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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/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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