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Date: Thu, 20 Feb 2020 12:51:22 -0600
From: Frank Rowand <frowand.list@...il.com>
To: Geert Uytterhoeven <geert+renesas@...der.be>,
Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <bgolaszewski@...libre.com>,
Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>
Cc: Peter Ujfalusi <peter.ujfalusi@...com>,
Chris Brandt <chris.brandt@...esas.com>,
linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
Frank Rowand <frowand.list@...il.com>
Subject: Re: [PATCH v2 2/2] gpio: of: Add DT overlay support for GPIO hogs
On 2/20/20 7:01 AM, Geert Uytterhoeven wrote:
> 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: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> v2:
> - Drop RFC state,
> - Document that modifying existing gpio-hog nodes is not supported.
> ---
> drivers/gpio/gpiolib-of.c | 90 +++++++++++++++++++++++++++++++++++++++
> drivers/gpio/gpiolib-of.h | 2 +
> drivers/gpio/gpiolib.c | 14 ++++--
> drivers/gpio/gpiolib.h | 3 ++
> 4 files changed, 106 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
> index 2b47f93886075294..ccc449df3792ae97 100644
> --- a/drivers/gpio/gpiolib-of.c
> +++ b/drivers/gpio/gpiolib-of.c
> @@ -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
> diff --git a/drivers/gpio/gpiolib-of.h b/drivers/gpio/gpiolib-of.h
> index 9768831b1fe2f25b..ed26664f153782fc 100644
> --- a/drivers/gpio/gpiolib-of.h
> +++ b/drivers/gpio/gpiolib-of.h
> @@ -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 */
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 56de871060ea211e..6f312220fe80acaf 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -2925,6 +2925,9 @@ 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;
> }
>
> @@ -5126,10 +5129,15 @@ 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 {
> - gpiolib_initialized = true;
> - gpiochip_setup_devs();
> + 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);
> diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
> index 3e0aab2945d82974..18c75e83fd7679ec 100644
> --- a/drivers/gpio/gpiolib.h
> +++ b/drivers/gpio/gpiolib.h
> @@ -119,6 +119,9 @@ 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);
>
Reviewed-by: Frank Rowand <frank.rowand@...y.com>
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