2 files changed, 101 insertions, 26 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index a7dcdc69b9e7..c50229bd9f85 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -320,38 +320,19 @@ static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
         mutex_unlock(&__i2c_board_lock);
 }
 
-
-/* -----
- * i2c_add_adapter is called from within the algorithm layer,
- * when a new hw adapter registers. A new device is register to be
- * available for clients.
- */
-int i2c_add_adapter(struct i2c_adapter *adap)
+static int i2c_register_adapter(struct i2c_adapter *adap)
 {
-        int id, res = 0;
+        int res = 0;
         struct list_head   *item;
         struct i2c_driver  *driver;
 
-        mutex_lock(&core_lists);
-
-        if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0) {
-                res = -ENOMEM;
-                goto out_unlock;
-        }
-
-        res = idr_get_new(&i2c_adapter_idr, adap, &id);
-        if (res < 0) {
-                if (res == -EAGAIN)
-                        res = -ENOMEM;
-                goto out_unlock;
-        }
-
-        adap->nr =  id & MAX_ID_MASK;
         mutex_init(&adap->bus_lock);
         mutex_init(&adap->clist_lock);
-        list_add_tail(&adap->list,&adapters);
         INIT_LIST_HEAD(&adap->clients);
 
+        mutex_lock(&core_lists);
+        list_add_tail(&adap->list, &adapters);
+
         /* Add the adapter to the driver core.
          * If the parent pointer is not set up,
          * we add this adapter to the host bus.
@@ -370,6 +351,10 @@ int i2c_add_adapter(struct i2c_adapter *adap)
 
         dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
 
+        /* create pre-declared device nodes for new-style drivers */
+        if (adap->nr < __i2c_first_dynamic_bus_num)
+                i2c_scan_static_board_info(adap);
+
         /* let legacy drivers scan this bus for matching devices */
         list_for_each(item,&drivers) {
                 driver = list_entry(item, struct i2c_driver, list);
@@ -388,6 +373,93 @@ out_list:
         goto out_unlock;
 }
 
+/**
+ * i2c_add_adapter - declare i2c adapter, use dynamic bus number
+ * @adapter: the adapter to add
+ *
+ * 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.
+ *
+ * When this returns zero, a new bus number was allocated and stored
+ * in adap->nr, and the specified adapter became available for clients.
+ * Otherwise, a negative errno value is returned.
+ */
+int i2c_add_adapter(struct i2c_adapter *adapter)
+{
+        int     id, res = 0;
+
+retry:
+        if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
+                return -ENOMEM;
+
+        mutex_lock(&core_lists);
+        /* "above" here means "above or equal to", sigh */
+        res = idr_get_new_above(&i2c_adapter_idr, adapter,
+                                __i2c_first_dynamic_bus_num, &id);
+        mutex_unlock(&core_lists);
+
+        if (res < 0) {
+                if (res == -EAGAIN)
+                        goto retry;
+                return res;
+        }
+
+        adapter->nr = id;
+        return i2c_register_adapter(adapter);
+}
+EXPORT_SYMBOL(i2c_add_adapter);
+
+/**
+ * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
+ * @adap: the adapter to register (with adap->nr initialized)
+ *
+ * This routine is used to declare an I2C adapter when its bus number
+ * matters.  Example: for I2C adapters from system-on-chip CPUs, or
+ * otherwise built in to the system's mainboard, and where i2c_board_info
+ * is used to properly configure I2C devices.
+ *
+ * If no devices have pre-been declared for this bus, then be sure to
+ * register the adapter before any dynamically allocated ones.  Otherwise
+ * the required bus ID may not be available.
+ *
+ * When this returns zero, the specified adapter became available for
+ * clients using the bus number provided in adap->nr.  Also, the table
+ * of I2C devices pre-declared using i2c_register_board_info() is scanned,
+ * and the appropriate driver model device nodes are created.  Otherwise, a
+ * negative errno value is returned.
+ */
+int i2c_add_numbered_adapter(struct i2c_adapter *adap)
+{
+        int     id;
+        int     status;
+
+        if (adap->nr & ~MAX_ID_MASK)
+                return -EINVAL;
+
+retry:
+        if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
+                return -ENOMEM;
+
+        mutex_lock(&core_lists);
+        /* "above" here means "above or equal to", sigh;
+         * we need the "equal to" result to force the result
+         */
+        status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
+        if (status == 0 && id != adap->nr) {
+                status = -EBUSY;
+                idr_remove(&i2c_adapter_idr, id);
+        }
+        mutex_unlock(&core_lists);
+        if (status == -EAGAIN)
+                goto retry;
+
+        if (status == 0)
+                status = i2c_register_adapter(adap);
+        return status;
+}
+EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
+
 int i2c_del_adapter(struct i2c_adapter *adap)
 {
         struct list_head  *item, *_n;
@@ -452,7 +524,7 @@ int i2c_del_adapter(struct i2c_adapter *adap)
         /* wait for sysfs to drop all references */
         wait_for_completion(&adap->dev_released);
 
-        /* free dynamically allocated bus id */
+        /* free bus id */
         idr_remove(&i2c_adapter_idr, adap->nr);
 
         dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
@@ -493,6 +565,9 @@ int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
         driver->driver.owner = owner;
         driver->driver.bus = &i2c_bus_type;
 
+        /* for new style drivers, when registration returns the driver core
+         * will have called probe() for all matching-but-unbound devices.
+         */
         res = driver_register(&driver->driver);
         if (res)
                 return res;
@@ -1377,7 +1452,6 @@ EXPORT_SYMBOL_GPL(i2c_adapter_dev_release);
 EXPORT_SYMBOL_GPL(i2c_adapter_class);
 EXPORT_SYMBOL_GPL(i2c_bus_type);
 
-EXPORT_SYMBOL(i2c_add_adapter);
 EXPORT_SYMBOL(i2c_del_adapter);
 EXPORT_SYMBOL(i2c_del_driver);
 EXPORT_SYMBOL(i2c_attach_client);
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 382a43bf3ad5..36d6814a6df4 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -363,6 +363,7 @@ struct i2c_client_address_data {
  */
 extern int i2c_add_adapter(struct i2c_adapter *);
 extern int i2c_del_adapter(struct i2c_adapter *);
+extern int i2c_add_numbered_adapter(struct i2c_adapter *);
 
 extern int i2c_register_driver(struct module *, struct i2c_driver *);
 extern int i2c_del_driver(struct i2c_driver *);