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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Linux I2C core slave support code4 *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_POINTS18#include <trace/events/i2c_slave.h>19 20int 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}58EXPORT_SYMBOL_GPL(i2c_slave_register);59 60int 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 else79 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);80 81 return ret;82}83EXPORT_SYMBOL_GPL(i2c_slave_unregister);84 85int 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}95EXPORT_SYMBOL_GPL(i2c_slave_event);96 97/**98 * i2c_detect_slave_mode - detect operation mode99 * @dev: The device owning the bus100 *101 * This checks the device nodes for an I2C slave by checking the address102 * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS103 * flag this means the device is configured to act as a I2C slave and it will104 * be listening at that address.105 *106 * Returns true if an I2C own slave address is detected, otherwise returns107 * false.108 */109bool i2c_detect_slave_mode(struct device *dev)110{111 if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {112 u32 reg;113 114 for_each_child_of_node_scoped(dev->of_node, child) {115 of_property_read_u32(child, "reg", ®);116 if (reg & I2C_OWN_SLAVE_ADDRESS)117 return true;118 }119 } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {120 dev_dbg(dev, "ACPI slave is not supported yet\n");121 }122 return false;123}124EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);125