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/**
* @file
*
* @ingroup raspberrypi
*
* @brief mailbox support.
*/
/*
* Copyright (c) 2015 Yang Qiao
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
*
* http://www.rtems.org/license/LICENSE
*
*/
#include <stdint.h>
#include <stdbool.h>
#include <bsp.h>
#include <bsp/raspberrypi.h>
#include <bsp/mailbox.h>
#define BCM2835_MBOX_DATA_MASK( data ) ( data & 0xFFFFFFF0U )
#define BCM2835_MBOX_CHANNEL_MASK( data ) ( data & 0xFU )
static inline bool bcm2835_mailbox_is_empty( void )
{
return ( BCM2835_REG( BCM2835_MBOX_STATUS ) & BCM2835_MBOX_EMPTY );
}
static inline bool bcm2835_mailbox_is_full( void )
{
return ( BCM2835_REG( BCM2835_MBOX_STATUS ) & BCM2835_MBOX_FULL );
}
unsigned int raspberrypi_mailbox_read( unsigned int channel )
{
unsigned int raw;
unsigned int read_channel;
while ( 1 ) {
while ( bcm2835_mailbox_is_empty() ) ;
raw = BCM2835_REG( BCM2835_MBOX_READ );
read_channel = BCM2835_MBOX_CHANNEL_MASK( raw );
if ( read_channel == channel )
return BCM2835_MBOX_DATA_MASK( raw );
}
}
void raspberrypi_mailbox_write(
unsigned int channel,
unsigned int data
)
{
while ( bcm2835_mailbox_is_full() ) ;
BCM2835_REG( BCM2835_MBOX_WRITE ) =
BCM2835_MBOX_DATA_MASK( data ) |
BCM2835_MBOX_CHANNEL_MASK( channel );
}
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