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| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2024-02-14 10:30:50 +0100 |
|---|---|---|
| committer | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2024-02-15 12:59:15 +0100 |
| commit | 024913dbf99f06f09d5c06c940ca39821697d41c (patch) | |
| tree | e016c7204bd9829b42f3bb4d39371aba9da5bc16 /Documentation/driver-api | |
| parent | 24003d501f112a9827aa8c59c00e12b2d5cbddf6 (diff) | |
pwm: Provide pwmchip_alloc() function and a devm variant of it
This function allocates a struct pwm_chip and driver data. Compared to
the status quo the split into pwm_chip and driver data is new, otherwise
it doesn't change anything relevant (yet).
The intention is that after all drivers are switched to use this
allocation function, its possible to add a struct device to struct
pwm_chip to properly track the latter's lifetime without touching all
drivers again. Proper lifetime tracking is a necessary precondition to
introduce character device support for PWMs (that implements atomic
setting and doesn't suffer from the sysfs overhead of the /sys/class/pwm
userspace support).
The new function pwmchip_priv() (obviously?) only works for chips
allocated with pwmchip_alloc().
Link: https://lore.kernel.org/r/9577d6053a5a52536057dc8654ff567181c2da82.1707900770.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/driver-model/devres.rst | 1 | ||||
| -rw-r--r-- | Documentation/driver-api/pwm.rst | 11 |
2 files changed, 7 insertions, 5 deletions
diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst index c5f99d834ec5..e4df72c408d2 100644 --- a/Documentation/driver-api/driver-model/devres.rst +++ b/Documentation/driver-api/driver-model/devres.rst @@ -420,6 +420,7 @@ POWER devm_reboot_mode_unregister() PWM + devm_pwmchip_alloc() devm_pwmchip_add() devm_pwm_get() devm_fwnode_pwm_get() diff --git a/Documentation/driver-api/pwm.rst b/Documentation/driver-api/pwm.rst index 3c28ccc4b611..b41b1c56477f 100644 --- a/Documentation/driver-api/pwm.rst +++ b/Documentation/driver-api/pwm.rst @@ -143,11 +143,12 @@ to implement the pwm_*() functions itself. This means that it's impossible to have multiple PWM drivers in the system. For this reason it's mandatory for new drivers to use the generic PWM framework. -A new PWM controller/chip can be added using pwmchip_add() and removed -again with pwmchip_remove(). pwmchip_add() takes a filled in struct -pwm_chip as argument which provides a description of the PWM chip, the -number of PWM devices provided by the chip and the chip-specific -implementation of the supported PWM operations to the framework. +A new PWM controller/chip can be allocated using pwmchip_alloc(), then +registered using pwmchip_add() and removed again with pwmchip_remove(). To undo +pwmchip_alloc() use pwmchip_put(). pwmchip_add() takes a filled in struct +pwm_chip as argument which provides a description of the PWM chip, the number +of PWM devices provided by the chip and the chip-specific implementation of the +supported PWM operations to the framework. When implementing polarity support in a PWM driver, make sure to respect the signal conventions in the PWM framework. By definition, normal polarity |