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Diffstat (limited to 'drivers/platform/x86/meegopad_anx7428.c')
-rw-r--r--drivers/platform/x86/meegopad_anx7428.c150
1 files changed, 150 insertions, 0 deletions
diff --git a/drivers/platform/x86/meegopad_anx7428.c b/drivers/platform/x86/meegopad_anx7428.c
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index 000000000000..b2c4d4f526c4
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+++ b/drivers/platform/x86/meegopad_anx7428.c
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+// 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");