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
i2c_slave_register(struct i2c_client * client,i2c_slave_cb_t slave_cb)20 int 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 }
58 EXPORT_SYMBOL_GPL(i2c_slave_register);
59
i2c_slave_unregister(struct i2c_client * client)60 int 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 }
83 EXPORT_SYMBOL_GPL(i2c_slave_unregister);
84
i2c_slave_event(struct i2c_client * client,enum i2c_slave_event event,u8 * val)85 int 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 }
95 EXPORT_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 */
i2c_detect_slave_mode(struct device * dev)109 bool 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", ®);
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 }
127 EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);
128