gpio: aggregator: stop using dev-sync-probe

dev-err-probe is an overengineered solution to a simple problem. Use a
combination of wait_for_probe() and device_is_bound() to synchronously
wait for the platform device to probe.

Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260327-gpio-kill-dev-sync-probe-v1-2-efac254f1a1d@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

Author: Bartosz Golaszewski

drivers/gpio/Kconfig

@@ -2010,7 +2010,6 @@ menu "Virtual GPIO drivers"
 config GPIO_AGGREGATOR
 	tristate "GPIO Aggregator"
 	select CONFIGFS_FS
-	select DEV_SYNC_PROBE
 	help
 	  Say yes here to enable the GPIO Aggregator, which provides a way to
 	  aggregate existing GPIO lines into a new virtual GPIO chip.

drivers/gpio/gpio-aggregator.c

@@ -32,8 +32,6 @@
 #include <linux/gpio/forwarder.h>
 #include <linux/gpio/machine.h>
 
-#include "dev-sync-probe.h"
-
 #define AGGREGATOR_MAX_GPIOS 512
 #define AGGREGATOR_LEGACY_PREFIX "_sysfs"
 
@@ -42,7 +40,7 @@
  */
 
 struct gpio_aggregator {
-	struct dev_sync_probe_data probe_data;
+	struct platform_device *pdev;
 	struct config_group group;
 	struct gpiod_lookup_table *lookups;
 	struct mutex lock;
@@ -135,15 +133,15 @@ static bool gpio_aggregator_is_active(struct gpio_aggregator *aggr)
 {
 	lockdep_assert_held(&aggr->lock);
 
-	return aggr->probe_data.pdev && platform_get_drvdata(aggr->probe_data.pdev);
+	return aggr->pdev && platform_get_drvdata(aggr->pdev);
 }
 
 /* Only aggregators created via legacy sysfs can be "activating". */
 static bool gpio_aggregator_is_activating(struct gpio_aggregator *aggr)
 {
 	lockdep_assert_held(&aggr->lock);
 
-	return aggr->probe_data.pdev && !platform_get_drvdata(aggr->probe_data.pdev);
+	return aggr->pdev && !platform_get_drvdata(aggr->pdev);
 }
 
 static size_t gpio_aggregator_count_lines(struct gpio_aggregator *aggr)
@@ -909,6 +907,7 @@ static int gpio_aggregator_activate(struct gpio_aggregator *aggr)
 {
 	struct platform_device_info pdevinfo;
 	struct gpio_aggregator_line *line;
+	struct platform_device *pdev;
 	struct fwnode_handle *swnode;
 	unsigned int n = 0;
 	int ret = 0;
@@ -962,12 +961,23 @@ static int gpio_aggregator_activate(struct gpio_aggregator *aggr)
 
 	gpiod_add_lookup_table(aggr->lookups);
 
-	ret = dev_sync_probe_register(&aggr->probe_data, &pdevinfo);
-	if (ret)
+	pdev = platform_device_register_full(&pdevinfo);
+	if (IS_ERR(pdev)) {
+		ret = PTR_ERR(pdev);
 		goto err_remove_lookup_table;
+	}
 
+	wait_for_device_probe();
+	if (!device_is_bound(&pdev->dev)) {
+		ret = -ENXIO;
+		goto err_unregister_pdev;
+	}
+
+	aggr->pdev = pdev;
 	return 0;
 
+err_unregister_pdev:
+	platform_device_unregister(pdev);
 err_remove_lookup_table:
 	kfree(aggr->lookups->dev_id);
 	gpiod_remove_lookup_table(aggr->lookups);
@@ -981,7 +991,8 @@ static int gpio_aggregator_activate(struct gpio_aggregator *aggr)
 
 static void gpio_aggregator_deactivate(struct gpio_aggregator *aggr)
 {
-	dev_sync_probe_unregister(&aggr->probe_data);
+	platform_device_unregister(aggr->pdev);
+	aggr->pdev = NULL;
 	gpiod_remove_lookup_table(aggr->lookups);
 	kfree(aggr->lookups->dev_id);
 	kfree(aggr->lookups);
@@ -1145,7 +1156,7 @@ gpio_aggregator_device_dev_name_show(struct config_item *item, char *page)
 
 	guard(mutex)(&aggr->lock);
 
-	pdev = aggr->probe_data.pdev;
+	pdev = aggr->pdev;
 	if (pdev)
 		return sysfs_emit(page, "%s\n", dev_name(&pdev->dev));
 
@@ -1322,7 +1333,6 @@ gpio_aggregator_make_group(struct config_group *group, const char *name)
 		return ERR_PTR(ret);
 
 	config_group_init_type_name(&aggr->group, name, &gpio_aggregator_device_type);
-	dev_sync_probe_init(&aggr->probe_data);
 
 	return &aggr->group;
 }
@@ -1471,12 +1481,6 @@ static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver,
 	scnprintf(name, sizeof(name), "%s.%d", AGGREGATOR_LEGACY_PREFIX, aggr->id);
 	config_group_init_type_name(&aggr->group, name, &gpio_aggregator_device_type);
 
-	/*
-	 * Since the device created by sysfs might be toggled via configfs
-	 * 'live' attribute later, this initialization is needed.
-	 */
-	dev_sync_probe_init(&aggr->probe_data);
-
 	/* Expose to configfs */
 	res = configfs_register_group(&gpio_aggregator_subsys.su_group,
 				      &aggr->group);
@@ -1495,7 +1499,7 @@ static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver,
 		goto remove_table;
 	}
 
-	aggr->probe_data.pdev = pdev;
+	aggr->pdev = pdev;
 	module_put(THIS_MODULE);
 	return count;