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
i2c_slave_register(struct i2c_client * client,i2c_slave_cb_t slave_cb)17 int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
18 {
19 int ret;
20
21 if (!client || !slave_cb) {
22 WARN(1, "insufficient data\n");
23 return -EINVAL;
24 }
25
26 if (!(client->flags & I2C_CLIENT_SLAVE))
27 dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n",
28 __func__);
29
30 if (!(client->flags & I2C_CLIENT_TEN)) {
31 /* Enforce stricter address checking */
32 ret = i2c_check_7bit_addr_validity_strict(client->addr);
33 if (ret) {
34 dev_err(&client->dev, "%s: invalid address\n", __func__);
35 return ret;
36 }
37 }
38
39 if (!client->adapter->algo->reg_slave) {
40 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
41 return -EOPNOTSUPP;
42 }
43
44 client->slave_cb = slave_cb;
45
46 i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
47 ret = client->adapter->algo->reg_slave(client);
48 i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
49
50 if (ret) {
51 client->slave_cb = NULL;
52 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
53 }
54
55 return ret;
56 }
57 EXPORT_SYMBOL_GPL(i2c_slave_register);
58
i2c_slave_unregister(struct i2c_client * client)59 int i2c_slave_unregister(struct i2c_client *client)
60 {
61 int ret;
62
63 if (!client->adapter->algo->unreg_slave) {
64 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
65 return -EOPNOTSUPP;
66 }
67
68 i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
69 ret = client->adapter->algo->unreg_slave(client);
70 i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
71
72 if (ret == 0)
73 client->slave_cb = NULL;
74 else
75 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
76
77 return ret;
78 }
79 EXPORT_SYMBOL_GPL(i2c_slave_unregister);
80
81 /**
82 * i2c_detect_slave_mode - detect operation mode
83 * @dev: The device owning the bus
84 *
85 * This checks the device nodes for an I2C slave by checking the address
86 * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
87 * flag this means the device is configured to act as a I2C slave and it will
88 * be listening at that address.
89 *
90 * Returns true if an I2C own slave address is detected, otherwise returns
91 * false.
92 */
i2c_detect_slave_mode(struct device * dev)93 bool i2c_detect_slave_mode(struct device *dev)
94 {
95 if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
96 struct device_node *child;
97 u32 reg;
98
99 for_each_child_of_node(dev->of_node, child) {
100 of_property_read_u32(child, "reg", ®);
101 if (reg & I2C_OWN_SLAVE_ADDRESS) {
102 of_node_put(child);
103 return true;
104 }
105 }
106 } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
107 dev_dbg(dev, "ACPI slave is not supported yet\n");
108 }
109 return false;
110 }
111 EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);
112