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/*
* Access system mailboxes
*/
#include "rpi_mailbox.h"
/* Mailbox memory addresses */
static volatile unsigned int *MAILBOX0READ = (unsigned int *) (0x2000b880);
static volatile unsigned int *MAILBOX0STATUS = (unsigned int *) (0x2000b898);
static volatile unsigned int *MAILBOX0WRITE = (unsigned int *) (0x2000b8a0);
/* Bit 31 set in status register if the write mailbox is full */
#define MAILBOX_FULL 0x80000000
/* Bit 30 set in status register if the read mailbox is empty */
#define MAILBOX_EMPTY 0x40000000
unsigned int rpi_readmailbox(unsigned int channel)
{
unsigned int val;
if (channel > 15)
return 0xFFFFFFFF;
/* Wait for mailbox to be full */
while (*MAILBOX0STATUS & MAILBOX_EMPTY);
val = *MAILBOX0READ;
if ((val & 15) == channel)
return (val & 0xFFFFFFF0);
else
return 0xFFFFFFFF;
}
void rpi_writemailbox(unsigned int channel, unsigned int data)
{
if (channel > 15)
return;
if (data & 0x000F)
return;
/* Wait for mailbox to be not full */
while (*MAILBOX0STATUS & MAILBOX_FULL);
*MAILBOX0WRITE = (data | channel);
}
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