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 #include <linux/property.h> 15 16 #include "i2c-core.h" 17 18 #define CREATE_TRACE_POINTS 19 #include <trace/events/i2c_slave.h> 20 21 int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb) 22 { 23 int ret; 24 25 if (WARN(IS_ERR_OR_NULL(client) || !slave_cb, "insufficient data\n")) 26 return -EINVAL; 27 28 if (!(client->flags & I2C_CLIENT_SLAVE)) 29 dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n", 30 __func__); 31 32 if (!(client->flags & I2C_CLIENT_TEN)) { 33 /* Enforce stricter address checking */ 34 ret = i2c_check_7bit_addr_validity_strict(client->addr); 35 if (ret) { 36 dev_err(&client->dev, "%s: invalid address\n", __func__); 37 return ret; 38 } 39 } 40 41 if (!client->adapter->algo->reg_slave) { 42 dev_err(&client->dev, "%s: not supported by adapter\n", __func__); 43 return -EOPNOTSUPP; 44 } 45 46 client->slave_cb = slave_cb; 47 48 i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); 49 ret = client->adapter->algo->reg_slave(client); 50 i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); 51 52 if (ret) { 53 client->slave_cb = NULL; 54 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret); 55 } 56 57 return ret; 58 } 59 EXPORT_SYMBOL_GPL(i2c_slave_register); 60 61 int i2c_slave_unregister(struct i2c_client *client) 62 { 63 int ret; 64 65 if (IS_ERR_OR_NULL(client)) 66 return -EINVAL; 67 68 if (!client->adapter->algo->unreg_slave) { 69 dev_err(&client->dev, "%s: not supported by adapter\n", __func__); 70 return -EOPNOTSUPP; 71 } 72 73 i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); 74 ret = client->adapter->algo->unreg_slave(client); 75 i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); 76 77 if (ret == 0) 78 client->slave_cb = NULL; 79 else 80 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret); 81 82 return ret; 83 } 84 EXPORT_SYMBOL_GPL(i2c_slave_unregister); 85 86 int i2c_slave_event(struct i2c_client *client, 87 enum i2c_slave_event event, u8 *val) 88 { 89 int ret = client->slave_cb(client, event, val); 90 91 if (trace_i2c_slave_enabled()) 92 trace_i2c_slave(client, event, val, ret); 93 94 return ret; 95 } 96 EXPORT_SYMBOL_GPL(i2c_slave_event); 97 98 /** 99 * i2c_detect_slave_mode - detect operation mode 100 * @dev: The device owning the bus 101 * 102 * This checks the device nodes for an I2C slave by checking the address 103 * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS 104 * flag this means the device is configured to act as a I2C slave and it will 105 * be listening at that address. 106 * 107 * Returns true if an I2C own slave address is detected, otherwise returns 108 * false. 109 */ 110 bool i2c_detect_slave_mode(struct device *dev) 111 { 112 struct fwnode_handle *fwnode = dev_fwnode(dev); 113 114 if (is_of_node(fwnode)) { 115 struct fwnode_handle *child __free(fwnode_handle) = NULL; 116 u32 reg; 117 118 fwnode_for_each_child_node(fwnode, child) { 119 fwnode_property_read_u32(child, "reg", ®); 120 if (reg & I2C_OWN_SLAVE_ADDRESS) 121 return true; 122 } 123 } else if (is_acpi_device_node(fwnode)) { 124 dev_dbg(dev, "ACPI slave is not supported yet\n"); 125 } 126 return false; 127 } 128 EXPORT_SYMBOL_GPL(i2c_detect_slave_mode); 129