[PATCH v6 000/164] pwm: Improve lifetime tracking for pwm_chips

[PATCH v6 000/164] pwm: Improve lifetime tracking for pwm_chips

[Uwe Kleine-König]

Hello,

this is v6 of the series introducing better lifetime tracking for
pwmchips that addresses (for now theoretic) lifetime issues of pwm
chips. Addressing these is a necessary precondition to introduce chardev
support for PWMs.

Locking got more complicated due to non-sleeping chips, so I dropped
the character device patch because it got still more incomplete now.
Also I'm not yet entirely sure about patches #162 and #163 and I expect
them to change before they can go in. My plan for the next merge window
is to get the patches in up to #160. After that the addition of chardev
support (including correct locking) can continue without having to touch
the lowlevel driver. So the idea of this series is to get the driver
adaptions out of the way as this requires some cross-tree coordination.

The patches that touch files outside of drivers/pwm include:

 - gpio: mvebu: Make use of devm_pwmchip_alloc() function
   It already has an Ack by Linus Walleij.

 - drm/bridge: ti-sn65dsi86: Make use of pwmchip_parent() accessor
 - drm/bridge: ti-sn65dsi86: Make use of devm_pwmchip_alloc() function
   The 2nd already has an Ack by Douglas Anderson which I tend to assume
   good enough to merge this via my pwm tree, too. An Ack for the first
   patch would be nice.

 - leds: qcom-lpg: Make use of devm_pwmchip_alloc() function
   Already has an Ack by Lee Jones.

 - staging: greybus: pwm: Change prototype of helpers to prepare further changes
 - staging: greybus: pwm: Make use of pwmchip_parent() accessor
 - staging: greybus: pwm: Rely on pwm framework to pass a valid hwpwm
 - staging: greybus: pwm: Drop unused gb_connection_set_data()
 - staging: greybus: pwm: Rework how the number of PWM lines is determined
 - staging: greybus: pwm: Make use of devm_pwmchip_alloc() function
   The greybus patches already got an Ack by Greg Kroah-Hartman in an
   earlier series, but I dropped it as the patches changed considerably.

For the patches that already have an Ack by the respective maintainers
I'll assume this is good enough to merge the patches via the pwm tree.
Please object if you don't agree.  For the others an Ack with that
semantic would be nice. If you want to merge via your tree, that would
need some coordination. The adaptions depend on patches #1 - #3, so this
would involve an immutable branch or waiting until these patches reached
your tree via the mainline tree. The series rebases fine on today's
next, so at least for now there are no conflicts that git cannot resolve
automatically.

The biggest changes compared to v5 are:

 - Make pwmchip_parent's parameter const
 - Use pwmchip_parent also in drivers/pwm/sysfs.c and drivers/pwm/core.c
 - Several bug fixes in the conversions I found during the rework
 - Provide a non-devm pwmchip_alloc() function earlier (for the greybus
   pwm driver)
 - Increase alignment of driver private data to ARCH_DMA_MINALIGN bytes
 - Split several patches to make the easier reviewable

The series is available via git at

	https://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux.git pwm-lifetime-tracking

if you want to give it a test. I'll keep this branch updated for the
feedback I get here.

