[3/4] pwm: tegra: Add DT binding details to configure pin in suspends/resume

Submitted by Laxman Dewangan on April 5, 2017, 2:13 p.m.

Details

Message ID 1491401626-31303-4-git-send-email-ldewangan@nvidia.com
State New
Headers show

Commit Message

Laxman Dewangan April 5, 2017, 2:13 p.m.
In some of NVIDIA Tegra's platform, PWM controller is used to
control the PWM controlled regulators. PWM signal is connected to
the VID pin of the regulator where duty cycle of PWM signal decide
the voltage level of the regulator output.

The tristate (high impedance of PWM pin form Tegra) also define
one of the state of PWM regulator which needs to be configure in
suspend state of system.

Add DT binding details to provide the pin configuration state
from PWM and pinctrl DT node in suspend and active state of
the system.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
---
 .../devicetree/bindings/pwm/nvidia,tegra20-pwm.txt | 43 ++++++++++++++++++++++
 1 file changed, 43 insertions(+)

Comments

Jon Hunter April 6, 2017, 8:57 a.m.
On 05/04/17 15:13, Laxman Dewangan wrote:
> In some of NVIDIA Tegra's platform, PWM controller is used to
> control the PWM controlled regulators. PWM signal is connected to
> the VID pin of the regulator where duty cycle of PWM signal decide
> the voltage level of the regulator output.
> 
> The tristate (high impedance of PWM pin form Tegra) also define
> one of the state of PWM regulator which needs to be configure in
> suspend state of system.
> 
> Add DT binding details to provide the pin configuration state
> from PWM and pinctrl DT node in suspend and active state of
> the system.
> 
> Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
> ---
>  .../devicetree/bindings/pwm/nvidia,tegra20-pwm.txt | 43 ++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> index b4e7377..145c323 100644
> --- a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> +++ b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> @@ -19,6 +19,19 @@ Required properties:
>  - reset-names: Must include the following entries:
>    - pwm
>  
> +Optional properties:
> +============================
> +In some of the interface like PWM based regualator device, it is required
> +to configure the pins diffrently in different states, specially in suspend

s/diffrently/differently
s/specially/especially

> +state of the system. The configuration of pin is provided via the pinctrl
> +DT node as detailed in the pinctrl DT binding document
> +	Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
> +
> +The PWM node will have following optional properties.
> +pinctrl-names:	Pin state names. Must be "suspend" and "resume".

Why not just use the pre-defined names here? There is a pre-defined name
for "default", "idle" and "sleep" and then you can use the following
APIs and avoid the lookup of the state ...

pinctrl_pm_select_default_state()
pinctrl_pm_select_idle_state()
pinctrl_pm_select_sleep_state()

Note for i2c [0][1], I used "default" as the active/on state (which I
know is not that descriptive) and then used 'idle' as the suspended
state. This way we don't need any custom names.

Cheers
Jon

[0]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/i2c/busses/i2c-tegra.c?id=718917b9875fcfa6450e7274d2727c4680c3591a
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/arm64/boot/dts/nvidia/tegra210.dtsi?id=66b2d6e9c93bc5bed55afda80c84bf0325c14ad4
Thierry Reding April 6, 2017, 1:03 p.m.
On Thu, Apr 06, 2017 at 09:57:09AM +0100, Jon Hunter wrote:
> 
> On 05/04/17 15:13, Laxman Dewangan wrote:
> > In some of NVIDIA Tegra's platform, PWM controller is used to
> > control the PWM controlled regulators. PWM signal is connected to
> > the VID pin of the regulator where duty cycle of PWM signal decide
> > the voltage level of the regulator output.
> > 
> > The tristate (high impedance of PWM pin form Tegra) also define
> > one of the state of PWM regulator which needs to be configure in
> > suspend state of system.
> > 
> > Add DT binding details to provide the pin configuration state
> > from PWM and pinctrl DT node in suspend and active state of
> > the system.
> > 
> > Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
> > ---
> >  .../devicetree/bindings/pwm/nvidia,tegra20-pwm.txt | 43 ++++++++++++++++++++++
> >  1 file changed, 43 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> > index b4e7377..145c323 100644
> > --- a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> > +++ b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> > @@ -19,6 +19,19 @@ Required properties:
> >  - reset-names: Must include the following entries:
> >    - pwm
> >  
> > +Optional properties:
> > +============================
> > +In some of the interface like PWM based regualator device, it is required
> > +to configure the pins diffrently in different states, specially in suspend
> 
> s/diffrently/differently
> s/specially/especially
> 
> > +state of the system. The configuration of pin is provided via the pinctrl
> > +DT node as detailed in the pinctrl DT binding document
> > +	Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
> > +
> > +The PWM node will have following optional properties.
> > +pinctrl-names:	Pin state names. Must be "suspend" and "resume".
> 
> Why not just use the pre-defined names here? There is a pre-defined name
> for "default", "idle" and "sleep" and then you can use the following
> APIs and avoid the lookup of the state ...
> 
> pinctrl_pm_select_default_state()
> pinctrl_pm_select_idle_state()
> pinctrl_pm_select_sleep_state()
> 
> Note for i2c [0][1], I used "default" as the active/on state (which I
> know is not that descriptive) and then used 'idle' as the suspended
> state. This way we don't need any custom names.

