diff --git a/MAINTAINERS b/MAINTAINERS
index 7a2345ce85213cd03ef4aca3735a26cc1677d018..d7d063667af0c9b29a9b0532c0c2e6423e020010 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -20667,6 +20667,13 @@ S: Maintained
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/mm
F: arch/x86/mm/
+X86 PLATFORM ANDROID TABLETS DSDT FIXUP DRIVER
+M: Hans de Goede <hdegoede@redhat.com>
+L: platform-driver-x86@vger.kernel.org
+S: Maintained
+T: git git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git
+F: drivers/platform/x86/x86-android-tablets.c
+
X86 PLATFORM DRIVERS
M: Hans de Goede <hdegoede@redhat.com>
M: Mark Gross <markgross@kernel.org>
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index afa0f9b0141da6be080f0652ccad4fbb4102042a..b9a73df1820f8805212f250648a777d3e45588a1 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -1004,6 +1004,23 @@ config TOUCHSCREEN_DMI
the OS-image for the device. This option supplies the missing info.
Enable this for x86 tablets with Silead or Chipone touchscreens.
+config X86_ANDROID_TABLETS
+ tristate "X86 Android tablet support"
+ depends on I2C && ACPI && GPIOLIB
+ help
+ X86 tablets which ship with Android as (part of) the factory image
+ typically have various problems with their DSDTs. The factory kernels
+ shipped on these devices typically have device addresses and GPIOs
+ hardcoded in the kernel, rather than specified in their DSDT.
+
+ With the DSDT containing a random collection of devices which may or
+ may not actually be present. This driver contains various fixes for
+ such tablets, including instantiating kernel devices for devices which
+ are missing from the DSDT.
+
+ If you have a x86 Android tablet say Y or M here, for a generic x86
+ distro config say M here.
+
config FW_ATTR_CLASS
tristate
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index d477aad34fabef3ee7c7922e2d1dcc9f11d8b693..dce8a0e40e1b674d4f5b3824e4b3b4fdcc6dcb67 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -113,6 +113,7 @@ obj-$(CONFIG_I2C_MULTI_INSTANTIATE) += i2c-multi-instantiate.o
obj-$(CONFIG_MLX_PLATFORM) += mlx-platform.o
obj-$(CONFIG_TOUCHSCREEN_DMI) += touchscreen_dmi.o
obj-$(CONFIG_WIRELESS_HOTKEY) += wireless-hotkey.o
+obj-$(CONFIG_X86_ANDROID_TABLETS) += x86-android-tablets.o
# Intel uncore drivers
obj-$(CONFIG_INTEL_IPS) += intel_ips.o
diff --git a/drivers/platform/x86/x86-android-tablets.c b/drivers/platform/x86/x86-android-tablets.c
new file mode 100644
index 0000000000000000000000000000000000000000..4a04da27a3f4ef3243e03d429369fb60ed66c9f3
--- /dev/null
+++ b/drivers/platform/x86/x86-android-tablets.c
@@ -0,0 +1,321 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * DMI based code to deal with broken DSDTs on X86 tablets which ship with
+ * Android as (part of) the factory image. The factory kernels shipped on these
+ * devices typically have a bunch of things hardcoded, rather than specified
+ * in their DSDT.
+ *
+ * Copyright (C) 2021 Hans de Goede <hdegoede@redhat.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/dmi.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/machine.h>
+#include <linux/i2c.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/string.h>
+/* For gpio_get_desc() which is EXPORT_SYMBOL_GPL() */
+#include "../../gpio/gpiolib.h"
+
+/*
+ * Helper code to get Linux IRQ numbers given a description of the IRQ source
+ * (either IOAPIC index, or GPIO chip name + pin-number).
