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path: root/drivers/pwm/core.c
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2020-04-03pwm: Make pwm_apply_state_debug() staticJason Yan
Fix the following gcc warning: drivers/pwm/core.c:467:6: warning: symbol 'pwm_apply_state_debug' was not declared. Should it be static? Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Jason Yan <yanaijie@huawei.com> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2020-03-30pwm: Implement some checks for lowlevel driversUwe Kleine-König
There are some expectations which the callbacks provided by lowlevel drivers should fulfill. Implement checks that help driver authors to get these semantics right. As these have some overhead the checks can be disabled using a Kconfig setting. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2020-01-20pwm: Implement tracing for .get_state() and .apply_state()Uwe Kleine-König
This allows to log all calls to the driver's lowlevel functions which simplifies debugging in some cases. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-12-09pwm: Read initial hardware state at request timeThierry Reding
Drivers that support reading the hardware state (using ->get_state()) may want to rely on per-PWM data to do so. Defer reading the hardware state for the first time until the PWM has been requested and after drivers have had a chance to allocate per-PWM data. Conceptually this is also a more natural place to read the hardware state because the PWM core doesn't need to know the hardware state of a PWM unless there is a user for it. This also ensures that the state is read everytime a user requests a PWM. If the PWM changes between users for some reason, the PWM core will reload the state from hardware and keep its copy of the state up-to-date. Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> Tested-by: Michal Vokáč <michal.vokac@ysoft.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-10-21Revert "pwm: Let pwm_get_state() return the last implemented state"Thierry Reding
It turns out that commit 01ccf903edd6 ("pwm: Let pwm_get_state() return the last implemented state") causes backlight failures on a number of boards. The reason is that some of the drivers do not write the full state through to the hardware registers, which means that ->get_state() subsequently does not return the correct state. Consumers which rely on pwm_get_state() returning the current state will therefore get confused and subsequently try to program a bad state. Before this change can be made, existing drivers need to be more carefully audited and fixed to behave as the framework expects. Until then, keep the original behaviour of returning the software state that was applied rather than reading the state back from hardware. Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> Tested-by: Michal Vokáč <michal.vokac@ysoft.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-09-21pwm: Ensure pwm_apply_state() doesn't modify the state argumentUwe Kleine-König
It is surprising for a PWM consumer when the variable holding the requested state is modified by pwm_apply_state(). Consider for example a driver doing: #define PERIOD 5000000 #define DUTY_LITTLE 10 ... struct pwm_state state = { .period = PERIOD, .duty_cycle = DUTY_LITTLE, .polarity = PWM_POLARITY_NORMAL, .enabled = true, }; pwm_apply_state(mypwm, &state); ... state.duty_cycle = PERIOD / 2; pwm_apply_state(mypwm, &state); For sure the second call to pwm_apply_state() should still have state.period = PERIOD and not something the hardware driver chose for a reason that doesn't necessarily apply to the second call. So declare the state argument as a pointer to a const type and adapt all drivers' .apply callbacks. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-09-21pwm: Let pwm_get_state() return the last implemented stateUwe Kleine-König
When pwm_apply_state() is called the lowlevel driver usually has to apply some rounding because the hardware doesn't support nanosecond resolution. So let pwm_get_state() return the actually implemented state instead of the last applied one if possible. Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-09-21pwm: Introduce local struct pwm_chip in pwm_apply_state()Uwe Kleine-König
pwm->chip is dereferenced several times in the pwm_apply_state() function. Introducing a local variable for it helps keeping some lines a bit shorter. Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-08-08pwm: Fallback to the static lookup-list when acpi_pwm_get failsHans de Goede
