[PATCH v3 0/4] pwm: add power management on sysfs and switch to SPDX

[PATCH v3 0/4] pwm: add power management on sysfs and switch to SPDX

[Yoshihiro Shimoda]

This patch series is affected from the following email:
https://marc.info/?l=linux-renesas-soc&m=155896668906609&w=2

- The patch 1 adds descriptions into Documentation/pwm.txt.
- The patch 2 is not related to the topic though, switches to
  SPDX identifier of sysfs.c.
- The patch 3 adds suspend/resume support into sysfs.c.
- The patch 4 removes suspend/resume support from pwm-rcar.c.

I'll make for other PWM drivers to remove suspend/resume support
after this patch series is applied.

Changes from v2 [1]:
 - Fix typo in the patch 1.
 - Add comments in the patch 3.
 - Add Reviewed-by Geert-san on the all patches.

Changes from v1 [2]:
 - Save pwm_state of suspend instead of own bool value on the patch 3.
 - Separate functions for suspend and resume on the patch 3.
 - Remove unnecessary condition of child_to_pwm_export() on the patch 3.
 - Add helper functions for suspend/resume into sysfs.c on the patch 3.
 - Add comment about the "roll back" on the patch 3.

[1]
https://patchwork.kernel.org/project/linux-renesas-soc/list/?series=125103

[2]
https://patchwork.kernel.org/project/linux-renesas-soc/list/?series=124235


Yoshihiro Shimoda (4):
  pwm: Add power management descriptions
  pwm: sysfs: Switch to SPDX identifier
  pwm: sysfs: Add suspend/resume support
  pwm: rcar: Remove suspend/resume support

 Documentation/pwm.txt  |   7 +++
 drivers/pwm/pwm-rcar.c |  39 -----------------
 drivers/pwm/sysfs.c    | 113 ++++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 110 insertions(+), 49 deletions(-)

-- 
2.7.4

[PATCH v3 1/4] pwm: Add power management descriptions

[Yoshihiro Shimoda]

This patch adds power management descriptions that consumers should
implement it.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 Documentation/pwm.txt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt
index 8fbf0aa..ab62f1b 100644
--- a/Documentation/pwm.txt
+++ b/Documentation/pwm.txt
@@ -65,6 +65,10 @@ period). struct pwm_args contains 2 fields (period and polarity) and should
 be used to set the initial PWM config (usually done in the probe function
 of the PWM user). PWM arguments are retrieved with pwm_get_args().
 
+All consumers should really be reconfiguring the PWM upon resume as
+appropriate. This is the only way to ensure that everything is resumed in
+the proper order.
+
 Using PWMs with the sysfs interface
 -----------------------------------
 
@@ -141,6 +145,9 @@ The implementation of ->get_state() (a method used to retrieve initial PWM
 state) is also encouraged for the same reason: letting the PWM user know
 about the current PWM state would allow him to avoid glitches.
 
+Drivers should not implement any power management. In other words,
+consumers should implement it as described in the "Using PWMs" section.
+
 Locking
 -------
 
-- 
2.7.4

[PATCH v3 2/4] pwm: sysfs: Switch to SPDX identifier

[Yoshihiro Shimoda]

Adopt the SPDX license identifier headers to ease license compliance
management.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/pwm/sysfs.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index 719f8fa..7eb4a13 100644
--- a/drivers/pwm/sysfs.c
+++ b/drivers/pwm/sysfs.c
@@ -1,19 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * A simple sysfs interface for the generic PWM framework
  *
  * Copyright (C) 2013 H Hartley Sweeten <hsweeten@visionengravers.com>
  *
  * Based on previous work by Lars Poeschel <poeschel@lemonage.de>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2, or (at your option)
- * any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
  */
 
 #include <linux/device.h>
-- 
2.7.4

[PATCH v3 3/4] pwm: sysfs: Add suspend/resume support

[Yoshihiro Shimoda]

According to the Documentation/pwm.txt, all PWM consumers should have
power management. Since this sysfs interface is one of consumers so that
this patch adds suspend/resume support.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/pwm/sysfs.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)

diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index 7eb4a13..a0618780 100644
--- a/drivers/pwm/sysfs.c
+++ b/drivers/pwm/sysfs.c
@@ -18,6 +18,7 @@ struct pwm_export {
 	struct device child;
 	struct pwm_device *pwm;
 	struct mutex lock;
+	struct pwm_state suspend;
 };
 
 static struct pwm_export *child_to_pwm_export(struct device *child)
@@ -372,10 +373,111 @@ static struct attribute *pwm_chip_attrs[] = {
 };
 ATTRIBUTE_GROUPS(pwm_chip);
 
