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@xxxxxxxxxxxx>
---
Changes in v3:
- Addressed Wolfram's feedback; rebased atop idr-cleanup series.
Changes in v2: None
drivers/i2c/i2c-core.c | 54 +++++++++++++++++++++++++++++++++++++-------------
1 file changed, 40 insertions(+), 14 deletions(-)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 0b599f2..5204818 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -921,13 +921,41 @@ out_list:
}
/**
+ * __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;
+
+ /* Handled by wrappers */
+ if (WARN_ON(adap->nr == -1))
+ return -EINVAL;
+
+ if (adap->nr & ~MAX_IDR_MASK)
+ return -EINVAL;
+
+ 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 +963,17 @@ out_list:
*/
int i2c_add_adapter(struct i2c_adapter *adapter)
{
+ struct device *dev = &adapter->dev;
int res;
+ if (dev->of_node) {
+ res = of_alias_get_id(dev->of_node, "i2c");
+ if (res >= 0) {
+ adapter->nr = res;
+ return __i2c_add_numbered_adapter(adapter);
+ }
+ }
+
mutex_lock(&core_lock);
res = idr_alloc(&i2c_adapter_idr, adapter,
__i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
@@ -974,20 +1011,9 @@ 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);
- if (adap->nr & ~MAX_IDR_MASK)
- return -EINVAL;
-
- 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);
--
1.8.1
--
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