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path: root/include/linux/pwm.h
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2017-01-30pwm: Try to load modules during pwm_get()Hans de Goede1-8/+15
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>
2017-01-04pwm: Remove .can_sleep from struct pwm_chipThierry Reding1-3/+0
All PWM devices have been marked as "might sleep" since v4.5, there is no longer a need to differentiate on a per-chip basis. Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2017-01-04pwm: Remove pwm_can_sleep()Thierry Reding1-7/+0
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 Hsu1-0/+5
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 Reding1-0/+24
2016-07-25Merge branch 'for-4.8/core' into for-nextThierry Reding1-1/+88
2016-07-08pwm: Remove gratuitous blank lineThierry Reding1-1/+0
Commit 5ec803edcb70 ("pwm: Add core infrastructure to allow atomic updates") introduced this double blank line by mistake. Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-07-08pwm: Add relative duty cycle manipulation helpersBoris Brezillon1-0/+55
The PWM framework expects PWM users to configure the duty cycle in nano- seconds, but many users want to express the duty cycle relatively to the period value (i.e. duty_cycle = 33% of the period). Add the pwm_{get,set}_relative_duty_cycle() helpers to ease this kind of conversion. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Tested-by: Heiko Stuebner <heiko@sntech.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-07-08pwm: Add a helper to prepare a new PWM stateBoris Brezillon1-0/+33
The pwm_init_state() helper prepares a new state object containing the current PWM state except for the polarity and period fields which are set to the reference values (those in struct pwm_args). This is particularly useful for PWM users who want to apply a new duty- cycle expressed relatively to the reference period without changing the enable state. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Tested-by: Heiko Stuebner <heiko@sntech.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-06-23pwm: Fix pwm_apply_args()Boris Brezillon1-6/+10
Commit 5ec803edcb70 ("pwm: Add core infrastructure to allow atomic updates"), implemented pwm_disable() as a wrapper around pwm_apply_state(), and then, commit ef2bf4997f7d ("pwm: Improve args checking in pwm_apply_state()") added missing checks on the ->period value in pwm_apply_state() to ensure we were not passing inappropriate values to the ->config() or ->apply() methods. The conjunction of these 2 commits led to a case where pwm_disable() was no longer succeeding, thus preventing the polarity setting done in pwm_apply_args(). Set a valid period in pwm_apply_args() to ensure polarity setting won't be rejected. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Suggested-by: Brian Norris <briannorris@chromium.org> Fixes: 5ec803edcb70 ("pwm: Add core infrastructure to allow atomic updates") Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Brian Norris <briannorris@chromium.org> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-06-10pwm: Add PWM capture supportLee Jones1-0/+24
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 Norris1-0/+3
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>
2016-05-17pwm: Add core infrastructure to allow atomic updatesBoris Brezillon1-85/+184
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 Brezillon1-0/+28
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 Brezillon1-3/+8
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 Brezillon1-12/+42
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 Brezillon1-1/+0
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 BREZILLON1-2/+0
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>
2016-05-03pwm: Introduce the pwm_args conceptBoris Brezillon1-0/+33
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>
2015-11-10pwm: Set enable state properly on failed call to enableJonathan Richardson1-0/+3
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 Reding1-0/+14
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 Reding1-39/+32
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 pwm_get_polarity() helper functionBoris Brezillon1-0/+5
Some drivers are directly accessing the ->polarity field in pwm_device. Add a helper to retrieve the current polarity so that we can easily move this field elsewhere (required to support atomic update). Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-07-20pwm: Constify PWM device where possibleBoris Brezillon1-2/+2
The PWM argument is not modified in PWM property accessors, make it a const argument so that the accessors can be used from sysfs. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-07-20pwm: Add the pwm_is_enabled() helperBoris Brezillon1-0/+5
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 Kryger1-0/+7
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 Kumar1-0/+5
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>
2014-05-21pwm: modify PWM_LOOKUP to initialize all struct pwm_lookup membersAlexandre Belloni1-1/+3
Now that PWM_LOOKUP is not used anymore, modify it to initialize all the members of struct pwm_lookup. Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2014-05-21pwm: add period and polarity to struct pwm_lookupAlexandre Belloni1-0/+2
Add period and polarity members to struct pwm_lookup so that platforms using the lookup table can be treated the same way as those using the device tree. Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2014-02-10pwm: Remove obsolete HAVE_PWM Kconfig symbolSascha Hauer1-1/+1
