[PATCH v3 000/108] pwm: Fix lifetime issues for pwm_chips

[PATCH v3 000/108] pwm: Fix lifetime issues for pwm_chips

[Uwe Kleine-König]

Hello,

this is v3 of the series improving life-time tracking for PWM chips. The
urgency is gone as device links now work as expected and so all
in-kernel users are fine since commit 2e84dc379200 ("driver core:
Release all resources during unbind before updating device links").

However proper lifetime tracking is a precondition to have robust
character device support, as we cannot kill a userspace process if the
used pwm driver goes away.

Changes since v2:

 - Cc: the relevant maintainers for wider testing/review audience
 - Rebase to v6.7-rc1 + https://lore.kernel.org/linux-pwm/20231121112029.gyv3gqirlycysyr4@pengutronix.de
 - Improvements for things pointed out during review and my own
   findings here and there.
 - Implementation for a few more ioctls in the WIP commit that adds
   character support

To go forward I'd like to get in patches up to #103 (i.e. adding
pwmchip_parent() (#2), devm_pwmchip_alloc() (#37) and the conversions of
the drivers to make use of these additions).

The few commits that touch drivers not living in drivers/pwm (i.e. #36,
#100-#103) can go in either via the pwm tree with the rest, or later
---when the used functions are in---via their trees.

After all in-tree drivers are prepared with the patches up to #103, we
can think about when and how we go on with the remaining bits.

Note that patch #104 breaks all drivers that don't use
devm_pwmchip_alloc(), so this is the commit that needs coordination with the
maintainers of

 drivers/gpio/gpio-mvebu.c
 drivers/gpu/drm/bridge/ti-sn65dsi86.c
 drivers/leds/rgb/leds-qcom-lpg.c
 drivers/staging/greybus/pwm.c

The motivation for this series is the last patch. It allows to control a
pwm device via ioctl. Compared to the sysfs API this already now has
some advantages:

- It changes all parameters in a single call.
  This simplifies things similar to the introduction of
  pwm_apply_state(). With sysfs it can happen that you want to
  switch polarity but that's refused because 

	pwm_get_state(mypwm, &state);
	state.polarity = new_value;

  sometimes yield an invalid state, e.g. because state.period is
  in some cases 0 after bootup. Theoretically it can even happen that you have
  to change two parameters before reaching an applicable state, then you're
  stuck with sysfs.

- It's faster than sysfs. In my measurements with stm32 about a factor
  4.

A userspace lib to make use of this can be found at
https://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/libpwm.git/ .
It makes use of the character devices if available and falls back to
sysfs. So it's somewhat useful already now.