Commit 4a6ef8e37c4d ("pwm: Add support referencing PWMs from ACPI") made pwm_get unconditionally return the acpi_pwm_get return value if the device passed to pwm_get has an ACPI fwnode. But even if the passed in device has an ACPI fwnode, it does not necessarily have the necessary ACPI package defining its pwm bindings, especially since the binding / API of this ACPI package has only been introduced very recently. Up until now X86/ACPI devices which use a separate pwm controller for controlling their LCD screen's backlight brightness have been relying on the static lookup-list to get their pwm. pwm_get unconditionally returning the acpi_pwm_get return value breaks this, breaking backlight control on these devices. This commit fixes this by making pwm_get fall back to the static lookup-list if acpi_pwm_get returns -ENOENT. BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=96571 Reported-by: youling257@gmail.com Fixes: 4a6ef8e37c4d ("pwm: Add support referencing PWMs from ACPI") Cc: Nikolaus Voss <nikolaus.voss@loewensteinmedical.de> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Nikolaus Voss <nikolaus.voss@loewensteinmedical.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-07-09Merge tag 'pwm/for-5.3-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm Pull pwm updates from Thierry Reding: "This set of changes contains a new driver for SiFive SoCs as well as enhancements to the core (device links are used to track dependencies between PWM providers and consumers, support for PWM controllers via ACPI, sysfs will now suspend/resume PWMs that it has claimed) and various existing drivers" * tag 'pwm/for-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm: (37 commits) pwm: fsl-ftm: Make sure to unlock mutex on failure pwm: fsl-ftm: Use write protection for prescaler & polarity pwm: fsl-ftm: More relaxed permissions for updating period pwm: atmel-hlcdc: Add compatible for SAM9X60 HLCDC's PWM pwm: bcm2835: Improve precision of PWM leds: pwm: Support ACPI via firmware-node framework pwm: Add support referencing PWMs from ACPI pwm: rcar: Remove suspend/resume support pwm: sysfs: Add suspend/resume support pwm: Add power management descriptions pwm: meson: Add documentation to the driver pwm: meson: Add support PWM_POLARITY_INVERSED when disabling pwm: meson: Don't cache struct pwm_state internally pwm: meson: Read the full hardware state in meson_pwm_get_state() pwm: meson: Simplify the calculation of the pre-divider and count pwm: meson: Move pwm_set_chip_data() to meson_pwm_request() pwm: meson: Add the per-channel register offsets and bits in a struct pwm: meson: Add the meson_pwm_channel data to struct meson_pwm pwm: meson: Pass struct pwm_device to meson_pwm_calc() pwm: meson: Don't duplicate the polarity internally ...
2019-06-26pwm: Add support referencing PWMs from ACPINikolaus Voss
In analogy to referencing a GPIO using the "gpios" property from ACPI, support referencing a PWM using the "pwms" property. ACPI entries must look like Package () {"pwms", Package () { <PWM device reference>, <PWM index>, <PWM period> [, <PWM flags>]}} In contrast to the DT implementation, only _one_ PWM entry in the "pwms" property is supported. As a consequence "pwm-names"-property and con_id lookup aren't supported. Support for ACPI is added via the firmware-node framework which is an abstraction layer on top of ACPI/DT. To keep this patch clean, DT and ACPI paths are kept separate. The firmware-node framework could be used to unify both paths in a future patch. To support leds-pwm driver, an additional method devm_fwnode_pwm_get() which supports both ACPI and DT configuration is exported. Signed-off-by: Nikolaus Voss <nikolaus.voss@loewensteinmedical.de> [thierry.reding@gmail.com: fix build failures for !ACPI] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-06-25pwm: Add consumer device linkFabrice Gasnier
Add a device link between the PWM consumer and the PWM provider. This enforces the PWM user to get suspended before the PWM provider. It allows proper synchronization of suspend/resume sequences: the PWM user is responsible for properly stopping PWM, before the provider gets suspended: see [1]. Add the device link in: - of_pwm_get() - pwm_get() - devm_*pwm_get() variants as it requires a reference to the device for the PWM consumer. [1] https://lkml.org/lkml/2019/2/5/770 Suggested-by: Thierry Reding <thierry.reding@gmail.com> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-05-21treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 18Thomas Gleixner