Before we had the PWM framework we used to have a barebone PWM api. The HAVE_PWM Kconfig symbol used to be selected by the PWM drivers to specify the PWM API is present in the kernel. Since the last legacy driver is gone the HAVE_PWM symbol can go aswell. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: Eric Miao <eric.y.miao@gmail.com> Cc: Haojian Zhuang <haojian.zhuang@gmail.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: Thierry Reding <thierry.reding@gmail.com> Cc: linux-pwm@vger.kernel.orig Cc: Russell King <linux@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2013-06-21pwm: Add sysfs interfaceH Hartley Sweeten1-1/+28
Add a simple sysfs interface to the generic PWM framework. /sys/class/pwm/ `-- pwmchipN/ for each PWM chip |-- export (w/o) ask the kernel to export a PWM channel |-- npwm (r/o) number of PWM channels in this PWM chip |-- pwmX/ for each exported PWM channel | |-- duty_cycle (r/w) duty cycle (in nanoseconds) | |-- enable (r/w) enable/disable PWM | |-- period (r/w) period (in nanoseconds) | `-- polarity (r/w) polarity of PWM (normal/inversed) `-- unexport (w/o) return a PWM channel to the kernel Based on work by Lars Poeschel. Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com> Cc: Thierry Reding <thierry.reding@gmail.com> Cc: Lars Poeschel <poeschel@lemonage.de> Cc: Ryan Mallon <rmallon@gmail.com> Cc: Rob Landley <rob@landley.net> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2013-02-26Merge tag 'for-3.9-rc1' of git://gitorious.org/linux-pwm/linux-pwmLinus Torvalds1-0/+10
Pull PWM changes from Thierry Reding: "A new driver has been added to support the PWM mode of the timer counter blocks found on Atmel AT91 SoCs. The VT8500 driver now supports changing the PWM signal polarity and the TI drivers (EHRPWM and ECAP) gained suspend and resume functionality. User drivers can now query the core for whether access to a PWM device will sleep (if the PWM chip is on a slow bus such as I2C or SPI). The pwm-backlight driver now handles the backlight BL_CORE_FBBLANK state in addition to the FB layer's blanking states. To round things off, a few fixes and cleanups are also included" * tag 'for-3.9-rc1' of git://gitorious.org/linux-pwm/linux-pwm: pwm: twl: Use to_twl() instead of container_of() pwm: tegra: assume CONFIG_OF pwm_backlight: Validate dft_brightness in main probe function pwm: Export pwm_{set,get}_chip_data() pwm: Make Kconfig entries more consistent pwm: Add can_sleep property to drivers pwm: Add pwm_can_sleep() as exported API to users pwm-backlight: handle BL_CORE_FBBLANK state pwm: pwm-tiecap: Low power sleep support pwm: pwm-tiehrpwm: Low power sleep support pwm: pwm-tiehrpwm: Update the clock handling of pwm-tiehrpwm driver pwm: vt8500: Add polarity support pwm: vt8500: Register write busy test performed incorrectly pwm: atmel: add Timer Counter Block PWM driver
2013-02-01pwm: Add devm_of_pwm_get() as exported API for usersPeter Ujfalusi1-0/+9
When booted with DT users can use devm version of of_pwm_get() to benefit from automatic resource release. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Acked-by: Thierry Reding <thierry.reding@avionic-design.de> Signed-off-by: Bryan Wu <cooloney@gmail.com>
2013-02-01pwm: core: Rename of_pwm_request() to of_pwm_get() and export itPeter Ujfalusi1-0/+7
Allow client driver to use of_pwm_get() to get the PWM they need. This is needed for drivers which handle more than one PWM separately, like leds-pwm driver, which have: pwmleds { compatible = "pwm-leds"; kpad { label = "omap4::keypad"; pwms = <&twl_pwm 0 7812500>; max-brightness = <127>; }; charging { label = "omap4:green:chrg"; pwms = <&twl_pwmled 0 7812500>; max-brightness = <255>; }; }; in the dts files. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Acked-by: Thierry Reding <thierry.reding@avionic-design.de> Signed-off-by: Bryan Wu <cooloney@gmail.com>
2013-02-01pwm: Correct parameter name in header for *pwm_get() functionsPeter Ujfalusi1-2/+2
To synchronize the header file definition and the actual code. In the code the consumer parameter is named as con_id, change the header file and replace consumer -> con_id in the parameter list. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Ackedy-by: Thierry Reding <thierry.reding@avionic-design.de> Signed-off-by: Bryan Wu <cooloney@gmail.com>
2013-01-30pwm: Add pwm_can_sleep() as exported API to usersFlorian Vaussard1-0/+10
Calls to some external PWM chips can sleep. To help users, add pwm_can_sleep() API. Cc: Thierry Reding <thierry.reding@avionic-design.de> Cc: Peter Ujfalusi <peter.ujfalusi@ti.com> Signed-off-by: Florian Vaussard <florian.vaussard@epfl.ch> Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
2012-11-22pwm: Device tree support for PWM polarityPhilip, Avinash1-0/+3
Add support for encoding PWM properties in bit encoded form with of_pwm_xlate_with_flags() function support. Platforms require platform specific PWM properties has to populate in 3rd cell of the pwm-specifier and PWM driver should also set .of_xlate support with this function. Currently PWM property polarity encoded in bit position 0 of the third cell in pwm-specifier. Signed-off-by: Philip, Avinash <avinashphilip@ti.com> Acked-by: Grant Likely <grant.likely@secretlab.ca> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
2012-09-20pwm: Fix compilation error when CONFIG_PWM is not definedTushar Behera1-2/+80
Add dummy implemention of public symbols for compilation-safe inclusion of include/linux/pwm.h file when CONFIG_PWM is not defined. Reported-by: Sachin Kamat <sachin.kamat@linaro.org> Signed-off-by: Tushar Behera <tushar.behera@linaro.org> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
