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, 31 insertions, 0 deletions

diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h
new file mode 100644
index 000000000000..cd5bff874855
--- /dev/null
+++ b/drivers/i2c/i2c-core.h
@@ -0,0 +1,31 @@
+/*
+ * i2c-core.h - interfaces internal to the I2C framework
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+struct i2c_devinfo {
+        struct list_head        list;
+        int                     busnum;
+        struct i2c_board_info   board_info;
+};
+
+/* board_lock protects board_list and first_dynamic_bus_num.
+ * only i2c core components are allowed to use these symbols.
+ */
+extern struct mutex     __i2c_board_lock;
+extern struct list_head __i2c_board_list;
+extern int              __i2c_first_dynamic_bus_num;
+