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https://github.com/rust-embedded/rust-raspberrypi-OS-tutorials.git
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64 lines
2.6 KiB
C
64 lines
2.6 KiB
C
/*
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* Copyright (C) 2018 bzt (bztsrc@github)
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy,
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* modify, merge, publish, distribute, sublicense, and/or sell copies
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* of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*
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*/
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#include "gpio.h"
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/* mailbox message buffer */
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volatile unsigned int __attribute__((aligned(16))) mbox[36];
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#define VIDEOCORE_MBOX (MMIO_BASE+0x0000B880)
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#define MBOX_READ ((volatile unsigned int*)(VIDEOCORE_MBOX+0x0))
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#define MBOX_POLL ((volatile unsigned int*)(VIDEOCORE_MBOX+0x10))
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#define MBOX_SENDER ((volatile unsigned int*)(VIDEOCORE_MBOX+0x14))
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#define MBOX_STATUS ((volatile unsigned int*)(VIDEOCORE_MBOX+0x18))
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#define MBOX_CONFIG ((volatile unsigned int*)(VIDEOCORE_MBOX+0x1C))
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#define MBOX_WRITE ((volatile unsigned int*)(VIDEOCORE_MBOX+0x20))
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#define MBOX_RESPONSE 0x80000000
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#define MBOX_FULL 0x80000000
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#define MBOX_EMPTY 0x40000000
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/**
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* Make a mailbox call. Returns 0 on failure, non-zero on success
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*/
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int mbox_call(unsigned char ch)
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{
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unsigned int r;
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/* wait until we can write to the mailbox */
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do{asm volatile("nop");}while(*MBOX_STATUS & MBOX_FULL);
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/* write the address of our message to the mailbox with channel identifier */
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*MBOX_WRITE = (((unsigned int)((unsigned long)&mbox)&~0xF) | (ch&0xF));
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/* now wait for the response */
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while(1) {
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/* is there a response? */
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do{asm volatile("nop");}while(*MBOX_STATUS & MBOX_EMPTY);
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r=*MBOX_READ;
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/* is it a response to our message? */
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if((unsigned char)(r&0xF)==ch && (r&~0xF)==(unsigned int)((unsigned long)&mbox))
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/* is it a valid successful response? */
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return mbox[1]==MBOX_RESPONSE;
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}
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return 0;
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}
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