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Commit 652162d4 authored by Stephen Warren's avatar Stephen Warren Committed by Linus Walleij
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pinctrl: allow concurrent gpio and mux function ownership of pins 



Per recent updates to Documentation/gpio.txt, gpiolib drivers should
inform pinctrl when a GPIO is requested. pinctrl then marks that pin as
in-use for that GPIO function.

When an SoC muxes pins in a group, it's quite possible for the group to
contain e.g. 6 pins, but only 4 of them actually be needed by the HW
module that's mux'd to them. In this case, the other 2 pins could be
used as GPIOs. However, pinctrl marks all the pins within the group as
in-use by the selected mux function. To allow the expected gpiolib
interaction, separate the concepts of pin ownership into two parts: One
for the mux function and one for GPIO usage. Finally, allow those two
ownerships to exist in parallel.

Signed-off-by: default avatarStephen Warren <swarren@nvidia.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent a6c3b33f

drivers/pinctrl/core.h

+7 −6
Original line number Diff line number Diff line
@@ -119,15 +119,15 @@ 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

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

 * @mux_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().

 * @mux_owner: The name of device that called pinctrl_get().

 * @mux_setting: The most recent selected mux setting for this pin, if any.

 * @gpio_owner: If pinctrl_request_gpio() was called for this pin, this is

 *	the name of the GPIO that "owns" this pin.

 */

struct pin_desc {

	struct pinctrl_dev *pctldev;
@@ -135,9 +135,10 @@ struct pin_desc { 
	bool dynamic_name;

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

#ifdef CONFIG_PINMUX

	unsigned usecount;

	const char *owner;

	unsigned mux_usecount;

	const char *mux_owner;

	const struct pinctrl_setting_mux *mux_setting;

	const char *gpio_owner;

#endif

};

drivers/pinctrl/pinmux.c

+49 −23
Original line number Diff line number Diff line
@@ -94,17 +94,28 @@ static int pin_request(struct pinctrl_dev *pctldev, 
		goto out;

	}



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

	if (gpio_range) {

		/* There's no need to support multiple GPIO requests */

		if (desc->gpio_owner) {

			dev_err(pctldev->dev,

				"pin already requested\n");

			goto out;

		}



	desc->usecount++;

	if (desc->usecount > 1)

		desc->gpio_owner = owner;

	} else {

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

			dev_err(pctldev->dev,

				"pin already requested\n");

			goto out;

		}



		desc->mux_usecount++;

		if (desc->mux_usecount > 1)

			return 0;



	desc->owner = owner;

		desc->mux_owner = owner;

	}



	/* Let each pin increase references to this module */

	if (!try_module_get(pctldev->owner)) {
@@ -135,9 +146,13 @@ static int pin_request(struct pinctrl_dev *pctldev, 


out_free_pin:

	if (status) {

		desc->usecount--;

		if (!desc->usecount)

			desc->owner = NULL;

		if (gpio_range) {

			desc->gpio_owner = NULL;

		} else {

			desc->mux_usecount--;

			if (!desc->mux_usecount)

				desc->mux_owner = NULL;

		}

	}

out:

	if (status)
@@ -172,9 +187,11 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin, 
		return NULL;

	}



	desc->usecount--;

	if (desc->usecount)

	if (!gpio_range) {

		desc->mux_usecount--;

		if (desc->mux_usecount)

			return NULL;

	}



	/*

	 * If there is no kind of request function for the pin we just assume
@@ -185,9 +202,15 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin, 
	else if (ops->free)

		ops->free(pctldev, pin);



	owner = desc->owner;

	desc->owner = NULL;

	if (gpio_range) {

		owner = desc->gpio_owner;

		desc->gpio_owner = NULL;

	} else {

		owner = desc->mux_owner;

		desc->mux_owner = NULL;

		desc->mux_setting = NULL;

	}



	module_put(pctldev->owner);



	return owner;
@@ -493,7 +516,7 @@ static int pinmux_pins_show(struct seq_file *s, void *what) 
	unsigned i, pin;



	seq_puts(s, "Pinmux settings per pin\n");

	seq_puts(s, "Format: pin (name): owner\n");

	seq_puts(s, "Format: pin (name): mux_owner gpio_owner hog?\n");



	mutex_lock(&pinctrl_mutex);
@@ -508,13 +531,16 @@ static int pinmux_pins_show(struct seq_file *s, void *what) 
		if (desc == NULL)

			continue;



		if (desc->owner &&

		    !strcmp(desc->owner, pinctrl_dev_get_name(pctldev)))

		if (desc->mux_owner &&

		    !strcmp(desc->mux_owner, pinctrl_dev_get_name(pctldev)))

			is_hog = true;



		seq_printf(s, "pin %d (%s): %s%s", pin,

		seq_printf(s, "pin %d (%s): %s %s%s", pin,

			   desc->name ? desc->name : "unnamed",

			   desc->owner ? desc->owner : "UNCLAIMED",

			   desc->mux_owner ? desc->mux_owner

				: "(MUX UNCLAIMED)",

			   desc->gpio_owner ? desc->gpio_owner

				: "(GPIO UNCLAIMED)",

			   is_hog ? " (HOG)" : "");



		if (desc->mux_setting)