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Message-Id: <20260105-reset-core-refactor-v1-2-ac443103498d@oss.qualcomm.com>
Date: Mon, 05 Jan 2026 15:15:21 +0100
From: Bartosz Golaszewski <bartosz.golaszewski@....qualcomm.com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
Philipp Zabel <p.zabel@...gutronix.de>
Cc: linux-kernel@...r.kernel.org,
Bartosz Golaszewski <bartosz.golaszewski@....qualcomm.com>
Subject: [PATCH 02/15] reset: gpio: add a devlink between reset-gpio and
its consumer
The device that requests the reset control managed by the reset-gpio
device is effectively its consumer but the devlink is only established
between it and the GPIO controller exposing the reset pin. Add a devlink
between the consumer of the reset control and its supplier. This will
allow us to simplify the GPIOLIB code managing shared GPIOs when
handling the corner case of reset-gpio and gpiolib-shared interacting.
While at it and since we need to store the address of the auxiliary
device: don't allocate memory for the device separately but fold it into
struct reset_gpio_lookup instead.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@....qualcomm.com>
---
drivers/reset/core.c | 80 ++++++++++++++++++++++++++++++++++++----------------
1 file changed, 56 insertions(+), 24 deletions(-)
diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index 0666dfc41ca9af6fbf1768f17157b4faf7849962..813b85cb2758e129c72c09267a387108d7ad683b 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -20,6 +20,7 @@
#include <linux/kref.h>
#include <linux/module.h>
#include <linux/of.h>
+#include <linux/of_platform.h>
#include <linux/reset.h>
#include <linux/reset-controller.h>
#include <linux/slab.h>
@@ -77,11 +78,13 @@ struct reset_control_array {
* @of_args: phandle to the reset controller with all the args like GPIO number
* @swnode: Software node containing the reference to the GPIO provider
* @list: list entry for the reset_gpio_lookup_list
+ * @adev: Auxiliary device representing the reset controller
*/
struct reset_gpio_lookup {
struct of_phandle_args of_args;
struct fwnode_handle *swnode;
struct list_head list;
+ struct auxiliary_device adev;
};
static const char *rcdev_name(struct reset_controller_dev *rcdev)
@@ -824,49 +827,72 @@ static void __reset_control_put_internal(struct reset_control *rstc)
static void reset_gpio_aux_device_release(struct device *dev)
{
- struct auxiliary_device *adev = to_auxiliary_dev(dev);
- kfree(adev);
}
-static int reset_add_gpio_aux_device(struct device *parent,
- struct fwnode_handle *swnode,
- int id, void *pdata)
+static int reset_create_gpio_aux_device(struct reset_gpio_lookup *rgpio_dev,
+ struct device *parent, int id)
{
- struct auxiliary_device *adev;
+ struct auxiliary_device *adev = &rgpio_dev->adev;
int ret;
- adev = kzalloc(sizeof(*adev), GFP_KERNEL);
- if (!adev)
- return -ENOMEM;
-
adev->id = id;
adev->name = "gpio";
adev->dev.parent = parent;
- adev->dev.platform_data = pdata;
+ adev->dev.platform_data = &rgpio_dev->of_args;
adev->dev.release = reset_gpio_aux_device_release;
- device_set_node(&adev->dev, swnode);
+ device_set_node(&adev->dev, rgpio_dev->swnode);
ret = auxiliary_device_init(adev);
- if (ret) {
- kfree(adev);
+ if (ret)
return ret;
- }
ret = __auxiliary_device_add(adev, "reset");
if (ret) {
auxiliary_device_uninit(adev);
- kfree(adev);
return ret;
}
- return ret;
+ return 0;
+}
+
+static void reset_gpio_add_devlink(struct device_node *np,
+ struct reset_gpio_lookup *rgpio_dev)
+{
+ struct device *consumer;
+
+ /*
+ * We must use get_dev_from_fwnode() and not of_find_device_by_node()
+ * because the latter only considers the platform bus while we want to
+ * get consumers of any kind that can be associated with firmware
+ * nodes: auxiliary, soundwire, etc.
+ */
+ consumer = get_dev_from_fwnode(of_fwnode_handle(np));
+ if (consumer) {
+ if (!device_link_add(consumer, &rgpio_dev->adev.dev,
+ DL_FLAG_AUTOREMOVE_CONSUMER))
+ pr_warn("Failed to create a device link between reset-gpio and its consumer");
+
+ put_device(consumer);
+ }
+ /*
+ * else { }
+ *
+ * TODO: If ever there's a case where we need to support shared
+ * reset-gpios retrieved from a device node for which there's no
+ * device present yet, this is where we'd set up a notifier waiting
+ * for the device to appear in the system. This would be a lot of code
+ * that would go unused for now so let's cross that bridge when and if
+ * we get there.
+ */
}
/*
- * @args: phandle to the GPIO provider with all the args like GPIO number
+ * @np: OF-node associated with the consumer
+ * @args: phandle to the GPIO provider with all the args like GPIO number
*/
-static int __reset_add_reset_gpio_device(const struct of_phandle_args *args)
+static int __reset_add_reset_gpio_device(struct device_node *np,
+ const struct of_phandle_args *args)
{
struct property_entry properties[3] = { };
unsigned int offset, of_flags, lflags;
@@ -916,8 +942,14 @@ static int __reset_add_reset_gpio_device(const struct of_phandle_args *args)
list_for_each_entry(rgpio_dev, &reset_gpio_lookup_list, list) {
if (args->np == rgpio_dev->of_args.np) {
- if (of_phandle_args_equal(args, &rgpio_dev->of_args))
- return 0; /* Already on the list, done */
+ if (of_phandle_args_equal(args, &rgpio_dev->of_args)) {
+ /*
+ * Already on the list, create the device link
+ * and stop here.
+ */
+ reset_gpio_add_devlink(np, rgpio_dev);
+ return 0;
+ }
}
}
@@ -951,11 +983,11 @@ static int __reset_add_reset_gpio_device(const struct of_phandle_args *args)
goto err_put_of_node;
}
- ret = reset_add_gpio_aux_device(parent, rgpio_dev->swnode, id,
- &rgpio_dev->of_args);
+ ret = reset_create_gpio_aux_device(rgpio_dev, parent, id);
if (ret)
goto err_del_swnode;
+ reset_gpio_add_devlink(np, rgpio_dev);
list_add(&rgpio_dev->list, &reset_gpio_lookup_list);
return 0;
@@ -1035,7 +1067,7 @@ __of_reset_control_get(struct device_node *node, const char *id, int index,
gpio_fallback = true;
- ret = __reset_add_reset_gpio_device(&args);
+ ret = __reset_add_reset_gpio_device(node, &args);
if (ret) {
rstc = ERR_PTR(ret);
goto out_put;
--
2.47.3
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