Best regards
Uwe

Uwe Kleine-König (108):
  pwm: cros-ec: Change prototype of helper to prepare further changes
  pwm: Provide a macro to get the parent device of a given chip
  pwm: ab8500: Make use of pwmchip_parent() macro
  pwm: atmel: Make use of pwmchip_parent() macro
  pwm: atmel-tcb: Make use of pwmchip_parent() macro
  pwm: bcm-kona: Make use of pwmchip_parent() macro
  pwm: crc: Make use of pwmchip_parent() macro
  pwm: cros-ec: Make use of pwmchip_parent() macro
  pwm: dwc: Make use of pwmchip_parent() macro
  pwm: ep93xx: Make use of pwmchip_parent() macro
  pwm: fsl-ftm: Make use of pwmchip_parent() macro
  pwm: img: Make use of parent device pointer in driver data
  pwm: imx27: Make use of pwmchip_parent() macro
  pwm: jz4740: Make use of pwmchip_parent() macro
  pwm: lpc18xx-sct: Make use of parent device pointer in driver data
  pwm: lpss: Make use of pwmchip_parent() macro
  pwm: mediatek: Make use of pwmchip_parent() macro
  pwm: meson: Make use of pwmchip_parent() macro
  pwm: mtk-disp: Make use of pwmchip_parent() macro
  pwm: omap: Make use of pwmchip_parent() macro
  pwm: pca9685: Store parent device in driver data
  pwm: raspberrypi-poe: Make use of pwmchip_parent() macro
  pwm: rcar: Make use of pwmchip_parent() macro
  pwm: rz-mtu3: Make use of pwmchip_parent() macro
  pwm: samsung: Make use of pwmchip_parent() macro
  pwm: sifive: Make use of pwmchip_parent() macro
  pwm: stm32-lp: Make use of pwmchip_parent() macro
  pwm: stm32: Make use of pwmchip_parent() macro
  pwm: stmpe: Make use of pwmchip_parent() macro
  pwm: sun4i: Make use of pwmchip_parent() macro
  pwm: tiecap: Make use of pwmchip_parent() macro
  pwm: tiehrpwm: Make use of pwmchip_parent() macro
  pwm: twl-led: Make use of pwmchip_parent() macro
  pwm: twl: Make use of pwmchip_parent() macro
  pwm: vt8500: Make use of pwmchip_parent() macro
  staging: greybus: pwm: Make use of pwmchip_parent() macro
  pwm: Provide devm_pwmchip_alloc() function
  pwm: ab8500: Make use of devm_pwmchip_alloc() function
  pwm: apple: Make use of devm_pwmchip_alloc() function
  pwm: atmel-hlcdc: Make use of devm_pwmchip_alloc() function
  pwm: atmel: Make use of devm_pwmchip_alloc() function
  pwm: atmel-tcb: Make use of devm_pwmchip_alloc() function
  pwm: bcm2835: Make use of devm_pwmchip_alloc() function
  pwm: bcm-iproc: Make use of devm_pwmchip_alloc() function
  pwm: bcm-kona: Make use of devm_pwmchip_alloc() function
  pwm: berlin: Make use of devm_pwmchip_alloc() function
  pwm: brcmstb: Make use of devm_pwmchip_alloc() function
  pwm: clk: Make use of devm_pwmchip_alloc() function
  pwm: clps711x: Make use of devm_pwmchip_alloc() function
  pwm: crc: Make use of devm_pwmchip_alloc() function
  pwm: cros-ec: Make use of devm_pwmchip_alloc() function
  pwm: dwc: Make use of devm_pwmchip_alloc() function
  pwm: ep93xx: Make use of devm_pwmchip_alloc() function
  pwm: fsl-ftm: Make use of devm_pwmchip_alloc() function
  pwm: hibvt: Make use of devm_pwmchip_alloc() function
  pwm: img: Make use of devm_pwmchip_alloc() function
  pwm: imx1: Make use of devm_pwmchip_alloc() function
  pwm: imx27: Make use of devm_pwmchip_alloc() function
  pwm: imx-tpm: Make use of devm_pwmchip_alloc() function
  pwm: intel-lgm: Make use of devm_pwmchip_alloc() function
  pwm: iqs620a: Make use of devm_pwmchip_alloc() function
  pwm: jz4740: Make use of devm_pwmchip_alloc() function
  pwm: keembay: Make use of devm_pwmchip_alloc() function
  pwm: lp3943: Make use of devm_pwmchip_alloc() function
  pwm: lpc18xx-sct: Make use of devm_pwmchip_alloc() function
  pwm: lpc32xx: Make use of devm_pwmchip_alloc() function
  pwm: lpss-*: Make use of devm_pwmchip_alloc() function
  pwm: mediatek: Make use of devm_pwmchip_alloc() function
  pwm: meson: Make use of devm_pwmchip_alloc() function
  pwm: microchip-core: Make use of devm_pwmchip_alloc() function
  pwm: mtk-disp: Make use of devm_pwmchip_alloc() function
  pwm: mxs: Make use of devm_pwmchip_alloc() function
  pwm: ntxec: Make use of devm_pwmchip_alloc() function
  pwm: omap-dmtimer: Make use of devm_pwmchip_alloc() function
  pwm: pca9685: Make use of devm_pwmchip_alloc() function
  pwm: pxa: Make use of devm_pwmchip_alloc() function
  pwm: raspberrypi-poe: Make use of devm_pwmchip_alloc() function
  pwm: rcar: Make use of devm_pwmchip_alloc() function
  pwm: renesas-tpu: Make use of devm_pwmchip_alloc() function
  pwm: rockchip: Make use of devm_pwmchip_alloc() function
  pwm: rz-mtu3: Make use of devm_pwmchip_alloc() function
  pwm: samsung: Make use of devm_pwmchip_alloc() function
  pwm: sifive: Make use of devm_pwmchip_alloc() function
  pwm: sl28cpld: Make use of devm_pwmchip_alloc() function
  pwm: spear: Make use of devm_pwmchip_alloc() function
  pwm: sprd: Make use of devm_pwmchip_alloc() function
  pwm: sti: Make use of devm_pwmchip_alloc() function
  pwm: stm32-lp: Make use of devm_pwmchip_alloc() function
  pwm: stm32: Make use of devm_pwmchip_alloc() function
  pwm: stmpe: Make use of devm_pwmchip_alloc() function
  pwm: sun4i: Make use of devm_pwmchip_alloc() function
  pwm: sunplus: Make use of devm_pwmchip_alloc() function
  pwm: tegra: Make use of devm_pwmchip_alloc() function
  pwm: tiecap: Make use of devm_pwmchip_alloc() function
  pwm: twl-led: Make use of devm_pwmchip_alloc() function
  pwm: twl: Make use of devm_pwmchip_alloc() function
  pwm: visconti: Make use of devm_pwmchip_alloc() function
  pwm: vt8500: Make use of devm_pwmchip_alloc() function
  pwm: xilinx: Make use of devm_pwmchip_alloc() function
  gpio: mvebu: Make use of devm_pwmchip_alloc() function
  drm/bridge: ti-sn65dsi86: Make use of devm_pwmchip_alloc() function
  leds: qcom-lpg: Make use of devm_pwmchip_alloc() function
  staging: greybus: pwm: Make use of devm_pwmchip_alloc() function
  pwm: Ensure that pwm_chips are allocated using pwmchip_alloc()
  pwm: Ensure a struct pwm has the same lifetime as its pwm_chip
  pwm: Ensure the memory backing a PWM chip isn't freed while used
  pwm: Add more locking
  WIP: pwm: Add support for pwmchip devices for faster and easier
    userspace access

