platform/x86: x86-android-tablets: Add support for getting serdev-controller by PCI parent

On the Vexia EDU ATLA 10 tablet, which ships with Android + a custom Linux
(guadalinex) using the custom Android kernel the UART controllers are not
enumerated as ACPI devices as they typically are.

Instead they are enumerated through PCI and getting the serdev-controller
by ACPI HID + UID does not work.

Add support for getting the serdev-controller by the PCI devfn of its
parent instead.

This also renames the use_pci_devname flag to use_pci since the former
name now no longer is accurate.

Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20241204204227.95757-8-hdegoede@redhat.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

3 files changed, 24 insertions, 5 deletions

diff --git a/drivers/platform/x86/x86-android-tablets/core.c b/drivers/platform/x86/x86-android-tablets/core.c
index 19962abba38d..2a9c47178505 100644
--- a/drivers/platform/x86/x86-android-tablets/core.c
+++ b/drivers/platform/x86/x86-android-tablets/core.c
@@ -212,7 +212,7 @@ static __init int x86_instantiate_i2c_client(const struct x86_dev_info *dev_info
 	if (board_info.irq < 0)
 		return board_info.irq;
 
-	if (dev_info->use_pci_devname)
+	if (dev_info->use_pci)
 		adap = get_i2c_adap_by_pci_parent(client_info);
 	else
 		adap = get_i2c_adap_by_handle(client_info);
@@ -271,6 +271,19 @@ static __init int x86_instantiate_spi_dev(const struct x86_dev_info *dev_info, i
 	return 0;
 }
 
+static __init struct device *
+get_serdev_controller_by_pci_parent(const struct x86_serdev_info *info)
+{
+	struct pci_dev *pdev;
+
+	pdev = pci_get_domain_bus_and_slot(0, 0, info->ctrl.pci.devfn);
+	if (!pdev)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	/* This puts our reference on pdev and returns a ref on the ctrl */
+	return get_serdev_controller_from_parent(&pdev->dev, 0, info->ctrl_devname);
+}
+
 static __init int x86_instantiate_serdev(const struct x86_dev_info *dev_info, int idx)
 {
 	const struct x86_serdev_info *info = &dev_info->serdev_info[idx];
@@ -279,8 +292,11 @@ static __init int x86_instantiate_serdev(const struct x86_dev_info *dev_info, in
 	struct device *ctrl_dev;
 	int ret = -ENODEV;
 
-	ctrl_dev = get_serdev_controller(info->ctrl.acpi.hid, info->ctrl.acpi.uid, 0,
-					 info->ctrl_devname);
+	if (dev_info->use_pci)
+		ctrl_dev = get_serdev_controller_by_pci_parent(info);
+	else
+		ctrl_dev = get_serdev_controller(info->ctrl.acpi.hid, info->ctrl.acpi.uid,
+						 0, info->ctrl_devname);
 	if (IS_ERR(ctrl_dev))
 		return PTR_ERR(ctrl_dev);
 
diff --git a/drivers/platform/x86/x86-android-tablets/other.c b/drivers/platform/x86/x86-android-tablets/other.c
index 3cd0db74c6c9..251c0ea1ab79 100644
--- a/drivers/platform/x86/x86-android-tablets/other.c
+++ b/drivers/platform/x86/x86-android-tablets/other.c
@@ -757,7 +757,7 @@ const struct x86_dev_info vexia_edu_atla10_info __initconst = {
 	.i2c_client_count = ARRAY_SIZE(vexia_edu_atla10_i2c_clients),
 	.gpiod_lookup_tables = vexia_edu_atla10_gpios,
 	.init = vexia_edu_atla10_init,
-	.use_pci_devname = true,
+	.use_pci = true,
 };
 
 /*
diff --git a/drivers/platform/x86/x86-android-tablets/x86-android-tablets.h b/drivers/platform/x86/x86-android-tablets/x86-android-tablets.h
index 5ddec4beb552..63a38a0069ba 100644
--- a/drivers/platform/x86/x86-android-tablets/x86-android-tablets.h
+++ b/drivers/platform/x86/x86-android-tablets/x86-android-tablets.h
@@ -62,6 +62,9 @@ struct x86_serdev_info {
 			const char *hid;
 			const char *uid;
 		} acpi;
+		struct {
+			unsigned int devfn;
+		} pci;
 	} ctrl;
 	const char *ctrl_devname;
 	/*
@@ -95,7 +98,7 @@ struct x86_dev_info {
 	int gpio_button_count;
 	int (*init)(struct device *dev);
 	void (*exit)(void);
-	bool use_pci_devname;
+	bool use_pci;
 };
 
 int x86_android_tablet_get_gpiod(const char *chip, int pin, const char *con_id,