Best regards
Uwe

Uwe Kleine-König (164):
  pwm: Provide an inline function to get the parent device of a given
    chip
  pwm: Provide wrappers for storing and getting driver private data
  pwm: Provide pwmchip_alloc() function and a devm variant of it
  pwm: ab8500: Make use of pwmchip_parent() accessor
  pwm: ab8500: Introduce a local pwm_chip variable in .probe()
  pwm: ab8500: Make use of devm_pwmchip_alloc() function
  pwm: apple: Make use of devm_pwmchip_alloc() function
  pwm: atmel: Change prototype of a helper to prepare further changes
  pwm: atmel: Make use of pwmchip_parent() accessor
  pwm: atmel: Make use of devm_pwmchip_alloc() function
  pwm: atmel-hlcdc: Prepare removing pwm_chip from driver data
  pwm: atmel-hlcdc: Make use of devm_pwmchip_alloc() function
  pwm: atmel-tcb: Make use of pwmchip_parent() accessor
  pwm: atmel-tcb: Prepare removing pwm_chip from driver data
  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 pwmchip_parent() accessor
  pwm: bcm-kona: Make use of devm_pwmchip_alloc() function
  pwm: berlin: Prepare removing pwm_chip from driver data
  pwm: berlin: Make use of devm_pwmchip_alloc() function
  pwm: brcmstb: Make use of devm_pwmchip_alloc() function
  pwm: clk: Prepare removing pwm_chip from driver data
  pwm: clk: Make use of devm_pwmchip_alloc() function
  pwm: clps711x: Make use of devm_pwmchip_alloc() function
  pwm: crc: Simplify code to determine the pwmchip's parent device
  pwm: crc: Make use of pwmchip_parent() accessor
  pwm: crc: Make use of devm_pwmchip_alloc() function
  pwm: cros-ec: Change prototype of helpers to prepare further changes
  pwm: cros-ec: Make use of pwmchip_parent() accessor
  pwm: cros-ec: Make use of devm_pwmchip_alloc() function
  pwm: dwc: Prepare removing pwm_chip from driver data
  pwm: dwc: Make use of devm_pwmchip_alloc() function
  pwm: dwc-core: Make use of pwmchip_parent() accessor
  pwm: ep93xx: Make use of pwmchip_parent() accessor
  pwm: ep93xx: Make use of devm_pwmchip_alloc() function
  pwm: fsl-ftm: Change prototype of a helper to prepare further changes
  pwm: fsl-ftm: Make use of pwmchip_parent() accessor
  pwm: fsl-ftm: Prepare removing pwm_chip from driver data
  pwm: fsl-ftm: Make use of devm_pwmchip_alloc() function
  pwm: hibvt: Consistently name driver data hi_pwm_chip
  pwm: hibvt: Make use of devm_pwmchip_alloc() function
  pwm: img: Drop write-only variable from driver private data
  pwm: img: Make use of pwmchip_parent() accessor
  pwm: img: Prepare removing pwm_chip from driver data
  pwm: img: Make use of devm_pwmchip_alloc() function
  pwm: imx1: Make use of devm_pwmchip_alloc() function
  pwm: imx27: Make use of pwmchip_parent() accessor
  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: Create a wrapper for converting a pwm_chip to driver
    data
  pwm: iqs620a: Prepare removing pwm_chip from driver data
  pwm: iqs620a: Make use of devm_pwmchip_alloc() function
  pwm: jz4740: Change prototype of a helper to prepare further changes
  pwm: jz4740: Make use of pwmchip_parent() accessor
  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: Drop hardly used member from driver private data
  pwm: lpc18xx-sct: Make use of pwmchip_parent() accessor
  pwm: lpc18xx-sct: Prepare removing pwm_chip from driver data
  pwm: lpc18xx-sct: Make use of devm_pwmchip_alloc() function
  pwm: lpc32xx: Make use of devm_pwmchip_alloc() function
  pwm: lpss: Make use of pwmchip_parent() accessor
  pwm: lpss: Don't set driver data
  pwm: lpss-*: Make use of devm_pwmchip_alloc() function
  pwm: mediatek: Make use of pwmchip_parent() accessor
  pwm: mediatek: Make use of devm_pwmchip_alloc() function
  pwm: meson: Change prototype of a few helpers to prepare further
    changes
  pwm: meson: Make use of pwmchip_parent() accessor
  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 pwmchip_parent() accessor
  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 pwmchip_parent() accessor
  pwm: omap-dmtimer: Prepare removing pwm_chip from driver data
  pwm: omap-dmtimer: Make use of devm_pwmchip_alloc() function
  pwm: pca9685: Prepare removing pwm_chip from driver data
  pwm: pca9685: Make use of pwmchip_parent() accessor
  pwm: pca9685: Make use of devm_pwmchip_alloc() function
  pwm: pxa: Make use of devm_pwmchip_alloc() function
  pwm: raspberrypi-poe: Make use of pwmchip_parent() accessor
  pwm: raspberrypi-poe: Make use of devm_pwmchip_alloc() function
  pwm: rcar: Make use of pwmchip_parent() accessor
  pwm: rcar: Prepare removing pwm_chip from driver data
  pwm: rcar: Make use of devm_pwmchip_alloc() function
  pwm: renesas-tpu: Make use of devm_pwmchip_alloc() function
  pwm: rochchip: Prepare removing pwm_chip from driver data
  pwm: rockchip: Make use of devm_pwmchip_alloc() function
  pwm: rz-mtu3: Make use of pwmchip_parent() accessor
  pwm: rz-mtu3: Prepare removing pwm_chip from driver data
  pwm: rz-mtu3: Make use of devm_pwmchip_alloc() function
  pwm: samsung: Simplify code to determine the pwmchip's parent device
  pwm: samsung: Change prototype of helpers to prepare further changes
  pwm: samsung: Make use of pwmchip_parent() accessor
  pwm: samsung: Simplify by using devm functions in probe
  pwm: samsung: Simplify using dev_err_probe()
  pwm: samsung: Make use of devm_pwmchip_alloc() function
  pwm: sifive: Simplify code to determine the pwmchip's parent device
  pwm: sifive: Prepare removing pwm_chip from driver data
  pwm: sifive: Make use of pwmchip_parent() accessor
  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: Rework how the available channels are counted
  pwm: sprd: Drop duplicated tracking of the parent device
  pwm: sprd: Make use of devm_pwmchip_alloc() function
  pwm: sti: Prepare removing pwm_chip from driver data
  pwm: sti: Make use of devm_pwmchip_alloc() function
  pwm: stm32: Simplify code to determine the pwmchip's parent device
  pwm: stm32: Change prototype of a helper to prepare further changes
  pwm: stm32: Prepare removing pwm_chip from driver data
  pwm: stm32: Change prototype of helper that detects npwm to prepare
    further changes
  pwm: stm32: Make use of devm_pwmchip_alloc() function
  pwm: stm32-lp: Simplify code to determine the pwmchip's parent device
  pwm: stm32-lp: Prepare removing pwm_chip from driver data
  pwm: stm32-lp: Make use of pwmchip_parent() accessor
  pwm: stm32-lp: Make use of devm_pwmchip_alloc() function
  pwm: stmpe: Make use of pwmchip_parent() accessor
  pwm: stmpe: Make use of devm_pwmchip_alloc() function
  pwm: sun4i: Make use of pwmchip_parent() accessor
  pwm: sun4i: Prepare removing pwm_chip from driver data
  pwm: sun4i: Consistently name driver data sun4ichip
  pwm: sun4i: Make use of devm_pwmchip_alloc() function
  pwm: sunplus: Make use of devm_pwmchip_alloc() function
  pwm: tegra: Drop duplicated tracking of the parent device
  pwm: tegra: Prepare removing pwm_chip from driver data
  pwm: tegra: Make use of devm_pwmchip_alloc() function
  pwm: tiecap: Simplify code to determine the pwmchip's parent device
  pwm: tiecap: Change prototype of helpers to prepare further changes
  pwm: tiecap: Make use of pwmchip_parent() accessor
  pwm: tiecap: Make use of devm_pwmchip_alloc() function
  pwm: tiehrpwm: Simplify code to determine the pwmchip's parent device
  pwm: tiehrpwm: Change prototype of helpers to prepare further changes
  pwm: tiehrpwm: Make use of pwmchip_parent() accessor
  pwm: tiehrpwm: Make use of devm_pwmchip_alloc() function
  pwm: twl: Make use of pwmchip_parent() accessor
  pwm: twl: Make use of devm_pwmchip_alloc() function
  pwm: twl-led: Make use of pwmchip_parent() accessor
  pwm: twl-led: Make use of devm_pwmchip_alloc() function
  pwm: visconti: Make use of devm_pwmchip_alloc() function
  pwm: vt8500: Change prototype of a helper to prepare further changes
  pwm: vt8500: Introduce a local pwm_chip variable in .probe()
  pwm: vt8500: Make use of pwmchip_parent() accessor
  pwm: vt8500: Make use of devm_pwmchip_alloc() function
  pwm: xilinx: Prepare removing pwm_chip from driver data
  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 pwmchip_parent() accessor
  drm/bridge: ti-sn65dsi86: Make use of devm_pwmchip_alloc() function
  leds: qcom-lpg: Make use of devm_pwmchip_alloc() function
  staging: greybus: pwm: Change prototype of helpers to prepare further
    changes
  staging: greybus: pwm: Make use of pwmchip_parent() accessor
  staging: greybus: pwm: Rely on pwm framework to pass a valid hwpwm
  staging: greybus: pwm: Drop unused gb_connection_set_data()
  staging: greybus: pwm: Rework how the number of PWM lines is
    determined
  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: Make pwmchip_[sg]et_drvdata() a wrapper around dev_set_drvdata()

