linux-stable.git/drivers/pwm, branch v5.7

pwm: pca9685: Fix PWM/GPIO inter-operation

2020-04-03T19:41:42+00:00

This driver allows pwms to be requested as gpios via gpiolib. Obviously,
it should not be allowed to request a GPIO when its corresponding PWM is
already requested (and vice versa). So it requires some exclusion code.

Given that the PWMm and GPIO cores are not synchronized with respect to
each other, this exclusion code will also require proper
synchronization.

Such a mechanism was in place, but was inadvertently removed by Uwe's
clean-up in commit e926b12c611c ("pwm: Clear chip_data in pwm_put()").

Upon revisiting the synchronization mechanism, we found that
theoretically, it could allow two threads to successfully request
conflicting PWMs/GPIOs.

Replace with a bitmap which tracks PWMs in-use, plus a mutex. As long as
PWM and GPIO's respective request/free functions modify the in-use
bitmap while holding the mutex, proper synchronization will be
guaranteed.

Reported-by: YueHaibing 
Fixes: e926b12c611c ("pwm: Clear chip_data in pwm_put()")
Cc: Mika Westerberg 
Cc: Uwe Kleine-König 
Cc: YueHaibing 
Link: https://lkml.org/lkml/2019/5/31/963
Signed-off-by: Sven Van Asbroeck 
Reviewed-by: Mika Westerberg 
[cg: Tested on an i.MX6Q board with two NXP PCA9685 chips]
Tested-by: Clemens Gruber 
Reviewed-by: Sven Van Asbroeck  # cg's rebase
Link: https://lore.kernel.org/lkml/20200330160238.GD2817345@ulmo/
Signed-off-by: Thierry Reding

pwm: Make pwm_apply_state_debug() static

2020-04-03T19:41:09+00:00

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 
Signed-off-by: Jason Yan 
Acked-by: Uwe Kleine-König 
Signed-off-by: Thierry Reding

pwm: meson: Remove redundant assignment to variable fin_freq

2020-04-03T19:40:56+00:00

The variable fin_freq is being initialized with a value that is never
read and it is being updated later with a new value. The initialization
is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King 
Acked-by: Uwe Kleine-König 
Signed-off-by: Thierry Reding

pwm: jz4740: Allow selection of PWM channels 0 and 1

2020-03-30T16:03:10+00:00

The TCU channels 0 and 1 were previously reserved for system tasks, and
thus unavailable for PWM.

Signed-off-by: Paul Cercueil 
Tested-by: Mathieu Malaterre 
Tested-by: Artur Rojek 
Signed-off-by: Thierry Reding

pwm: jz4740: Obtain regmap from parent node

2020-03-30T16:03:09+00:00

The TCU registers are shared between a handful of drivers, accessing
them through the same regmap.

While this driver is devicetree-compatible, it is never (as of now)
probed from devicetree, so this change does not introduce a ABI problem
with current devicetree files.

Signed-off-by: Paul Cercueil 
Tested-by: Mathieu Malaterre 
Tested-by: Artur Rojek 
Signed-off-by: Thierry Reding

pwm: jz4740: Improve algorithm of clock calculation

2020-03-30T16:03:09+00:00

The previous algorithm hardcoded details about how the TCU clocks work.
The new algorithm will use clk_round_rate to find the perfect clock rate
for the PWM channel.

This code relies on the fact that clk_round_rate() will always round
down, which is not a valid assumption given by the clk API, but only
happens to be true with the clk drivers used for Ingenic SoCs.

Right now, there is no alternative as the clk API does not have a
round-down function (and won't have one for a while), but if it ever
comes to light, a round-down function should be used instead.

Signed-off-by: Paul Cercueil 
Tested-by: Mathieu Malaterre 
Tested-by: Artur Rojek 
Signed-off-by: Thierry Reding

pwm: jz4740: Use clocks from TCU driver

2020-03-30T16:03:09+00:00

The ingenic-timer "TCU" driver provides us with clocks, that can be
(un)gated, reparented or reclocked from devicetree, instead of having
these settings hardcoded in this driver.

The new code now uses a clk pointer per PWM (instead of a clk per
pwm-chip before). So the pointer is stored in per-pwm data now.
The calls to arch-specific timer code is replaced with standard
clock API calls to start and stop each channel's clock.

While this driver is devicetree-compatible, it is never (as of now)
probed from devicetree, so this change does not introduce a ABI problem
with current devicetree files.

Signed-off-by: Paul Cercueil 
Tested-by: Mathieu Malaterre 
Tested-by: Artur Rojek 
Signed-off-by: Thierry Reding

pwm: sun4i: Remove redundant needs_delay

2020-03-30T16:03:08+00:00

'needs_delay' does now always evaluate to true, so remove all
occurrences.

Signed-off-by: Pascal Roeleven 
Signed-off-by: Thierry Reding

pwm: omap-dmtimer: Implement .apply callback

2020-03-30T16:03:08+00:00

Implement .apply callback and drop the legacy callbacks(enable, disable,
config, set_polarity). In .apply() check for the current hardware status
before changing the PWM configuration.

Signed-off-by: Lokesh Vutla 
Tested-by: Tony Lindgren 
Signed-off-by: Thierry Reding

pwm: omap-dmtimer: Do not disable PWM before changing period/duty_cycle

2020-03-30T16:03:07+00:00

Only the Timer control register(TCLR) cannot be updated when the timer
is running. Registers like Counter register (TCRR), loader register
(TLDR) and match register (TMAR) can be updated while the counter is
running. Since TCLR is not updated in pwm_omap_dmtimer_config(), do not
stop the timer for period/duty_cycle update.

Tested-by: Tony Lindgren 
Signed-off-by: Lokesh Vutla 
Signed-off-by: Thierry Reding