ACPI: video: Switch over to auxiliary bus type

Commit 02c057ddefef ("ACPI: video: Convert the driver to a platform one")
switched over the ACPI video bus driver from an ACPI driver to a platform
driver, but that change introduced an unwanted and unexpected side effect.
Namely, on some systems, the ACPI device object of the ACPI video bus
device is an ACPI companion of multiple platform devices and, after
adding video_device_ids[] as an acpi_match_table to the acpi_video_bus
platform driver, all of those devices started to match that driver and
its probe callback is invoked for all of them (it fails, but it leaves
a confusing message in the log). Moreover, the MODULE_DEVICE_TABLE()
of the ACPI video driver module matches all of the devices sharing the
ACPI companion with the ACPI video bus device.

To address this, make the core ACPI device enumeration code create an
auxiliary device for the ACPI video bus device object instead of a
platform device and switch over the ACPI video bus driver (once more)
to an auxiliary driver.

Auxiliary driver generally is a better match for ACPI video bus than
platform driver, among other things because the ACPI video bus device
does not require any resources to be allocated for it during
enumeration. It also allows the ACPI video bus driver to stop abusing
device matching based on ACPI device IDs and it allows a special case
to be dropped from acpi_create_platform_device() because that function
need not worry about the ACPI video bus device any more.

Fixes: 02c057ddefef ("ACPI: video: Convert the driver to a platform one")
Reported-by: Pratap Nirujogi <[e-mail]>
Closes: https://lore.kernel.org/linux-acpi/[e-mail]/
Tested-by: Pratap Nirujogi <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>
Reviewed-by: Mario Limonciello (AMD) <[e-mail]>
[ rjw: Added AUXILIARY_BUS selection to CONFIG_ACPI to fix build issue ]
[ rjw: Fixed error path in acpi_create_video_bus_device() ]
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/Kconfig

···
 menuconfig ACPI
 	bool "ACPI (Advanced Configuration and Power Interface) Support"
 	depends on ARCH_SUPPORTS_ACPI
+	select AUXILIARY_BUS
 	select PNP
 	select NLS
 	select CRC32

drivers/acpi/acpi_platform.c

···
 		}
 	}
 
-	if (adev->device_type == ACPI_BUS_TYPE_DEVICE && !adev->pnp.type.backlight) {
+	if (adev->device_type == ACPI_BUS_TYPE_DEVICE) {
 		LIST_HEAD(resource_list);
 
 		count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);

drivers/acpi/acpi_video.c

···
 
 #define pr_fmt(fmt) "ACPI: video: " fmt
 
+#include <linux/auxiliary_bus.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
···
 #include <linux/sort.h>
 #include <linux/pci.h>
 #include <linux/pci_ids.h>
-#include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/dmi.h>
 #include <linux/suspend.h>
···
 static DEFINE_MUTEX(register_count_mutex);
 static DEFINE_MUTEX(video_list_lock);
 static LIST_HEAD(video_bus_head);
-static int acpi_video_bus_probe(struct platform_device *pdev);
-static void acpi_video_bus_remove(struct platform_device *pdev);
+static int acpi_video_bus_probe(struct auxiliary_device *aux_dev,
+				const struct auxiliary_device_id *id);
+static void acpi_video_bus_remove(struct auxiliary_device *aux);
 static void acpi_video_bus_notify(acpi_handle handle, u32 event, void *data);
 
 /*
···
 	ACPI_VIDEO_FIRST_LEVEL,		/* actual supported levels begin here */
 };
 
-static const struct acpi_device_id video_device_ids[] = {
-	{ACPI_VIDEO_HID, 0},
-	{"", 0},
+static const struct auxiliary_device_id video_bus_auxiliary_id_table[] = {
+	{ .name = "acpi.video_bus" },
+	{},
 };
-MODULE_DEVICE_TABLE(acpi, video_device_ids);
+MODULE_DEVICE_TABLE(auxiliary, video_bus_auxiliary_id_table);
 
-static struct platform_driver acpi_video_bus = {
+static struct auxiliary_driver acpi_video_bus = {
 	.probe = acpi_video_bus_probe,
 	.remove = acpi_video_bus_remove,
-	.driver = {
-		.name = "acpi-video",
-		.acpi_match_table = video_device_ids,
-	},
+	.id_table = video_bus_auxiliary_id_table,
 };
 
 struct acpi_video_bus_flags {
···
 }
 
 static int acpi_video_bus_add_notify_handler(struct acpi_video_bus *video,
-					     struct platform_device *pdev)
+					     struct device *parent)
 {
 	struct input_dev *input;
 	struct acpi_video_device *dev;
···
 	input->phys = video->phys;
 	input->id.bustype = BUS_HOST;
 	input->id.product = 0x06;
-	input->dev.parent = &pdev->dev;
+	input->dev.parent = parent;
 	input->evbit[0] = BIT(EV_KEY);
 	set_bit(KEY_SWITCHVIDEOMODE, input->keybit);
 	set_bit(KEY_VIDEO_NEXT, input->keybit);
···
 
 static int instance;
 