Agreed, I think that's how these states are meant to be used.

Thierry
Laxman Dewangan April 6, 2017, 1:19 p.m.
On Thursday 06 April 2017 06:33 PM, Thierry Reding wrote:
> * PGP Signed by an unknown key
>
> On Thu, Apr 06, 2017 at 09:57:09AM +0100, Jon Hunter wrote:
>> On 05/04/17 15:13, Laxman Dewangan wrote:
>>> +state of the system. The configuration of pin is provided via the pinctrl
>>> +DT node as detailed in the pinctrl DT binding document
>>> +	Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
>>> +
>>> +The PWM node will have following optional properties.
>>> +pinctrl-names:	Pin state names. Must be "suspend" and "resume".
>> Why not just use the pre-defined names here? There is a pre-defined name
>> for "default", "idle" and "sleep" and then you can use the following
>> APIs and avoid the lookup of the state ...
>>
>> pinctrl_pm_select_default_state()
>> pinctrl_pm_select_idle_state()
>> pinctrl_pm_select_sleep_state()
>>
>> Note for i2c [0][1], I used "default" as the active/on state (which I
>> know is not that descriptive) and then used 'idle' as the suspended
>> state. This way we don't need any custom names.
> Agreed, I think that's how these states are meant to be used.
I did quick grep for the pinctrl_pm_select_* functions in the code tree 
and found usage of these APIs in some of the places.
I am taking the reference of i2c-st, i2c-nomadic and 
extcon/extcon-usb-gpio.c drivers and from this the interpretation is

default state: When interface active and transfer need to be done in IO 
interface.
idle state: Active state of the system but interface is not active, put 
in non-active state of the interface.
sleep state: When system entering into suspend and IO interface is going 
to be inactive.

So in PWM case, we will need the "default" and "sleep" state.

In suspend(), set the "sleep" state and in resume, set the "default" state.

+ Linus W as I refereed his st/nomadik driver for reference.

--
To unsubscribe from this list: send the line "unsubscribe linux-tegra" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Jon Hunter April 6, 2017, 2:03 p.m.
On 06/04/17 14:19, Laxman Dewangan wrote:
> 
> On Thursday 06 April 2017 06:33 PM, Thierry Reding wrote:
>> * PGP Signed by an unknown key
>>
>> On Thu, Apr 06, 2017 at 09:57:09AM +0100, Jon Hunter wrote:
>>> On 05/04/17 15:13, Laxman Dewangan wrote:
>>>> +state of the system. The configuration of pin is provided via the
>>>> pinctrl
>>>> +DT node as detailed in the pinctrl DT binding document
>>>> +    Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
>>>> +
>>>> +The PWM node will have following optional properties.
>>>> +pinctrl-names:    Pin state names. Must be "suspend" and "resume".
>>> Why not just use the pre-defined names here? There is a pre-defined name
>>> for "default", "idle" and "sleep" and then you can use the following
>>> APIs and avoid the lookup of the state ...
>>>
>>> pinctrl_pm_select_default_state()
>>> pinctrl_pm_select_idle_state()
>>> pinctrl_pm_select_sleep_state()
>>>
>>> Note for i2c [0][1], I used "default" as the active/on state (which I
>>> know is not that descriptive) and then used 'idle' as the suspended
>>> state. This way we don't need any custom names.
>> Agreed, I think that's how these states are meant to be used.
> I did quick grep for the pinctrl_pm_select_* functions in the code tree
> and found usage of these APIs in some of the places.
> I am taking the reference of i2c-st, i2c-nomadic and
> extcon/extcon-usb-gpio.c drivers and from this the interpretation is
> 
> default state: When interface active and transfer need to be done in IO
> interface.
> idle state: Active state of the system but interface is not active, put
> in non-active state of the interface.
> sleep state: When system entering into suspend and IO interface is going
> to be inactive.
> 
> So in PWM case, we will need the "default" and "sleep" state.
> 
> In suspend(), set the "sleep" state and in resume, set the "default" state.
> 
> + Linus W as I refereed his st/nomadik driver for reference.

I mis-spoke before, I used 'idle' for i2c as I am using it in the
context of the runtime-pm callbacks and not suspend. So sleep is fine
with me.