 .../driver-api/driver-model/devres.rst        |   1 +
 Documentation/driver-api/pwm.rst              |  11 +-
 drivers/gpio/gpio-mvebu.c                     |  18 +-
 drivers/gpu/drm/bridge/ti-sn65dsi86.c         |  31 +--
 drivers/leds/rgb/leds-qcom-lpg.c              |  16 +-
 drivers/pinctrl/intel/pinctrl-intel.c         |   6 +-
 drivers/pwm/Kconfig                           |   4 -
 drivers/pwm/Makefile                          |   3 +-
 drivers/pwm/core.c                            | 184 +++++++++++++-----
 drivers/pwm/pwm-ab8500.c                      |  36 ++--
 drivers/pwm/pwm-apple.c                       |  18 +-
 drivers/pwm/pwm-atmel-hlcdc.c                 |  37 ++--
 drivers/pwm/pwm-atmel-tcb.c                   |  32 +--
 drivers/pwm/pwm-atmel.c                       |  34 ++--
 drivers/pwm/pwm-bcm-iproc.c                   |  19 +-
 drivers/pwm/pwm-bcm-kona.c                    |  23 ++-
 drivers/pwm/pwm-bcm2835.c                     |  19 +-
 drivers/pwm/pwm-berlin.c                      |  29 +--
 drivers/pwm/pwm-brcmstb.c                     |  17 +-
 drivers/pwm/pwm-clk.c                         |  27 +--
 drivers/pwm/pwm-clps711x.c                    |  17 +-
 drivers/pwm/pwm-crc.c                         |  22 +--
 drivers/pwm/pwm-cros-ec.c                     |  58 +++---
 drivers/pwm/pwm-dwc-core.c                    |  26 +--
 drivers/pwm/pwm-dwc.c                         |  17 +-
 drivers/pwm/pwm-dwc.h                         |   9 +-
 drivers/pwm/pwm-ep93xx.c                      |  21 +-
 drivers/pwm/pwm-fsl-ftm.c                     |  49 ++---
 drivers/pwm/pwm-hibvt.c                       |  70 ++++---
 drivers/pwm/pwm-img.c                         |  60 +++---
 drivers/pwm/pwm-imx-tpm.c                     |  34 ++--
 drivers/pwm/pwm-imx1.c                        |  20 +-
 drivers/pwm/pwm-imx27.c                       |  26 +--
 drivers/pwm/pwm-intel-lgm.c                   |  17 +-
 drivers/pwm/pwm-iqs620a.c                     |  30 +--
 drivers/pwm/pwm-jz4740.c                      |  36 ++--
 drivers/pwm/pwm-keembay.c                     |  17 +-
 drivers/pwm/pwm-lp3943.c                      |  17 +-
 drivers/pwm/pwm-lpc18xx-sct.c                 |  34 ++--
 drivers/pwm/pwm-lpc32xx.c                     |  21 +-
 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                    |  29 +--
 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                       |  14 +-
 drivers/pwm/pwm-omap-dmtimer.c                |  47 +++--
 drivers/pwm/pwm-pca9685.c                     | 161 +++++++--------
 drivers/pwm/pwm-pxa.c                         |  21 +-
 drivers/pwm/pwm-raspberrypi-poe.c             |  20 +-
 drivers/pwm/pwm-rcar.c                        |  27 ++-
 drivers/pwm/pwm-renesas-tpu.c                 |  20 +-
 drivers/pwm/pwm-rockchip.c                    |  24 +--
 drivers/pwm/pwm-rz-mtu3.c                     |  60 +++---
 drivers/pwm/pwm-samsung.c                     |  94 ++++-----
 drivers/pwm/pwm-sifive.c                      |  30 +--
 drivers/pwm/pwm-sl28cpld.c                    |  13 +-
 drivers/pwm/pwm-spear.c                       |  18 +-
 drivers/pwm/pwm-sprd.c                        |  58 +++---
 drivers/pwm/pwm-sti.c                         |  61 +++---
 drivers/pwm/pwm-stm32-lp.c                    |  31 ++-
 drivers/pwm/pwm-stm32.c                       |  56 +++---
 drivers/pwm/pwm-stmpe.c                       |  58 +++---
 drivers/pwm/pwm-sun4i.c                       | 100 +++++-----
 drivers/pwm/pwm-sunplus.c                     |  17 +-
 drivers/pwm/pwm-tegra.c                       |  50 ++---
 drivers/pwm/pwm-tiecap.c                      |  55 +++---
 drivers/pwm/pwm-tiehrpwm.c                    |  72 +++----
 drivers/pwm/pwm-twl-led.c                     |  55 +++---
 drivers/pwm/pwm-twl.c                         |  50 +++--
 drivers/pwm/pwm-visconti.c                    |  17 +-
 drivers/pwm/pwm-vt8500.c                      |  43 ++--
 drivers/pwm/pwm-xilinx.c                      |  34 ++--
 drivers/pwm/sysfs.c                           |  45 +----
 drivers/staging/greybus/pwm.c                 | 133 ++++++-------
 include/linux/platform_data/x86/pwm-lpss.h    |   4 +-
 include/linux/pwm.h                           |  56 ++++--
 81 files changed, 1502 insertions(+), 1423 deletions(-)


base-commit: ab105bfee27776dd946f8003d1e895fbf7674a3f
-- 
2.43.0

[PATCH v6 003/164] pwm: Provide pwmchip_alloc() function and a devm variant of it

[Uwe Kleine-König]

This function allocates a struct pwm_chip and driver data. Compared to
the status quo the split into pwm_chip and driver data is new, otherwise
it doesn't change anything relevant (yet).

The intention is that after all drivers are switched to use this
allocation function, its possible to add a struct device to struct
pwm_chip to properly track the latter's lifetime without touching all
drivers again. Proper lifetime tracking is a necessary precondition to
introduce character device support for PWMs (that implements atomic
setting and doesn't suffer from the sysfs overhead of the /sys/class/pwm
userspace support).

The new function pwmchip_priv() (obviously?) only works for chips
allocated with pwmchip_alloc().

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 .../driver-api/driver-model/devres.rst        |  1 +
 Documentation/driver-api/pwm.rst              | 11 ++--
 drivers/pwm/core.c                            | 58 +++++++++++++++++++
 include/linux/pwm.h                           | 22 +++++++
 4 files changed, 87 insertions(+), 5 deletions(-)

diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst
index c5f99d834ec5..e4df72c408d2 100644
--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -420,6 +420,7 @@ POWER
   devm_reboot_mode_unregister()
 
 PWM
+  devm_pwmchip_alloc()
   devm_pwmchip_add()
   devm_pwm_get()
   devm_fwnode_pwm_get()
diff --git a/Documentation/driver-api/pwm.rst b/Documentation/driver-api/pwm.rst
index 3c28ccc4b611..b41b1c56477f 100644
--- a/Documentation/driver-api/pwm.rst
+++ b/Documentation/driver-api/pwm.rst
@@ -143,11 +143,12 @@ to implement the pwm_*() functions itself. This means that it's impossible
 to have multiple PWM drivers in the system. For this reason it's mandatory
 for new drivers to use the generic PWM framework.
 
