int i2c_add_numbered_adapter(struct i2c_adapter *adap)
{
int id;
int status;
if (adap->nr & ~MAX_ID_MASK)
return -EINVAL;
retry:
if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
return -ENOMEM;
mutex_lock(&core_lock);
/* "above" here means "above or equal to", sigh;
* we need the "equal to" result to force the result
*/
status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
if (status == 0 && id != adap->nr) {
status = -EBUSY;
idr_remove(&i2c_adapter_idr, id);
}
mutex_unlock(&core_lock);
if (status == -EAGAIN)
goto retry;
if (status == 0)
status = i2c_register_adapter(adap);
return status;
}
static int i2c_register_adapter(struct i2c_adapter *adap)
{
int res = 0, dummy;
/* Can't register until after driver model init */
if (unlikely(WARN_ON(!i2c_bus_type.p))) {
res = -EAGAIN;
goto out_list;
}
mutex_init(&adap->bus_lock);
/* Set default timeout to 1 second if not already set */
if (adap->timeout == 0)
adap->timeout = HZ;
dev_set_name(&adap->dev, "i2c-%d", adap->nr);//I2C控制器的设备名字
adap->dev.release = &i2c_adapter_dev_release;
adap->dev.class = &i2c_adapter_class;
res = device_register(&adap->dev); //注册I2C控制器设备
if (res)
goto out_list;
dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
/* create pre-declared device nodes */
if (adap->nr < __i2c_first_dynamic_bus_num)
i2c_scan_static_board_info(adap); //主意这里了，准备添加I2C从设备了，通过遍历那个什么链表，然后和adapter的nr进行比较，相等，说明有控制器存在
/* Notify drivers */
mutex_lock(&core_lock);
dummy = bus_for_each_drv(&i2c_bus_type, NULL, adap,
i2c_do_add_adapter);
mutex_unlock(&core_lock);
return 0;
out_list:
mutex_lock(&core_lock);
idr_remove(&i2c_adapter_idr, adap->nr);
mutex_unlock(&core_lock);
return res;
}
static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
{
struct i2c_devinfo *devinfo;
down_read(&__i2c_board_lock);
list_for_each_entry(devinfo, &__i2c_board_list, list) {
if (devinfo->busnum == adapter->nr /////////////此处就是之前用i2c_register_boardinfo时候给出的从设备的控制器号
&& !i2c_new_device(adapter,
&devinfo->board_info))
dev_err(&adapter->dev,
"Can't create device at 0x%02x\n",
devinfo->board_info.addr);
}
up_read(&__i2c_board_lock);
}
struct i2c_client *
i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
{
struct i2c_client *client;
int status;
client = kzalloc(sizeof *client, GFP_KERNEL);
if (!client)
return NULL;
client->adapter = adap; //这里设置主控制器，当VFS调用file operations时，会调用adapter里的那个什么算法
client->dev.platform_data = info->platform_data;
if (info->archdata)
client->dev.archdata = *info->archdata;
client->flags = info->flags;
client->addr = info->addr; //从设备的地址
client->irq = info->irq;
//从设备的中断号
strlcpy(client->name,
info->type, sizeof(client->name)); //设备的名字，总线会根据此和device_driver中ID_TABLE中的每个成员进行配对，最后调用probe函数
status = i2c_check_addr(adap, client->addr);
if (status)
goto out_err;
client->dev.parent = &client->adapter->dev;
client->dev.bus = &i2c_bus_type;
client->dev.release = i2c_client_dev_release;
dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
client->addr);
status = device_register(&client->dev);
if (status)
goto out_err;
dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
client->name, dev_name(&client->dev));
return client;
out_err:
dev_err(&adap->dev, "Failed to register i2c client %s at 0x%02x "
"(%d)\n", client->name, client->addr, status);
kfree(client);
return NULL;
}
static int i2c_do_add_adapter(struct device_driver *d, void *data)
{
struct i2c_driver *driver = to_i2c_driver(d);
struct i2c_adapter *adap = data;
/* Detect supported devices on that bus, and instantiate them */
i2c_detect(adap, driver);
/* Let legacy drivers scan this bus for matching devices */
if (driver->attach_adapter) {
/* We ignore the return code; if it fails, too bad */
driver->attach_adapter(adap);
}
return 0;
}