Commit 63636d95 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Linus Walleij
Browse files

gpio: of: Add DT overlay support for GPIO hogs 



As GPIO hogs are configured at GPIO controller initialization time,
adding/removing GPIO hogs in DT overlays does not work.

Add support for GPIO hogs described in DT overlays by registering an OF
reconfiguration notifier, to handle the addition and removal of GPIO hog
subnodes to/from a GPIO controller device node.

Note that when a GPIO hog device node is being removed, its "gpios"
properties is no longer available, so we have to keep track of which
node a hog belongs to, which is done by adding a pointer to the hog's
device node to struct gpio_desc.

Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200220130149.26283-3-geert+renesas@glider.be


Reviewed-by: default avatarFrank Rowand <frank.rowand@sony.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent bc21077e

drivers/gpio/gpiolib-of.c

+90 −0
Original line number Diff line number Diff line
@@ -628,6 +628,10 @@ static int of_gpiochip_add_hog(struct gpio_chip *chip, struct device_node *hog) 
		ret = gpiod_hog(desc, name, lflags, dflags);

		if (ret < 0)

			return ret;



#ifdef CONFIG_OF_DYNAMIC

		desc->hog = hog;

#endif

	}



	return 0;
@@ -655,11 +659,97 @@ static int of_gpiochip_scan_gpios(struct gpio_chip *chip) 
			of_node_put(np);

			return ret;

		}



		of_node_set_flag(np, OF_POPULATED);

	}



	return 0;

}



#ifdef CONFIG_OF_DYNAMIC

/**

 * of_gpiochip_remove_hog - Remove all hogs in a hog device node

 * @chip:	gpio chip to act on

 * @hog:	device node describing the hogs

 */

static void of_gpiochip_remove_hog(struct gpio_chip *chip,

				   struct device_node *hog)

{

	struct gpio_desc *descs = chip->gpiodev->descs;

	unsigned int i;



	for (i = 0; i < chip->ngpio; i++) {

		if (test_bit(FLAG_IS_HOGGED, &descs[i].flags) &&

		    descs[i].hog == hog)

			gpiochip_free_own_desc(&descs[i]);

	}

}



static int of_gpiochip_match_node(struct gpio_chip *chip, void *data)

{

	return chip->gpiodev->dev.of_node == data;

}



static struct gpio_chip *of_find_gpiochip_by_node(struct device_node *np)

{

	return gpiochip_find(np, of_gpiochip_match_node);

}



static int of_gpio_notify(struct notifier_block *nb, unsigned long action,

			  void *arg)

{

	struct of_reconfig_data *rd = arg;

	struct gpio_chip *chip;

	int ret;



	/*

	 * This only supports adding and removing complete gpio-hog nodes.

	 * Modifying an existing gpio-hog node is not supported (except for

	 * changing its "status" property, which is treated the same as

	 * addition/removal).

	 */

	switch (of_reconfig_get_state_change(action, arg)) {

	case OF_RECONFIG_CHANGE_ADD:

		if (!of_property_read_bool(rd->dn, "gpio-hog"))

			return NOTIFY_OK;	/* not for us */



		if (of_node_test_and_set_flag(rd->dn, OF_POPULATED))

			return NOTIFY_OK;



		chip = of_find_gpiochip_by_node(rd->dn->parent);

		if (chip == NULL)

			return NOTIFY_OK;	/* not for us */



		ret = of_gpiochip_add_hog(chip, rd->dn);

		if (ret < 0) {

			pr_err("%s: failed to add hogs for %pOF\n", __func__,

			       rd->dn);

			of_node_clear_flag(rd->dn, OF_POPULATED);

			return notifier_from_errno(ret);

		}

		break;



	case OF_RECONFIG_CHANGE_REMOVE:

		if (!of_node_check_flag(rd->dn, OF_POPULATED))

			return NOTIFY_OK;	/* already depopulated */



		chip = of_find_gpiochip_by_node(rd->dn->parent);

		if (chip == NULL)

			return NOTIFY_OK;	/* not for us */



		of_gpiochip_remove_hog(chip, rd->dn);

		of_node_clear_flag(rd->dn, OF_POPULATED);

		break;

	}



	return NOTIFY_OK;

}



struct notifier_block gpio_of_notifier = {

	.notifier_call = of_gpio_notify,

};

#endif /* CONFIG_OF_DYNAMIC */



/**

 * of_gpio_simple_xlate - translate gpiospec to the GPIO number and flags

 * @gc:		pointer to the gpio_chip structure

drivers/gpio/gpiolib-of.h

+2 −0
Original line number Diff line number Diff line
@@ -35,4 +35,6 @@ static inline bool of_gpio_need_valid_mask(const struct gpio_chip *gc) 
}

#endif /* CONFIG_OF_GPIO */



extern struct notifier_block gpio_of_notifier;



#endif /* GPIOLIB_OF_H */

drivers/gpio/gpiolib.c

+11 −3
Original line number Diff line number Diff line
@@ -3103,6 +3103,9 @@ static bool gpiod_free_commit(struct gpio_desc *desc) 
		clear_bit(FLAG_PULL_DOWN, &desc->flags);

		clear_bit(FLAG_BIAS_DISABLE, &desc->flags);

		clear_bit(FLAG_IS_HOGGED, &desc->flags);

#ifdef CONFIG_OF_DYNAMIC

		desc->hog = NULL;

#endif

		ret = true;

	}
@@ -5281,10 +5284,15 @@ static int __init gpiolib_dev_init(void) 
	if (ret < 0) {

		pr_err("gpiolib: failed to allocate char dev region\n");

		bus_unregister(&gpio_bus_type);

	} else {

		return ret;

	}



	gpiolib_initialized = true;

	gpiochip_setup_devs();

	}



	if (IS_ENABLED(CONFIG_OF_DYNAMIC))

		WARN_ON(of_reconfig_notifier_register(&gpio_of_notifier));



	return ret;

}

core_initcall(gpiolib_dev_init);

drivers/gpio/gpiolib.h

+3 −0
Original line number Diff line number Diff line
@@ -120,6 +120,9 @@ struct gpio_desc { 
	const char		*label;

	/* Name of the GPIO */

	const char		*name;

#ifdef CONFIG_OF_DYNAMIC

	struct device_node	*hog;

#endif

};



int gpiod_request(struct gpio_desc *desc, const char *label);

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