 .../driver-api/driver-model/devres.rst        |   1 +
 Documentation/driver-api/pwm.rst              |  10 +-
 drivers/gpio/gpio-mvebu.c                     |  18 +-
 drivers/gpu/drm/bridge/ti-sn65dsi86.c         |  25 +-
 drivers/leds/rgb/leds-qcom-lpg.c              |  30 +-
 drivers/pwm/Kconfig                           |   4 -
 drivers/pwm/Makefile                          |   3 +-
 drivers/pwm/core.c                            | 480 +++++++++++++++---
 drivers/pwm/pwm-ab8500.c                      |  36 +-
 drivers/pwm/pwm-apple.c                       |  18 +-
 drivers/pwm/pwm-atmel-hlcdc.c                 |  35 +-
 drivers/pwm/pwm-atmel-tcb.c                   |  26 +-
 drivers/pwm/pwm-atmel.c                       |  37 +-
 drivers/pwm/pwm-bcm-iproc.c                   |  19 +-
 drivers/pwm/pwm-bcm-kona.c                    |  21 +-
 drivers/pwm/pwm-bcm2835.c                     |  17 +-
 drivers/pwm/pwm-berlin.c                      |  29 +-
 drivers/pwm/pwm-brcmstb.c                     |  17 +-
 drivers/pwm/pwm-clk.c                         |  27 +-
 drivers/pwm/pwm-clps711x.c                    |  21 +-
 drivers/pwm/pwm-crc.c                         |  26 +-
 drivers/pwm/pwm-cros-ec.c                     |  51 +-
 drivers/pwm/pwm-dwc-core.c                    |  25 +-
 drivers/pwm/pwm-dwc.c                         |  18 +-
 drivers/pwm/pwm-dwc.h                         |   9 +-
 drivers/pwm/pwm-ep93xx.c                      |  21 +-
 drivers/pwm/pwm-fsl-ftm.c                     |  48 +-
 drivers/pwm/pwm-hibvt.c                       |  25 +-
 drivers/pwm/pwm-img.c                         |  51 +-
 drivers/pwm/pwm-imx-tpm.c                     |  34 +-
 drivers/pwm/pwm-imx1.c                        |  17 +-
 drivers/pwm/pwm-imx27.c                       |  26 +-
 drivers/pwm/pwm-intel-lgm.c                   |  17 +-
 drivers/pwm/pwm-iqs620a.c                     |  37 +-
 drivers/pwm/pwm-jz4740.c                      |  35 +-
 drivers/pwm/pwm-keembay.c                     |  17 +-
 drivers/pwm/pwm-lp3943.c                      |  17 +-
 drivers/pwm/pwm-lpc18xx-sct.c                 |  35 +-
 drivers/pwm/pwm-lpc32xx.c                     |  19 +-
 drivers/pwm/pwm-lpss-pci.c                    |  10 +-
 drivers/pwm/pwm-lpss-platform.c               |  10 +-
 drivers/pwm/pwm-lpss.c                        |  34 +-
 drivers/pwm/pwm-lpss.h                        |   1 -
 drivers/pwm/pwm-mediatek.c                    |  28 +-
 drivers/pwm/pwm-meson.c                       |  57 ++-
 drivers/pwm/pwm-microchip-core.c              |  17 +-
 drivers/pwm/pwm-mtk-disp.c                    |  25 +-
 drivers/pwm/pwm-mxs.c                         |  32 +-
 drivers/pwm/pwm-ntxec.c                       |  30 +-
 drivers/pwm/pwm-omap-dmtimer.c                |  46 +-
 drivers/pwm/pwm-pca9685.c                     |  98 ++--
 drivers/pwm/pwm-pxa.c                         |  21 +-
 drivers/pwm/pwm-raspberrypi-poe.c             |  20 +-
 drivers/pwm/pwm-rcar.c                        |  25 +-
 drivers/pwm/pwm-renesas-tpu.c                 |  18 +-
 drivers/pwm/pwm-rockchip.c                    |  24 +-
 drivers/pwm/pwm-rz-mtu3.c                     |  38 +-
 drivers/pwm/pwm-samsung.c                     |  56 +-
 drivers/pwm/pwm-sifive.c                      |  30 +-
 drivers/pwm/pwm-sl28cpld.c                    |  13 +-
 drivers/pwm/pwm-spear.c                       |  17 +-
 drivers/pwm/pwm-sprd.c                        |  50 +-
 drivers/pwm/pwm-sti.c                         |  34 +-
 drivers/pwm/pwm-stm32-lp.c                    |  29 +-
 drivers/pwm/pwm-stm32.c                       |  53 +-
 drivers/pwm/pwm-stmpe.c                       |  58 ++-
 drivers/pwm/pwm-sun4i.c                       |  38 +-
 drivers/pwm/pwm-sunplus.c                     |  17 +-
 drivers/pwm/pwm-tegra.c                       |  27 +-
 drivers/pwm/pwm-tiecap.c                      |  55 +-
 drivers/pwm/pwm-tiehrpwm.c                    |  72 +--
 drivers/pwm/pwm-twl-led.c                     |  58 ++-
 drivers/pwm/pwm-twl.c                         |  50 +-
 drivers/pwm/pwm-visconti.c                    |  17 +-
 drivers/pwm/pwm-vt8500.c                      |  41 +-
 drivers/pwm/pwm-xilinx.c                      |  34 +-
 drivers/pwm/sysfs.c                           |  64 +--
 drivers/staging/greybus/pwm.c                 | 130 ++---
 include/linux/platform_data/x86/pwm-lpss.h    |   4 +-
 include/linux/pwm.h                           |  36 +-
 include/uapi/linux/pwm.h                      |  23 +
 81 files changed, 1651 insertions(+), 1291 deletions(-)
 create mode 100644 include/uapi/linux/pwm.h