+/* takes export->lock on success */
+static struct pwm_export *pwm_class_get_state(struct device *parent,
+					      struct pwm_device *pwm,
+					      struct pwm_state *state)
+{
+	struct device *child;
+	struct pwm_export *export;
+
+	if (!test_bit(PWMF_EXPORTED, &pwm->flags))
+		return NULL;
+
+	child = device_find_child(parent, pwm, pwm_unexport_match);
+	if (!child)
+		return NULL;
+
+	export = child_to_pwm_export(child);
+	put_device(child);	/* for device_find_child() */
+
+	mutex_lock(&export->lock);
+	pwm_get_state(pwm, state);
+
+	return export;
+}
+
+static int pwm_class_apply_state(struct pwm_export *export,
+				 struct pwm_device *pwm,
+				 struct pwm_state *state)
+{
+	int ret = pwm_apply_state(pwm, state);
+
+	/* release lock taken in pwm_class_get_state */
+	mutex_unlock(&export->lock);
+
+	return ret;
+}
+
+static int pwm_class_resume_npwm(struct device *parent, unsigned int npwm)
+{
+	struct pwm_chip *chip = dev_get_drvdata(parent);
+	unsigned int i;
+	int ret = 0;
+
+	for (i = 0; i < npwm; i++) {
+		struct pwm_device *pwm = &chip->pwms[i];
+		struct pwm_state state;
+		struct pwm_export *export;
+
+		export = pwm_class_get_state(parent, pwm, &state);
+		if (!export)
+			continue;
+
+		state.enabled = export->suspend.enabled;
+		ret = pwm_class_apply_state(export, pwm, &state);
+		if (ret < 0)
+			break;
+	}
+
+	return ret;
+}
+
+static int pwm_class_resume(struct device *parent)
+{
+	struct pwm_chip *chip = dev_get_drvdata(parent);
+
+	return pwm_class_resume_npwm(parent, chip->npwm);
+}
+
+static int pwm_class_suspend(struct device *parent)
+{
+	struct pwm_chip *chip = dev_get_drvdata(parent);
+	unsigned int i;
+	int ret = 0;
+
+	for (i = 0; i < chip->npwm; i++) {
+		struct pwm_device *pwm = &chip->pwms[i];
+		struct pwm_state state;
+		struct pwm_export *export;
+
+		export = pwm_class_get_state(parent, pwm, &state);
+		if (!export)
+			continue;
+
+		export->suspend = state;
+		state.enabled = false;
+		ret = pwm_class_apply_state(export, pwm, &state);
+		if (ret < 0) {
+			/*
+			 * roll back the PWM devices that were disabled by
+			 * this suspend function.
+			 */
+			pwm_class_resume_npwm(parent, i);
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(pwm_class_pm_ops, pwm_class_suspend, pwm_class_resume);
+
 static struct class pwm_class = {
 	.name = "pwm",
 	.owner = THIS_MODULE,
 	.dev_groups = pwm_chip_groups,
+	.pm = &pwm_class_pm_ops,
 };
 
 static int pwmchip_sysfs_match(struct device *parent, const void *data)
-- 
2.7.4

[PATCH v3 4/4] pwm: rcar: Remove suspend/resume support

[Yoshihiro Shimoda]

According to the Documentation/pwm.txt, all PWM consumers should
implement power management instead of the PWM driver. So, this
patch removes suspend/resume support.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/pwm/pwm-rcar.c | 39 ---------------------------------------
 1 file changed, 39 deletions(-)

diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c
index cfe7dd1..5b2b8ec 100644
--- a/drivers/pwm/pwm-rcar.c
+++ b/drivers/pwm/pwm-rcar.c
@@ -254,50 +254,11 @@ static const struct of_device_id rcar_pwm_of_table[] = {
 };
 MODULE_DEVICE_TABLE(of, rcar_pwm_of_table);
 