-A new PWM controller/chip can be added using pwmchip_add() and removed
-again with pwmchip_remove(). pwmchip_add() takes a filled in struct
-pwm_chip as argument which provides a description of the PWM chip, the
-number of PWM devices provided by the chip and the chip-specific
-implementation of the supported PWM operations to the framework.
+A new PWM controller/chip can be allocated using pwmchip_alloc(), then
+registered using pwmchip_add() and removed again with pwmchip_remove(). To undo
+pwmchip_alloc() use pwmchip_put(). pwmchip_add() takes a filled in struct
+pwm_chip as argument which provides a description of the PWM chip, the number
+of PWM devices provided by the chip and the chip-specific implementation of the
+supported PWM operations to the framework.
 
 When implementing polarity support in a PWM driver, make sure to respect the
 signal conventions in the PWM framework. By definition, normal polarity
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 830a697826af..9fc6f4fa71d6 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -454,6 +454,64 @@ of_pwm_single_xlate(struct pwm_chip *chip, const struct of_phandle_args *args)
 }
 EXPORT_SYMBOL_GPL(of_pwm_single_xlate);
 
+#define PWMCHIP_ALIGN ARCH_DMA_MINALIGN
+
+static void *pwmchip_priv(struct pwm_chip *chip)
+{
+	return (void *)chip + ALIGN(sizeof(*chip), PWMCHIP_ALIGN);
+}
+
+/* This is the counterpart to pwmchip_alloc */
+void pwmchip_put(struct pwm_chip *chip)
+{
+	kfree(chip);
+}
+EXPORT_SYMBOL_GPL(pwmchip_put);
+
+struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv)
+{
+	struct pwm_chip *chip;
+	size_t alloc_size;
+
+	alloc_size = size_add(ALIGN(sizeof(*chip), PWMCHIP_ALIGN), sizeof_priv);
+
+	chip = kzalloc(alloc_size, GFP_KERNEL);
+	if (!chip)
+		return ERR_PTR(-ENOMEM);
+
+	chip->dev = parent;
+	chip->npwm = npwm;
+
+	pwmchip_set_drvdata(chip, pwmchip_priv(chip));
+
+	return chip;
+}
+EXPORT_SYMBOL_GPL(pwmchip_alloc);
+
+static void devm_pwmchip_put(void *data)
+{
+	struct pwm_chip *chip = data;
+
+	pwmchip_put(chip);
+}
+
+struct pwm_chip *devm_pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv)
+{
+	struct pwm_chip *chip;
+	int ret;
+
+	chip = pwmchip_alloc(parent, npwm, sizeof_priv);
+	if (IS_ERR(chip))
+		return chip;
+
+	ret = devm_add_action_or_reset(parent, devm_pwmchip_put, chip);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return chip;
+}
+EXPORT_SYMBOL_GPL(devm_pwmchip_alloc);
+
 static void of_pwmchip_add(struct pwm_chip *chip)
 {
 	if (!pwmchip_parent(chip) || !pwmchip_parent(chip)->of_node)
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 29a7d9140f77..4a6568dfdf3f 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -403,6 +403,10 @@ static inline bool pwm_might_sleep(struct pwm_device *pwm)
 int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
 		unsigned long timeout);
 
+void pwmchip_put(struct pwm_chip *chip);
+struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv);
+struct pwm_chip *devm_pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv);
+
 int __pwmchip_add(struct pwm_chip *chip, struct module *owner);
 #define pwmchip_add(chip) __pwmchip_add(chip, THIS_MODULE)
 void pwmchip_remove(struct pwm_chip *chip);
@@ -475,6 +479,24 @@ static inline int pwm_capture(struct pwm_device *pwm,
 	return -EINVAL;
 }
 
+static inline void pwmchip_put(struct pwm_chip *chip)
+{
+}
+
+static inline struct pwm_chip *pwmchip_alloc(struct device *parent,
+					     unsigned int npwm,
+					     size_t sizeof_priv)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline struct pwm_chip *devm_pwmchip_alloc(struct device *parent,
+						  unsigned int npwm,
+						  size_t sizeof_priv)
+{
+	return pwmchip_alloc(parent, npwm, sizeof_priv);
+}
+
 static inline int pwmchip_add(struct pwm_chip *chip)
 {
 	return -EINVAL;
-- 
2.43.0

[PATCH v6 067/164] pwm: lpss-*: Make use of devm_pwmchip_alloc() function

[Uwe Kleine-König]

This prepares the pwm-lpc drivers 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/pinctrl/intel/pinctrl-intel.c      |  6 +++---
 drivers/pwm/pwm-lpss-pci.c                 |  8 ++++----
 drivers/pwm/pwm-lpss-platform.c            |  8 ++++----
 drivers/pwm/pwm-lpss.c                     | 20 ++++++++++----------
 drivers/pwm/pwm-lpss.h                     |  1 -
 include/linux/platform_data/x86/pwm-lpss.h |  4 ++--
 6 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/drivers/pinctrl/intel/pinctrl-intel.c b/drivers/pinctrl/intel/pinctrl-intel.c
index d6f29e6faab7..89bd7ce6711a 100644
--- a/drivers/pinctrl/intel/pinctrl-intel.c
+++ b/drivers/pinctrl/intel/pinctrl-intel.c
@@ -1492,7 +1492,7 @@ static int intel_pinctrl_probe_pwm(struct intel_pinctrl *pctrl,
 		.base_unit_bits = 22,
 		.bypass = true,
 	};
-	struct pwm_lpss_chip *pwm;
+	struct pwm_chip *chip;
 
 	if (!(community->features & PINCTRL_FEATURE_PWM))
 		return 0;
@@ -1500,8 +1500,8 @@ static int intel_pinctrl_probe_pwm(struct intel_pinctrl *pctrl,
 	if (!IS_REACHABLE(CONFIG_PWM_LPSS))
 		return 0;
 
