i2c: Add i2c_board_info and i2c_new_device()

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>

1 files changed, 86 insertions, 4 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 3aac1b5c7cbd..a7dcdc69b9e7 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -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);