From c5ee0b3104e0b292d353e63fd31cb8c692645d8c Mon Sep 17 00:00:00 2001
From: Punit Agrawal <punit1.agrawal@toshiba.co.jp>
Date: Thu, 19 Dec 2019 19:03:45 +0900
Subject: [PATCH] serdev: Don't claim unsupported ACPI serial devices
Git-commit: c5ee0b3104e0b292d353e63fd31cb8c692645d8c
Patch-mainline: v5.5-rc6
References: git-fixes

Serdev sub-system claims all ACPI serial devices that are not already
initialised. As a result, no device node is created for serial ports
on certain boards such as the Apollo Lake based UP2. This has the
unintended consequence of not being able to raise the login prompt via
serial connection.

Introduce a blacklist to reject ACPI serial devices that should not be
claimed by serdev sub-system. Add the peripheral ids for Intel HS UART
to the blacklist to bring back serial port on SoCs carrying them.

Cc: stable@vger.kernel.org
Signed-off-by: Punit Agrawal <punit1.agrawal@toshiba.co.jp>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Johan Hovold <johan@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20191219100345.911093-1-punit1.agrawal@toshiba.co.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/tty/serdev/core.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -582,6 +582,12 @@ static acpi_status acpi_serdev_register_
 	return AE_OK;
 }
 
+static const struct acpi_device_id serdev_acpi_devices_blacklist[] = {
+	{ "INT3511", 0 },
+	{ "INT3512", 0 },
+	{ },
+};
+
 static acpi_status acpi_serdev_add_device(acpi_handle handle, u32 level,
 				       void *data, void **return_value)
 {
@@ -591,6 +597,10 @@ static acpi_status acpi_serdev_add_devic
 	if (acpi_bus_get_device(handle, &adev))
 		return AE_OK;
 
+	/* Skip if black listed */
+	if (!acpi_match_device_ids(adev, serdev_acpi_devices_blacklist))
+		return AE_OK;
+
 	return acpi_serdev_register_device(ctrl, adev);
 }