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>
W1 master implementations are expected to return 0 or 1 from their
read_bit() function. However, not all platforms do return these values
from gpio_get_value() - namely PXAs won't. Hence the w1 gpio-master needs
to break the result down to 0 or 1 itself.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Ville Syrjala <syrjala@sci.fi>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a GPIO 1-wire bus master driver. The driver used the GPIO API to
control the wire and the GPIO pin can be specified using platform data
similar to i2c-gpio. The driver was tested with AT91SAM9260 + DS2401.
Signed-off-by: Ville Syrjala <syrjala@sci.fi>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Daniel Mack