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Commit ee5c2744 authored by Doug Anderson's avatar Doug Anderson Committed by Wolfram Sang
Browse files

i2c: core: Pick i2c bus number from dt alias if present 



This allows you to get the equivalent functionality of
i2c_add_numbered_adapter() with all data in the device tree and no
special case code in your driver.  This is a common device tree
technique.

For quick reference, the FDT syntax for using an alias to provide an
ID looks like:
  aliases {
    i2c0 = &i2c_0;
    i2c1 = &i2c_1;
  };

Signed-off-by: default avatarDoug Anderson <dianders@chromium.org>
[wsa: removed one check from static function. We know our callers]
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 8bb96604

drivers/i2c/i2c-core.c

+34 −11
Original line number Diff line number Diff line
@@ -920,14 +920,36 @@ static int i2c_register_adapter(struct i2c_adapter *adap) 
	return res;

}



/**

 * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1

 * @adap: the adapter to register (with adap->nr initialized)

 * Context: can sleep

 *

 * See i2c_add_numbered_adapter() for details.

 */

static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)

{

	int	id;



	mutex_lock(&core_lock);

	id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1,

		       GFP_KERNEL);

	mutex_unlock(&core_lock);

	if (id < 0)

		return id == -ENOSPC ? -EBUSY : id;



	return i2c_register_adapter(adap);

}



/**

 * i2c_add_adapter - declare i2c adapter, use dynamic bus number

 * @adapter: the adapter to add

 * Context: can sleep

 *

 * This routine is used to declare an I2C adapter when its bus number

 * doesn't matter.  Examples: for I2C adapters dynamically added by

 * USB links or PCI plugin cards.

 * doesn't matter or when its bus number is specified by an dt alias.

 * Examples of bases when the bus number doesn't matter: I2C adapters

 * dynamically added by USB links or PCI plugin cards.

 *

 * When this returns zero, a new bus number was allocated and stored

 * in adap->nr, and the specified adapter became available for clients.
@@ -935,8 +957,17 @@ static int i2c_register_adapter(struct i2c_adapter *adap) 
 */

int i2c_add_adapter(struct i2c_adapter *adapter)

{

	struct device *dev = &adapter->dev;

	int id;



	if (dev->of_node) {

		id = of_alias_get_id(dev->of_node, "i2c");

		if (id >= 0) {

			adapter->nr = id;

			return __i2c_add_numbered_adapter(adapter);

		}

	}



	mutex_lock(&core_lock);

	id = idr_alloc(&i2c_adapter_idr, adapter,

		       __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
@@ -975,18 +1006,10 @@ EXPORT_SYMBOL(i2c_add_adapter); 
 */

int i2c_add_numbered_adapter(struct i2c_adapter *adap)

{

	int	id;



	if (adap->nr == -1) /* -1 means dynamically assign bus id */

		return i2c_add_adapter(adap);



	mutex_lock(&core_lock);

	id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1,

		       GFP_KERNEL);

	mutex_unlock(&core_lock);

	if (id < 0)

		return id == -ENOSPC ? -EBUSY : id;

	return i2c_register_adapter(adap);

	return __i2c_add_numbered_adapter(adap);

}

EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);