linux-hardened/include/linux/w1-gpio.h
Daniel Mack c8a06c1ef0 w1-gpio: add external pull-up enable callback
On embedded devices, sleep mode conditions can be tricky to handle,
Especially when processors tend to pull-down the w1 bus during sleep.  Bus
slaves (such as the ds2760) may interpret this as a reason for power-down
conditions and entirely switch off the device.

This patch adds a callback function pointer to let users switch on and off
the external pull-up resistor.  This lets the outside world know whether
the processor is currently actively driving the bus or not.

When this callback is not provided, the code behaviour won't change.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Acked-by: Ville Syrjala <syrjala@sci.fi>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-18 13:03:58 -07:00

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C

/*
* w1-gpio interface to platform code
*
* Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*/
#ifndef _LINUX_W1_GPIO_H
#define _LINUX_W1_GPIO_H
/**
* struct w1_gpio_platform_data - Platform-dependent data for w1-gpio
* @pin: GPIO pin to use
* @is_open_drain: GPIO pin is configured as open drain
*/
struct w1_gpio_platform_data {
unsigned int pin;
unsigned int is_open_drain:1;
void (*enable_external_pullup)(int enable);
};
#endif /* _LINUX_W1_GPIO_H */