1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Linux I2C core slave support code
4 *
5 * Copyright (C) 2014 by Wolfram Sang <wsa@sang-engineering.com>
6 */
7
8#include <dt-bindings/i2c/i2c.h>
9#include <linux/acpi.h>
10#include <linux/device.h>
11#include <linux/err.h>
12#include <linux/i2c.h>
13#include <linux/of.h>
14
15#include "i2c-core.h"
16
17#define CREATE_TRACE_POINTS
18#include <trace/events/i2c_slave.h>
19
20int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
21{
22	int ret;
23
24	if (WARN(IS_ERR_OR_NULL(client) || !slave_cb, "insufficient data\n"))
25		return -EINVAL;
26
27	if (!(client->flags & I2C_CLIENT_SLAVE))
28		dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n",
29			 __func__);
30
31	if (!(client->flags & I2C_CLIENT_TEN)) {
32		/* Enforce stricter address checking */
33		ret = i2c_check_7bit_addr_validity_strict(client->addr);
34		if (ret) {
35			dev_err(&client->dev, "%s: invalid address\n", __func__);
36			return ret;
37		}
38	}
39
40	if (!client->adapter->algo->reg_slave) {
41		dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
42		return -EOPNOTSUPP;
43	}
44
45	client->slave_cb = slave_cb;
46
47	i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
48	ret = client->adapter->algo->reg_slave(client);
49	i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
50
51	if (ret) {
52		client->slave_cb = NULL;
53		dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
54	}
55
56	return ret;
57}
58EXPORT_SYMBOL_GPL(i2c_slave_register);
59
60int i2c_slave_unregister(struct i2c_client *client)
61{
62	int ret;
63
64	if (IS_ERR_OR_NULL(client))
65		return -EINVAL;
66
67	if (!client->adapter->algo->unreg_slave) {
68		dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
69		return -EOPNOTSUPP;
70	}
71
72	i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
73	ret = client->adapter->algo->unreg_slave(client);
74	i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
75
76	if (ret == 0)
77		client->slave_cb = NULL;
78	else
79		dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
80
81	return ret;
82}
83EXPORT_SYMBOL_GPL(i2c_slave_unregister);
84
85int i2c_slave_event(struct i2c_client *client,
86		    enum i2c_slave_event event, u8 *val)
87{
88	int ret = client->slave_cb(client, event, val);
89
90	if (trace_i2c_slave_enabled())
91		trace_i2c_slave(client, event, val, ret);
92
93	return ret;
94}
95EXPORT_SYMBOL_GPL(i2c_slave_event);
96
97/**
98 * i2c_detect_slave_mode - detect operation mode
99 * @dev: The device owning the bus
100 *
101 * This checks the device nodes for an I2C slave by checking the address
102 * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
103 * flag this means the device is configured to act as a I2C slave and it will
104 * be listening at that address.
105 *
106 * Returns true if an I2C own slave address is detected, otherwise returns
107 * false.
108 */
109bool i2c_detect_slave_mode(struct device *dev)
110{
111	if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
112		struct device_node *child;
113		u32 reg;
114
115		for_each_child_of_node(dev->of_node, child) {
116			of_property_read_u32(child, "reg", &reg);
117			if (reg & I2C_OWN_SLAVE_ADDRESS) {
118				of_node_put(child);
119				return true;
120			}
121		}
122	} else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
123		dev_dbg(dev, "ACPI slave is not supported yet\n");
124	}
125	return false;
126}
127EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);
128