	bus_dmc_opp_table: opp_table1 {
		compatible = "operating-points-v2";
		opp-shared;

		opp@50000000 {
			opp-hz = /bits/ 64 <50000000>;
			opp-microvolt = <800000>;
		};
		opp@100000000 {
			opp-hz = /bits/ 64 <100000000>;
			opp-microvolt = <800000>;
		};
		opp@134000000 {
			opp-hz = /bits/ 64 <134000000>;
			opp-microvolt = <800000>;
		};
		opp@200000000 {
			opp-hz = /bits/ 64 <200000000>;
			opp-microvolt = <825000>;
		};
		opp@400000000 {
			opp-hz = /bits/ 64 <400000000>;
			opp-microvolt = <875000>;
		};
	};

- Usage case to handle the frequency and voltage of bus on runtime
  in exynos3250-rinato.dts are listed below:

	&bus_dmc {
		devfreq-events = <&ppmu_dmc0_3>, <&ppmu_dmc1_3>;
		vdd-supply = <&buck1_reg>;	/* VDD_MIF */
		status = "okay";
	};

2. Add new passive governor of DEVFREQ framework
: This patch-set add the new passive governor for DEVFREQ framework.
The existing governors (ondemand, performance and so on) are used for DVFS
(Dynamic Voltage and Frequency Scaling) drivers. The existing governors
are independently used for specific device driver which don't give the
influence to other device drviers and also don't receive the effect from
other device drivers.

 The passive governor depends on operation of parent driver with existing
governors(ondemand, performance and so on) extremely and is not able to
decide the new frequency by oneself. According to the decided new frequency
of parent driver with governor, the passive governor uses it to decide
the appropriate frequency for own device driver. The passive governor
must need the following information from device tree:

For exameple,
 There are one more bus device drivers in Exynos3250 which need to
change their source clock according to their utilization on runtime.
But, they share the same power line (e.g., regulator). So, LEFTBUS bus
driver is operated as parent with ondemand governor and then the rest
device driver with passive governor.

 The buses of Internal block in exynos3250.dtsi are listed below:
When LEFTBUS bus driver (parent) changes the bus frequency with
ondemand governor on runtime, the rest bus devices which sharing
the same power line (VDD_INT) will change the each bus frequency
according to the decision of LEFTBUS bus driver (parent).

- INT (Internal) block
	: VDD_INT |--- LEFTBUS
		  |--- PERIL
		  |--- MFC
		  |--- G3D
		  |--- RIGHTBUS
		  |--- FSYS
		  |--- LCD0
		  |--- PERIR
		  |--- ISP
		  |--- CAM

- The buss of INT block in exynos3250.dtsi are listed below:
	bus_leftbus: bus_leftbus {
		compatible = "samsung,exynos-bus";
		clocks = <&cmu CLK_DIV_GDL>;
		clock-names = "bus";
		operating-points-v2 = <&bus_leftbus_opp_table>;
		status = "disabled";
	};

	bus_rightbus: bus_rightbus {
		compatible = "samsung,exynos-bus";
		clocks = <&cmu CLK_DIV_GDR>;
		clock-names = "bus";
		operating-points-v2 = <&bus_leftbus_opp_table>;
		status = "disabled";
	};

	(Omit the rest bus dt node)

- Usage case to handle the frequency and voltage of bus on runtime
  in exynos3250-rinato.dts are listed below:
	/* Parent bus device of VDD_INT */
	&bus_leftbus {
		devfreq-events = <&ppmu_leftbus_3>, <&ppmu_rightbus_3>;
		vdd-supply = <&buck3_reg>;
		status = "okay";
	};

	/* Passive bus device depend on LEFTBUS bus. */
	&bus_rightbus {
		devfreq = <&bus_leftbus>; /* 'devfreq' property indicates
					     the phandle of parent device. */
		status = "okay";
	};

	(Omit the rest bus dt node)