2012-09-10pwm: add devm_pwm_get() and devm_pwm_put()Alexandre Courbot1-0/+3
Add resource managed variants of pwm_get() and pwm_put() for convenience. Code is largely inspired by the equivalent devm functions of the regulator framework. Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
2012-09-10pwm: Add support for configuring the PWM polarityPhilip, Avinash1-0/+23
Some hardware supports inverting the polarity of the PWM signal. This commit adds support to the PWM framework to allow users of the PWM API to configure the polarity. Note that in order to reduce complexity, changing the polarity of a PWM signal is only allowed while the PWM is disabled. A practical example where this can prove useful is to simulate inversion of the duty cycle. While inversion of polarity and duty cycle are not exactly the same, the differences for most use-cases are negligible. Signed-off-by: Philip, Avinash <avinashphilip@ti.com> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
2012-06-15pwm: Add device tree supportThierry Reding1-0/+6
This patch adds helpers to support device tree bindings for the generic PWM API. Device tree binding documentation for PWM controllers is also provided. Acked-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
2012-06-15pwm: Add table-based lookup for static mappingsThierry Reding1-0/+22
In order to get rid of the global namespace for PWM devices, this commit provides an alternative method, similar to that of the regulator or clock frameworks, for registering a static mapping for PWM devices. This works by providing a table with a provider/consumer map in the board setup code. With the new pwm_get() and pwm_put() functions available, usage of pwm_request() and pwm_free() becomes deprecated. Reviewed-by: Shawn Guo <shawn.guo@linaro.org> Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
2012-06-15pwm: Add debugfs interfaceThierry Reding1-0/+6
This commit adds a debugfs interface that can be used to list the current internal state of the PWM devices registered with the PWM framework. Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Reviewed-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
2012-06-15pwm: Allow chips to support multiple PWMsThierry Reding1-13/+58
Many PWM controllers provide access to more than a single PWM output and may even share some resource among them. Allowing a PWM chip to provide multiple PWM devices enables better sharing of those resources. As a side-effect this change allows easy integration with the device tree where a given PWM can be looked up based on the PWM chip's phandle and a corresponding index. This commit modifies the PWM core to support multiple PWMs per struct pwm_chip. It achieves this in a similar way to how gpiolib works, by allowing PWM ranges to be requested dynamically (pwm_chip.base == -1) or starting at a given offset (pwm_chip.base >= 0). A chip specifies how many PWMs it controls using the npwm member. Each of the functions in the pwm_ops structure gets an additional argument that specified the PWM number (it can be converted to a per-chip index by subtracting the chip's base). The total maximum number of PWM devices is currently fixed to 1024 while the data is actually stored in a radix tree, thus saving resources if not all of them are used. Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Reviewed-by: Shawn Guo <shawn.guo@linaro.org> [eric@eukrea.com: fix error handling in pwmchip_add] Signed-off-by: Eric BĂ©nard <eric@eukrea.com> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
2012-06-15pwm: Add PWM framework supportSascha Hauer1-0/+38
This patch adds framework support for PWM (pulse width modulation) devices. The is a barebone PWM API already in the kernel under include/linux/pwm.h, but it does not allow for multiple drivers as each of them implements the pwm_*() functions. There are other PWM framework patches around from Bill Gatliff. Unlike his framework this one does not change the existing API for PWMs so that this framework can act as a drop in replacement for the existing API. Why another framework? Several people argue that there should not be another framework for PWMs but they should be integrated into one of the existing frameworks like led or hwmon. Unlike these frameworks the PWM framework is agnostic to the purpose of the PWM. In fact, a PWM can drive a LED, but this makes the LED framework a user of a PWM, like already done in leds-pwm.c. The gpio framework also is not suitable for PWMs. Every gpio could be turned into a PWM using timer based toggling, but on the other hand not every PWM hardware device can be turned into a gpio due to the lack of hardware capabilities. This patch does not try to improve the PWM API yet, this could be done in subsequent patches. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Acked-by: Kurt Van Dijck <kurt.van.dijck@eia.be> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Matthias Kaehlcke <matthias@kaehlcke.net> Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Reviewed-by: Shawn Guo <shawn.guo@linaro.org> [thierry.reding@avionic-design.de: fixup typos, kerneldoc comments] Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
2009-03-30trivial: PWM: fix of #endif commentMark Vels1-1/+1
Signed-off-by: Mark Vels <mark.vels@team-embedded.nl> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2008-05-19[ARM] pxa: Add bare bones PWM APIRussell King1-0/+31
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>