gpiolib: Extend software-node support to support secondary software-nodes

When a software-node gets added to a device which already has another fwnode as primary node it will become the secondary fwnode for that device.

Currently if a software-node with GPIO properties ends up as the secondary fwnode then gpiod_find_by_fwnode() will fail to find the GPIOs.

Add a new gpiod_fwnode_lookup() helper which falls back to calling gpiod_find_by_fwnode() with the secondary fwnode if the GPIO was not found in the primary fwnode.

Fixes e7f9ff5dc90c ("gpiolib: add support for software nodes")

Cc [email protected]

Cc Dmitry Torokhov <[email protected]>

Signed-off-by Hans de Goede <[email protected]>

---
Changes in v2:
- Add a new gpiod_fwnode_lookup() helper instead of putting the secondary fwnode check inside gpiod_find_by_fwnode()

---
 drivers/gpio/gpiolib.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

drivers/gpio/gpiolib.c +5 -0

index 0d2b470a252e..74d54513730a 100644
@@ -4604,6 +4604,23 @@ static struct gpio_desc *gpiod_find_by_fwnode(struct fwnode_handle *fwnode,
 	return desc;
 }
 
+static struct gpio_desc *gpiod_fwnode_lookup(struct fwnode_handle *fwnode,
+					     struct device *consumer,
+					     const char *con_id,
+					     unsigned int idx,
+					     enum gpiod_flags *flags,

drivers/gpio/gpiolib.c +2 -0

+}
+
 struct gpio_desc *gpiod_find_and_request(struct device *consumer,
 					 struct fwnode_handle *fwnode,
 					 const char *con_id,

Quoted 7 lines · Hans de Goede

When a software-node gets added to a device which already has another fwnode as primary node it will become the secondary fwnode for that device.

Currently if a software-node with GPIO properties ends up as the secondary fwnode then gpiod_find_by_fwnode() will fail to find the GPIOs.

Quoted 8 lines

Add a new gpiod_fwnode_lookup() helper which falls back to calling gpiod_find_by_fwnode() with the secondary fwnode if the GPIO was not found in the primary fwnode.

Fixes e7f9ff5dc90c ("gpiolib: add support for software nodes")

Cc [email protected]

Cc Dmitry Torokhov <[email protected]>

Signed-off-by Hans de Goede <[email protected]>

Reviewed-by Dmitry Torokhov <[email protected]>

Quoted 21 lines

---
Changes in v2:
- Add a new gpiod_fwnode_lookup() helper instead of putting the secondary fwnode check inside gpiod_find_by_fwnode()

---
 drivers/gpio/gpiolib.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

drivers/gpio/gpiolib.c +5 -0

index 0d2b470a252e..74d54513730a 100644
@@ -4604,6 +4604,23 @@ static struct gpio_desc *gpiod_find_by_fwnode(struct fwnode_handle *fwnode,
 	return desc;
 }
 
+static struct gpio_desc *gpiod_fwnode_lookup(struct fwnode_handle *fwnode,
+					     struct device *consumer,
+					     const char *con_id,
+					     unsigned int idx,
+					     enum gpiod_flags *flags,

drivers/gpio/gpiolib.c static struct gpio_desc *gpiod_find_by_fwnode(struct fwnode_handle *fwnode, · line 4621

Quoted 10 lines

drivers/gpio/gpiolib.c +10 -0

+					     unsigned long *lookupflags)
+{
+	struct gpio_desc *desc;
+
+	desc = gpiod_find_by_fwnode(fwnode, consumer, con_id, idx, flags, lookupflags);
+	if (gpiod_not_found(desc) && !IS_ERR_OR_NULL(fwnode))
+		desc = gpiod_find_by_fwnode(fwnode->secondary, consumer, con_id,
+					    idx, flags, lookupflags);
+
+	return desc;

Bikeshedding for later. Maybe do it like this in case we can have more than 2 nodes at some point?

        do {
		desc = gpiod_find_by_fwnode(fwnode, consumer, con_id, idx, flags, lookupflags);
		if (!gpiod_not_found(desc))
			return desc;

		fwnode = fwnode->secondary;
	} while (!IS_ERR_OR_NULL(fwnode));

	return ERR_PTR(-ENOENT);

Quoted 7 lines

drivers/gpio/gpiolib.c +2 -0

+}
+
 struct gpio_desc *gpiod_find_and_request(struct device *consumer,
 					 struct fwnode_handle *fwnode,
 					 const char *con_id,

drivers/gpio/gpiolib.c struct gpio_desc *gpiod_find_and_request(struct device *consumer, · line 4646

Quoted 10 lines

drivers/gpio/gpiolib.c +2 -2

@@ -4622,8 +4639,8 @@ struct gpio_desc *gpiod_find_and_request(struct device *consumer,
 	int ret = 0;
 
 	scoped_guard(srcu, &gpio_devices_srcu) {
-		desc = gpiod_find_by_fwnode(fwnode, consumer, con_id, idx,
-					    &flags, &lookupflags);
+		desc = gpiod_fwnode_lookup(fwnode, consumer, con_id, idx,
+					   &flags, &lookupflags);
 		if (gpiod_not_found(desc) && platform_lookup_allowed) {
 			/*
 			 * Either we are not using DT or ACPI, or their lookup

Thanks.

Quoted 1 line · Dmitry Torokhov

On Sat, Sep 20, 2025 at 10:09:55PM +0200, Hans de Goede wrote:

Quoted 11 lines

Bikeshedding for later. Maybe do it like this in case we can have more than 2 nodes at some point?

        do {
              desc = gpiod_find_by_fwnode(fwnode, consumer, con_id, idx, flags, lookupflags);
              if (!gpiod_not_found(desc))
                      return desc;

              fwnode = fwnode->secondary;
      } while (!IS_ERR_OR_NULL(fwnode));

Quoted 1 line

      return ERR_PTR(-ENOENT);

At a minimum this would need to a regular while () {} loop then, the initial fwnode may also be NULL and we don't want to deref that.

Andy did mention turning the fwnode-s into a regular linked-list in the future, but I think that would be using <linux/list.h> then, replacing the secondary pointer with a list head ?

Quoted 1 line

Quoted 1 line

+}

When a software-node gets added to a device which already has another fwnode as primary node it will become the secondary fwnode for that device.

Currently if a software-node with GPIO properties ends up as the secondary fwnode then gpiod_find_by_fwnode() will fail to find the GPIOs.

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