1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * ChromeOS Device Tree Hardware Prober
  4 *
  5 * Copyright (c) 2024 Google LLC
  6 */
  7
  8#include <linux/array_size.h>
  9#include <linux/errno.h>
 10#include <linux/i2c-of-prober.h>
 11#include <linux/module.h>
 12#include <linux/of.h>
 13#include <linux/platform_device.h>
 14#include <linux/stddef.h>
 15
 16#define DRV_NAME	"chromeos_of_hw_prober"
 17
 18/**
 19 * struct hw_prober_entry - Holds an entry for the hardware prober
 20 *
 21 * @compatible:	compatible string to match against the machine
 22 * @prober:	prober function to call when machine matches
 23 * @data:	extra data for the prober function
 24 */
 25struct hw_prober_entry {
 26	const char *compatible;
 27	int (*prober)(struct device *dev, const void *data);
 28	const void *data;
 29};
 30
 31struct chromeos_i2c_probe_data {
 32	const struct i2c_of_probe_cfg *cfg;
 33	const struct i2c_of_probe_simple_opts *opts;
 34};
 35
 36static int chromeos_i2c_component_prober(struct device *dev, const void *_data)
 37{
 38	const struct chromeos_i2c_probe_data *data = _data;
 39	struct i2c_of_probe_simple_ctx ctx = {
 40		.opts = data->opts,
 41	};
 42
 43	return i2c_of_probe_component(dev, data->cfg, &ctx);
 44}
 45
 46#define DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(_type)					\
 47	static const struct i2c_of_probe_cfg chromeos_i2c_probe_simple_ ## _type ## _cfg = {	\
 48		.type = #_type,									\
 49		.ops = &i2c_of_probe_simple_ops,						\
 50	}
 51
 52#define DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(_type)					\
 53	static const struct chromeos_i2c_probe_data chromeos_i2c_probe_dumb_ ## _type = {	\
 54		.cfg = &(const struct i2c_of_probe_cfg) {					\
 55			.type = #_type,								\
 56		},										\
 57	}
 58
 59DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(touchscreen);
 60
 61DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(trackpad);
 62
 63static const struct chromeos_i2c_probe_data chromeos_i2c_probe_hana_trackpad = {
 64	.cfg = &chromeos_i2c_probe_simple_trackpad_cfg,
 65	.opts = &(const struct i2c_of_probe_simple_opts) {
 66		.res_node_compatible = "elan,ekth3000",
 67		.supply_name = "vcc",
 68		/*
 69		 * ELAN trackpad needs 2 ms for H/W init and 100 ms for F/W init.
 70		 * Synaptics trackpad needs 100 ms.
 71		 * However, the regulator is set to "always-on", presumably to
 72		 * avoid this delay. The ELAN driver is also missing delays.
 73		 */
 74		.post_power_on_delay_ms = 0,
 75	},
 76};
 77
 78static const struct hw_prober_entry hw_prober_platforms[] = {
 79	{
 80		.compatible = "google,hana",
 81		.prober = chromeos_i2c_component_prober,
 82		.data = &chromeos_i2c_probe_dumb_touchscreen,
 83	}, {
 84		.compatible = "google,hana",
 85		.prober = chromeos_i2c_component_prober,
 86		.data = &chromeos_i2c_probe_hana_trackpad,
 87	},
 88};
 89
 90static int chromeos_of_hw_prober_probe(struct platform_device *pdev)
 91{
 92	for (size_t i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++) {
 93		int ret;
 94
 95		if (!of_machine_is_compatible(hw_prober_platforms[i].compatible))
 96			continue;
 97
 98		ret = hw_prober_platforms[i].prober(&pdev->dev, hw_prober_platforms[i].data);
 99		/* Ignore unrecoverable errors and keep going through other probers */
100		if (ret == -EPROBE_DEFER)
101			return ret;
102	}
103
104	return 0;
105}
106
107static struct platform_driver chromeos_of_hw_prober_driver = {
108	.probe	= chromeos_of_hw_prober_probe,
109	.driver	= {
110		.name = DRV_NAME,
111	},
112};
113
114static struct platform_device *chromeos_of_hw_prober_pdev;
115
116static int chromeos_of_hw_prober_driver_init(void)
117{
118	size_t i;
119	int ret;
120
121	for (i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++)
122		if (of_machine_is_compatible(hw_prober_platforms[i].compatible))
123			break;
124	if (i == ARRAY_SIZE(hw_prober_platforms))
125		return -ENODEV;
126
127	ret = platform_driver_register(&chromeos_of_hw_prober_driver);
128	if (ret)
129		return ret;
130
131	chromeos_of_hw_prober_pdev =
132			platform_device_register_simple(DRV_NAME, PLATFORM_DEVID_NONE, NULL, 0);
133	if (IS_ERR(chromeos_of_hw_prober_pdev))
134		goto err;
135
136	return 0;
137
138err:
139	platform_driver_unregister(&chromeos_of_hw_prober_driver);
140
141	return PTR_ERR(chromeos_of_hw_prober_pdev);
142}
143module_init(chromeos_of_hw_prober_driver_init);
144
145static void chromeos_of_hw_prober_driver_exit(void)
146{
147	platform_device_unregister(chromeos_of_hw_prober_pdev);
148	platform_driver_unregister(&chromeos_of_hw_prober_driver);
149}
150module_exit(chromeos_of_hw_prober_driver_exit);
151
152MODULE_LICENSE("GPL");
153MODULE_DESCRIPTION("ChromeOS device tree hardware prober");
154MODULE_IMPORT_NS("I2C_OF_PROBER");