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Commit 15fa8a43 authored by Boris Brezillon's avatar Boris Brezillon Committed by Thierry Reding
Browse files

pwm: Add hardware readout infrastructure 



Add a ->get_state() function to the pwm_ops struct to let PWM drivers
initialize the PWM state attached to a PWM device.

Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 09a7e4a3

drivers/pwm/core.c

+3 −0
Original line number Diff line number Diff line
@@ -270,6 +270,9 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip, 
		pwm->hwpwm = i;

		pwm->state.polarity = polarity;



		if (chip->ops->get_state)

			chip->ops->get_state(chip, pwm, &pwm->state);



		radix_tree_insert(&pwm_tree, pwm->pwm, pwm);

	}

include/linux/pwm.h

+28 −0
Original line number Diff line number Diff line
@@ -206,6 +206,29 @@ static inline void pwm_get_args(const struct pwm_device *pwm, 


static inline void pwm_apply_args(struct pwm_device *pwm)

{

	/*

	 * PWM users calling pwm_apply_args() expect to have a fresh config

	 * where the polarity and period are set according to pwm_args info.

	 * The problem is, polarity can only be changed when the PWM is

	 * disabled.

	 *

	 * PWM drivers supporting hardware readout may declare the PWM device

	 * as enabled, and prevent polarity setting, which changes from the

	 * existing behavior, where all PWM devices are declared as disabled

	 * at startup (even if they are actually enabled), thus authorizing

	 * polarity setting.

	 *

	 * Instead of setting ->enabled to false, we call pwm_disable()

	 * before pwm_set_polarity() to ensure that everything is configured

	 * as expected, and the PWM is really disabled when the user request

	 * it.

	 *

	 * Note that PWM users requiring a smooth handover between the

	 * bootloader and the kernel (like critical regulators controlled by

	 * PWM devices) will have to switch to the atomic API and avoid calling

	 * pwm_apply_args().

	 */

	pwm_disable(pwm);

	pwm_set_polarity(pwm, pwm->args.polarity);

}
@@ -217,6 +240,9 @@ static inline void pwm_apply_args(struct pwm_device *pwm) 
 * @set_polarity: configure the polarity of this PWM

 * @enable: enable PWM output toggling

 * @disable: disable PWM output toggling

 * @get_state: get the current PWM state. This function is only

 *	       called once per PWM device when the PWM chip is

 *	       registered.

 * @dbg_show: optional routine to show contents in debugfs

 * @owner: helps prevent removal of modules exporting active PWMs

 */
@@ -229,6 +255,8 @@ struct pwm_ops { 
			    enum pwm_polarity polarity);

	int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);

	void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);

	void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,

			  struct pwm_state *state);

#ifdef CONFIG_DEBUG_FS

	void (*dbg_show)(struct pwm_chip *chip, struct seq_file *s);

#endif