[RESEND PATCH v5 0/3] Add PM support to STM32 LP Timer drivers

[RESEND PATCH v5 0/3] Add PM support to STM32 LP Timer drivers

[Fabrice Gasnier]

This patch series adds power management support for STM32 LP Timer:
- PWM driver
- Document the pinctrl states for sleep mode

It also adds device link between the PWM consumer and the PWM provider.
This allows proper sequencing for suspend/resume (e.g. user will likely
do a pwm_disable() before the PWM provider suspend executes), see [1].

[1] https://lkml.org/lkml/2019/2/5/770

---
resend v5:
- update collected acks

Changes in v5:
- improve a warning message, fix a style issue.

Changes in v4:
- improve error handling when adding the PWM consumer device link.

Changes in v3:
- Move the device_link_add() call to of_pwm_get() as discussed with Uwe.

Changes in v2:
- Don't disable PWM channel in PWM provider: rather refuse to suspend
  and report an error as suggested by Uwe and Thierry.
- Add patch 3/3 to propose device link addition.
- No updates for STM32 LP Timer IIO driver. Patches can be send separately.

Fabrice Gasnier (3):
  dt-bindings: pwm-stm32-lp: document pinctrl sleep state
  pwm: stm32-lp: Add power management support
  pwm: core: add consumer device link

 .../devicetree/bindings/pwm/pwm-stm32-lp.txt       |  9 ++--
 drivers/pwm/core.c                                 | 50 ++++++++++++++++++++--
 drivers/pwm/pwm-stm32-lp.c                         | 25 +++++++++++
 include/linux/pwm.h                                |  6 ++-
 4 files changed, 82 insertions(+), 8 deletions(-)

-- 
2.7.4

[RESEND PATCH v5 1/3] dt-bindings: pwm-stm32-lp: document pinctrl sleep state

[Fabrice Gasnier]

Add documentation for pinctrl sleep state on STM32 LPTimer PWM.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 Documentation/devicetree/bindings/pwm/pwm-stm32-lp.txt | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/pwm-stm32-lp.txt b/Documentation/devicetree/bindings/pwm/pwm-stm32-lp.txt
index bd23302..6521bc4 100644
--- a/Documentation/devicetree/bindings/pwm/pwm-stm32-lp.txt
+++ b/Documentation/devicetree/bindings/pwm/pwm-stm32-lp.txt
@@ -11,8 +11,10 @@ Required parameters:
 			bindings defined in pwm.txt.
 
 Optional properties:
-- pinctrl-names: 	Set to "default".
-- pinctrl-0: 		Phandle pointing to pin configuration node for PWM.
+- pinctrl-names: 	Set to "default". An additional "sleep" state can be
+			defined to set pins in sleep state when in low power.
+- pinctrl-n: 		Phandle(s) pointing to pin configuration node for PWM,
+			respectively for "default" and "sleep" states.
 
 Example:
 	timer@40002400 {
@@ -21,7 +23,8 @@ Example:
 		pwm {
 			compatible = "st,stm32-pwm-lp";
 			#pwm-cells = <3>;
-			pinctrl-names = "default";
+			pinctrl-names = "default", "sleep";
 			pinctrl-0 = <&lppwm1_pins>;
+			pinctrl-1 = <&lppwm1_sleep_pins>;
 		};
 	};
-- 
2.7.4

[RESEND PATCH v5 2/3] pwm: stm32-lp: Add power management support

[Fabrice Gasnier]

Add suspend/resume PM sleep ops. When going to low power, enforce the PWM
channel isn't active. Let the PWM consumers disable it during their own
suspend sequence. Only perform a check here, and handle the pinctrl states.
See [1].
[1] https://lkml.org/lkml/2019/2/5/770

