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authorDavid Brownell <david-b@pacbell.net>2007-05-02 01:26:31 +0400
committerJean Delvare <khali@hyperion.delvare>2007-05-02 01:26:31 +0400
commit9c1600eda42e52796f49b36cf15b9debcfd09bea (patch)
treefe93f5924c7777cd5c3cc1ef6033dd2dfae542b5 /drivers/i2c/i2c-boardinfo.c
parent4298cfc3eb6110df989f784be516c6340c597a66 (diff)
downloadlinux-9c1600eda42e52796f49b36cf15b9debcfd09bea.tar.xz
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>
Diffstat (limited to 'drivers/i2c/i2c-boardinfo.c')
-rw-r--r--drivers/i2c/i2c-boardinfo.c90
1 files changed, 90 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-boardinfo.c b/drivers/i2c/i2c-boardinfo.c
new file mode 100644
index 000000000000..ffb35f09df03
--- /dev/null
+++ b/drivers/i2c/i2c-boardinfo.c
@@ -0,0 +1,90 @@
+/*
+ * i2c-boardinfo.h - collect pre-declarations of I2C devices
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/i2c.h>
+
+#include "i2c-core.h"
+
+
+/* These symbols are exported ONLY FOR the i2c core.
+ * No other users will be supported.
+ */
+DEFINE_MUTEX(__i2c_board_lock);
+EXPORT_SYMBOL_GPL(__i2c_board_lock);
+
+LIST_HEAD(__i2c_board_list);
+EXPORT_SYMBOL_GPL(__i2c_board_list);
+
+int __i2c_first_dynamic_bus_num;
+EXPORT_SYMBOL_GPL(__i2c_first_dynamic_bus_num);
+
+
+/**
+ * i2c_register_board_info - statically declare I2C devices
+ * @busnum: identifies the bus to which these devices belong
+ * @info: vector of i2c device descriptors
+ * @len: how many descriptors in the vector; may be zero to reserve
+ * the specified bus number.
+ *
+ * Systems using the Linux I2C driver stack can declare tables of board info
+ * while they initialize. This should be done in board-specific init code
+ * near arch_initcall() time, or equivalent, before any I2C adapter driver is
+ * registered. For example, mainboard init code could define several devices,
+ * as could the init code for each daughtercard in a board stack.
+ *
+ * The I2C devices will be created later, after the adapter for the relevant
+ * bus has been registered. After that moment, standard driver model tools
+ * are used to bind "new style" I2C drivers to the devices. The bus number
+ * for any device declared using this routine is not available for dynamic
+ * allocation.
+ *
+ * The board info passed can safely be __initdata, but be careful of embedded
+ * pointers (for platform_data, functions, etc) since that won't be copied.
+ */
+int __init
+i2c_register_board_info(int busnum,
+ struct i2c_board_info const *info, unsigned len)
+{
+ int status;
+
+ mutex_lock(&__i2c_board_lock);
+
+ /* dynamic bus numbers will be assigned after the last static one */
+ if (busnum >= __i2c_first_dynamic_bus_num)
+ __i2c_first_dynamic_bus_num = busnum + 1;
+
+ for (status = 0; len; len--, info++) {
+ struct i2c_devinfo *devinfo;
+
+ devinfo = kzalloc(sizeof(*devinfo), GFP_KERNEL);
+ if (!devinfo) {
+ pr_debug("i2c-core: can't register boardinfo!\n");
+ status = -ENOMEM;
+ break;
+ }
+
+ devinfo->busnum = busnum;
+ devinfo->board_info = *info;
+ list_add_tail(&devinfo->list, &__i2c_board_list);
+ }
+
+ mutex_unlock(&__i2c_board_lock);
+
+ return status;
+}