// SPDX-License-Identifier: GPL-2.0-or-later /* * Linux I2C core slave support code * * Copyright (C) 2014 by Wolfram Sang <wsa@sang-engineering.com> */ #include <dt-bindings/i2c/i2c.h> #include <linux/acpi.h> #include <linux/device.h> #include <linux/err.h> #include <linux/i2c.h> #include <linux/of.h> #include "i2c-core.h" int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb) { int ret; if (WARN(IS_ERR_OR_NULL(client) || !slave_cb, "insufficient data\n")) return -EINVAL; if (!(client->flags & I2C_CLIENT_SLAVE)) dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n", __func__); if (!(client->flags & I2C_CLIENT_TEN)) { /* Enforce stricter address checking */ ret = i2c_check_7bit_addr_validity_strict(client->addr); if (ret) { dev_err(&client->dev, "%s: invalid address\n", __func__); return ret; } } if (!client->adapter->algo->reg_slave) { dev_err(&client->dev, "%s: not supported by adapter\n", __func__); return -EOPNOTSUPP; } client->slave_cb = slave_cb; i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); ret = client->adapter->algo->reg_slave(client); i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); if (ret) { client->slave_cb = NULL; dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret); } return ret; } EXPORT_SYMBOL_GPL(i2c_slave_register); int i2c_slave_unregister(struct i2c_client *client) { int ret; if (IS_ERR_OR_NULL(client)) return -EINVAL; if (!client->adapter->algo->unreg_slave) { dev_err(&client->dev, "%s: not supported by adapter\n", __func__); return -EOPNOTSUPP; } i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); ret = client->adapter->algo->unreg_slave(client); i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); if (ret == 0) client->slave_cb = NULL; else dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret); return ret; } EXPORT_SYMBOL_GPL(i2c_slave_unregister); /** * i2c_detect_slave_mode - detect operation mode * @dev: The device owning the bus * * This checks the device nodes for an I2C slave by checking the address * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS * flag this means the device is configured to act as a I2C slave and it will * be listening at that address. * * Returns true if an I2C own slave address is detected, otherwise returns * false. */ bool i2c_detect_slave_mode(struct device *dev) { if (IS_BUILTIN(CONFIG_OF) && dev->of_node) { struct device_node *child; u32 reg; for_each_child_of_node(dev->of_node, child) { of_property_read_u32(child, "reg", ®); if (reg & I2C_OWN_SLAVE_ADDRESS) { of_node_put(child); return true; } } } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) { dev_dbg(dev, "ACPI slave is not supported yet\n"); } return false; } EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);