BMC/Intel-BMC/linux.git/include/linux/pwm.h, branch dev-4.7

pwm: Fix pwm_apply_args()

2016-06-23T16:37:05+00:00

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 Reported-by: Geert Uytterhoeven Suggested-by: Brian Norris Fixes: 5ec803edcb70 ("pwm: Add core infrastructure to allow atomic updates") Tested-by: Geert Uytterhoeven Reviewed-by: Brian Norris Signed-off-by: Thierry Reding

pwm: Improve args checking in pwm_apply_state()

2016-06-10T12:21:00+00:00

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 Acked-by: Boris Brezillon Signed-off-by: Thierry Reding

pwm: Add core infrastructure to allow atomic updates

2016-05-17T12:48:03+00:00

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 [thierry.reding@gmail.com: fix a couple of typos] Signed-off-by: Thierry Reding

pwm: Add hardware readout infrastructure

2016-05-17T12:48:03+00:00

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 Signed-off-by: Thierry Reding

pwm: Move the enabled/disabled info into pwm_state

2016-05-17T12:48:02+00:00

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 Signed-off-by: Thierry Reding

pwm: Introduce the pwm_state concept

2016-05-17T12:48:02+00:00

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 Signed-off-by: Thierry Reding

pwm: Keep PWM state in sync with hardware state

2016-05-17T12:47:30+00:00

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 Signed-off-by: Thierry Reding

pwm: Get rid of pwm->lock

2016-05-17T12:44:59+00:00

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 Signed-off-by: Thierry Reding

pwm: Introduce the pwm_args concept

2016-05-03T11:44:37+00:00

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 [thierry.reding@gmail.com: reword kerneldoc comments] Signed-off-by: Thierry Reding

pwm: Set enable state properly on failed call to enable

2015-11-10T12:06:16+00:00

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 Reviewed-by: Dmitry Torokhov Signed-off-by: Jonathan Richardson [thierry.reding@gmail.com: add missing kerneldoc for the lock] Signed-off-by: Thierry Reding