[PATCH] ACPI / scan: Create platform device for BCM4752 and LNV4752 ACPI nodes

[Hans de Goede <hdegoede@redhat.com>]

BCM4752 and LNV4752 ACPI nodes describe a Broadcom 4752 GPS module
attached to an UART of the system.

The GPS modules talk a custom protocol which only works with a closed-
source Android gpsd daemon which knows this protocol.

The ACPI nodes also describe GPIOs to turn the GPS on/off these are
handled by the net/rfkill/rfkill-gpio.c code. This handling predates the
addition of enumeration of ACPI instantiated serdevs to the kernel and
was broken by that addition, because the ACPI scan code now no longer
instantiates platform_device-s for these nodes.

Rename the i2c_multi_instantiate_ids HID list to ignore_serial_bus_ids
and add the BCM4752 and LNV4752 HIDs, so that rfkill-gpio gets
a platform_device to bind to again; and so that a tty cdev for gpsd
gets created for these.

Fixes: e361d1f85855 ("ACPI / scan: Fix enumeration for special UART devices")
Cc: Frédéric Danis <frederic.danis.oss@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Note there is some work on reverse-engineering the protocol for these
GPS modules here, but this is not complete:
https://redmine.replicant.us/projects/replicant/wiki/BCM4751
https://git.replicant.us/contrib/PaulK/bcm4751/
---
 drivers/acpi/scan.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 526e823a33fb..c5dfbe26a0cb 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1701,6 +1701,7 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device)
 {
 	struct list_head resource_list;
 	bool is_serial_bus_slave = false;
+	static const struct acpi_device_id ignore_serial_bus_ids[] = {
 	/*
 	 * These devices have multiple I2cSerialBus resources and an i2c-client
 	 * must be instantiated for each, each with its own i2c_device_id.
@@ -1709,11 +1710,18 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device)
 	 * drivers/platform/x86/i2c-multi-instantiate.c driver, which knows
 	 * which i2c_device_id to use for each resource.
 	 */
-	static const struct acpi_device_id i2c_multi_instantiate_ids[] = {
 		{"BSG1160", },
 		{"BSG2150", },
 		{"INT33FE", },
 		{"INT3515", },
+	/*
+	 * HIDs of device with an UartSerialBusV2 resource for which userspace
+	 * expects a regular tty cdev to be created (instead of the in kernel
+	 * serdev) and which have a kernel driver which expects a platform_dev
+	 * such as the rfkill-gpio driver.
+	 */
+		{"BCM4752", },
+		{"LNV4752", },
 		{}
 	};
 
@@ -1727,8 +1735,7 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device)
 	     fwnode_property_present(&device->fwnode, "baud")))
 		return true;
 
-	/* Instantiate a pdev for the i2c-multi-instantiate drv to bind to */
-	if (!acpi_match_device_ids(device, i2c_multi_instantiate_ids))
+	if (!acpi_match_device_ids(device, ignore_serial_bus_ids))
 		return false;
 
 	INIT_LIST_HEAD(&resource_list);
-- 
2.33.1