Subject: [PATCH 1/3] pwm: Add pwm_cansleep() as exported API to users

From: [email-masked] (Peter Ujfalusi)
Date: Fri, 25 Jan 2013 13:32:03 +0100

On 01/25/2013 11:01 AM, Florian Vaussard wrote:
> Calls to some external PWM chips can sleep. To help users,
> add pwm_cansleep() API.
> 
> Signed-off-by: Florian Vaussard <[email-masked]>
> ---
>  drivers/pwm/core.c  |   12 ++++++++++++
>  include/linux/pwm.h |   10 ++++++++++
>  2 files changed, 22 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
> index 4a13da4..f49bfa6 100644
> --- a/drivers/pwm/core.c
> +++ b/drivers/pwm/core.c
> @@ -763,6 +763,18 @@ void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
>  }
>  EXPORT_SYMBOL_GPL(devm_pwm_put);
>  
> +/**
> +  * pwm_can_sleep() - report whether pwm access will sleep
> +  * @pwm: PWM device
> +  *
> +  * It returns nonzero if accessing the PWM can sleep.
> +  */
> +int pwm_can_sleep(struct pwm_device *pwm)
> +{
> +	return pwm->chip->can_sleep;
> +}
> +EXPORT_SYMBOL_GPL(pwm_can_sleep);

Can we name this as pwm_cansleep() to be more alligned with the
gpio_cansleep() API?

> +
>  #ifdef CONFIG_DEBUG_FS
>  static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
>  {
> diff --git a/include/linux/pwm.h b/include/linux/pwm.h
> index 70655a2..2aee75d 100644
> --- a/include/linux/pwm.h
> +++ b/include/linux/pwm.h
> @@ -146,6 +146,8 @@ struct pwm_ops {
>   * @base: number of first PWM controlled by this chip
>   * @npwm: number of PWMs controlled by this chip
>   * @pwms: array of PWM devices allocated by the framework
> + * @can_sleep: flag must be set iff config()/enable()/disable() methods sleep,
> + *      as they must while accessing PWM chips over I2C or SPI
>   */
>  struct pwm_chip {
>  	struct device		*dev;
> @@ -159,6 +161,7 @@ struct pwm_chip {
>  	struct pwm_device *	(*of_xlate)(struct pwm_chip *pc,
>  					    const struct of_phandle_args *args);
>  	unsigned int		of_pwm_n_cells;
> +	unsigned int		can_sleep:1;
>  };
>  
>  #if IS_ENABLED(CONFIG_PWM)
> @@ -182,6 +185,8 @@ struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
>  struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
>  				   const char *con_id);
>  void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
> +
> +int pwm_can_sleep(struct pwm_device *pwm);
>  #else
>  static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
>  {
> @@ -242,6 +247,11 @@ static inline struct pwm_device *devm_of_pwm_get(struct device *dev,
>  static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
>  {
>  }
> +
> +static inline int pwm_can_sleep(struct pwm_device *pwm)
> +{
> +	return -EINVAL;

I think we should return 0 here instead an error.

> +}
>  #endif
>  struct pwm_lookup {

-- 
P?ter