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9c1600eda4
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>
91 lines
2.9 KiB
C
91 lines
2.9 KiB
C
/*
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* i2c-boardinfo.h - collect pre-declarations of I2C devices
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/kernel.h>
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#include <linux/i2c.h>
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#include "i2c-core.h"
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/* These symbols are exported ONLY FOR the i2c core.
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* No other users will be supported.
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*/
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DEFINE_MUTEX(__i2c_board_lock);
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EXPORT_SYMBOL_GPL(__i2c_board_lock);
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LIST_HEAD(__i2c_board_list);
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EXPORT_SYMBOL_GPL(__i2c_board_list);
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int __i2c_first_dynamic_bus_num;
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EXPORT_SYMBOL_GPL(__i2c_first_dynamic_bus_num);
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/**
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* i2c_register_board_info - statically declare I2C devices
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* @busnum: identifies the bus to which these devices belong
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* @info: vector of i2c device descriptors
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* @len: how many descriptors in the vector; may be zero to reserve
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* the specified bus number.
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*
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* Systems using the Linux I2C driver stack can declare tables of board info
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* while they initialize. This should be done in board-specific init code
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* near arch_initcall() time, or equivalent, before any I2C adapter driver is
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* registered. For example, mainboard init code could define several devices,
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* as could the init code for each daughtercard in a board stack.
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*
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* The I2C devices will be created later, after the adapter for the relevant
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* bus has been registered. After that moment, standard driver model tools
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* are used to bind "new style" I2C drivers to the devices. The bus number
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* for any device declared using this routine is not available for dynamic
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* allocation.
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*
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* The board info passed can safely be __initdata, but be careful of embedded
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* pointers (for platform_data, functions, etc) since that won't be copied.
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*/
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int __init
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i2c_register_board_info(int busnum,
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struct i2c_board_info const *info, unsigned len)
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{
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int status;
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mutex_lock(&__i2c_board_lock);
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/* dynamic bus numbers will be assigned after the last static one */
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if (busnum >= __i2c_first_dynamic_bus_num)
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__i2c_first_dynamic_bus_num = busnum + 1;
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for (status = 0; len; len--, info++) {
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struct i2c_devinfo *devinfo;
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devinfo = kzalloc(sizeof(*devinfo), GFP_KERNEL);
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if (!devinfo) {
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pr_debug("i2c-core: can't register boardinfo!\n");
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status = -ENOMEM;
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break;
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}
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devinfo->busnum = busnum;
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devinfo->board_info = *info;
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list_add_tail(&devinfo->list, &__i2c_board_list);
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}
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mutex_unlock(&__i2c_board_lock);
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return status;
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}
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