-#ifdef CONFIG_PM_SLEEP
-static struct pwm_device *rcar_pwm_dev_to_pwm_dev(struct device *dev)
-{
-	struct rcar_pwm_chip *rcar_pwm = dev_get_drvdata(dev);
-	struct pwm_chip *chip = &rcar_pwm->chip;
-
-	return &chip->pwms[0];
-}
-
-static int rcar_pwm_suspend(struct device *dev)
-{
-	struct pwm_device *pwm = rcar_pwm_dev_to_pwm_dev(dev);
-
-	if (!test_bit(PWMF_REQUESTED, &pwm->flags))
-		return 0;
-
-	pm_runtime_put(dev);
-
-	return 0;
-}
-
-static int rcar_pwm_resume(struct device *dev)
-{
-	struct pwm_device *pwm = rcar_pwm_dev_to_pwm_dev(dev);
-	struct pwm_state state;
-
-	if (!test_bit(PWMF_REQUESTED, &pwm->flags))
-		return 0;
-
-	pm_runtime_get_sync(dev);
-
-	pwm_get_state(pwm, &state);
-
-	return rcar_pwm_apply(pwm->chip, pwm, &state);
-}
-#endif /* CONFIG_PM_SLEEP */
-static SIMPLE_DEV_PM_OPS(rcar_pwm_pm_ops, rcar_pwm_suspend, rcar_pwm_resume);
-
 static struct platform_driver rcar_pwm_driver = {
 	.probe = rcar_pwm_probe,
 	.remove = rcar_pwm_remove,
 	.driver = {
 		.name = "pwm-rcar",
-		.pm	= &rcar_pwm_pm_ops,
 		.of_match_table = of_match_ptr(rcar_pwm_of_table),
 	}
 };
-- 
2.7.4

Re: [PATCH v3 1/4] pwm: Add power management descriptions

[Simon Horman]

On Fri, May 31, 2019 at 06:54:58PM +0900, Yoshihiro Shimoda wrote:
> This patch adds power management descriptions that consumers should
> implement it.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>

> ---
>  Documentation/pwm.txt | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt
> index 8fbf0aa..ab62f1b 100644
> --- a/Documentation/pwm.txt
> +++ b/Documentation/pwm.txt
> @@ -65,6 +65,10 @@ period). struct pwm_args contains 2 fields (period and polarity) and should
>  be used to set the initial PWM config (usually done in the probe function
>  of the PWM user). PWM arguments are retrieved with pwm_get_args().
>  
> +All consumers should really be reconfiguring the PWM upon resume as
> +appropriate. This is the only way to ensure that everything is resumed in
> +the proper order.
> +
>  Using PWMs with the sysfs interface
>  -----------------------------------
>  
> @@ -141,6 +145,9 @@ The implementation of ->get_state() (a method used to retrieve initial PWM
>  state) is also encouraged for the same reason: letting the PWM user know
>  about the current PWM state would allow him to avoid glitches.
>  
> +Drivers should not implement any power management. In other words,
> +consumers should implement it as described in the "Using PWMs" section.
> +
>  Locking
>  -------
>  
> -- 
> 2.7.4
> 

Re: [PATCH v3 2/4] pwm: sysfs: Switch to SPDX identifier

[Simon Horman]

On Fri, May 31, 2019 at 06:54:59PM +0900, Yoshihiro Shimoda wrote:
> Adopt the SPDX license identifier headers to ease license compliance
> management.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>

> ---
>  drivers/pwm/sysfs.c | 11 +----------
>  1 file changed, 1 insertion(+), 10 deletions(-)
> 
> diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
> index 719f8fa..7eb4a13 100644
> --- a/drivers/pwm/sysfs.c
> +++ b/drivers/pwm/sysfs.c
> @@ -1,19 +1,10 @@
> +// SPDX-License-Identifier: GPL-2.0+
>  /*
>   * A simple sysfs interface for the generic PWM framework
>   *
>   * Copyright (C) 2013 H Hartley Sweeten <hsweeten@visionengravers.com>
>   *
>   * Based on previous work by Lars Poeschel <poeschel@lemonage.de>
> - *
> - * This program is free software; you can redistribute it and/or modify
> - * it under the terms of the GNU General Public License as published by
> - * the Free Software Foundation; either version 2, or (at your option)
> - * any later version.
> - *
> - * This program is distributed in the hope that it will be useful,
> - * but WITHOUT ANY WARRANTY; without even the implied warranty of
> - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> - * GNU General Public License for more details.
>   */
>  
>  #include <linux/device.h>
> -- 
> 2.7.4
> 

Re: [PATCH v3 3/4] pwm: sysfs: Add suspend/resume support

[Simon Horman]

On Fri, May 31, 2019 at 06:55:00PM +0900, Yoshihiro Shimoda wrote:
> According to the Documentation/pwm.txt, all PWM consumers should have
> power management. Since this sysfs interface is one of consumers so that
> this patch adds suspend/resume support.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>

Re: [PATCH v3 4/4] pwm: rcar: Remove suspend/resume support

[Simon Horman]

On Fri, May 31, 2019 at 06:55:01PM +0900, Yoshihiro Shimoda wrote:
> According to the Documentation/pwm.txt, all PWM consumers should
> implement power management instead of the PWM driver. So, this
> patch removes suspend/resume support.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>