base-commit: 869de350ff3834145273a6d39faedea878c6715a
-- 
2.42.0

[PATCH v3 030/108] pwm: sun4i: Make use of pwmchip_parent() macro

[Uwe Kleine-König]

struct pwm_chip::dev is about to change. To not have to touch this
driver in the same commit as struct pwm_chip::dev, use the macro
provided for exactly this purpose.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/pwm-sun4i.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 1a439025540d..44edf1ce5739 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -245,7 +245,7 @@ static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	if (!cstate.enabled) {
 		ret = clk_prepare_enable(sun4i_pwm->clk);
 		if (ret) {
-			dev_err(chip->dev, "failed to enable PWM clock\n");
+			dev_err(pwmchip_parent(chip), "failed to enable PWM clock\n");
 			return ret;
 		}
 	}
@@ -253,7 +253,7 @@ static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	ret = sun4i_pwm_calculate(sun4i_pwm, state, &duty, &period, &prescaler,
 				  &bypass);
 	if (ret) {
-		dev_err(chip->dev, "period exceeds the maximum value\n");
+		dev_err(pwmchip_parent(chip), "period exceeds the maximum value\n");
 		if (!cstate.enabled)
 			clk_disable_unprepare(sun4i_pwm->clk);
 		return ret;
-- 
2.42.0

[PATCH v3 091/108] pwm: sun4i: Make use of devm_pwmchip_alloc() function

[Uwe Kleine-König]

