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 (!client || !slave_cb) {
  22                 WARN(1, "insufficient data\n");
  23                 return -EINVAL;
  24         }
  25
  26         if (!(client->flags & I2C_CLIENT_SLAVE))
  27                 dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n",
  28                          __func__);
  29
  30         if (!(client->flags & I2C_CLIENT_TEN)) {
  31                 /* Enforce stricter address checking */
  32                 ret = i2c_check_7bit_addr_validity_strict(client->addr);
  33                 if (ret) {
  34                         dev_err(&client->dev, "%s: invalid address\n", __func__);
  35                         return ret;
  36                 }
  37         }
  38
  39         if (!client->adapter->algo->reg_slave) {
  40                 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
  41                 return -EOPNOTSUPP;
  42         }
  43
  44         client->slave_cb = slave_cb;
  45
  46         i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
  47         ret = client->adapter->algo->reg_slave(client);
  48         i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
  49
  50         if (ret) {
  51                 client->slave_cb = NULL;
  52                 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
  53         }
  54
  55         return ret;
  56 }
  57 EXPORT_SYMBOL_GPL(i2c_slave_register);
  58
  59 int i2c_slave_unregister(struct i2c_client *client)
  60 {
  61         int ret;
  62
  63         if (!client->adapter->algo->unreg_slave) {
  64                 dev_err(&client->dev, "%s: not supported by adapter\n", __func__);
  65                 return -EOPNOTSUPP;
  66         }
  67
  68         i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
  69         ret = client->adapter->algo->unreg_slave(client);
  70         i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER);
  71
  72         if (ret == 0)
  73                 client->slave_cb = NULL;
  74         else
  75                 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
  76
  77         return ret;
  78 }
  79 EXPORT_SYMBOL_GPL(i2c_slave_unregister);
  80
  81 /**
  82  * i2c_detect_slave_mode - detect operation mode
  83  * @dev: The device owning the bus
  84  *
  85  * This checks the device nodes for an I2C slave by checking the address
  86  * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
  87  * flag this means the device is configured to act as a I2C slave and it will
  88  * be listening at that address.
  89  *
  90  * Returns true if an I2C own slave address is detected, otherwise returns
  91  * false.
  92  */
  93 bool i2c_detect_slave_mode(struct device *dev)
  94 {
  95         if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
  96                 struct device_node *child;
  97                 u32 reg;
  98
  99                 for_each_child_of_node(dev->of_node, child) {
 100                         of_property_read_u32(child, "reg", &reg);
 101                         if (reg & I2C_OWN_SLAVE_ADDRESS) {
 102                                 of_node_put(child);
 103                                 return true;
 104                         }
 105                 }
 106         } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
 107                 dev_dbg(dev, "ACPI slave is not supported yet\n");
 108         }
 109         return false;
 110 }
 111 EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);