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
17int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
18{
19	int ret;
20
21	if (WARN(IS_ERR_OR_NULL(client) || !slave_cb, "insufficient data\n"))
22		return -EINVAL;
23
24	if (!(client->flags & I2C_CLIENT_SLAVE))
25		dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n",
26			 __func__);
27
28	if (!(client->flags & I2C_CLIENT_TEN)) {
29		/* Enforce stricter address checking */
30		ret = i2c_check_7bit_addr_validity_strict(client->addr);
31		if (ret) {
32			dev_err(&client->dev, "%s: invalid address\n", __func__);
33			return ret;
34		}
35	}
36
37	if (!client->adapter->algo->reg_slave) {
38		dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
39		return -EOPNOTSUPP;
40	}
41
42	client->slave_cb = slave_cb;
43
44	i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
45	ret = client->adapter->algo->reg_slave(client);
46	i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
47
48	if (ret) {
49		client->slave_cb = NULL;
50		dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
51	}
52
53	return ret;
54}
55EXPORT_SYMBOL_GPL(i2c_slave_register);
56
57int i2c_slave_unregister(struct i2c_client *client)
58{
59	int ret;
60
61	if (IS_ERR_OR_NULL(client))
62		return -EINVAL;
63
64	if (!client->adapter->algo->unreg_slave) {
65		dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
66		return -EOPNOTSUPP;
67	}
68
69	i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
70	ret = client->adapter->algo->unreg_slave(client);
71	i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
72
73	if (ret == 0)
74		client->slave_cb = NULL;
75	else
76		dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
77
78	return ret;
79}
80EXPORT_SYMBOL_GPL(i2c_slave_unregister);
81
82/**
83 * i2c_detect_slave_mode - detect operation mode
84 * @dev: The device owning the bus
85 *
86 * This checks the device nodes for an I2C slave by checking the address
87 * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
88 * flag this means the device is configured to act as a I2C slave and it will
89 * be listening at that address.
90 *
91 * Returns true if an I2C own slave address is detected, otherwise returns
92 * false.
93 */
94bool i2c_detect_slave_mode(struct device *dev)
95{
96	if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
97		struct device_node *child;
98		u32 reg;
99
100		for_each_child_of_node(dev->of_node, child) {
101			of_property_read_u32(child, "reg", &reg);
102			if (reg & I2C_OWN_SLAVE_ADDRESS) {
103				of_node_put(child);
104				return true;
105			}
106		}
107	} else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
108		dev_dbg(dev, "ACPI slave is not supported yet\n");
109	}
110	return false;
111}
112EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);
113