From 024913dbf99f06f09d5c06c940ca39821697d41c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= Date: Wed, 14 Feb 2024 10:30:50 +0100 Subject: [PATCH] pwm: Provide pwmchip_alloc() function and a devm variant of it MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- .../driver-api/driver-model/devres.rst | 1 + Documentation/driver-api/pwm.rst | 11 ++-- drivers/pwm/core.c | 58 +++++++++++++++++++ include/linux/pwm.h | 22 +++++++ 4 files changed, 87 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 diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 830a697826af..d70f793ce4b3 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -454,6 +454,64 @@ of_pwm_single_xlate(struct pwm_chip *chip, const struct of_phandle_args *args) } EXPORT_SYMBOL_GPL(of_pwm_single_xlate); +#define PWMCHIP_ALIGN ARCH_DMA_MINALIGN + +static void *pwmchip_priv(struct pwm_chip *chip) +{ + return (void *)chip + ALIGN(sizeof(*chip), PWMCHIP_ALIGN); +} + +/* This is the counterpart to pwmchip_alloc() */ +void pwmchip_put(struct pwm_chip *chip) +{ + kfree(chip); +} +EXPORT_SYMBOL_GPL(pwmchip_put); + +struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv) +{ + struct pwm_chip *chip; + size_t alloc_size; + + alloc_size = size_add(ALIGN(sizeof(*chip), PWMCHIP_ALIGN), sizeof_priv); + + chip = kzalloc(alloc_size, GFP_KERNEL); + if (!chip) + return ERR_PTR(-ENOMEM); + + chip->dev = parent; + chip->npwm = npwm; + + pwmchip_set_drvdata(chip, pwmchip_priv(chip)); + + return chip; +} +EXPORT_SYMBOL_GPL(pwmchip_alloc); + +static void devm_pwmchip_put(void *data) +{ + struct pwm_chip *chip = data; + + pwmchip_put(chip); +} + +struct pwm_chip *devm_pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv) +{ + struct pwm_chip *chip; + int ret; + + chip = pwmchip_alloc(parent, npwm, sizeof_priv); + if (IS_ERR(chip)) + return chip; + + ret = devm_add_action_or_reset(parent, devm_pwmchip_put, chip); + if (ret) + return ERR_PTR(ret); + + return chip; +} +EXPORT_SYMBOL_GPL(devm_pwmchip_alloc); + static void of_pwmchip_add(struct pwm_chip *chip) { if (!pwmchip_parent(chip) || !pwmchip_parent(chip)->of_node) diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 29a7d9140f77..4a6568dfdf3f 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -403,6 +403,10 @@ static inline bool pwm_might_sleep(struct pwm_device *pwm) int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result, unsigned long timeout); +void pwmchip_put(struct pwm_chip *chip); +struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv); +struct pwm_chip *devm_pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv); + int __pwmchip_add(struct pwm_chip *chip, struct module *owner); #define pwmchip_add(chip) __pwmchip_add(chip, THIS_MODULE) void pwmchip_remove(struct pwm_chip *chip); @@ -475,6 +479,24 @@ static inline int pwm_capture(struct pwm_device *pwm, return -EINVAL; } +static inline void pwmchip_put(struct pwm_chip *chip) +{ +} + +static inline struct pwm_chip *pwmchip_alloc(struct device *parent, + unsigned int npwm, + size_t sizeof_priv) +{ + return ERR_PTR(-EINVAL); +} + +static inline struct pwm_chip *devm_pwmchip_alloc(struct device *parent, + unsigned int npwm, + size_t sizeof_priv) +{ + return pwmchip_alloc(parent, npwm, sizeof_priv); +} + static inline int pwmchip_add(struct pwm_chip *chip) { return -EINVAL;