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
Changes in v2:
- Don't disable PWM channel: let the PWM user disable it. Refuse to
  suspend in case it's been left enabled.
- Drop the ifdefs, use __maybe_unused instead.
---
 drivers/pwm/pwm-stm32-lp.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/pwm/pwm-stm32-lp.c b/drivers/pwm/pwm-stm32-lp.c
index 0059b24c..2211a64 100644
--- a/drivers/pwm/pwm-stm32-lp.c
+++ b/drivers/pwm/pwm-stm32-lp.c
@@ -13,6 +13,7 @@
 #include <linux/mfd/stm32-lptimer.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 
@@ -223,6 +224,29 @@ static int stm32_pwm_lp_remove(struct platform_device *pdev)
 	return pwmchip_remove(&priv->chip);
 }
 
+static int __maybe_unused stm32_pwm_lp_suspend(struct device *dev)
+{
+	struct stm32_pwm_lp *priv = dev_get_drvdata(dev);
+	struct pwm_state state;
+
+	pwm_get_state(&priv->chip.pwms[0], &state);
+	if (state.enabled) {
+		dev_err(dev, "The consumer didn't stop us (%s)\n",
+			priv->chip.pwms[0].label);
+		return -EBUSY;
+	}
+
+	return pinctrl_pm_select_sleep_state(dev);
+}
+
+static int __maybe_unused stm32_pwm_lp_resume(struct device *dev)
+{
+	return pinctrl_pm_select_default_state(dev);
+}
+
+static SIMPLE_DEV_PM_OPS(stm32_pwm_lp_pm_ops, stm32_pwm_lp_suspend,
+			 stm32_pwm_lp_resume);
+
 static const struct of_device_id stm32_pwm_lp_of_match[] = {
 	{ .compatible = "st,stm32-pwm-lp", },
 	{},
@@ -235,6 +259,7 @@ static struct platform_driver stm32_pwm_lp_driver = {
 	.driver	= {
 		.name = "stm32-pwm-lp",
 		.of_match_table = of_match_ptr(stm32_pwm_lp_of_match),
+		.pm = &stm32_pwm_lp_pm_ops,
 	},
 };
 module_platform_driver(stm32_pwm_lp_driver);
-- 
2.7.4

[RESEND PATCH v5 3/3] pwm: core: add consumer device link

[Fabrice Gasnier]

Add a device link between the PWM consumer and the PWM provider. This
enforces the PWM user to get suspended before the PWM provider. It
allows proper synchronization of suspend/resume sequences: the PWM user
is responsible for properly stopping PWM, before the provider gets
suspended: see [1]. Add the device link in:
- of_pwm_get()
- pwm_get()
- devm_*pwm_get() variants
as it requires a reference to the device for the PWM consumer.

[1] https://lkml.org/lkml/2019/2/5/770

Suggested-by: Thierry Reding <thierry.reding@gmail.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
Changes in v5:
- fix a style issue
- use dev_warn() instead of pr_warn

Changes in v4:
- rework error handling following Thierry's comments
- turn/split pr_debug() into dev_err()/pr_warn().

Changes in v3:
- add struct device to of_get_pwm() arguments to handle device link from
  there as discussed with Uwe.
---
 drivers/pwm/core.c  | 50 +++++++++++++++++++++++++++++++++++++++++++++++---
 include/linux/pwm.h |  6 ++++--
 2 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 3149204..e8d4958 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -639,8 +639,35 @@ static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
 	return ERR_PTR(-EPROBE_DEFER);
 }
 
