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gpio: nomadik: grab optional reset control and deassert it at probe

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Fetch a reference to the optional shared reset control and deassert it
if it exists.

Optional because not all platforms that use this driver have a reset
attached to the reset block. Shared because some platforms that use the
reset (at least Mobileye EyeQ5) share the reset across banks.

Do not keep a reference to the reset control as it is not needed
afterwards; the driver does not handle suspend, does not use runtime
PM, does not register a remove callback and does not support unbinding
from sysfs (made explicit with suppress_bind_attrs).

The operation is done in nmk_gpio_populate_chip(). This function is
called by either gpio-nomadik or pinctrl-nomadik, whoever comes first.
This is here for historic reasons and could probably be removed now; it
seems gpio-ranges enforces the ordering to be pinctrl-first. It is not
the topic of the present patch however.

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://lore.kernel.org/r/20240228-mbly-gpio-v2-25-3ba757474006@bootlin.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Théo Lebrun 2024-02-28 12:28:23 +01:00 committed by Linus Walleij
parent 3c30cc26df
commit 6ad679cfae
1 changed files with 21 additions and 0 deletions
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21
drivers/gpio/gpio-nomadik.c
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@ -509,11 +509,13 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct device_node *np,
{
struct nmk_gpio_chip *nmk_chip;
struct platform_device *gpio_pdev;
struct reset_control *reset;
struct device *gpio_dev;
struct gpio_chip *chip;
struct clk *clk;
void __iomem *base;
u32 id, ngpio;
int ret;
gpio_dev = bus_find_device_by_of_node(&platform_bus_type, np);
if (!gpio_dev) {
@ -572,6 +574,24 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct device_node *np,
clk_prepare(clk);
nmk_chip->clk = clk;
reset = devm_reset_control_get_optional_shared(gpio_dev, NULL);
if (IS_ERR(reset)) {
dev_err(&pdev->dev, "failed getting reset control: %ld\n",
PTR_ERR(reset));
return ERR_CAST(reset);
}
/*
* Reset might be shared and asserts/deasserts calls are unbalanced. We
* only support sharing this reset with other gpio-nomadik devices that
* use this reset to ensure deassertion at probe.
*/
ret = reset_control_deassert(reset);
if (ret) {
dev_err(&pdev->dev, "failed reset deassert: %d\n", ret);
return ERR_PTR(ret);
}
#ifdef CONFIG_PINCTRL_NOMADIK
BUG_ON(nmk_chip->bank >= ARRAY_SIZE(nmk_gpio_chips));
nmk_gpio_chips[id] = nmk_chip;
@ -690,6 +710,7 @@ static struct platform_driver nmk_gpio_driver = {
.driver = {
.name = "nomadik-gpio",
.of_match_table = nmk_gpio_match,
.suppress_bind_attrs = true,
},
.probe = nmk_gpio_probe,
};