-static int acpi_video_bus_probe(struct platform_device *pdev)
+static int acpi_video_bus_probe(struct auxiliary_device *aux_dev,
+				const struct auxiliary_device_id *id_unused)
 {
-	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
+	struct acpi_device *device = ACPI_COMPANION(&aux_dev->dev);
 	struct acpi_video_bus *video;
 	bool auto_detect;
 	int error;
···
 		instance++;
 	}
 
-	platform_set_drvdata(pdev, video);
+	auxiliary_set_drvdata(aux_dev, video);
 
 	video->device = device;
 	strscpy(acpi_device_name(device), ACPI_VIDEO_BUS_NAME);
···
 	    !auto_detect)
 		acpi_video_bus_register_backlight(video);
 
-	error = acpi_video_bus_add_notify_handler(video, pdev);
+	error = acpi_video_bus_add_notify_handler(video, &aux_dev->dev);
 	if (error)
 		goto err_del;
 
···
 	return error;
 }
 
-static void acpi_video_bus_remove(struct platform_device *pdev)
+static void acpi_video_bus_remove(struct auxiliary_device *aux_dev)
 {
-	struct acpi_video_bus *video = platform_get_drvdata(pdev);
-	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
+	struct acpi_video_bus *video = auxiliary_get_drvdata(aux_dev);
+	struct acpi_device *device = ACPI_COMPANION(&aux_dev->dev);
 
 	acpi_dev_remove_notify_handler(device, ACPI_DEVICE_NOTIFY,
 				       acpi_video_bus_notify);
···
 
 	dmi_check_system(video_dmi_table);
 
-	ret = platform_driver_register(&acpi_video_bus);
+	ret = auxiliary_driver_register(&acpi_video_bus);
 	if (ret)
 		goto leave;
 
···
 {
 	mutex_lock(&register_count_mutex);
 	if (register_count) {
-		platform_driver_unregister(&acpi_video_bus);
+		auxiliary_driver_unregister(&acpi_video_bus);
 		register_count = 0;
 		may_report_brightness_keys = false;
 	}

drivers/acpi/scan.c

···
 #define pr_fmt(fmt) "ACPI: " fmt
 
 #include <linux/async.h>
+#include <linux/auxiliary_bus.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
···
 	return acpi_bus_check_add(handle, false, (struct acpi_device **)ret_p);
 }
 
+static void acpi_video_bus_device_release(struct device *dev)
+{
+	struct auxiliary_device *aux_dev = to_auxiliary_dev(dev);
+
+	kfree(aux_dev);
+}
+
+static void acpi_create_video_bus_device(struct acpi_device *adev,
+					 struct acpi_device *parent)
+{
+	struct auxiliary_device *aux_dev;
+	static unsigned int aux_dev_id;
+
+	aux_dev = kzalloc_obj(*aux_dev);
+	if (!aux_dev)
+		return;
+
+	aux_dev->id = aux_dev_id++;
+	aux_dev->name = "video_bus";
+	aux_dev->dev.parent = acpi_get_first_physical_node(parent);
+	if (!aux_dev->dev.parent)
+		goto err;
+
+	aux_dev->dev.release = acpi_video_bus_device_release;
+
+	if (auxiliary_device_init(aux_dev))
+		goto err;
+
+	ACPI_COMPANION_SET(&aux_dev->dev, adev);
+	if (__auxiliary_device_add(aux_dev, "acpi"))
+		auxiliary_device_uninit(aux_dev);
+
+	return;
+
+err:
+	kfree(aux_dev);
+}
+
 struct acpi_scan_system_dev {
 	struct list_head node;
 	struct acpi_device *adev;
···
 			sd->adev = device;
 			list_add_tail(&sd->node, &acpi_scan_system_dev_list);
 		}
+	} else if (device->pnp.type.backlight) {
+		struct acpi_device *parent;
+
+		parent = acpi_dev_parent(device);
+		if (parent)
+			acpi_create_video_bus_device(device, parent);
 	} else {
 		/* For a regular device object, create a platform device. */
 		acpi_create_platform_device(device, NULL);