+ */
+enum x86_acpi_irq_type {
+ X86_ACPI_IRQ_TYPE_NONE,
+ X86_ACPI_IRQ_TYPE_APIC,
+ X86_ACPI_IRQ_TYPE_GPIOINT,
+};
+
+struct x86_acpi_irq_data {
+ char *chip; /* GPIO chip label (GPIOINT) */
+ enum x86_acpi_irq_type type;
+ int index;
+ int trigger; /* ACPI_EDGE_SENSITIVE / ACPI_LEVEL_SENSITIVE */
+ int polarity; /* ACPI_ACTIVE_HIGH / ACPI_ACTIVE_LOW / ACPI_ACTIVE_BOTH */
+};
+
+static int x86_acpi_irq_helper_gpiochip_find(struct gpio_chip *gc, void *data)
+{
+ return gc->label && !strcmp(gc->label, data);
+}
+
+static int x86_acpi_irq_helper_get(const struct x86_acpi_irq_data *data)
+{
+ struct gpio_desc *gpiod;
+ struct gpio_chip *chip;
+ unsigned int irq_type;
+ int irq, ret;
+
+ switch (data->type) {
+ case X86_ACPI_IRQ_TYPE_APIC:
+ irq = acpi_register_gsi(NULL, data->index, data->trigger, data->polarity);
+ if (irq < 0)
+ pr_err("error %d getting APIC IRQ %d\n", irq, data->index);
+
+ return irq;
+ case X86_ACPI_IRQ_TYPE_GPIOINT:
+ /* Like acpi_dev_gpio_irq_get(), but without parsing ACPI resources */
+ chip = gpiochip_find(data->chip, x86_acpi_irq_helper_gpiochip_find);
+ if (!chip)
+ return -EPROBE_DEFER;
+
+ gpiod = gpiochip_get_desc(chip, data->index);
+ if (IS_ERR(gpiod)) {
+ ret = PTR_ERR(gpiod);
+ pr_err("error %d getting GPIO %s %d\n", ret, data->chip, data->index);
+ return ret;
+ }
+
+ irq = gpiod_to_irq(gpiod);
+ if (irq < 0) {
+ pr_err("error %d getting IRQ %s %d\n", irq, data->chip, data->index);
+ return irq;
+ }
+
+ irq_type = acpi_dev_get_irq_type(data->trigger, data->polarity);
+ if (irq_type != IRQ_TYPE_NONE && irq_type != irq_get_trigger_type(irq))
+ irq_set_irq_type(irq, irq_type);
+
+ return irq;
+ default:
+ return 0;
+ }
+}
+
+struct x86_i2c_client_info {
+ struct i2c_board_info board_info;
+ char *adapter_path;
+ struct x86_acpi_irq_data irq_data;
+};
+
+struct x86_dev_info {
+ const struct x86_i2c_client_info *i2c_client_info;
+ int i2c_client_count;
+};
+
+/*
+ * When booted with the BIOS set to Android mode the Chuwi Hi8 (CWI509) DSDT
+ * contains a whole bunch of bogus ACPI I2C devices and is missing entries
+ * for the touchscreen and the accelerometer.
+ */
+static const struct property_entry chuwi_hi8_gsl1680_props[] = {
+ PROPERTY_ENTRY_U32("touchscreen-size-x", 1665),
+ PROPERTY_ENTRY_U32("touchscreen-size-y", 1140),
+ PROPERTY_ENTRY_BOOL("touchscreen-swapped-x-y"),
+ PROPERTY_ENTRY_BOOL("silead,home-button"),
+ PROPERTY_ENTRY_STRING("firmware-name", "gsl1680-chuwi-hi8.fw"),
+ { }
+};
+
+static const struct software_node chuwi_hi8_gsl1680_node = {
+ .properties = chuwi_hi8_gsl1680_props,
+};
+
+static const char * const chuwi_hi8_mount_matrix[] = {
+ "1", "0", "0",
+ "0", "-1", "0",
+ "0", "0", "1"
+};
+
+static const struct property_entry chuwi_hi8_bma250e_props[] = {
+ PROPERTY_ENTRY_STRING_ARRAY("mount-matrix", chuwi_hi8_mount_matrix),
+ { }
+};
+
+static const struct software_node chuwi_hi8_bma250e_node = {
+ .properties = chuwi_hi8_bma250e_props,
+};
+
+static const struct x86_i2c_client_info chuwi_hi8_i2c_clients[] __initconst = {
+ {
+ /* Silead touchscreen */
+ .board_info = {
+ .type = "gsl1680",
+ .addr = 0x40,
+ .swnode = &chuwi_hi8_gsl1680_node,
+ },
+ .adapter_path = "\\_SB_.I2C4",
+ .irq_data = {
+ .type = X86_ACPI_IRQ_TYPE_APIC,
+ .index = 0x44,
+ .trigger = ACPI_EDGE_SENSITIVE,
+ .polarity = ACPI_ACTIVE_HIGH,
+ },
+ }, {
+ /* BMA250E accelerometer */
+ .board_info = {
+ .type = "bma250e",
+ .addr = 0x18,
+ .swnode = &chuwi_hi8_bma250e_node,
+ },
+ .adapter_path = "\\_SB_.I2C3",
+ .irq_data = {
+ .type = X86_ACPI_IRQ_TYPE_GPIOINT,
+ .chip = "INT33FC:02",
+ .index = 23,
+ .trigger = ACPI_LEVEL_SENSITIVE,
+ .polarity = ACPI_ACTIVE_HIGH,
+ },
+ },
+};
+
+static const struct x86_dev_info chuwi_hi8_info __initconst = {
+ .i2c_client_info = chuwi_hi8_i2c_clients,
+ .i2c_client_count = ARRAY_SIZE(chuwi_hi8_i2c_clients),
+};
+
+/*
+ * If the EFI bootloader is not Xiaomi's own signed Android loader, then the
+ * Xiaomi Mi Pad 2 X86 tablet sets OSID in the DSDT to 1 (Windows), causing
+ * a bunch of devices to be hidden.
+ *
+ * This takes care of instantiating the hidden devices manually.