Chanwoo Choi (21):
  PM / devfreq: exynos: Add generic exynos bus frequency driver
  PM / devfreq: exynos: Add documentation for generic exynos bus frequency driver
  PM / devfreq: Add devfreq_get_devfreq_by_phandle()
  PM / devfreq: Add new DEVFREQ_TRANSITION_NOTIFIER notifier
  PM / devfreq: Add governer type with unique number
  PM / devfreq: Add new passive governor
  PM / devfreq: exynos: Add support of bus frequency of sub-blocks using passive governor
  PM / devfreq: exynos: Update documentation for bus devices using passive governor
  PM / devfreq: exynos: Add the detailed correlation between sub-blocks and power line
  PM / devfreq: exynos: Remove unused exynos4/5 busfreq driver
  MAINTAINERS: Add samsung bus frequency driver entry
  ARM: dts: Add DMC bus node for Exynos3250
  ARM: dts: Add DMC bus frequency for exynos3250-rinato/monk
  ARM: dts: Add bus nodes using VDD_INT for Exynos3250
  ARM: dts: Add bus nodes using VDD_MIF for Exynos4x12
  ARM: dts: Add bus nodes using VDD_INT for Exynos4x12
  ARM: dts: Add bus nodes using VDD_MIF for Exynos4210
  ARM: dts: Add exynos4412-ppmu-common dtsi to delete duplicate PPMU nodes
  ARM: dts: Add support of bus frequency using VDD_INT for exynos3250-rinato
  ARM: dts: Expand the voltage range of buck1/3 regulator for exynos4412-odroidu3
  ARM: dts: Add support of bus frequency for exynos4412-trats/odroidu3

 .../devicetree/bindings/devfreq/exynos-bus.txt     |  390 ++++++++
 MAINTAINERS                                        |    9 +
 arch/arm/boot/dts/exynos3250-monk.dts              |   47 +-
 arch/arm/boot/dts/exynos3250-rinato.dts            |   88 +-
 arch/arm/boot/dts/exynos3250.dtsi                  |  181 ++++
 arch/arm/boot/dts/exynos4210.dtsi                  |  159 +++
 arch/arm/boot/dts/exynos4412-odroid-common.dtsi    |   56 +-
 arch/arm/boot/dts/exynos4412-ppmu-common.dtsi      |   50 +
 arch/arm/boot/dts/exynos4412-trats2.dts            |   88 +-
 arch/arm/boot/dts/exynos4x12.dtsi                  |  174 ++++
 drivers/devfreq/Kconfig                            |   35 +-
 drivers/devfreq/Makefile                           |    4 +-
 drivers/devfreq/devfreq.c                          |  224 ++++-
 drivers/devfreq/exynos-bus.c                       |  561 +++++++++++
 drivers/devfreq/exynos/Makefile                    |    3 -
 drivers/devfreq/exynos/exynos4_bus.c               | 1055 --------------------
 drivers/devfreq/exynos/exynos4_bus.h               |  110 --
 drivers/devfreq/exynos/exynos5_bus.c               |  431 --------
 drivers/devfreq/exynos/exynos_ppmu.c               |  119 ---
 drivers/devfreq/exynos/exynos_ppmu.h               |   86 --
 drivers/devfreq/governor.h                         |   21 +
 drivers/devfreq/governor_passive.c                 |  192 ++++
 drivers/devfreq/governor_performance.c             |    1 +
 drivers/devfreq/governor_powersave.c               |    1 +
 drivers/devfreq/governor_simpleondemand.c          |    1 +
 drivers/devfreq/governor_userspace.c               |    1 +
 include/linux/devfreq.h                            |   70 ++
 27 files changed, 2209 insertions(+), 1948 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/devfreq/exynos-bus.txt
 create mode 100644 arch/arm/boot/dts/exynos4412-ppmu-common.dtsi
 create mode 100644 drivers/devfreq/exynos-bus.c
 delete mode 100644 drivers/devfreq/exynos/Makefile
 delete mode 100644 drivers/devfreq/exynos/exynos4_bus.c
 delete mode 100644 drivers/devfreq/exynos/exynos4_bus.h
 delete mode 100644 drivers/devfreq/exynos/exynos5_bus.c
 delete mode 100644 drivers/devfreq/exynos/exynos_ppmu.c
 delete mode 100644 drivers/devfreq/exynos/exynos_ppmu.h
 create mode 100644 drivers/devfreq/governor_passive.c

