b5527a7766
SMBus alert support. The SMBus alert protocol allows several SMBus slave devices to share a single interrupt pin on the SMBus master, while still allowing the master to know which slave triggered the interrupt. This is based on preliminary work by David Brownell. The key difference between David's implementation and mine is that his was part of i2c-core, while mine is split into a separate, standalone module named i2c-smbus. The i2c-smbus module is meant to include support for all SMBus extensions to the I2C protocol in the future. The benefit of this approach is a zero cost for I2C bus segments which do not need SMBus alert support. Where David's implementation increased the size of struct i2c_adapter by 7% (40 bytes on i386), mine doesn't touch it. Where David's implementation added over 150 lines of code to i2c-core (+10%), mine doesn't touch it. The only change that touches all the users of the i2c subsystem is a new callback in struct i2c_driver (common to both implementations.) I seem to remember Trent was worried about the footprint of David'd implementation, hopefully mine addresses the issue. Signed-off-by: Jean Delvare <khali@linux-fr.org> Acked-by: Jonathan Cameron <jic23@cam.ac.uk> Cc: David Brownell <dbrownell@users.sourceforge.net> Cc: Trent Piepho <tpiepho@freescale.com>
50 lines
1.7 KiB
C
50 lines
1.7 KiB
C
/*
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* i2c-smbus.h - SMBus extensions to the I2C protocol
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*
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* Copyright (C) 2010 Jean Delvare <khali@linux-fr.org>
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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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#ifndef _LINUX_I2C_SMBUS_H
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#define _LINUX_I2C_SMBUS_H
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#include <linux/i2c.h>
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/**
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* i2c_smbus_alert_setup - platform data for the smbus_alert i2c client
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* @alert_edge_triggered: whether the alert interrupt is edge (1) or level (0)
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* triggered
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* @irq: IRQ number, if the smbus_alert driver should take care of interrupt
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* handling
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*
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* If irq is not specified, the smbus_alert driver doesn't take care of
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* interrupt handling. In that case it is up to the I2C bus driver to either
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* handle the interrupts or to poll for alerts.
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*
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* If irq is specified then it it crucial that alert_edge_triggered is
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* properly set.
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*/
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struct i2c_smbus_alert_setup {
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unsigned int alert_edge_triggered:1;
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int irq;
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};
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struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
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struct i2c_smbus_alert_setup *setup);
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int i2c_handle_smbus_alert(struct i2c_client *ara);
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#endif /* _LINUX_I2C_SMBUS_H */
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