[PATCH v3 1/2] i2c-core: dt: Pick i2c bus number from i2c alias if present
From: dianders@chromium.org (Doug Anderson)
Date: 2013-02-12 00:48:18
Also in:
linux-i2c, linux-samsung-soc, lkml
Subsystem:
i2c subsystem, the rest · Maintainers:
Andi Shyti, Linus Torvalds
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>
---
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