-- 
1.9.1

[PATCH v6 06/21] PM / devfreq: Add new passive governor

[Chanwoo Choi]

This patch adds the new passive governor for DEVFREQ framework. The following
governors are already present and used for DVFS (Dynamic Voltage and Frequency
Scaling) drivers. The following governors are independently used for one device
driver which don't give the influence to other device drviers and also don't
receive the effect from other device drivers.
- ondemand / performance / powersave / userspace

The passive governor depends on operation of parent driver with specific
governos extremely and is not able to decide the new frequency by oneself.
According to the decided new frequency of parent driver with governor,
the passive governor uses it to decide the appropriate frequency for own
device driver. The passive governor must need the following information
from device tree:
- the source clock and OPP tables
- the instance of parent device

For exameple,
there are one more devfreq device drivers which need to change their source
clock according to their utilization on runtime. But, they share the same
power line (e.g., regulator). So, specific device driver is operated as parent
with ondemand governor and then the rest device driver with passive governor
is influenced by parent device.

Suggested-by: Myungjoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
[tjakobi: Reported RCU locking issue and cw00.choi fix it.]
Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
[m.reichl and linux.amoon: Tested it on exynos4412-odroidu3 board]
Tested-by: Markus Reichl <m.reichl@fivetechno.de>
Tested-by: Anand Moon <linux.amoon@gmail.com>
---
 drivers/devfreq/Kconfig            |   7 ++
 drivers/devfreq/Makefile           |   1 +
 drivers/devfreq/devfreq.c          |  17 ++++
 drivers/devfreq/governor.h         |  15 +++
 drivers/devfreq/governor_passive.c | 192 +++++++++++++++++++++++++++++++++++++
 include/linux/devfreq.h            |   3 +
 6 files changed, 235 insertions(+)
 create mode 100644 drivers/devfreq/governor_passive.c

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index cedda8f1e5eb..bf4f4c70cb6a 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -64,6 +64,13 @@ config DEVFREQ_GOV_USERSPACE
 	  Otherwise, the governor does not change the frequency
 	  given at the initialization.
 
+config DEVFREQ_GOV_PASSIVE
+	tristate "Passive"
+	help
+	  Sets the frequency based on the frequency of its parent devfreq
+	  device. This governor does not change the frequency by itself
+	  through sysfs entries.
+
 comment "DEVFREQ Drivers"
 
 config ARM_EXYNOS_BUS_DEVFREQ
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 8af8aaf922a8..2633087d5c63 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)	+= governor_simpleondemand.o
 obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE)	+= governor_performance.o
 obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE)	+= governor_powersave.o
 obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)	+= governor_userspace.o
+obj-$(CONFIG_DEVFREQ_GOV_PASSIVE)	+= governor_passive.o
 
 # DEVFREQ Drivers
 obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ)	+= exynos-bus.o
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 1d6c803804d5..9f84bbc2994c 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -478,7 +478,13 @@ static void _remove_devfreq(struct devfreq *devfreq)
 		dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
 		return;
 	}
+
+	if (devfreq->governor->type == DEVFREQ_GOV_PASSIVE)
+		devfreq_passive_unregister_notifier(devfreq);
+
 	list_del(&devfreq->node);
+	list_del_init(&devfreq->passive_node);
+
 	mutex_unlock(&devfreq_list_lock);
 
 	if (devfreq->governor)
@@ -598,6 +604,17 @@ struct devfreq *devfreq_add_device(struct device *dev,
 		goto err_init;
 	}
 
