[PATCH 1/2] PWM: add pwm framework support

[Matthias Kaehlcke]

El Tue, Jun 28, 2011 at 12:02:47PM +0200 Sascha Hauer ha dit:

> This patch adds framework support for PWM (pulse width modulation) devices.
[...]
> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
> new file mode 100644
> index 0000000..79dc051
> --- /dev/null
> +++ b/drivers/pwm/core.c
[...]
> +/**
> + * pwmchip_add() - register a new pwm
> + * @chip: the pwm
> + *
> + * register a new pwm. pwm->pwm_id must be initialized. if pwm_id < 0 then
> + * a dynamically assigned id will be used, otherwise the id specified,
> + */
> +int pwmchip_add(struct pwm_chip *chip)
> +{
> +	struct pwm_device *pwm;
> +	int ret = 0;
> +
> +	pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
> +	if (!pwm)
> +		return -ENOMEM;
> +
> +	pwm->chip = chip;
> +
> +	mutex_lock(&pwm_lock);
> +
> +	if (chip->pwm_id >= 0 && find_pwm(chip->pwm_id)) {
> +		ret = -EBUSY;
> +		goto out;
> +	}
> +
> +	if (chip->pwm_id < 0)
> +		chip->pwm_id = next_pwm_id++;
> +
> +	list_add_tail(&pwm->node, &pwm_list);
> +out:
> +	mutex_unlock(&pwm_lock);
> +
> +	kfree(pwm);

as already pointed out by kurt, pwm should only be freed in case of an
error

> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(pwmchip_add);
> +
> +/**
> + * pwmchip_remove() - remove a pwm
> + * @chip: the pwm
> + *
> + * remove a pwm. This function may return busy if the pwm is still requested.
> + */
> +int pwmchip_remove(struct pwm_chip *chip)
> +{
> +	struct pwm_device *pwm;
> +	int ret = 0;
> +
> +	mutex_lock(&pwm_lock);
> +
> +	pwm = find_pwm(chip->pwm_id);
> +	if (!pwm) {
> +		ret = -ENOENT;
> +		goto out;
> +	}
> +
> +	if (test_bit(FLAG_REQUESTED, &pwm->flags)) {
> +		ret = -EBUSY;
> +		goto out;
> +	}
> +
> +	list_del(&pwm->node);
  +	kfree(pwm);
> +out:
> +	mutex_unlock(&pwm_lock);
> +
> +	return ret;
> +}

[...]

best regards

-- 
Matthias Kaehlcke
Embedded Linux Developer
Amsterdam

             It always seems impossible until it's done
                        (Nelson Mandela)
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