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 #define CREATE_TRACE_POINTS
  18 #include <trace/events/i2c_slave.h>
  19
  20 int 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 }
  58 EXPORT_SYMBOL_GPL(i2c_slave_register);
  59
  60 int 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         else
  79                 dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret);
  80
  81         return ret;
  82 }
  83 EXPORT_SYMBOL_GPL(i2c_slave_unregister);
  84
  85 int 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 }
  95 EXPORT_SYMBOL_GPL(i2c_slave_event);
  96
  97 /**
  98  * i2c_detect_slave_mode - detect operation mode
  99  * @dev: The device owning the bus
 100  *
 101  * This checks the device nodes for an I2C slave by checking the address
 102  * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
 103  * flag this means the device is configured to act as a I2C slave and it will
 104  * be listening at that address.
 105  *
 106  * Returns true if an I2C own slave address is detected, otherwise returns
 107  * false.
 108  */
 109 bool 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", &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 }
 124 EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);