+	if (devfreq->governor->type == DEVFREQ_GOV_PASSIVE) {
+		struct devfreq *parent_devfreq = (struct devfreq *)data;
+		list_add(&devfreq->passive_node, &parent_devfreq->passive_node);
+
+		err = devfreq_passive_register_notifier(devfreq);
+		if (err <0)
+			goto err_init;
+	} else {
+		INIT_LIST_HEAD(&devfreq->passive_node);
+	}
+
 	return devfreq;
 
 err_init:
diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
index cf19b923c362..64d1dffcdb43 100644
--- a/drivers/devfreq/governor.h
+++ b/drivers/devfreq/governor.h
@@ -23,6 +23,7 @@
 #define DEVFREQ_GOV_PERFORMANCE			0x2
 #define DEVFREQ_GOV_POWERSAVE			0x3
 #define DEVFREQ_GOV_USERSPACE			0x4
+#define DEVFREQ_GOV_PASSIVE			0x5
 
 /* Devfreq events */
 #define DEVFREQ_GOV_START			0x1
@@ -44,4 +45,18 @@ extern void devfreq_interval_update(struct devfreq *devfreq,
 extern int devfreq_add_governor(struct devfreq_governor *governor);
 extern int devfreq_remove_governor(struct devfreq_governor *governor);
 
