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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: Doug Anderson <dianders@chromium.org>
[wsa: removed one check from static function. We know our callers]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
hifive-unleashed-5.1
Doug Anderson 2013-03-01 08:57:31 -08:00 committed by Wolfram Sang
parent 8bb9660418
commit ee5c27440c
1 changed files with 34 additions and 11 deletions
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45
drivers/i2c/i2c-core.c
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@ -920,14 +920,36 @@ out_list:
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 @@ out_list:
*/
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);