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i2c: Add i2c_board_info and i2c_new_device()

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This provides partial support for new-style I2C driver binding.  It builds
on "struct i2c_board_info" declarations that identify I2C devices on a given
board.  This is needed on systems with I2C devices that can't be fully probed
and/or autoconfigured, such as many embedded Linux configurations where the
way a given I2C device is wired may affect how it must be used.

There are two models for declaring such devices:

 * LATE -- using a public function i2c_new_device().  This lets modules
   declare I2C devices found *AFTER* a given I2C adapter becomes available.
   
   For example, a PCI card could create adapters giving access to utility
   chips on that card, and this would be used to associate those chips with
   those adapters.

 * EARLY -- from arch_initcall() level code, using a non-exported function
   i2c_register_board_info().  This copies the declarations *BEFORE* such
   an i2c_adapter becomes available, arranging that i2c_new_device() will
   be called later when i2c-core registers the relevant i2c_adapter.

   For example, arch/.../.../board-*.c files would declare the I2C devices
   along with their platform data, and I2C devices would behave much like
   PNPACPI devices.  (That is, both enumerate from board-specific tables.)

To match the exported i2c_new_device(), the previously-private function
i2c_unregister_device() is now exported.

Pending later patches using these new APIs, this is effectively a NOP.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
David Brownell
2007-05-01 23:26:31 +02:00
committed by Jean Delvare
parent 4298cfc3eb
commit 9c1600eda4
7 changed files with 276 additions and 5 deletions
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90
drivers/i2c/i2c-core.c
View File

@@ -35,6 +35,8 @@
#include <linux/completion.h>
#include <asm/uaccess.h>
#include "i2c-core.h"
static LIST_HEAD(adapters);
static LIST_HEAD(drivers);
@@ -162,6 +164,11 @@ static void i2c_client_release(struct device *dev)
complete(&client->released);
}
static void i2c_client_dev_release(struct device *dev)
{
kfree(to_i2c_client(dev));
}
static ssize_t show_client_name(struct device *dev, struct device_attribute *attr, char *buf)
{
struct i2c_client *client = to_i2c_client(dev);
@@ -195,7 +202,60 @@ struct bus_type i2c_bus_type = {
.resume = i2c_device_resume,
};
static void i2c_unregister_device(struct i2c_client *client)
/**
* i2c_new_device - instantiate an i2c device for use with a new style driver
* @adap: the adapter managing the device
* @info: describes one I2C device; bus_num is ignored
*
* Create a device to work with a new style i2c driver, where binding is
* handled through driver model probe()/remove() methods. This call is not
* appropriate for use by mainboad initialization logic, which usually runs
* during an arch_initcall() long before any i2c_adapter could exist.
*
* This returns the new i2c client, which may be saved for later use with
* i2c_unregister_device(); or NULL to indicate an error.
*/
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;
client->dev.platform_data = info->platform_data;
client->flags = info->flags;
client->addr = info->addr;
client->irq = info->irq;
strlcpy(client->driver_name, info->driver_name,
sizeof(client->driver_name));
strlcpy(client->name, info->type, sizeof(client->name));
/* a new style driver may be bound to this device when we
* return from this function, or any later moment (e.g. maybe
* hotplugging will load the driver module). and the device
* refcount model is the standard driver model one.
*/
status = i2c_attach_client(client);
if (status < 0) {
kfree(client);
client = NULL;
}
return client;
}
EXPORT_SYMBOL_GPL(i2c_new_device);
/**
* i2c_unregister_device - reverse effect of i2c_new_device()
* @client: value returned from i2c_new_device()
*/
void i2c_unregister_device(struct i2c_client *client)
{
struct i2c_adapter *adapter = client->adapter;
struct i2c_driver *driver = client->driver;
@@ -213,6 +273,7 @@ static void i2c_unregister_device(struct i2c_client *client)
device_unregister(&client->dev);
}
EXPORT_SYMBOL_GPL(i2c_unregister_device);
/* ------------------------------------------------------------------------- */
@@ -243,6 +304,22 @@ struct class i2c_adapter_class = {
.dev_attrs = i2c_adapter_attrs,
};
static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
{
struct i2c_devinfo *devinfo;
mutex_lock(&__i2c_board_lock);
list_for_each_entry(devinfo, &__i2c_board_list, list) {
if (devinfo->busnum == adapter->nr
&& !i2c_new_device(adapter,
&devinfo->board_info))
printk(KERN_ERR "i2c-core: can't create i2c%d-%04x\n",
i2c_adapter_id(adapter),
devinfo->board_info.addr);
}
mutex_unlock(&__i2c_board_lock);
}
/* -----
* i2c_add_adapter is called from within the algorithm layer,
@@ -311,7 +388,6 @@ out_list:
goto out_unlock;
}
int i2c_del_adapter(struct i2c_adapter *adap)
{
struct list_head *item, *_n;
@@ -541,9 +617,15 @@ int i2c_attach_client(struct i2c_client *client)
client->usage_count = 0;
client->dev.parent = &client->adapter->dev;
client->dev.driver = &client->driver->driver;
client->dev.bus = &i2c_bus_type;
client->dev.release = &i2c_client_release;
if (client->driver)
client->dev.driver = &client->driver->driver;
if (client->driver && !is_newstyle_driver(client->driver))
client->dev.release = i2c_client_release;
else
client->dev.release = i2c_client_dev_release;
snprintf(&client->dev.bus_id[0], sizeof(client->dev.bus_id),
"%d-%04x", i2c_adapter_id(adapter), client->addr);