Based on 1 normalized pattern(s): 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 you should have received a copy of the gnu general public license along with this program see the file copying if not write to the free software foundation 675 mass ave cambridge ma 02139 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 52 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com> Reviewed-by: Steve Winslow <swinslow@gmail.com> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190519154042.342335923@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-09pwm: Clear chip_data in pwm_put()Uwe Kleine-König
After a PWM is disposed by its user the per chip data becomes invalid. Clear the data in common code instead of the device drivers to get consistent behaviour. Before this patch only three of nine drivers cleaned up here. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-03-20pwm: Fix deadlock warning when removing PWM devicePhong Hoang
This patch fixes deadlock warning if removing PWM device when CONFIG_PROVE_LOCKING is enabled. This issue can be reproceduced by the following steps on the R-Car H3 Salvator-X board if the backlight is disabled: # cd /sys/class/pwm/pwmchip0 # echo 0 > export # ls device export npwm power pwm0 subsystem uevent unexport # cd device/driver # ls bind e6e31000.pwm uevent unbind # echo e6e31000.pwm > unbind [ 87.659974] ====================================================== [ 87.666149] WARNING: possible circular locking dependency detected [ 87.672327] 5.0.0 #7 Not tainted [ 87.675549] ------------------------------------------------------ [ 87.681723] bash/2986 is trying to acquire lock: [ 87.686337] 000000005ea0e178 (kn->count#58){++++}, at: kernfs_remove_by_name_ns+0x50/0xa0 [ 87.694528] [ 87.694528] but task is already holding lock: [ 87.700353] 000000006313b17c (pwm_lock){+.+.}, at: pwmchip_remove+0x28/0x13c [ 87.707405] [ 87.707405] which lock already depends on the new lock. [ 87.707405] [ 87.715574] [ 87.715574] the existing dependency chain (in reverse order) is: [ 87.723048] [ 87.723048] -> #1 (pwm_lock){+.+.}: [ 87.728017] __mutex_lock+0x70/0x7e4 [ 87.732108] mutex_lock_nested+0x1c/0x24 [ 87.736547] pwm_request_from_chip.part.6+0x34/0x74 [ 87.741940] pwm_request_from_chip+0x20/0x40 [ 87.746725] export_store+0x6c/0x1f4 [ 87.750820] dev_attr_store+0x18/0x28 [ 87.754998] sysfs_kf_write+0x54/0x64 [ 87.759175] kernfs_fop_write+0xe4/0x1e8 [ 87.763615] __vfs_write+0x40/0x184 [ 87.767619] vfs_write+0xa8/0x19c [ 87.771448] ksys_write+0x58/0xbc [ 87.775278] __arm64_sys_write+0x18/0x20 [ 87.779721] el0_svc_common+0xd0/0x124 [ 87.783986] el0_svc_compat_handler+0x1c/0x24 [ 87.788858] el0_svc_compat+0x8/0x18 [ 87.792947] [ 87.792947] -> #0 (kn->count#58){++++}: [ 87.798260] lock_acquire+0xc4/0x22c [ 87.802353] __kernfs_remove+0x258/0x2c4 [ 87.806790] kernfs_remove_by_name_ns+0x50/0xa0 [ 87.811836] remove_files.isra.1+0x38/0x78 [ 87.816447] sysfs_remove_group+0x48/0x98 [ 87.820971] sysfs_remove_groups+0x34/0x4c [ 87.825583] device_remove_attrs+0x6c/0x7c [ 87.830197] device_del+0x11c/0x33c [ 87.834201] device_unregister+0x14/0x2c [ 87.838638] pwmchip_sysfs_unexport+0x40/0x4c [ 87.843509] pwmchip_remove+0xf4/0x13c [ 87.847773] rcar_pwm_remove+0x28/0x34 [ 87.852039] platform_drv_remove+0x24/0x64 [ 87.856651] device_release_driver_internal+0x18c/0x21c [ 87.862391] device_release_driver+0x14/0x1c [ 87.867175] unbind_store+0xe0/0x124 [ 87.871265] drv_attr_store+0x20/0x30 [ 87.875442] sysfs_kf_write+0x54/0x64 [ 87.879618] kernfs_fop_write+0xe4/0x1e8 [ 87.884055] __vfs_write+0x40/0x184 [ 87.888057] vfs_write+0xa8/0x19c [ 87.891887] ksys_write+0x58/0xbc [ 87.895716] __arm64_sys_write+0x18/0x20 [ 87.900154] el0_svc_common+0xd0/0x124 [ 87.904417] el0_svc_compat_handler+0x1c/0x24 [ 87.909289] el0_svc_compat+0x8/0x18 [ 87.913378] [ 87.913378] other info that might help us debug this: [ 87.913378] [ 87.921374] Possible unsafe locking scenario: [ 87.921374] [ 87.927286] CPU0 CPU1 [ 87.931808] ---- ---- [ 87.936331] lock(pwm_lock); [ 87.939293] lock(kn->count#58); [ 87.945120] lock(pwm_lock); [ 87.950599] lock(kn->count#58); [ 87.953908] [ 87.953908] *** DEADLOCK *** [ 87.953908] [ 87.959821] 4 locks held by bash/2986: [ 87.963563] #0: 00000000ace7bc30 (sb_writers#6){.+.+}, at: vfs_write+0x188/0x19c [ 87.971044] #1: 00000000287991b2 (&of->mutex){+.+.}, at: kernfs_fop_write+0xb4/0x1e8 [ 87.978872] #2: 00000000f739d016 (&dev->mutex){....}, at: device_release_driver_internal+0x40/0x21c [ 87.988001] #3: 000000006313b17c (pwm_lock){+.+.