-	pwm = devm_pwm_lpss_probe(pctrl->dev, community->regs + PWMC, &info);
-	return PTR_ERR_OR_ZERO(pwm);
+	chip = devm_pwm_lpss_probe(pctrl->dev, community->regs + PWMC, &info);
+	return PTR_ERR_OR_ZERO(chip);
 }
 
 int intel_pinctrl_probe(struct platform_device *pdev,
diff --git a/drivers/pwm/pwm-lpss-pci.c b/drivers/pwm/pwm-lpss-pci.c
index 34acfe99b74f..25045c229520 100644
--- a/drivers/pwm/pwm-lpss-pci.c
+++ b/drivers/pwm/pwm-lpss-pci.c
@@ -18,7 +18,7 @@ static int pwm_lpss_probe_pci(struct pci_dev *pdev,
 			      const struct pci_device_id *id)
 {
 	const struct pwm_lpss_boardinfo *info;
-	struct pwm_lpss_chip *lpwm;
+	struct pwm_chip *chip;
 	int err;
 
 	err = pcim_enable_device(pdev);
@@ -30,9 +30,9 @@ static int pwm_lpss_probe_pci(struct pci_dev *pdev,
 		return err;
 
 	info = (struct pwm_lpss_boardinfo *)id->driver_data;
-	lpwm = devm_pwm_lpss_probe(&pdev->dev, pcim_iomap_table(pdev)[0], info);
-	if (IS_ERR(lpwm))
-		return PTR_ERR(lpwm);
+	chip = devm_pwm_lpss_probe(&pdev->dev, pcim_iomap_table(pdev)[0], info);
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
 
 	pm_runtime_put(&pdev->dev);
 	pm_runtime_allow(&pdev->dev);
diff --git a/drivers/pwm/pwm-lpss-platform.c b/drivers/pwm/pwm-lpss-platform.c
index 5f6ee300e342..dbc9f5b17bdc 100644
--- a/drivers/pwm/pwm-lpss-platform.c
+++ b/drivers/pwm/pwm-lpss-platform.c
@@ -20,7 +20,7 @@
 static int pwm_lpss_probe_platform(struct platform_device *pdev)
 {
 	const struct pwm_lpss_boardinfo *info;
-	struct pwm_lpss_chip *lpwm;
+	struct pwm_chip *chip;
 	void __iomem *base;
 
 	info = device_get_match_data(&pdev->dev);
@@ -31,9 +31,9 @@ static int pwm_lpss_probe_platform(struct platform_device *pdev)
 	if (IS_ERR(base))
 		return PTR_ERR(base);
 
-	lpwm = devm_pwm_lpss_probe(&pdev->dev, base, info);
-	if (IS_ERR(lpwm))
-		return PTR_ERR(lpwm);
+	chip = devm_pwm_lpss_probe(&pdev->dev, base, info);
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
 
 	/*
 	 * On Cherry Trail devices the GFX0._PS0 AML checks if the controller
diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
index 394c768f5a5f..b79fd3405e15 100644
--- a/drivers/pwm/pwm-lpss.c
+++ b/drivers/pwm/pwm-lpss.c
@@ -68,7 +68,7 @@ EXPORT_SYMBOL_GPL(pwm_lpss_tng_info);
 
 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
 {
-	return container_of(chip, struct pwm_lpss_chip, chip);
+	return pwmchip_get_drvdata(chip);
 }
 
 static inline u32 pwm_lpss_read(const struct pwm_device *pwm)
@@ -245,9 +245,10 @@ static const struct pwm_ops pwm_lpss_ops = {
 	.get_state = pwm_lpss_get_state,
 };
 
-struct pwm_lpss_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
+struct pwm_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
 					  const struct pwm_lpss_boardinfo *info)
 {
+	struct pwm_chip *chip;
 	struct pwm_lpss_chip *lpwm;
 	unsigned long c;
 	int i, ret;
@@ -256,9 +257,10 @@ struct pwm_lpss_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base
 	if (WARN_ON(info->npwm > LPSS_MAX_PWMS))
 		return ERR_PTR(-ENODEV);
 
-	lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
-	if (!lpwm)
+	chip = devm_pwmchip_alloc(dev, info->npwm, sizeof(*lpwm));
+	if (!chip)
 		return ERR_PTR(-ENOMEM);
+	lpwm = to_lpwm(chip);
 
 	lpwm->regs = base;
 	lpwm->info = info;
@@ -267,23 +269,21 @@ struct pwm_lpss_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base
 	if (!c)
 		return ERR_PTR(-EINVAL);
 
-	lpwm->chip.dev = dev;
-	lpwm->chip.ops = &pwm_lpss_ops;
-	lpwm->chip.npwm = info->npwm;
+	chip->ops = &pwm_lpss_ops;
 
-	ret = devm_pwmchip_add(dev, &lpwm->chip);
+	ret = devm_pwmchip_add(dev, chip);
 	if (ret) {
 		dev_err(dev, "failed to add PWM chip: %d\n", ret);
 		return ERR_PTR(ret);
 	}
 
 	for (i = 0; i < lpwm->info->npwm; i++) {
-		ctrl = pwm_lpss_read(&lpwm->chip.pwms[i]);
+		ctrl = pwm_lpss_read(&chip->pwms[i]);
 		if (ctrl & PWM_ENABLE)
 			pm_runtime_get(dev);
 	}
 
-	return lpwm;
+	return chip;
 }
 EXPORT_SYMBOL_GPL(devm_pwm_lpss_probe);
 
diff --git a/drivers/pwm/pwm-lpss.h b/drivers/pwm/pwm-lpss.h
index bf841250385f..b5267ab5193b 100644
--- a/drivers/pwm/pwm-lpss.h
+++ b/drivers/pwm/pwm-lpss.h
@@ -18,7 +18,6 @@
 #define LPSS_MAX_PWMS			4
 
 struct pwm_lpss_chip {
-	struct pwm_chip chip;
 	void __iomem *regs;
 	const struct pwm_lpss_boardinfo *info;
 };
diff --git a/include/linux/platform_data/x86/pwm-lpss.h b/include/linux/platform_data/x86/pwm-lpss.h
index c852fe24fe2a..752c06b47cc8 100644
--- a/include/linux/platform_data/x86/pwm-lpss.h
+++ b/include/linux/platform_data/x86/pwm-lpss.h
@@ -27,7 +27,7 @@ struct pwm_lpss_boardinfo {
 	bool other_devices_aml_touches_pwm_regs;
 };
 
-struct pwm_lpss_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
-					  const struct pwm_lpss_boardinfo *info);
+struct pwm_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
+				     const struct pwm_lpss_boardinfo *info);
 
 #endif	/* __PLATFORM_DATA_X86_PWM_LPSS_H */
-- 
2.43.0

[PATCH v6 151/164] gpio: mvebu: Make use of devm_pwmchip_alloc() function

[Uwe Kleine-König]

This prepares the pwm sub-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.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/gpio/gpio-mvebu.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index a13f3c18ccd4..8cfd3a89c018 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -99,7 +99,6 @@ struct mvebu_pwm {
 	u32			 offset;
 	unsigned long		 clk_rate;
 	struct gpio_desc	*gpiod;
-	struct pwm_chip		 chip;
 	spinlock_t		 lock;
 	struct mvebu_gpio_chip	*mvchip;
 
