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gpiolib: support shared GPIOs in core subsystem code 

As the final step in adding official support for shared GPIOs, enable
the previously added elements in core GPIO subsystem code. Set-up shared
GPIOs when adding a GPIO chip, tear it down on removal and check if a
GPIO descriptor looked up during the firmware-node stage is shared and
fall-back to machine lookup in this case.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20251112-gpio-shared-v4-5-b51f97b1abd8@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Bartosz Golaszewski 2025-11-12 14:55:34 +01:00
parent e992d54c6f
commit 1e4f6db614
1 changed files with 41 additions and 9 deletions
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50
drivers/gpio/gpiolib.c
View File

@ -37,6 +37,7 @@
#include "gpiolib-acpi.h"
#include "gpiolib-cdev.h"
#include "gpiolib-of.h"
#include "gpiolib-shared.h"
#include "gpiolib-swnode.h"
#include "gpiolib-sysfs.h"
#include "gpiolib.h"
@ -1200,6 +1201,10 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
if (ret)
goto err_remove_irqchip_mask;
ret = gpio_device_setup_shared(gdev);
if (ret)
goto err_remove_irqchip;
/*
* By first adding the chardev, and then adding the device,
* we get a device node entry in sysfs under
@ -1211,10 +1216,13 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
if (gpiolib_initialized) {
ret = gpiochip_setup_dev(gdev);
if (ret)
goto err_remove_irqchip;
goto err_teardown_shared;
}
return 0;
err_teardown_shared:
gpio_device_teardown_shared(gdev);
err_remove_irqchip:
gpiochip_irqchip_remove(gc);
err_remove_irqchip_mask:
@ -1283,6 +1291,7 @@ void gpiochip_remove(struct gpio_chip *gc)
/* Numb the device, cancelling all outstanding operations */
rcu_assign_pointer(gdev->chip, NULL);
synchronize_srcu(&gdev->srcu);
gpio_device_teardown_shared(gdev);
gpiochip_irqchip_remove(gc);
acpi_gpiochip_remove(gc);
of_gpiochip_remove(gc);
@ -4652,11 +4661,29 @@ struct gpio_desc *gpiod_find_and_request(struct device *consumer,
scoped_guard(srcu, &gpio_devices_srcu) {
desc = gpiod_fwnode_lookup(fwnode, consumer, con_id, idx,
&flags, &lookupflags);
if (!IS_ERR_OR_NULL(desc) &&
test_bit(GPIOD_FLAG_SHARED, &desc->flags)) {
/*
* We're dealing with a GPIO shared by multiple
* consumers. This is the moment to add the machine
* lookup table for the proxy device as previously
* we only knew the consumer's fwnode.
*/
ret = gpio_shared_add_proxy_lookup(consumer, lookupflags);
if (ret)
return ERR_PTR(ret);
/* Trigger platform lookup for shared GPIO proxy. */
desc = ERR_PTR(-ENOENT);
/* Trigger it even for fwnode-only gpiod_get(). */
platform_lookup_allowed = true;
}
if (gpiod_not_found(desc) && platform_lookup_allowed) {
/*
* Either we are not using DT or ACPI, or their lookup
* did not return a result. In that case, use platform
* lookup as a fallback.
* did not return a result or this is a shared GPIO. In
* that case, use platform lookup as a fallback.
*/
dev_dbg(consumer,
"using lookup tables for GPIO lookup\n");
@ -4679,14 +4706,19 @@ struct gpio_desc *gpiod_find_and_request(struct device *consumer,
return ERR_PTR(ret);
/*
* This happens when there are several consumers for
* the same GPIO line: we just return here without
* further initialization. It is a bit of a hack.
* This is necessary to support fixed regulators.
* This happens when there are several consumers for the same
* GPIO line: we just return here without further
* initialization. It's a hack introduced long ago to support
* fixed regulators. We now have a better solution with
* automated scanning where affected platforms just need to
* select the provided Kconfig option.
*
* FIXME: Make this more sane and safe.
* FIXME: Remove the GPIOD_FLAGS_BIT_NONEXCLUSIVE flag after
* making sure all platforms use the new mechanism.
*/
dev_info(consumer, "nonexclusive access to GPIO for %s\n", name);
dev_info(consumer,
"nonexclusive access to GPIO for %s, consider updating your code to using gpio-shared-proxy\n",
name);
return desc;
}