}, at: pwmchip_remove+0x28/0x13c [ 87.995481] [ 87.995481] stack backtrace: [ 87.999836] CPU: 0 PID: 2986 Comm: bash Not tainted 5.0.0 #7 [ 88.005489] Hardware name: Renesas Salvator-X board based on r8a7795 ES1.x (DT) [ 88.012791] Call trace: [ 88.015235] dump_backtrace+0x0/0x190 [ 88.018891] show_stack+0x14/0x1c [ 88.022204] dump_stack+0xb0/0xec [ 88.025514] print_circular_bug.isra.32+0x1d0/0x2e0 [ 88.030385] __lock_acquire+0x1318/0x1864 [ 88.034388] lock_acquire+0xc4/0x22c [ 88.037958] __kernfs_remove+0x258/0x2c4 [ 88.041874] kernfs_remove_by_name_ns+0x50/0xa0 [ 88.046398] remove_files.isra.1+0x38/0x78 [ 88.050487] sysfs_remove_group+0x48/0x98 [ 88.054490] sysfs_remove_groups+0x34/0x4c [ 88.058580] device_remove_attrs+0x6c/0x7c [ 88.062671] device_del+0x11c/0x33c [ 88.066154] device_unregister+0x14/0x2c [ 88.070070] pwmchip_sysfs_unexport+0x40/0x4c [ 88.074421] pwmchip_remove+0xf4/0x13c [ 88.078163] rcar_pwm_remove+0x28/0x34 [ 88.081906] platform_drv_remove+0x24/0x64 [ 88.085996] device_release_driver_internal+0x18c/0x21c [ 88.091215] device_release_driver+0x14/0x1c [ 88.095478] unbind_store+0xe0/0x124 [ 88.099048] drv_attr_store+0x20/0x30 [ 88.102704] sysfs_kf_write+0x54/0x64 [ 88.106359] kernfs_fop_write+0xe4/0x1e8 [ 88.110275] __vfs_write+0x40/0x184 [ 88.113757] vfs_write+0xa8/0x19c [ 88.117065] ksys_write+0x58/0xbc [ 88.120374] __arm64_sys_write+0x18/0x20 [ 88.124291] el0_svc_common+0xd0/0x124 [ 88.128034] el0_svc_compat_handler+0x1c/0x24 [ 88.132384] el0_svc_compat+0x8/0x18 The sysfs unexport in pwmchip_remove() is completely asymmetric to what we do in pwmchip_add_with_polarity() and commit 0733424c9ba9 ("pwm: Unexport children before chip removal") is a strong indication that this was wrong to begin with. We should just move pwmchip_sysfs_unexport() where it belongs, which is right after pwmchip_sysfs_unexport_children(). In that case, we do not need separate functions anymore either. We also really want to remove sysfs irrespective of whether or not the chip will be removed as a result of pwmchip_remove(). We can only assume that the driver will be gone after that, so we shouldn't leave any dangling sysfs files around. This warning disappears if we move pwmchip_sysfs_unexport() to the top of pwmchip_remove(), pwmchip_sysfs_unexport_children(). That way it is also outside of the pwm_lock section, which indeed doesn't seem to be needed. Moving the pwmchip_sysfs_export() call outside of that section also seems fine and it'd be perfectly symmetric with pwmchip_remove() again. So, this patch fixes them. Signed-off-by: Phong Hoang <phong.hoang.wz@renesas.com> [shimoda: revise the commit log and code] Fixes: 76abbdde2d95 ("pwm: Add sysfs interface") Fixes: 0733424c9ba9 ("pwm: Unexport children before chip removal") Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Tested-by: Hoan Nguyen An <na-hoan@jinso.co.jp> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-01-10pwm: Drop per-chip dbg_show callbackUwe Kleine-König
This callback was introduced in commit 62099abf67a2 ("pwm: Add debugfs interface") in 2012 and up to now there is not a single user. So drop this unused code. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> [thierry.reding@gmail.com: remove kerneldoc for ->dbg_show()] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-01-10pwm: Don't use memcmp() to compare state variablesUwe Kleine-König
Given that struct pwm_state is sparse (at least on some platforms), variables of this type might represent the same state because all fields are pairwise identical but still memcmp() returns a difference because some of the unused bits are different. To prevent surprises compare member by member instead of the whole occupied memory. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2017-07-06pwm: Silently error out on EPROBE_DEFERJerome Brunet
In of_pwm_get(), if we fail to get the PWM chip due to probe deferal, we shouldn't print an error message. Just be silent in this case. Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> Reviewed-by: Andreas Färber <afaerber@suse.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2017-01-30pwm: Try to load modules during pwm_get()Hans de Goede
Add a module name string to the pwm_lookup struct and if specified try to load the module using request_module() if pwmchip_find_by_name() is unable to find the PWM chip. This is a last resort to work around drivers that can't - and can't be made to - deal with deferred probe. Signed-off-by: Hans de Goede <hdegoede@redhat.com> [thierry.reding@gmail.com: rename new macro, reword commit message] [thierry.reding@gmail.com: add comment explaining use-case] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2017-01-30pwm: Don't hold pwm_lookup_lock longer than necessaryHans de Goede
