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Commit 0e3db173 authored by Stephen Warren's avatar Stephen Warren Committed by Linus Walleij
Browse files

pinctrl: add usecount to pins for muxing 



Multiple mapping table entries could reference the same pin, and hence
"own" it. This would be unusual now that pinctrl_get() represents a single
state for a client device, but in the future when it represents all known
states for a device, this is quite likely. Implement reference counting
for pin ownership to handle this.

Signed-off-by: default avatarStephen Warren <swarren@nvidia.com>
Acked-by: default avatarDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 7ecdb16f

drivers/pinctrl/core.h

+9 −1
Original line number Diff line number Diff line
@@ -82,7 +82,14 @@ struct pinctrl_setting { 
 * @name: a name for the pin, e.g. the name of the pin/pad/finger on a

 *	datasheet or such

 * @dynamic_name: if the name of this pin was dynamically allocated

 * @owner: the device holding this pin or NULL of no device has claimed it

 * @usecount: If zero, the pin is not claimed, and @owner should be NULL.

 *	If non-zero, this pin is claimed by @owner. This field is an integer

 *	rather than a boolean, since pinctrl_get() might process multiple

 *	mapping table entries that refer to, and hence claim, the same group

 *	or pin, and each of these will increment the @usecount.

 * @owner: The name of the entity owning the pin. Typically, this is the name

 *	of the device that called pinctrl_get(). Alternatively, it may be the

 *	name of the GPIO passed to pinctrl_request_gpio().

 */

struct pin_desc {

	struct pinctrl_dev *pctldev;
@@ -90,6 +97,7 @@ struct pin_desc { 
	bool dynamic_name;

	/* These fields only added when supporting pinmux drivers */

#ifdef CONFIG_PINMUX

	unsigned usecount;

	const char *owner;

#endif

};

drivers/pinctrl/pinmux.c

+19 −4
Original line number Diff line number Diff line
@@ -83,11 +83,16 @@ static int pin_request(struct pinctrl_dev *pctldev, 
		goto out;

	}



	if (desc->owner && strcmp(desc->owner, owner)) {

	if (desc->usecount && strcmp(desc->owner, owner)) {

		dev_err(pctldev->dev,

			"pin already requested\n");

		goto out;

	}



	desc->usecount++;

	if (desc->usecount > 1)

		return 0;



	desc->owner = owner;



	/* Let each pin increase references to this module */
@@ -111,12 +116,18 @@ static int pin_request(struct pinctrl_dev *pctldev, 
	else

		status = 0;



	if (status)

	if (status) {

		dev_err(pctldev->dev, "->request on device %s failed for pin %d\n",

		       pctldev->desc->name, pin);

		module_put(pctldev->owner);

	}



out_free_pin:

	if (status)

	if (status) {

		desc->usecount--;

		if (!desc->usecount)

			desc->owner = NULL;

	}

out:

	if (status)

		dev_err(pctldev->dev, "pin-%d (%s) status %d\n",
@@ -150,6 +161,10 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin, 
		return NULL;

	}



	desc->usecount--;

	if (desc->usecount)

		return NULL;



	/*

	 * If there is no kind of request function for the pin we just assume

	 * we got it by default and proceed.