1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * Definitions for the Linux I2C OF component prober
4 *
5 * Copyright (C) 2024 Google LLC
6 */
7
8#ifndef _LINUX_I2C_OF_PROBER_H
9#define _LINUX_I2C_OF_PROBER_H
10
11#include <linux/kconfig.h>
12#include <linux/types.h>
13
14struct device;
15struct device_node;
16
17/**
18 * struct i2c_of_probe_ops - I2C OF component prober callbacks
19 *
20 * A set of callbacks to be used by i2c_of_probe_component().
21 *
22 * All callbacks are optional. Callbacks are called only once per run, and are
23 * used in the order they are defined in this structure.
24 *
25 * All callbacks that have return values shall return %0 on success,
26 * or a negative error number on failure.
27 *
28 * The @dev parameter passed to the callbacks is the same as @dev passed to
29 * i2c_of_probe_component(). It should only be used for dev_printk() calls
30 * and nothing else, especially not managed device resource (devres) APIs.
31 */
32struct i2c_of_probe_ops {
33 /**
34 * @enable: Retrieve and enable resources so that the components respond to probes.
35 *
36 * It is OK for this callback to return -EPROBE_DEFER since the intended use includes
37 * retrieving resources and enables them. Resources should be reverted to their initial
38 * state and released before returning if this fails.
39 */
40 int (*enable)(struct device *dev, struct device_node *bus_node, void *data);
41
42 /**
43 * @cleanup_early: Release exclusive resources prior to calling probe() on a
44 * detected component.
45 *
46 * Only called if a matching component is actually found. If none are found,
47 * resources that would have been released in this callback should be released in
48 * @free_resourcs_late instead.
49 */
50 void (*cleanup_early)(struct device *dev, void *data);
51
52 /**
53 * @cleanup: Opposite of @enable to balance refcounts and free resources after probing.
54 *
55 * Should check if resources were already freed by @cleanup_early.
56 */
57 void (*cleanup)(struct device *dev, void *data);
58};
59
60/**
61 * struct i2c_of_probe_cfg - I2C OF component prober configuration
62 * @ops: Callbacks for the prober to use.
63 * @type: A string to match the device node name prefix to probe for.
64 */
65struct i2c_of_probe_cfg {
66 const struct i2c_of_probe_ops *ops;
67 const char *type;
68};
69
70#if IS_ENABLED(CONFIG_OF_DYNAMIC)
71
72int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cfg, void *ctx);
73
74/**
75 * DOC: I2C OF component prober simple helpers
76 *
77 * Components such as trackpads are commonly connected to a devices baseboard
78 * with a 6-pin ribbon cable. That gives at most one voltage supply and one
79 * GPIO (commonly a "enable" or "reset" line) besides the I2C bus, interrupt
80 * pin, and common ground. Touchscreens, while integrated into the display
81 * panel's connection, typically have the same set of connections.
82 *
83 * A simple set of helpers are provided here for use with the I2C OF component
84 * prober. This implementation targets such components, allowing for at most
85 * one regulator supply.
86 *
87 * The following helpers are provided:
88 * * i2c_of_probe_simple_enable()
89 * * i2c_of_probe_simple_cleanup_early()
90 * * i2c_of_probe_simple_cleanup()
91 */
92
93/**
94 * struct i2c_of_probe_simple_opts - Options for simple I2C component prober callbacks
95 * @res_node_compatible: Compatible string of device node to retrieve resources from.
96 * @supply_name: Name of regulator supply.
97 * @gpio_name: Name of GPIO. NULL if no GPIO line is used. Empty string ("") if GPIO
98 * line is unnamed.
99 * @post_power_on_delay_ms: Delay after regulators are powered on. Passed to msleep().
100 * @post_gpio_config_delay_ms: Delay after GPIO is configured. Passed to msleep().
101 * @gpio_assert_to_enable: %true if GPIO should be asserted, i.e. set to logical high,
102 * to enable the component.
103 *
104 * This describes power sequences common for the class of components supported by the
105 * simple component prober:
106 * * @gpio_name is configured to the non-active setting according to @gpio_assert_to_enable.
107 * * @supply_name regulator supply is enabled.
108 * * Wait for @post_power_on_delay_ms to pass.
109 * * @gpio_name is configured to the active setting according to @gpio_assert_to_enable.
110 * * Wait for @post_gpio_config_delay_ms to pass.
111 */
112struct i2c_of_probe_simple_opts {
113 const char *res_node_compatible;
114 const char *supply_name;
115 const char *gpio_name;
116 unsigned int post_power_on_delay_ms;
117 unsigned int post_gpio_config_delay_ms;
118 bool gpio_assert_to_enable;
119};
120
121struct gpio_desc;
122struct regulator;
123
124struct i2c_of_probe_simple_ctx {
125 /* public: provided by user before helpers are used. */
126 const struct i2c_of_probe_simple_opts *opts;
127 /* private: internal fields for helpers. */
128 struct regulator *supply;
129 struct gpio_desc *gpiod;
130};
131
132int i2c_of_probe_simple_enable(struct device *dev, struct device_node *bus_node, void *data);
133void i2c_of_probe_simple_cleanup_early(struct device *dev, void *data);
134void i2c_of_probe_simple_cleanup(struct device *dev, void *data);
135
136extern struct i2c_of_probe_ops i2c_of_probe_simple_ops;
137
138#endif /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
139
140#endif /* _LINUX_I2C_OF_PROBER_H */
141

source code of linux/include/linux/i2c-of-prober.h