Jon
Linus Walleij April 7, 2017, 10:19 a.m.
On Thu, Apr 6, 2017 at 3:19 PM, Laxman Dewangan <ldewangan@nvidia.com> wrote:
> On Thursday 06 April 2017 06:33 PM, Thierry Reding wrote:
>> On Thu, Apr 06, 2017 at 09:57:09AM +0100, Jon Hunter wrote:
>>> On 05/04/17 15:13, Laxman Dewangan wrote:
>>>>
>>>> +state of the system. The configuration of pin is provided via the
>>>> pinctrl
>>>> +DT node as detailed in the pinctrl DT binding document
>>>> +       Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
>>>> +
>>>> +The PWM node will have following optional properties.
>>>> +pinctrl-names: Pin state names. Must be "suspend" and "resume".
>>>
>>> Why not just use the pre-defined names here? There is a pre-defined name
>>> for "default", "idle" and "sleep" and then you can use the following
>>> APIs and avoid the lookup of the state ...
>>>
>>> pinctrl_pm_select_default_state()
>>> pinctrl_pm_select_idle_state()
>>> pinctrl_pm_select_sleep_state()
>>>
>>> Note for i2c [0][1], I used "default" as the active/on state (which I
>>> know is not that descriptive) and then used 'idle' as the suspended
>>> state. This way we don't need any custom names.
>>
>> Agreed, I think that's how these states are meant to be used.
>
> I did quick grep for the pinctrl_pm_select_* functions in the code tree and
> found usage of these APIs in some of the places.
> I am taking the reference of i2c-st, i2c-nomadic and
> extcon/extcon-usb-gpio.c drivers and from this the interpretation is
>
> default state: When interface active and transfer need to be done in IO
> interface.
> idle state: Active state of the system but interface is not active, put in
> non-active state of the interface.
> sleep state: When system entering into suspend and IO interface is going to
> be inactive.
>
> So in PWM case, we will need the "default" and "sleep" state.
>
> In suspend(), set the "sleep" state and in resume, set the "default" state.
>
> + Linus W as I refereed his st/nomadik driver for reference.

It is actually documented:
include/linux/pinctrl/pinctrl-state.h

/*
 * Standard pin control state definitions
 */

/**
 * @PINCTRL_STATE_DEFAULT: the state the pinctrl handle shall be put
 *      into as default, usually this means the pins are up and ready to
 *      be used by the device driver. This state is commonly used by
 *      hogs to configure muxing and pins at boot, and also as a state
 *      to go into when returning from sleep and idle in
 *      .pm_runtime_resume() or ordinary .resume() for example.
 * @PINCTRL_STATE_INIT: normally the pinctrl will be set to "default"
 *      before the driver's probe() function is called.  There are some
 *      drivers where that is not appropriate becausing doing so would
 *      glitch the pins.  In those cases you can add an "init" pinctrl
 *      which is the state of the pins before drive probe.  After probe
 *      if the pins are still in "init" state they'll be moved to
 *      "default".
 * @PINCTRL_STATE_IDLE: the state the pinctrl handle shall be put into
 *      when the pins are idle. This is a state where the system is relaxed
 *      but not fully sleeping - some power may be on but clocks gated for
 *      example. Could typically be set from a pm_runtime_suspend() or
 *      pm_runtime_idle() operation.
 * @PINCTRL_STATE_SLEEP: the state the pinctrl handle shall be put into
 *      when the pins are sleeping. This is a state where the system is in
 *      its lowest sleep state. Could typically be set from an
 *      ordinary .suspend() function.
 */
#define PINCTRL_STATE_DEFAULT "default"
#define PINCTRL_STATE_INIT "init"
#define PINCTRL_STATE_IDLE "idle"
#define PINCTRL_STATE_SLEEP "sleep"

Yours,
Linus Walleij
--
To unsubscribe from this list: send the line "unsubscribe linux-tegra" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch hide | download patch | download mbox

diff --git a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
index b4e7377..145c323 100644
--- a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
+++ b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
@@ -19,6 +19,19 @@  Required properties:
 - reset-names: Must include the following entries:
   - pwm
 
+Optional properties:
+============================
+In some of the interface like PWM based regualator device, it is required
+to configure the pins diffrently in different states, specially in suspend
+state of the system. The configuration of pin is provided via the pinctrl
+DT node as detailed in the pinctrl DT binding document
+	Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
+
+The PWM node will have following optional properties.
+pinctrl-names:	Pin state names. Must be "suspend" and "resume".
+pinctrl-0:	Node handle of the suspend state configuration of pins.
+pinctrl-1:	Node handle of the resume state configuration of pins.
+
 Example:
 
 	pwm: pwm@7000a000 {
@@ -29,3 +42,33 @@  Example:
 		resets = <&tegra_car 17>;
 		reset-names = "pwm";
 	};
+
+
+Example with the pin configuration for suspend and resume:
+=========================================================
+Here Pin PE7 is used as PWM.
+
+#include <dt-bindings/pinctrl/pinctrl-tegra.h>
+
+	pinmux@70000868 {
+		pwm_suspend: pwm_suspend_state {
+                        pe7 {
+                                nvidia,pins = "pe7";
+                                nvidia,tristate = <TEGRA_PIN_DISABLE>;
+			};
+		};
+
+		pwm_resume: pwm_resume_state {
+                        pe7 {
+                                nvidia,pins = "pe7";
+                                nvidia,tristate = <TEGRA_PIN_DISABLE>;
+			};
+		};
+	};
+
+	pwm@7000a000 {
+		/* Mandatory pwm properties */
+		pinctrl-names = "suspend", "resume";
+		pinctrl-0 = <&pwm_suspend>;
+		pinctrl-1 = <&pwm_resume>;
+	};