There is no need to hold pwm_lookup_lock after we're done with looping over pwm_lookup_list, so release it earlier. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2017-01-30pwm: Make the PWM_POLARITY flag in DTB optionalLothar Wassmann
Change the PWM chip driver registration so that a chip driver that supports polarity inversion can still be used with DTBs that don't provide the polarity flag as part of the specifier. This is done to provide polarity inversion support for the pwm-imx driver without having to modify all existing DTS files. Signed-off-by: Lothar Wassmann <LW@KARO-electronics.de> Signed-off-by: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com> Suggested-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Lukasz Majewski <l.majewski@majess.pl> Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2017-01-30pwm: Print error messages with pr_err() instead of pr_debug()Lothar Wassmann
Make the messages that are printed in case of fatal errors actually visible to the user without having to recompile the driver with debugging enabled. Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de> Signed-off-by: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com> Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2017-01-04pwm: Remove pwm_can_sleep()Thierry Reding
The last user of this function has been removed, so it is no longer needed. Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-09-05pwm: Unexport children before chip removalDavid Hsu
Exported pwm channels aren't removed before the pwmchip and are leaked. This results in invalid sysfs files. This fix removes all exported pwm channels before chip removal. Signed-off-by: David Hsu <davidhsu@google.com> Fixes: 76abbdde2d95 ("pwm: Add sysfs interface") Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-07-25Merge branch 'for-4.8/capture' into for-nextThierry Reding
2016-06-10pwm: Add PWM capture supportLee Jones
Supply a PWM capture callback op in order to pass back information obtained by running analysis on a PWM signal. This would normally (at least during testing) be called from the sysfs routines with a view to printing out PWM capture data which has been encoded into a string. Signed-off-by: Lee Jones <lee.jones@linaro.org> [thierry.reding@gmail.com: make capture data unsigned int for symmetry] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-06-10pwm: Improve args checking in pwm_apply_state()Brian Norris
It seems like in the process of refactoring pwm_config() to utilize the newly-introduced pwm_apply_state() API, some args/bounds checking was dropped. In particular, I noted that we are now allowing invalid period selections, e.g.: # echo 1 > /sys/class/pwm/pwmchip0/export # cat /sys/class/pwm/pwmchip0/pwm1/period 100 # echo 101 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle [... driver may or may not reject the value, or trigger some logic bug ...] It's better to see: # echo 1 > /sys/class/pwm/pwmchip0/export # cat /sys/class/pwm/pwmchip0/pwm1/period 100 # echo 101 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle -bash: echo: write error: Invalid argument This patch reintroduces some bounds checks in both pwm_config() (for its signed parameters; we don't want to convert negative values into large unsigned values) and in pwm_apply_state() (which fix the above described behavior, as well as other potential API misuses). Fixes: 5ec803edcb70 ("pwm: Add core infrastructure to allow atomic updates") Signed-off-by: Brian Norris <briannorris@chromium.org> Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-17Merge branch 'for-4.7/pwm-atomic' into for-nextThierry Reding
2016-05-17Merge branch 'for-4.7/pwm-args' into for-nextThierry Reding
2016-05-17pwm: Add information about polarity, duty cycle and period to debugfsHeiko Stübner
The PWM states make it possible to also output the polarity, duty cycle and period information in the debugfs summary output. This simplifies gathering information about PWMs without needing to walk through the sysfs attributes of every PWM. Signed-off-by: Heiko Stuebner <heiko@sntech.de> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> [thierry.reding@gmail.com: use more spaces in debugfs output] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-17pwm: Switch to the atomic APIBoris Brezillon
Replace legacy pwm_get/set_xxx() and pwm_config/enable/disable() calls by pwm_get/apply_state(). Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-17pwm: Add core infrastructure to allow atomic updatesBoris Brezillon
