3 files changed, 164 insertions, 0 deletions
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index e5601d8fba68..0ec952b5d03e 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -666,6 +666,17 @@ config ACPI_QUICKSTART
 	  To compile this driver as a module, choose M here: the module will be
 	  called quickstart.
 
+config MEEGOPAD_ANX7428
+	tristate "MeeGoPad ANX7428 Type-C Switch"
+	depends on ACPI && GPIOLIB && I2C
+	help
+	  Some MeeGoPad top-set boxes have an ANX7428 Type-C Switch for
+	  USB3.1 Gen 1 and DisplayPort over Type-C alternate mode support.
+
+	  This driver takes care of powering on the ANX7428 on supported
+	  MeeGoPad top-set boxes. After this the ANX7428 takes care of Type-C
+	  connector orientation and PD alternate mode switching autonomously.
+
 config MSI_EC
 	tristate "MSI EC Extras"
 	depends on ACPI
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index cf3032e4e27f..e1b142947067 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -75,6 +75,9 @@ obj-y				+= intel/
 # Microsoft
 obj-$(CONFIG_ACPI_QUICKSTART)  += quickstart.o
 
+# MeeGoPad
+obj-$(CONFIG_MEEGOPAD_ANX7428)	+= meegopad_anx7428.o
+
 # MSI
 obj-$(CONFIG_MSI_EC)		+= msi-ec.o
 obj-$(CONFIG_MSI_LAPTOP)	+= msi-laptop.o
diff --git a/drivers/platform/x86/meegopad_anx7428.c b/drivers/platform/x86/meegopad_anx7428.c
new file mode 100644
index 000000000000..b2c4d4f526c4
--- /dev/null
+++ b/drivers/platform/x86/meegopad_anx7428.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver to power on the Analogix ANX7428 USB Type-C crosspoint switch
+ * on MeeGoPad top-set boxes.
+ *
+ * The MeeGoPad T8 and T9 are Cherry Trail top-set boxes which
+ * use an ANX7428 to provide a Type-C port with USB3.1 Gen 1 and
+ * DisplayPort over Type-C alternate mode support.
+ *
+ * The ANX7428 has a microcontroller which takes care of the PD
+ * negotiation and automatically sets the builtin Crosspoint Switch
+ * to send the right signal to the 4 highspeed pairs of the Type-C
+ * connector. It also takes care of HPD and AUX channel routing for
+ * DP alternate mode.
+ *
+ * IOW the ANX7428 operates fully autonomous and to the x5-Z8350 SoC
+ * things look like there simply is a USB-3 Type-A connector and a
+ * separate DisplayPort connector. Except that the BIOS does not
+ * power on the ANX7428 at boot. This driver takes care of powering
+ * on the ANX7428.
+ *
+ * It should be possible to tell the micro-controller which data- and/or
+ * power-role to negotiate and to swap the role(s) after negotiation
+ * but the MeeGoPad top-set boxes always draw their power from a separate
+ * power-connector and they only support USB host-mode. So this functionality
+ * is unnecessary and due to lack of documentation this is tricky to support.
+ *
+ * For a more complete ANX7428 driver see drivers/usb/misc/anx7418/ of
+ * the LineageOS kernel for the LG G5 (International) aka the LG H850:
+ * https://github.com/LineageOS/android_kernel_lge_msm8996/
+ *
+ * (C) Copyright 2024 Hans de Goede <hansg@kernel.org>
+ */
+
+#include <linux/acpi.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/dev_printk.h>
+#include <linux/dmi.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+/* Register addresses and fields */
+#define VENDOR_ID			0x00
+#define DEVICE_ID			0x02
+
+#define TX_STATUS			0x16
+#define STATUS_SUCCESS			BIT(0)
+#define STATUS_ERROR			BIT(1)
+#define OCM_STARTUP			BIT(7)
+
+static bool force;
+module_param(force, bool, 0444);
+MODULE_PARM_DESC(force, "Force the driver to probe on unknown boards");
+
+static const struct acpi_gpio_params enable_gpio = { 0, 0, false };
+static const struct acpi_gpio_params reset_gpio = { 1, 0, true };
+
+static const struct acpi_gpio_mapping meegopad_anx7428_gpios[] = {
+	{ "enable-gpios", &enable_gpio, 1 },
+	{ "reset-gpios", &reset_gpio, 1 },
+	{ }
+};
+
+static const struct dmi_system_id meegopad_anx7428_ids[] = {
+	{
+		/* Meegopad T08 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Default string"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Default string"),
+			DMI_MATCH(DMI_BOARD_NAME, "T3 MRD"),
+			DMI_MATCH(DMI_BOARD_VERSION, "V1.1"),
+		},
+	},
+	{ }
+};
+
+static int anx7428_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct gpio_desc *gpio;
+	int ret, val;
+
+	if (!dmi_check_system(meegopad_anx7428_ids) && !force) {
+		dev_warn(dev, "Not probing unknown board, pass meegopad_anx7428.force=1 to probe");
+		return -ENODEV;
+	}
+
+	ret = devm_acpi_dev_add_driver_gpios(dev, meegopad_anx7428_gpios);
+	if (ret)
+		return ret;
+
+	/*
+	 * Set GPIOs to desired values while getting them, they are not needed
+	 * afterwards. Ordering and delays come from android_kernel_lge_msm8996.
+	 */
+	gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_HIGH);
+	if (IS_ERR(gpio))
+		return dev_err_probe(dev, PTR_ERR(gpio), "getting enable GPIO\n");
+
+	fsleep(10000);
+
+	gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(gpio))
+		return dev_err_probe(dev, PTR_ERR(gpio), "getting reset GPIO\n");
+
+	/* Wait for the OCM (On Chip Microcontroller) to start */
+	ret = read_poll_timeout(i2c_smbus_read_byte_data, val,
+				val >= 0 && (val & OCM_STARTUP),
+				5000, 50000, true, client, TX_STATUS);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "On Chip Microcontroller did not start, status: 0x%02x\n",
+				     val);
+
+	ret = i2c_smbus_read_word_data(client, VENDOR_ID);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "reading vendor-id register\n");
+	val = ret;
+
+	ret = i2c_smbus_read_word_data(client, DEVICE_ID);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "reading device-id register\n");
+
+	dev_dbg(dev, "Powered on ANX7428 id %04x:%04x\n", val, ret);
+	return 0;
+}
+
+static const struct acpi_device_id anx7428_acpi_match[] = {
+	{ "ANXO7418" }, /* ACPI says 7418 (max 2 DP lanes version) but HW is 7428 */
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, anx7428_acpi_match);
+
+static struct i2c_driver anx7428_driver = {
+	.driver = {
+		.name = "meegopad_anx7428",
+		.acpi_match_table = anx7428_acpi_match,
+	},
+	.probe = anx7428_probe,
+};
+module_i2c_driver(anx7428_driver);
+
+MODULE_AUTHOR("Hans de Goede <hansg@kernel.org>");
+MODULE_DESCRIPTION("MeeGoPad ANX7428 driver");
+MODULE_LICENSE("GPL");