1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Driver to power on the Analogix ANX7428 USB Type-C crosspoint switch
  4 * on MeeGoPad top-set boxes.
  5 *
  6 * The MeeGoPad T8 and T9 are Cherry Trail top-set boxes which
  7 * use an ANX7428 to provide a Type-C port with USB3.1 Gen 1 and
  8 * DisplayPort over Type-C alternate mode support.
  9 *
 10 * The ANX7428 has a microcontroller which takes care of the PD
 11 * negotiation and automatically sets the builtin Crosspoint Switch
 12 * to send the right signal to the 4 highspeed pairs of the Type-C
 13 * connector. It also takes care of HPD and AUX channel routing for
 14 * DP alternate mode.
 15 *
 16 * IOW the ANX7428 operates fully autonomous and to the x5-Z8350 SoC
 17 * things look like there simply is a USB-3 Type-A connector and a
 18 * separate DisplayPort connector. Except that the BIOS does not
 19 * power on the ANX7428 at boot. This driver takes care of powering
 20 * on the ANX7428.
 21 *
 22 * It should be possible to tell the micro-controller which data- and/or
 23 * power-role to negotiate and to swap the role(s) after negotiation
 24 * but the MeeGoPad top-set boxes always draw their power from a separate
 25 * power-connector and they only support USB host-mode. So this functionality
 26 * is unnecessary and due to lack of documentation this is tricky to support.
 27 *
 28 * For a more complete ANX7428 driver see drivers/usb/misc/anx7418/ of
 29 * the LineageOS kernel for the LG G5 (International) aka the LG H850:
 30 * https://github.com/LineageOS/android_kernel_lge_msm8996/
 31 *
 32 * (C) Copyright 2024 Hans de Goede <hansg@kernel.org>
 33 */
 34
 35#include <linux/acpi.h>
 36#include <linux/bits.h>
 37#include <linux/delay.h>
 38#include <linux/dev_printk.h>
 39#include <linux/dmi.h>
 40#include <linux/err.h>
 41#include <linux/gpio/consumer.h>
 42#include <linux/i2c.h>
 43#include <linux/iopoll.h>
 44#include <linux/module.h>
 45#include <linux/types.h>
 46
 47/* Register addresses and fields */
 48#define VENDOR_ID			0x00
 49#define DEVICE_ID			0x02
 50
 51#define TX_STATUS			0x16
 52#define STATUS_SUCCESS			BIT(0)
 53#define STATUS_ERROR			BIT(1)
 54#define OCM_STARTUP			BIT(7)
 55
 56static bool force;
 57module_param(force, bool, 0444);
 58MODULE_PARM_DESC(force, "Force the driver to probe on unknown boards");
 59
 60static const struct acpi_gpio_params enable_gpio = { 0, 0, false };
 61static const struct acpi_gpio_params reset_gpio = { 1, 0, true };
 62
 63static const struct acpi_gpio_mapping meegopad_anx7428_gpios[] = {
 64	{ "enable-gpios", &enable_gpio, 1 },
 65	{ "reset-gpios", &reset_gpio, 1 },
 66	{ }
 67};
 68
 69static const struct dmi_system_id meegopad_anx7428_ids[] = {
 70	{
 71		/* Meegopad T08 */
 72		.matches = {
 73			DMI_MATCH(DMI_SYS_VENDOR, "Default string"),
 74			DMI_MATCH(DMI_PRODUCT_NAME, "Default string"),
 75			DMI_MATCH(DMI_BOARD_NAME, "T3 MRD"),
 76			DMI_MATCH(DMI_BOARD_VERSION, "V1.1"),
 77		},
 78	},
 79	{ }
 80};
 81
 82static int anx7428_probe(struct i2c_client *client)
 83{
 84	struct device *dev = &client->dev;
 85	struct gpio_desc *gpio;
 86	int ret, val;
 87
 88	if (!dmi_check_system(meegopad_anx7428_ids) && !force) {
 89		dev_warn(dev, "Not probing unknown board, pass meegopad_anx7428.force=1 to probe");
 90		return -ENODEV;
 91	}
 92
 93	ret = devm_acpi_dev_add_driver_gpios(dev, meegopad_anx7428_gpios);
 94	if (ret)
 95		return ret;
 96
 97	/*
 98	 * Set GPIOs to desired values while getting them, they are not needed
 99	 * afterwards. Ordering and delays come from android_kernel_lge_msm8996.
100	 */
101	gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_HIGH);
102	if (IS_ERR(gpio))
103		return dev_err_probe(dev, PTR_ERR(gpio), "getting enable GPIO\n");
104
105	fsleep(10000);
106
107	gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
108	if (IS_ERR(gpio))
109		return dev_err_probe(dev, PTR_ERR(gpio), "getting reset GPIO\n");
110
111	/* Wait for the OCM (On Chip Microcontroller) to start */
112	ret = read_poll_timeout(i2c_smbus_read_byte_data, val,
113				val >= 0 && (val & OCM_STARTUP),
114				5000, 50000, true, client, TX_STATUS);
115	if (ret)
116		return dev_err_probe(dev, ret,
117				     "On Chip Microcontroller did not start, status: 0x%02x\n",
118				     val);
119
120	ret = i2c_smbus_read_word_data(client, VENDOR_ID);
121	if (ret < 0)
122		return dev_err_probe(dev, ret, "reading vendor-id register\n");
123	val = ret;
124
125	ret = i2c_smbus_read_word_data(client, DEVICE_ID);
126	if (ret < 0)
127		return dev_err_probe(dev, ret, "reading device-id register\n");
128
129	dev_dbg(dev, "Powered on ANX7428 id %04x:%04x\n", val, ret);
130	return 0;
131}
132
133static const struct acpi_device_id anx7428_acpi_match[] = {
134	{ "ANXO7418" }, /* ACPI says 7418 (max 2 DP lanes version) but HW is 7428 */
135	{ }
136};
137MODULE_DEVICE_TABLE(acpi, anx7428_acpi_match);
138
139static struct i2c_driver anx7428_driver = {
140	.driver = {
141		.name = "meegopad_anx7428",
142		.acpi_match_table = anx7428_acpi_match,
143	},
144	.probe = anx7428_probe,
145};
146module_i2c_driver(anx7428_driver);
147
148MODULE_AUTHOR("Hans de Goede <hansg@kernel.org>");
149MODULE_DESCRIPTION("MeeGoPad ANX7428 driver");
150MODULE_LICENSE("GPL");