@@ -615,7 +614,7 @@ static const struct regmap_config mvebu_gpio_regmap_config = {
  */
 static struct mvebu_pwm *to_mvebu_pwm(struct pwm_chip *chip)
 {
-	return container_of(chip, struct mvebu_pwm, chip);
+	return pwmchip_get_drvdata(chip);
 }
 
 static int mvebu_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
@@ -789,6 +788,7 @@ static int mvebu_pwm_probe(struct platform_device *pdev,
 {
 	struct device *dev = &pdev->dev;
 	struct mvebu_pwm *mvpwm;
+	struct pwm_chip *chip;
 	void __iomem *base;
 	u32 offset;
 	u32 set;
@@ -813,9 +813,11 @@ static int mvebu_pwm_probe(struct platform_device *pdev,
 	if (IS_ERR(mvchip->clk))
 		return PTR_ERR(mvchip->clk);
 
-	mvpwm = devm_kzalloc(dev, sizeof(struct mvebu_pwm), GFP_KERNEL);
-	if (!mvpwm)
-		return -ENOMEM;
+	chip = devm_pwmchip_alloc(dev, mvchip->chip.ngpio, sizeof(*mvpwm));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+	mvpwm = to_mvebu_pwm(chip);
+
 	mvchip->mvpwm = mvpwm;
 	mvpwm->mvchip = mvchip;
 	mvpwm->offset = offset;
@@ -868,13 +870,11 @@ static int mvebu_pwm_probe(struct platform_device *pdev,
 		return -EINVAL;
 	}
 
-	mvpwm->chip.dev = dev;
-	mvpwm->chip.ops = &mvebu_pwm_ops;
-	mvpwm->chip.npwm = mvchip->chip.ngpio;
+	chip->ops = &mvebu_pwm_ops;
 
 	spin_lock_init(&mvpwm->lock);
 
-	return devm_pwmchip_add(dev, &mvpwm->chip);
+	return devm_pwmchip_add(dev, chip);
 }
 
 #ifdef CONFIG_DEBUG_FS
-- 
2.43.0

Re: [PATCH v6 067/164] pwm: lpss-*: Make use of devm_pwmchip_alloc() function

[Andy Shevchenko]

On Wed, Feb 14, 2024 at 10:31:54AM +0100, Uwe Kleine-König wrote:
> This prepares the pwm-lpc drivers to further changes of the pwm core

lpc --> lpss
pwm --> PWM

> outlined in the commit introducing devm_pwmchip_alloc(). There is no
> intended semantical change and the driver should behave as before.

...

> -struct pwm_lpss_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
> +struct pwm_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
>  					  const struct pwm_lpss_boardinfo *info)

Missing indentation amendment for the second line.

...

> +	struct pwm_chip *chip;
>  	struct pwm_lpss_chip *lpwm;
>  	unsigned long c;
>  	int i, ret;


Please, keep reversed xmas tree order in place.

	struct pwm_lpss_chip *lpwm;
	struct pwm_chip *chip;
	unsigned long c;
	int i, ret;

...


With the above being addressed,
Reviewed-by: Andy Shevchenko <andy@kernel.org>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 003/164] pwm: Provide pwmchip_alloc() function and a devm variant of it

[Andy Shevchenko]

On Wed, Feb 14, 2024 at 10:30:50AM +0100, Uwe Kleine-König wrote:
> This function allocates a struct pwm_chip and driver data. Compared to
> the status quo the split into pwm_chip and driver data is new, otherwise
> it doesn't change anything relevant (yet).
> 
> The intention is that after all drivers are switched to use this
> allocation function, its possible to add a struct device to struct
> pwm_chip to properly track the latter's lifetime without touching all
> drivers again. Proper lifetime tracking is a necessary precondition to
> introduce character device support for PWMs (that implements atomic
> setting and doesn't suffer from the sysfs overhead of the /sys/class/pwm
> userspace support).
> 
> The new function pwmchip_priv() (obviously?) only works for chips
> allocated with pwmchip_alloc().

...

> +#define PWMCHIP_ALIGN ARCH_DMA_MINALIGN
> +
> +static void *pwmchip_priv(struct pwm_chip *chip)
> +{
> +	return (void *)chip + ALIGN(sizeof(*chip), PWMCHIP_ALIGN);
> +}

Why not use dma_get_cache_alignment() ?

...

> +/* This is the counterpart to pwmchip_alloc */

pwmchip_alloc()

...

> +EXPORT_SYMBOL_GPL(pwmchip_put);

> +EXPORT_SYMBOL_GPL(pwmchip_alloc);

> +EXPORT_SYMBOL_GPL(devm_pwmchip_alloc);

Are these exported via namespace? If no, can they be from day 1?

...

> +static inline void pwmchip_put(struct pwm_chip *chip)
> +{
> +}

Can be one line, but it's up to the present style in this header.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 067/164] pwm: lpss-*: Make use of devm_pwmchip_alloc() function

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 1316 bytes --]

Hello,

On Wed, Feb 14, 2024 at 10:31:54AM +0100, Uwe Kleine-König wrote:
> @@ -256,9 +257,10 @@ struct pwm_lpss_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base
>  	if (WARN_ON(info->npwm > LPSS_MAX_PWMS))
>  		return ERR_PTR(-ENODEV);
>  
> -	lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
> -	if (!lpwm)
> +	chip = devm_pwmchip_alloc(dev, info->npwm, sizeof(*lpwm));
> +	if (!chip)
>  		return ERR_PTR(-ENOMEM);

while adapting the patch for Andy's feedback I noticed this being wrong,
devm_pwmchip_alloc() returns an error pointer and not NULL on failure.
I'll squash the following change into the commit:

diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
index 3247b420b67a..867e2bc8c601 100644
--- a/drivers/pwm/pwm-lpss.c
+++ b/drivers/pwm/pwm-lpss.c
@@ -258,8 +258,8 @@ struct pwm_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
 		return ERR_PTR(-ENODEV);
 
 	chip = devm_pwmchip_alloc(dev, info->npwm, sizeof(*lpwm));
-	if (!chip)
-		return ERR_PTR(-ENOMEM);
+	if (IS_ERR(chip))
+		return chip;
 	lpwm = to_lpwm(chip);
 
 	lpwm->regs = base;

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v6 067/164] pwm: lpss-*: Make use of devm_pwmchip_alloc() function

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 1012 bytes --]

Hello,

On Wed, Feb 14, 2024 at 02:46:17PM +0200, Andy Shevchenko wrote:
> On Wed, Feb 14, 2024 at 10:31:54AM +0100, Uwe Kleine-König wrote:
> > This prepares the pwm-lpc drivers to further changes of the pwm core
> 
> lpc --> lpss
> pwm --> PWM

I'd keep pwm in lower case. While I agree that the thing the pwm core is
about is written PWM, I use "pwm" to describe the framework. So the
directory is drivers/pwm (and not drivers/PWM), the subject prefix is
"pwm", the function prefix for pwm functions is pwm_.