Add an ->apply() method to the pwm_ops struct to allow PWM drivers to implement atomic updates. This method is preferred over the ->enable(), ->disable() and ->config() methods if available. Add the pwm_apply_state() function to the PWM user API. Note that the pwm_apply_state() does not guarantee the atomicity of the update operation, it all depends on the availability and implementation of the ->apply() method. pwm_enable/disable/set_polarity/config() are now implemented as wrappers around the pwm_apply_state() function. pwm_adjust_config() is allowing smooth handover between the bootloader and the kernel. This function tries to adapt the current PWM state to the PWM arguments coming from a PWM lookup table or a DT definition without changing the duty_cycle/period proportion. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> [thierry.reding@gmail.com: fix a couple of typos] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-17pwm: Add hardware readout infrastructureBoris Brezillon
Add a ->get_state() function to the pwm_ops struct to let PWM drivers initialize the PWM state attached to a PWM device. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-17pwm: Move the enabled/disabled info into pwm_stateBoris Brezillon
Prepare the transition to PWM atomic update by moving the enabled and disabled state into the pwm_state struct. This way we can easily update the whole PWM state by copying the new state in the ->state field. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-17pwm: Introduce the pwm_state conceptBoris Brezillon
The PWM state, represented by its period, duty_cycle and polarity is currently directly stored in the PWM device. Declare a pwm_state structure embedding those field so that we can later use this struct to atomically update all the PWM parameters at once. All pwm_get_xxx() helpers are now implemented as wrappers around pwm_get_state(). Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-17pwm: Keep PWM state in sync with hardware stateBoris Brezillon
Before the introduction of pwm_args, the core was resetting the PWM period and polarity states to the reference values (those provided through the DT, a PWM lookup table or hardcoded in the driver). Now that all PWM users are correctly using pwm_args to configure their PWM device, we can safely remove the pwm_apply_args() call in pwm_get() and of_pwm_get(). We can also get rid of the pwm_set_period() call in pwm_apply_args(), because PWM users are now directly using pargs->period instead of pwm_get_period(). By doing that we avoid messing with the current PWM period. The only remaining bit in pwm_apply_args() is the initial polarity setting, and it should go away when all PWM users have been patched to use the atomic API (with this API the polarity will be set along with other PWM arguments when configuring the PWM). Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-17pwm: Get rid of pwm->lockBoris BREZILLON
PWM devices are not protected against concurrent accesses. The lock in struct pwm_device might let PWM users think it is, but it's actually only protecting the enabled state. Removing this lock should be fine as long as all PWM users are aware that accesses to the PWM device have to be serialized, which seems to be the case for all of them except the sysfs interface. Patch the sysfs code by adding a lock to the pwm_export struct and making sure it's taken for all relevant accesses to the exported PWM device. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-17pwm: Fix pwm_apply_args() call sitesBoris Brezillon
pwm_apply_args() is supposed to initialize a PWM device according to the arguments provided by the DT or the PWM lookup, but this function was called inside pwm_device_request(), which in turn was called before the core had a chance to initialize the pwm->args fields. Fix that by calling pwm_apply_args directly in pwm_get() and of_pwm_get() after initializing pwm->args field. This commit also fixes an invalid pointer dereference introduced by commit e39c0df1be5a ("pwm: Introduce the pwm_args concept"). Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Fixes: e39c0df1be5a ("pwm: Introduce the pwm_args concept") Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-03pwm: Use kcalloc() instead of kzalloc()Thierry Reding
kcalloc() should be preferred for allocations of arrays over kzalloc() with multiplication. Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-03pwm: Add missing newlineThierry Reding
checkpatch requires that declarations be separated from code by a blank line. Add one for readability and to silence the warning. Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-05-03pwm: Introduce the pwm_args conceptBoris Brezillon