+static struct device_link *pwm_device_link_add(struct device *dev,
+					       struct pwm_device *pwm)
+{
+	struct device_link *dl;
+
+	if (!dev) {
+		/*
+		 * No device for the PWM consumer has been provided. It may
+		 * impact the PM sequence ordering: the PWM supplier may get
+		 * suspended before the consumer.
+		 */
+		dev_warn(pwm->chip->dev,
+			 "No consumer device specified to create a link to\n");
+		return NULL;
+	}
+
+	dl = device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER);
+	if (!dl) {
+		dev_err(dev, "failed to create device link to %s\n",
+			dev_name(pwm->chip->dev));
+		return ERR_PTR(-EINVAL);
+	}
+
+	return dl;
+}
+
 /**
  * of_pwm_get() - request a PWM via the PWM framework
+ * @dev: device for PWM consumer
  * @np: device node to get the PWM from
  * @con_id: consumer name
  *
@@ -658,10 +685,12 @@ static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
  * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
  * error code on failure.
  */
-struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id)
+struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np,
+			      const char *con_id)
 {
 	struct pwm_device *pwm = NULL;
 	struct of_phandle_args args;
+	struct device_link *dl;
 	struct pwm_chip *pc;
 	int index = 0;
 	int err;
@@ -692,6 +721,14 @@ struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id)
 	if (IS_ERR(pwm))
 		goto put;
 
+	dl = pwm_device_link_add(dev, pwm);
+	if (IS_ERR(dl)) {
+		/* of_xlate ended up calling pwm_request_from_chip() */
+		pwm_free(pwm);
+		pwm = ERR_CAST(dl);
+		goto put;
+	}
+
 	/*
 	 * If a consumer name was not given, try to look it up from the
 	 * "pwm-names" property if it exists. Otherwise use the name of
@@ -767,6 +804,7 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
 	const char *dev_id = dev ? dev_name(dev) : NULL;
 	struct pwm_device *pwm;
 	struct pwm_chip *chip;
+	struct device_link *dl;
 	unsigned int best = 0;
 	struct pwm_lookup *p, *chosen = NULL;
 	unsigned int match;
@@ -774,7 +812,7 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
 
 	/* look up via DT first */
 	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
-		return of_pwm_get(dev->of_node, con_id);
+		return of_pwm_get(dev, dev->of_node, con_id);
 
 	/*
 	 * We look up the provider in the static table typically provided by
@@ -851,6 +889,12 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
 	if (IS_ERR(pwm))
 		return pwm;
 
+	dl = pwm_device_link_add(dev, pwm);
+	if (IS_ERR(dl)) {
+		pwm_free(pwm);
+		return ERR_CAST(dl);
+	}
+
 	pwm->args.period = chosen->period;
 	pwm->args.polarity = chosen->polarity;
 
@@ -942,7 +986,7 @@ struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
 	if (!ptr)
 		return ERR_PTR(-ENOMEM);
 
-	pwm = of_pwm_get(np, con_id);
+	pwm = of_pwm_get(dev, np, con_id);
 	if (!IS_ERR(pwm)) {
 		*ptr = pwm;
 		devres_add(dev, ptr);
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index b628abf..7dad301 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -405,7 +405,8 @@ struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
 		const struct of_phandle_args *args);
 
 struct pwm_device *pwm_get(struct device *dev, const char *con_id);
-struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id);
+struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np,
+			      const char *con_id);
 void pwm_put(struct pwm_device *pwm);
 
 struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
@@ -493,7 +494,8 @@ static inline struct pwm_device *pwm_get(struct device *dev,
 	return ERR_PTR(-ENODEV);
 }
 
-static inline struct pwm_device *of_pwm_get(struct device_node *np,
+static inline struct pwm_device *of_pwm_get(struct device *dev,
+					    struct device_node *np,
 					    const char *con_id)
 {
 	return ERR_PTR(-ENODEV);
-- 
2.7.4

Re: [RESEND PATCH v5 0/3] Add PM support to STM32 LP Timer drivers

[Fabrice Gasnier]

On 4/18/19 11:37 AM, Fabrice Gasnier wrote:
> This patch series adds power management support for STM32 LP Timer:
> - PWM driver
> - Document the pinctrl states for sleep mode
> 
> It also adds device link between the PWM consumer and the PWM provider.
> This allows proper sequencing for suspend/resume (e.g. user will likely
> do a pwm_disable() before the PWM provider suspend executes), see [1].
> 
> [1] https://lkml.org/lkml/2019/2/5/770
> 

Hi Thierry,

Please let me know if you have some more comments on this series. It's
been under review since quite some time now.