Agreed for the other changes. The current state of the patch is
available at:

	https://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux.git/commit/?h=pwm-lifetime-tracking&id=5b8f3aa33b3def3c8441ce28c93062766f278b09

(i.e. I didn't add your Reviewed-by tag because I didn't capitalize
pwm).

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v6 067/164] pwm: lpss-*: Make use of devm_pwmchip_alloc() function

[Andy Shevchenko]

On Wed, Feb 14, 2024 at 6:01 PM Uwe Kleine-König
<u.kleine-koenig@pengutronix.de> wrote:
> On Wed, Feb 14, 2024 at 02:46:17PM +0200, Andy Shevchenko wrote:

> (i.e. I didn't add your Reviewed-by tag because I didn't capitalize
> pwm).

Are you expecting me to bikeshed?! :-)
Please, add it there.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 067/164] pwm: lpss-*: Make use of devm_pwmchip_alloc() function

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 778 bytes --]

On Wed, Feb 14, 2024 at 06:09:47PM +0200, Andy Shevchenko wrote:
> On Wed, Feb 14, 2024 at 6:01 PM Uwe Kleine-König
> <u.kleine-koenig@pengutronix.de> wrote:
> > On Wed, Feb 14, 2024 at 02:46:17PM +0200, Andy Shevchenko wrote:
> 
> > (i.e. I didn't add your Reviewed-by tag because I didn't capitalize
> > pwm).
> 
> Are you expecting me to bikeshed?! :-)
> Please, add it there.

No, not expecting it, but taking the possibility into account :-)
And I prefer being told that I'm over-cautious and should add it over
being told to have made a wrong assumption and should drop it.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v6 000/164] pwm: Improve lifetime tracking for pwm_chips

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 2539 bytes --]

Hello,

On Wed, Feb 14, 2024 at 10:30:47AM +0100, Uwe Kleine-König wrote:
> this is v6 of the series introducing better lifetime tracking for
> pwmchips that addresses (for now theoretic) lifetime issues of pwm
> chips. Addressing these is a necessary precondition to introduce chardev
> support for PWMs.
> 
> Locking got more complicated due to non-sleeping chips, so I dropped
> the character device patch because it got still more incomplete now.
> Also I'm not yet entirely sure about patches #162 and #163 and I expect
> them to change before they can go in. My plan for the next merge window
> is to get the patches in up to #160. After that the addition of chardev
> support (including correct locking) can continue without having to touch
> the lowlevel driver. So the idea of this series is to get the driver
> adaptions out of the way as this requires some cross-tree coordination.
> 
> The patches that touch files outside of drivers/pwm include:
> 
>  - gpio: mvebu: Make use of devm_pwmchip_alloc() function
>    It already has an Ack by Linus Walleij.
> 
>  - drm/bridge: ti-sn65dsi86: Make use of pwmchip_parent() accessor
>  - drm/bridge: ti-sn65dsi86: Make use of devm_pwmchip_alloc() function
>    The 2nd already has an Ack by Douglas Anderson which I tend to assume
>    good enough to merge this via my pwm tree, too. An Ack for the first
>    patch would be nice.
> 
>  - leds: qcom-lpg: Make use of devm_pwmchip_alloc() function
>    Already has an Ack by Lee Jones.
> 
>  - staging: greybus: pwm: Change prototype of helpers to prepare further changes
>  - staging: greybus: pwm: Make use of pwmchip_parent() accessor
>  - staging: greybus: pwm: Rely on pwm framework to pass a valid hwpwm
>  - staging: greybus: pwm: Drop unused gb_connection_set_data()
>  - staging: greybus: pwm: Rework how the number of PWM lines is determined
>  - staging: greybus: pwm: Make use of devm_pwmchip_alloc() function
>    The greybus patches already got an Ack by Greg Kroah-Hartman in an
>    earlier series, but I dropped it as the patches changed considerably.

After getting the needed acks, I pushed out this series in

https://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux.git pwm/for-next

up to patch #161.

(But don't let you stop looking at the changes, reviews are still
welcome.)

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v6 003/164] pwm: Provide pwmchip_alloc() function and a devm variant of it

[Uwe Kleine-König]

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On Wed, Feb 14, 2024 at 02:49:26PM +0200, Andy Shevchenko wrote:
> On Wed, Feb 14, 2024 at 10:30:50AM +0100, Uwe Kleine-König wrote:
> > This function allocates a struct pwm_chip and driver data. Compared to
> > the status quo the split into pwm_chip and driver data is new, otherwise
> > it doesn't change anything relevant (yet).
> > 
> > The intention is that after all drivers are switched to use this
> > allocation function, its possible to add a struct device to struct
> > pwm_chip to properly track the latter's lifetime without touching all
> > drivers again. Proper lifetime tracking is a necessary precondition to
> > introduce character device support for PWMs (that implements atomic
> > setting and doesn't suffer from the sysfs overhead of the /sys/class/pwm
> > userspace support).
> > 
> > The new function pwmchip_priv() (obviously?) only works for chips
> > allocated with pwmchip_alloc().
> 
> ...
> 
> > +#define PWMCHIP_ALIGN ARCH_DMA_MINALIGN
> > +
> > +static void *pwmchip_priv(struct pwm_chip *chip)
> > +{
> > +	return (void *)chip + ALIGN(sizeof(*chip), PWMCHIP_ALIGN);
> > +}
> 
> Why not use dma_get_cache_alignment() ?

Hmm, that function returns 1 if ARCH_HAS_DMA_MINALIGN isn't defined. The
idea of using ARCH_DMA_MINALIGN was to ensure that the priv data has the
same minimal alignment as kmalloc(). Took my inspriration from
https://lore.kernel.org/r/20240209-counter-align-fix-v2-1-5777ea0a2722@analog.com
. The implementation of dma_get_cache_alignment suggests that not all
archs provide ARCH_DMA_MINALIGN? Also there is ARCH_KMALLOC_MINALIGN.
Hmm, don't know yet what to do here.

> > +/* This is the counterpart to pwmchip_alloc */
> 
> pwmchip_alloc()

Ack.
 