Currently the PWM core mixes the current PWM state with the per-platform reference config (specified through the PWM lookup table, DT definition or directly hardcoded in PWM drivers). Create a struct pwm_args to store this reference configuration, so that PWM users can differentiate between the current and reference configurations. Patch all places where pwm->args should be initialized. We keep the pwm_set_polarity/period() calls until all PWM users are patched to use pwm_args instead of pwm_get_period/polarity(). Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> [thierry.reding@gmail.com: reword kerneldoc comments] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-01-21pwm: Mark all devices as "might sleep"Thierry Reding
Commit d1cd21427747 ("pwm: Set enable state properly on failed call to enable") introduced a mutex that is needed to protect internal state of PWM devices. Since that mutex is acquired in pwm_set_polarity() and in pwm_enable() and might potentially block, all PWM devices effectively become "might sleep". It's rather pointless to keep the .can_sleep field around, but given that there are external users let's postpone the removal for the next release cycle. Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-11-10pwm: Return -ENODEV if no PWM lookup match is foundThierry Reding
When looking up a PWM using the lookup table, assume that all entries will have been added already, so failure to find a match means that no corresponding entry has been registered. This fixes an issue where -EPROBE_DEFER would be returned if the PWM lookup table is empty. After this fix, -EPROBE_DEFER is reserved for situations where no provider has yet registered for a matching entry. Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-11-10pwm: Set enable state properly on failed call to enableJonathan Richardson
The pwm_enable() function didn't clear the enabled bit if a call to the driver's ->enable() callback returned an error. The result was that the state of the PWM core was wrong. Clearing the bit when enable returns an error ensures the state is properly set. Tested-by: Jonathan Richardson <jonathar@broadcom.com> Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Jonathan Richardson <jonathar@broadcom.com> [thierry.reding@gmail.com: add missing kerneldoc for the lock] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-08-17pwm: Clean up kerneldocThierry Reding
Clean up kerneldoc in preparation for including the PWM documentation in DocBook. Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-08-17pwm: Remove useless whitespaceThierry Reding
Remove useless tabs used for padding in structure definitions as well as some blank lines. Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-07-20pwm: Add the pwm_is_enabled() helperBoris Brezillon
Some PWM drivers are testing the PWMF_ENABLED flag. Create a helper function to hide the logic behind enabled test. This will allow us to smoothly move from the current approach to an atomic PWM update approach. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-06-12pwm: Add pwmchip_add_with_polarity() APITim Kryger
Add a new function to register a PWM chip with channels that have their initial polarity as specified by an additional parameter. This benefits drivers of controllers that by default operate with inversed polarity by removing the need to modify the polarity during initialization. Signed-off-by: Tim Kryger <tim.kryger@gmail.com> Signed-off-by: Jonathan Richardson <jonathar@broadcom.com> [thierry.reding@gmail.com: export pwmchip_add_with_polarity()] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-05-06pwm: Add support to remove registered consumer lookup tablesShobhit Kumar
In case some drivers are unloading, they can remove lookup tables which they had registered during their load time to avoid redundant entries if loaded again. CC: Samuel Ortiz <sameo@linux.intel.com> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Alexandre Courbot <gnurou@gmail.com> Cc: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-04-23pwm: Remove __init initializer for pwm_add_table()Shobhit Kumar
For platforms that don't support DT, some early MFD modules can register lookup tables. Remove the __init annotation so that this works. This is similar to gpio_add_lookup_table() which allows late additions. CC: Samuel Ortiz <sameo@linux.intel.com> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Alexandre Courbot <gnurou@gmail.com> Cc: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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