+#if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
+extern int devfreq_passive_register_notifier(struct devfreq *passive);
+extern void devfreq_passive_unregister_notifier(struct devfreq *passive);
+#else
+static inline int devfreq_passive_register_notifier(struct devfreq *passive)
+{
+	return 0;
+}
+
+static inline void devfreq_passive_unregister_notifier(struct devfreq *passive)
+{
+}
+#endif
+
 #endif /* _GOVERNOR_H */
diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
new file mode 100644
index 000000000000..521e93b68c11
--- /dev/null
+++ b/drivers/devfreq/governor_passive.c
@@ -0,0 +1,192 @@
+/*
+ * linux/drivers/devfreq/governor_passive.c
+ *
+ * Copyright (C) 2016 Samsung Electronics
+ * Author: Chanwoo Choi <cw00.choi@samsung.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.
+ */
+
+#include <linux/devfreq.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/devfreq.h>
+#include "governor.h"
+
+static int devfreq_passive_get_target_freq(struct devfreq *passive,
+					unsigned long *freq)
+{
+	struct devfreq *parent_devfreq = (struct devfreq *)passive->data;
+	unsigned long child_freq = ULONG_MAX;
+	struct dev_pm_opp *opp;
+	int i, count;
+	u32 flags;
+
+	/*
+	 * Each devfreq has the OPP table. After deciding the new frequency
+	 * from the governor of parent devfreq device, the passive governor
+	 * need to get the index of new frequency on OPP table of parent
+	 * device. And then the index is used for getting the suitable
+	 * new frequency for passive devfreq device.
+	 */
+
+	if (!passive->profile || !passive->profile->freq_table
+		|| passive->profile->max_state <= 0)
+		return -EINVAL;
+
+	/*
+	 * The passive governor have to get the correct frequency from OPP
+	 * list of parent device. Because in this case, *freq is temporary
+	 * value which is decided by ondemand governor.
+	 */
+	if (parent_devfreq->previous_freq < *freq)
+		flags = DEVFREQ_FLAG_LEAST_UPPER_BOUND;
+
+	rcu_read_lock();
+	opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, flags);
+	rcu_read_unlock();
+	if (IS_ERR_OR_NULL(opp))
+		return PTR_ERR(opp);
+
+	/*
+	 * Get the OPP table's index of decided freqeuncy by governor
+	 * of parent device.
+	 */
+	for (i = 0; i < parent_devfreq->profile->max_state; i++)
+		if (parent_devfreq->profile->freq_table[i] == *freq)
+			break;
+
+	if (i == parent_devfreq->profile->max_state)
+		return -EINVAL;
+
+	/* Get the suitable frequency by using index of parent device. */
+	if (i < passive->profile->max_state) {
+		child_freq = passive->profile->freq_table[i];
+	} else {
+		count = passive->profile->max_state;
+		child_freq = passive->profile->freq_table[count - 1];
+	}
+
+	/* Return the suitable frequency for passive device. */
+	*freq = child_freq;
+
+	return 0;
+}
+
+static int devfreq_passive_event_handler(struct devfreq *devfreq,
+				unsigned int event, void *data)
+{
+	return 0;
+}
+
+static struct devfreq_governor devfreq_passive = {
+	.name = "passive",
+	.type = DEVFREQ_GOV_PASSIVE,
+	.get_target_freq = devfreq_passive_get_target_freq,
+	.event_handler = devfreq_passive_event_handler,
+};
+
+static int update_devfreq_passive(struct devfreq *parent, unsigned long freq)
+{
+	struct devfreq *passive;
+	unsigned long rate;
+	int ret;
+
+	list_for_each_entry(passive, &parent->passive_node, passive_node) {
+		if (!passive->governor)
+			continue;
+		rate = freq;
+
+		ret = passive->governor->get_target_freq(passive, &rate);
+		if (ret)
+			return ret;
+
+		ret = passive->profile->target(passive->dev.parent, &rate, 0);
+		if (ret)
+			return ret;
+
+		passive->previous_freq = rate;
+	}
+
+	return 0;
+}
+
+static int devfreq_passive_notifier_call(struct notifier_block *nb,
+				unsigned long event, void *ptr)
+{
+	struct devfreq *passive = container_of(nb, struct devfreq, passive_nb);
+	struct devfreq *parent = (struct devfreq *)passive->data;
+	struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr;
+	unsigned long freq = freqs->new;
+
+	switch (event) {
+	case DEVFREQ_PRECHANGE:
+		if (parent->previous_freq > freq);
+			update_devfreq_passive(parent, freq);
+		break;
+	case DEVFREQ_POSTCHANGE:
+		if (parent->previous_freq < freq);
+			update_devfreq_passive(parent, freq);
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+/**
+ * devfreq_passive_register_notifier() - Register notifier block of passive
+ *					devfreq to parent devfreq device.
+ * @passive:	The parent devfreq object using passive governor.
+ *
+ * Register notifier block of passive devfreq device to receive the changed
+ * frequency of parent devfreq device through DEVFREQ_TRANSITION_NOTIFIER.
+ */
+int devfreq_passive_register_notifier(struct devfreq *passive)
+{
+	struct device *dev = passive->dev.parent;
+	struct devfreq *parent = (struct devfreq *)passive->data;
+	struct notifier_block *nb = &passive->passive_nb;
+
+	nb->notifier_call = devfreq_passive_notifier_call;
+	return devm_devfreq_register_notifier(dev, parent, nb,
+					DEVFREQ_TRANSITION_NOTIFIER);
+}
+
+/**
+ * devfreq_passive_register_notifier() - Unregister notifier block of passive
+ *					devfreq from parent devfreq device.
+ * @passive:	The parent devfreq object using passive governor.
+ */
+void devfreq_passive_unregister_notifier(struct devfreq *passive)
+{
+	struct devfreq *parent = (struct devfreq *)passive->data;
+	struct device *dev = passive->dev.parent;
+	struct notifier_block *nb = &passive->passive_nb;
+
+	devm_devfreq_unregister_notifier(dev, parent, nb,
+					DEVFREQ_TRANSITION_NOTIFIER);
+}
+
+static int __init devfreq_passive_init(void)
+{
+	return devfreq_add_governor(&devfreq_passive);
+}
+subsys_initcall(devfreq_passive_init);
+
+static void __exit devfreq_passive_exit(void)
+{
+	int ret;
+
+	ret = devfreq_remove_governor(&devfreq_passive);
+	if (ret)
+		pr_err("%s: failed remove governor %d\n", __func__, ret);
+
+	return;
+}
+module_exit(devfreq_passive_exit);
+
+MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
+MODULE_DESCRIPTION("DEVFREQ Passive governor");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 9baf45f661ad..bf073c74134f 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -188,6 +188,9 @@ struct devfreq {
 	unsigned long last_stat_updated;
 
 	struct srcu_notifier_head transition_notifier_list;
+
+	struct list_head passive_node;
+	struct notifier_block passive_nb;
 };
 
 struct devfreq_freqs {
-- 
1.9.1