+ */
+static const char * const bq27520_suppliers[] = { "bq25890-charger" };
+
+static const struct property_entry bq27520_props[] = {
+ PROPERTY_ENTRY_STRING_ARRAY("supplied-from", bq27520_suppliers),
+ { }
+};
+
+static const struct software_node bq27520_node = {
+ .properties = bq27520_props,
+};
+
+static const struct x86_i2c_client_info xiaomi_mipad2_i2c_clients[] __initconst = {
+ {
+ /* BQ27520 fuel-gauge */
+ .board_info = {
+ .type = "bq27520",
+ .addr = 0x55,
+ .dev_name = "bq27520",
+ .swnode = &bq27520_node,
+ },
+ .adapter_path = "\\_SB_.PCI0.I2C1",
+ }, {
+ /* KTD2026 RGB notification LED controller */
+ .board_info = {
+ .type = "ktd2026",
+ .addr = 0x30,
+ .dev_name = "ktd2026",
+ },
+ .adapter_path = "\\_SB_.PCI0.I2C3",
+ },
+};
+
+static const struct x86_dev_info xiaomi_mipad2_info __initconst = {
+ .i2c_client_info = xiaomi_mipad2_i2c_clients,
+ .i2c_client_count = ARRAY_SIZE(xiaomi_mipad2_i2c_clients),
+};
+
+static const struct dmi_system_id x86_android_tablet_ids[] __initconst = {
+ {
+ /* Chuwi Hi8 (CWI509) */
+ .matches = {
+ DMI_MATCH(DMI_BOARD_VENDOR, "Hampoo"),
+ DMI_MATCH(DMI_BOARD_NAME, "BYT-PA03C"),
+ DMI_MATCH(DMI_SYS_VENDOR, "ilife"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "S806"),
+ },
+ .driver_data = (void *)&chuwi_hi8_info,
+ }, {
+ /* Xiaomi Mi Pad 2 */
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Xiaomi Inc"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "Mipad2"),
+ },
+ .driver_data = (void *)&xiaomi_mipad2_info,
+ },
+ { }
+};
+MODULE_DEVICE_TABLE(dmi, x86_android_tablet_ids);
+
+static int i2c_client_count;
+static struct i2c_client **i2c_clients;
+
+static __init int x86_instantiate_i2c_client(const struct x86_dev_info *dev_info,
+ int idx)
+{
+ const struct x86_i2c_client_info *client_info = &dev_info->i2c_client_info[idx];
+ struct i2c_board_info board_info = client_info->board_info;
+ struct i2c_adapter *adap;
+ acpi_handle handle;
+ acpi_status status;
+
+ board_info.irq = x86_acpi_irq_helper_get(&client_info->irq_data);
+ if (board_info.irq < 0)
+ return board_info.irq;
+
+ status = acpi_get_handle(NULL, client_info->adapter_path, &handle);
+ if (ACPI_FAILURE(status)) {
+ pr_err("Error could not get %s handle\n", client_info->adapter_path);
+ return -ENODEV;
+ }
+
+ adap = i2c_acpi_find_adapter_by_handle(handle);
+ if (!adap) {
+ pr_err("error could not get %s adapter\n", client_info->adapter_path);
+ return -ENODEV;
+ }
+
+ i2c_clients[idx] = i2c_new_client_device(adap, &board_info);
+ put_device(&adap->dev);
+ if (IS_ERR(i2c_clients[idx]))
+ return dev_err_probe(&adap->dev, PTR_ERR(i2c_clients[idx]),
+ "creating I2C-client %d\n", idx);
+
+ return 0;
+}
+
+static void x86_android_tablet_cleanup(void)
+{
+ int i;
+
+ for (i = 0; i < i2c_client_count; i++)
+ i2c_unregister_device(i2c_clients[i]);
+
+ kfree(i2c_clients);
+}
+
+static __init int x86_android_tablet_init(void)
+{
+ const struct x86_dev_info *dev_info;
+ const struct dmi_system_id *id;
+ int i, ret = 0;
+
+ id = dmi_first_match(x86_android_tablet_ids);
+ if (!id)
+ return -ENODEV;
+
+ dev_info = id->driver_data;
+
+ i2c_client_count = dev_info->i2c_client_count;
+
+ i2c_clients = kcalloc(i2c_client_count, sizeof(*i2c_clients), GFP_KERNEL);
+ if (!i2c_clients)
+ return -ENOMEM;
+
+ for (i = 0; i < dev_info->i2c_client_count; i++) {
+ ret = x86_instantiate_i2c_client(dev_info, i);
+ if (ret < 0) {
+ x86_android_tablet_cleanup();
+ break;
+ }
+ }
+
+ return ret;
+}
+
+module_init(x86_android_tablet_init);
+module_exit(x86_android_tablet_cleanup);
+
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com");
+MODULE_DESCRIPTION("X86 Android tablets DSDT fixups driver");
+MODULE_LICENSE("GPL");