This prepares the pwm-sun4i driver to further changes of the pwm core
outlined in the commit introducing devm_pwmchip_alloc(). There is no
intended semantical change and the driver should behave as before.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/pwm-sun4i.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 44edf1ce5739..65652f510237 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -81,7 +81,6 @@ struct sun4i_pwm_data {
 };
 
 struct sun4i_pwm_chip {
-	struct pwm_chip chip;
 	struct clk *bus_clk;
 	struct clk *clk;
 	struct reset_control *rst;
@@ -92,7 +91,7 @@ struct sun4i_pwm_chip {
 
 static inline struct sun4i_pwm_chip *to_sun4i_pwm_chip(struct pwm_chip *chip)
 {
-	return container_of(chip, struct sun4i_pwm_chip, chip);
+	return pwmchip_priv(chip);
 }
 
 static inline u32 sun4i_pwm_readl(struct sun4i_pwm_chip *chip,
@@ -384,17 +383,22 @@ MODULE_DEVICE_TABLE(of, sun4i_pwm_dt_ids);
 
 static int sun4i_pwm_probe(struct platform_device *pdev)
 {
+	struct pwm_chip *chip;
 	struct sun4i_pwm_chip *sun4ichip;
+	const struct sun4i_pwm_data *data;
 	int ret;
 
-	sun4ichip = devm_kzalloc(&pdev->dev, sizeof(*sun4ichip), GFP_KERNEL);
-	if (!sun4ichip)
-		return -ENOMEM;
-
-	sun4ichip->data = of_device_get_match_data(&pdev->dev);
-	if (!sun4ichip->data)
+	data = of_device_get_match_data(&pdev->dev);
+	if (!data)
 		return -ENODEV;
 
+	chip = devm_pwmchip_alloc(&pdev->dev, data->npwm, sizeof(*sun4ichip));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+	sun4ichip = to_sun4i_pwm_chip(chip);
+
+	sun4ichip->data = data;
+
 	sun4ichip->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(sun4ichip->base))
 		return PTR_ERR(sun4ichip->base);
@@ -451,19 +455,18 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
 		goto err_bus;
 	}
 
-	sun4ichip->chip.dev = &pdev->dev;
-	sun4ichip->chip.ops = &sun4i_pwm_ops;
-	sun4ichip->chip.npwm = sun4ichip->data->npwm;
+	chip->ops = &sun4i_pwm_ops;
+	chip->npwm = sun4ichip->data->npwm;
 
 	spin_lock_init(&sun4ichip->ctrl_lock);
 
-	ret = pwmchip_add(&sun4ichip->chip);
+	ret = pwmchip_add(chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 		goto err_pwm_add;
 	}
 
-	platform_set_drvdata(pdev, sun4ichip);
+	platform_set_drvdata(pdev, chip);
 
 	return 0;
 
@@ -477,9 +480,10 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
 
 static void sun4i_pwm_remove(struct platform_device *pdev)
 {
-	struct sun4i_pwm_chip *sun4ichip = platform_get_drvdata(pdev);
+	struct pwm_chip *chip = platform_get_drvdata(pdev);
+	struct sun4i_pwm_chip *sun4ichip = to_sun4i_pwm_chip(chip);
 
-	pwmchip_remove(&sun4ichip->chip);
+	pwmchip_remove(chip);
 
 	clk_disable_unprepare(sun4ichip->bus_clk);
 	reset_control_assert(sun4ichip->rst);
-- 
2.42.0

Re: [PATCH v3 030/108] pwm: sun4i: Make use of pwmchip_parent() macro

[Jernej Škrabec]

Dne torek, 21. november 2023 ob 14:49:32 CET je Uwe Kleine-König napisal(a):
> struct pwm_chip::dev is about to change. To not have to touch this
> driver in the same commit as struct pwm_chip::dev, use the macro
> provided for exactly this purpose.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>

Best regards,
Jernej

> ---
>  drivers/pwm/pwm-sun4i.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> index 1a439025540d..44edf1ce5739 100644
> --- a/drivers/pwm/pwm-sun4i.c
> +++ b/drivers/pwm/pwm-sun4i.c
> @@ -245,7 +245,7 @@ static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>  	if (!cstate.enabled) {
>  		ret = clk_prepare_enable(sun4i_pwm->clk);
>  		if (ret) {
> -			dev_err(chip->dev, "failed to enable PWM clock\n");
> +			dev_err(pwmchip_parent(chip), "failed to enable PWM clock\n");
>  			return ret;
>  		}
>  	}
> @@ -253,7 +253,7 @@ static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>  	ret = sun4i_pwm_calculate(sun4i_pwm, state, &duty, &period, &prescaler,
>  				  &bypass);
>  	if (ret) {
> -		dev_err(chip->dev, "period exceeds the maximum value\n");
> +		dev_err(pwmchip_parent(chip), "period exceeds the maximum value\n");
>  		if (!cstate.enabled)
>  			clk_disable_unprepare(sun4i_pwm->clk);
>  		return ret;
>