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