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 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 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 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 */ 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