Thanks in advance,
Best Regards,
Fabrice

> ---
> resend v5:
> - update collected acks
> 
> Changes in v5:
> - improve a warning message, fix a style issue.
> 
> Changes in v4:
> - improve error handling when adding the PWM consumer device link.
> 
> Changes in v3:
> - Move the device_link_add() call to of_pwm_get() as discussed with Uwe.
> 
> Changes in v2:
> - Don't disable PWM channel in PWM provider: rather refuse to suspend
>   and report an error as suggested by Uwe and Thierry.
> - Add patch 3/3 to propose device link addition.
> - No updates for STM32 LP Timer IIO driver. Patches can be send separately.
> 
> Fabrice Gasnier (3):
>   dt-bindings: pwm-stm32-lp: document pinctrl sleep state
>   pwm: stm32-lp: Add power management support
>   pwm: core: add consumer device link
> 
>  .../devicetree/bindings/pwm/pwm-stm32-lp.txt       |  9 ++--
>  drivers/pwm/core.c                                 | 50 ++++++++++++++++++++--
>  drivers/pwm/pwm-stm32-lp.c                         | 25 +++++++++++
>  include/linux/pwm.h                                |  6 ++-
>  4 files changed, 82 insertions(+), 8 deletions(-)
> 

Re: [RESEND PATCH v5 0/3] Add PM support to STM32 LP Timer drivers

[Benjamin Gaignard]

Le ven. 10 mai 2019 à 09:51, Fabrice Gasnier <fabrice.gasnier@st.com> a écrit :
>
> On 4/18/19 11:37 AM, Fabrice Gasnier wrote:
> > This patch series adds power management support for STM32 LP Timer:
> > - PWM driver
> > - Document the pinctrl states for sleep mode
> >
> > It also adds device link between the PWM consumer and the PWM provider.
> > This allows proper sequencing for suspend/resume (e.g. user will likely
> > do a pwm_disable() before the PWM provider suspend executes), see [1].
> >
> > [1] https://lkml.org/lkml/2019/2/5/770
> >
>
> Hi Thierry,
>
> Please let me know if you have some more comments on this series. It's
> been under review since quite some time now.
>

Hi Thierry,

Does something is blocking on this series ?
How can we progress on it ?

Regards,
Benjamin

> Thanks in advance,
> Best Regards,
> Fabrice
>
> > ---
> > resend v5:
> > - update collected acks
> >
> > Changes in v5:
> > - improve a warning message, fix a style issue.
> >
> > Changes in v4:
> > - improve error handling when adding the PWM consumer device link.
> >
> > Changes in v3:
> > - Move the device_link_add() call to of_pwm_get() as discussed with Uwe.
> >
> > Changes in v2:
> > - Don't disable PWM channel in PWM provider: rather refuse to suspend
> >   and report an error as suggested by Uwe and Thierry.
> > - Add patch 3/3 to propose device link addition.
> > - No updates for STM32 LP Timer IIO driver. Patches can be send separately.
> >
> > Fabrice Gasnier (3):
> >   dt-bindings: pwm-stm32-lp: document pinctrl sleep state
> >   pwm: stm32-lp: Add power management support
> >   pwm: core: add consumer device link
> >
> >  .../devicetree/bindings/pwm/pwm-stm32-lp.txt       |  9 ++--
> >  drivers/pwm/core.c                                 | 50 ++++++++++++++++++++--
> >  drivers/pwm/pwm-stm32-lp.c                         | 25 +++++++++++
> >  include/linux/pwm.h                                |  6 ++-
> >  4 files changed, 82 insertions(+), 8 deletions(-)
> >
>
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