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@pengutroni... - 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