1 files changed, 34 insertions, 1 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index b346a687ab59..42e852d79ffa 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -437,6 +437,10 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 {
         int res = 0, dummy;
 
+        /* Can't register until after driver model init */
+        if (unlikely(WARN_ON(!i2c_bus_type.p)))
+                return -EAGAIN;
+
         mutex_init(&adap->bus_lock);
         mutex_init(&adap->clist_lock);
         INIT_LIST_HEAD(&adap->clients);
@@ -696,6 +700,10 @@ int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
 {
         int res;
 
+        /* Can't register until after driver model init */
+        if (unlikely(WARN_ON(!i2c_bus_type.p)))
+                return -EAGAIN;
+
         /* new style driver methods can't mix with legacy ones */
         if (is_newstyle_driver(driver)) {
                 if (driver->attach_adapter || driver->detach_adapter
@@ -978,7 +986,10 @@ static void __exit i2c_exit(void)
         bus_unregister(&i2c_bus_type);
 }
 
-subsys_initcall(i2c_init);
+/* We must initialize early, because some subsystems register i2c drivers
+ * in subsys_initcall() code, but are linked (and initialized) before i2c.
+ */
+postcore_initcall(i2c_init);
 module_exit(i2c_exit);
 
 /* ----------------------------------------------------
@@ -1677,6 +1688,28 @@ s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value)
 EXPORT_SYMBOL(i2c_smbus_write_word_data);
 
 /**
+ * i2c_smbus_process_call - SMBus "process call" protocol
+ * @client: Handle to slave device
+ * @command: Byte interpreted by slave
+ * @value: 16-bit "word" being written
+ *
+ * This executes the SMBus "process call" protocol, returning negative errno
+ * else a 16-bit unsigned "word" received from the device.
+ */
+s32 i2c_smbus_process_call(struct i2c_client *client, u8 command, u16 value)
+{
+        union i2c_smbus_data data;
+        int status;
+        data.word = value;
+
+        status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+                                I2C_SMBUS_WRITE, command,
+                                I2C_SMBUS_PROC_CALL, &data);
+        return (status < 0) ? status : data.word;
+}
+EXPORT_SYMBOL(i2c_smbus_process_call);
+
+/**
  * i2c_smbus_read_block_data - SMBus "block read" protocol
  * @client: Handle to slave device
  * @command: Byte interpreted by slave