> > +EXPORT_SYMBOL_GPL(pwmchip_put);
> 
> > +EXPORT_SYMBOL_GPL(pwmchip_alloc);
> 
> > +EXPORT_SYMBOL_GPL(devm_pwmchip_alloc);
> 
> Are these exported via namespace? If no, can they be from day 1?

I added that to my todo list for all pwm functions. Will address that
separately.

Thanks for your feedback
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v6 003/164] pwm: Provide pwmchip_alloc() function and a devm variant of it

[Nuno Sá]

On Thu, 2024-02-15 at 13:01 +0100, Uwe Kleine-König wrote:
> On Wed, Feb 14, 2024 at 02:49:26PM +0200, Andy Shevchenko wrote:
> > On Wed, Feb 14, 2024 at 10:30:50AM +0100, Uwe Kleine-König wrote:
> > > This function allocates a struct pwm_chip and driver data. Compared to
> > > the status quo the split into pwm_chip and driver data is new, otherwise
> > > it doesn't change anything relevant (yet).
> > > 
> > > The intention is that after all drivers are switched to use this
> > > allocation function, its possible to add a struct device to struct
> > > pwm_chip to properly track the latter's lifetime without touching all
> > > drivers again. Proper lifetime tracking is a necessary precondition to
> > > introduce character device support for PWMs (that implements atomic
> > > setting and doesn't suffer from the sysfs overhead of the /sys/class/pwm
> > > userspace support).
> > > 
> > > The new function pwmchip_priv() (obviously?) only works for chips
> > > allocated with pwmchip_alloc().
> > 
> > ...
> > 
> > > +#define PWMCHIP_ALIGN ARCH_DMA_MINALIGN
> > > +
> > > +static void *pwmchip_priv(struct pwm_chip *chip)
> > > +{
> > > +	return (void *)chip + ALIGN(sizeof(*chip), PWMCHIP_ALIGN);
> > > +}
> > 
> > Why not use dma_get_cache_alignment() ?
> 
> Hmm, that function returns 1 if ARCH_HAS_DMA_MINALIGN isn't defined. The
> idea of using ARCH_DMA_MINALIGN was to ensure that the priv data has the
> same minimal alignment as kmalloc(). Took my inspriration from
> https://lore.kernel.org/r/20240209-counter-align-fix-v2-1-5777ea0a2722@analog.com
> . The implementation of dma_get_cache_alignment suggests that not all
> archs provide ARCH_DMA_MINALIGN? Also there is ARCH_KMALLOC_MINALIGN.
> Hmm, don't know yet what to do here.

Here it goes my 2 cents... AFAIK, ARCH_DMA_MINALIGN gives you the same alignment
guarantees than devm_kmalloc() for instance. In some archs it will effectively be the
same as ARCH_KMALLOC_MINALIGN. Now, I think it only matters if the owners of private
data intend to have a DMA safe buffer in their structs. If that is the case, we need
to ensure a proper alignment for that structure. In IIO for example, the construct is
like this:

https://elixir.bootlin.com/linux/latest/source/drivers/iio/dac/ltc2688.c#L96

The buffers should come last in the struct so they are alone in the line. In IIO,
Jonathan has a strict policy for this. Like, even if you just want to transfer 2/4
bytes via spi, we need to make the buffer safe (apparently there are some controllers
only doing DMA - even for small transfers).

I would say that if unsure, go with ARCH_DMA_MINALIGN. You just might waste some
space in some archs. OTOH, if you think DMA is not really a thing for pwm chips, you
might go ARCH_KMALLOC_MINALIGN. And since you already have your own PWMCHIP_ALIGN, it
should be easy to change the requirements down the road (if needed).

That said, I'm not familiar with dma_get_cache_alignment().

- Nuno Sá

Re: [PATCH v6 000/164] pwm: Improve lifetime tracking for pwm_chips

[patchwork-bot+chrome-platform]

Hello:

This series was applied to chrome-platform/linux.git (for-kernelci)
by Uwe Kleine-König <u.kleine-koenig@pengutronix.de>:

On Wed, 14 Feb 2024 10:30:47 +0100 you wrote:
> Hello,
> 
> this is v6 of the series introducing better lifetime tracking for
> pwmchips that addresses (for now theoretic) lifetime issues of pwm
> chips. Addressing these is a necessary precondition to introduce chardev
> support for PWMs.
> 
> [...]

Here is the summary with links:
  - [v6,001/164] pwm: Provide an inline function to get the parent device of a given chip
    https://git.kernel.org/chrome-platform/c/4e59267c7a20
  - [v6,003/164] pwm: Provide pwmchip_alloc() function and a devm variant of it
    https://git.kernel.org/chrome-platform/c/024913dbf99f
  - [v6,029/164] pwm: cros-ec: Change prototype of helpers to prepare further changes
    https://git.kernel.org/chrome-platform/c/7256c2e79b8e
  - [v6,030/164] pwm: cros-ec: Make use of pwmchip_parent() accessor
    https://git.kernel.org/chrome-platform/c/19a568a8d3c4
  - [v6,031/164] pwm: cros-ec: Make use of devm_pwmchip_alloc() function
    https://git.kernel.org/chrome-platform/c/452be9421eda

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH v6 000/164] pwm: Improve lifetime tracking for pwm_chips

[patchwork-bot+chrome-platform]

Hello:

This series was applied to chrome-platform/linux.git (for-next)
by Uwe Kleine-König <u.kleine-koenig@pengutronix.de>:

On Wed, 14 Feb 2024 10:30:47 +0100 you wrote:
> Hello,
> 
> this is v6 of the series introducing better lifetime tracking for
> pwmchips that addresses (for now theoretic) lifetime issues of pwm
> chips. Addressing these is a necessary precondition to introduce chardev
> support for PWMs.
> 
> [...]

Here is the summary with links:
  - [v6,001/164] pwm: Provide an inline function to get the parent device of a given chip
    https://git.kernel.org/chrome-platform/c/4e59267c7a20
  - [v6,003/164] pwm: Provide pwmchip_alloc() function and a devm variant of it
    https://git.kernel.org/chrome-platform/c/024913dbf99f
  - [v6,029/164] pwm: cros-ec: Change prototype of helpers to prepare further changes
    https://git.kernel.org/chrome-platform/c/7256c2e79b8e
  - [v6,030/164] pwm: cros-ec: Make use of pwmchip_parent() accessor
    https://git.kernel.org/chrome-platform/c/19a568a8d3c4
  - [v6,031/164] pwm: cros-ec: Make use of devm_pwmchip_alloc() function
    https://git.kernel.org/chrome-platform/c/452be9421eda

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html