drivers/i2c/i2c-core-slave.c

   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 int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
  18 {
  19         int ret;
  20
  21         if (WARN(IS_ERR_OR_NULL(client) || !slave_cb, "insufficient data\n"))
  22                 return -EINVAL;
  23
  24         if (!(client->flags & I2C_CLIENT_SLAVE))
  25                 dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n",
  26                          __func__);
  27
  28         if (!(client->flags & I2C_CLIENT_TEN)) {
  29                 /* Enforce stricter address checking */
  30                 ret = i2c_check_7bit_addr_validity_strict(client->addr);
  31                 if (ret) {
  32                         dev_err(&client->dev, "%s: invalid address\n", __func__);
  33                         return ret;
  34                 }
  35         }
  36
  37         if (!client->adapter->algo->reg_slave) {
  38                 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
  39                 return -EOPNOTSUPP;
  40         }
  41
  42         client->slave_cb = slave_cb;
  43
  44         i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
  45         ret = client->adapter->algo->reg_slave(client);
  46         i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
  47
  48         if (ret) {
  49                 client->slave_cb = NULL;
  50                 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
  51         }
  52
  53         return ret;
  54 }
  55 EXPORT_SYMBOL_GPL(i2c_slave_register);
  56
  57 int i2c_slave_unregister(struct i2c_client *client)
  58 {
  59         int ret;
  60
  61         if (IS_ERR_OR_NULL(client))
  62                 return -EINVAL;
  63
  64         if (!client->adapter->algo->unreg_slave) {
  65                 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
  66                 return -EOPNOTSUPP;
  67         }
  68
  69         i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
  70         ret = client->adapter->algo->unreg_slave(client);
  71         i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
  72
  73         if (ret == 0)
  74                 client->slave_cb = NULL;
  75         else
  76                 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
  77
  78         return ret;
  79 }
  80 EXPORT_SYMBOL_GPL(i2c_slave_unregister);
  81
  82 /**
  83  * i2c_detect_slave_mode - detect operation mode
  84  * @dev: The device owning the bus
  85  *
  86  * This checks the device nodes for an I2C slave by checking the address
  87  * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
  88  * flag this means the device is configured to act as a I2C slave and it will
  89  * be listening at that address.
  90  *
  91  * Returns true if an I2C own slave address is detected, otherwise returns
  92  * false.
  93  */
  94 bool i2c_detect_slave_mode(struct device *dev)
  95 {
  96         if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
  97                 struct device_node *child;
  98                 u32 reg;
  99
 100                 for_each_child_of_node(dev->of_node, child) {
 101                         of_property_read_u32(child, "reg", &reg);
 102                         if (reg & I2C_OWN_SLAVE_ADDRESS) {
 103                                 of_node_put(child);
 104                                 return true;
 105                         }
 106                 }
 107         } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
 108                 dev_dbg(dev, "ACPI slave is not supported yet\n");
 109         }
 110         return false;
 111 }
 112 EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);