drivers/platform/chrome/chromeos_of_hw_prober.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * ChromeOS Device Tree Hardware Prober
 *
 * Copyright (c) 2024 Google LLC
 */

#include <linux/array_size.h>
#include <linux/errno.h>
#include <linux/i2c-of-prober.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/stddef.h>

#define DRV_NAME	"chromeos_of_hw_prober"

/**
 * struct hw_prober_entry - Holds an entry for the hardware prober
 *
 * @compatible:	compatible string to match against the machine
 * @prober:	prober function to call when machine matches
 * @data:	extra data for the prober function
 */
struct hw_prober_entry {
	const char *compatible;
	int (*prober)(struct device *dev, const void *data);
	const void *data;
};

struct chromeos_i2c_probe_data {
	const struct i2c_of_probe_cfg *cfg;
	const struct i2c_of_probe_simple_opts *opts;
};

static int chromeos_i2c_component_prober(struct device *dev, const void *_data)
{
	const struct chromeos_i2c_probe_data *data = _data;
	struct i2c_of_probe_simple_ctx ctx = {
		.opts = data->opts,
	};

	return i2c_of_probe_component(dev, data->cfg, &ctx);
}

#define DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(_type)					\
	static const struct i2c_of_probe_cfg chromeos_i2c_probe_simple_ ## _type ## _cfg = {	\
		.type = #_type,									\
		.ops = &i2c_of_probe_simple_ops,						\
	}

#define DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(_type)					\
	static const struct chromeos_i2c_probe_data chromeos_i2c_probe_dumb_ ## _type = {	\
		.cfg = &(const struct i2c_of_probe_cfg) {					\
			.type = #_type,								\
		},										\
	}

DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(touchscreen);
DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(trackpad);

DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(touchscreen);
DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(trackpad);

static const struct chromeos_i2c_probe_data chromeos_i2c_probe_hana_trackpad = {
	.cfg = &chromeos_i2c_probe_simple_trackpad_cfg,
	.opts = &(const struct i2c_of_probe_simple_opts) {
		.res_node_compatible = "elan,ekth3000",
		.supply_name = "vcc",
		/*
		 * ELAN trackpad needs 2 ms for H/W init and 100 ms for F/W init.
		 * Synaptics trackpad needs 100 ms.
		 * However, the regulator is set to "always-on", presumably to
		 * avoid this delay. The ELAN driver is also missing delays.
		 */
		.post_power_on_delay_ms = 0,
	},
};

static const struct chromeos_i2c_probe_data chromeos_i2c_probe_squirtle_touchscreen = {
	.cfg = &chromeos_i2c_probe_simple_touchscreen_cfg,
	.opts = &(const struct i2c_of_probe_simple_opts) {
		.res_node_compatible = "elan,ekth6a12nay",
		.supply_name = "vcc33",
		.gpio_name = "reset",
		.post_power_on_delay_ms = 10,
		.post_gpio_config_delay_ms = 300,
	},
};

static const struct hw_prober_entry hw_prober_platforms[] = {
	{
		.compatible = "google,hana",
		.prober = chromeos_i2c_component_prober,
		.data = &chromeos_i2c_probe_dumb_touchscreen,
	}, {
		.compatible = "google,hana",
		.prober = chromeos_i2c_component_prober,
		.data = &chromeos_i2c_probe_hana_trackpad,
	}, {
		.compatible = "google,spherion",
		.prober = chromeos_i2c_component_prober,
		.data = &chromeos_i2c_probe_hana_trackpad,
	}, {
		.compatible = "google,squirtle",
		.prober = chromeos_i2c_component_prober,
		.data = &chromeos_i2c_probe_dumb_trackpad,
	}, {
		.compatible = "google,squirtle",
		.prober = chromeos_i2c_component_prober,
		.data = &chromeos_i2c_probe_squirtle_touchscreen,
	}, {
		.compatible = "google,steelix",
		.prober = chromeos_i2c_component_prober,
		.data = &chromeos_i2c_probe_dumb_trackpad,
	}, {
		.compatible = "google,voltorb",
		.prober = chromeos_i2c_component_prober,
		.data = &chromeos_i2c_probe_dumb_trackpad,
	},
};

static int chromeos_of_hw_prober_probe(struct platform_device *pdev)
{
	for (size_t i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++) {
		int ret;

		if (!of_machine_is_compatible(hw_prober_platforms[i].compatible))
			continue;

		ret = hw_prober_platforms[i].prober(&pdev->dev, hw_prober_platforms[i].data);
		/* Ignore unrecoverable errors and keep going through other probers */
		if (ret == -EPROBE_DEFER)
			return ret;
	}

	return 0;
}

static struct platform_driver chromeos_of_hw_prober_driver = {
	.probe	= chromeos_of_hw_prober_probe,
	.driver	= {
		.name = DRV_NAME,
	},
};

static struct platform_device *chromeos_of_hw_prober_pdev;

static int chromeos_of_hw_prober_driver_init(void)
{
	size_t i;
	int ret;

	for (i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++)
		if (of_machine_is_compatible(hw_prober_platforms[i].compatible))
			break;
	if (i == ARRAY_SIZE(hw_prober_platforms))
		return -ENODEV;

	ret = platform_driver_register(&chromeos_of_hw_prober_driver);
	if (ret)
		return ret;

	chromeos_of_hw_prober_pdev =
			platform_device_register_simple(DRV_NAME, PLATFORM_DEVID_NONE, NULL, 0);
	if (IS_ERR(chromeos_of_hw_prober_pdev))
		goto err;

	return 0;

err:
	platform_driver_unregister(&chromeos_of_hw_prober_driver);

	return PTR_ERR(chromeos_of_hw_prober_pdev);
}
module_init(chromeos_of_hw_prober_driver_init);

static void chromeos_of_hw_prober_driver_exit(void)
{
	platform_device_unregister(chromeos_of_hw_prober_pdev);
	platform_driver_unregister(&chromeos_of_hw_prober_driver);
}
module_exit(chromeos_of_hw_prober_driver_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ChromeOS device tree hardware prober");
MODULE_IMPORT_NS("I2C_OF_PROBER");