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127 lines
3.8 KiB
C
127 lines
3.8 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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#include "mbox.h"
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/* PL011 UART registers */
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#define UART0_DR ((volatile unsigned int*)(MMIO_BASE+0x00201000))
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#define UART0_FR ((volatile unsigned int*)(MMIO_BASE+0x00201018))
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#define UART0_IBRD ((volatile unsigned int*)(MMIO_BASE+0x00201024))
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#define UART0_FBRD ((volatile unsigned int*)(MMIO_BASE+0x00201028))
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#define UART0_LCRH ((volatile unsigned int*)(MMIO_BASE+0x0020102C))
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#define UART0_CR ((volatile unsigned int*)(MMIO_BASE+0x00201030))
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#define UART0_IMSC ((volatile unsigned int*)(MMIO_BASE+0x00201038))
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#define UART0_ICR ((volatile unsigned int*)(MMIO_BASE+0x00201044))
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/**
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* Set baud rate and characteristics (115200 8N1) and map to GPIO
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*/
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void uart_init()
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{
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register unsigned int r;
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/* initialize UART */
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*UART0_CR = 0; // turn off UART0
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/* set up clock for consistent divisor values */
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mbox[0] = 8*4;
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mbox[1] = MBOX_REQUEST;
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mbox[2] = MBOX_TAG_SETCLKRATE; // set clock rate
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mbox[3] = 12;
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mbox[4] = 8;
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mbox[5] = 2; // UART clock
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mbox[6] = 4000000; // 4Mhz
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mbox[7] = MBOX_TAG_LAST;
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mbox_call(MBOX_CH_PROP);
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/* map UART0 to GPIO pins */
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r=*GPFSEL1;
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r&=~((7<<12)|(7<<15)); // gpio14, gpio15
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r|=(2<<12)|(2<<15); // alt5
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*GPFSEL1 = r;
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*GPPUD = 0; // enable pins 14 and 15
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r=150; while(r--) { asm volatile("nop"); }
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*GPPUDCLK0 = (1<<14)|(1<<15);
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r=150; while(r--) { asm volatile("nop"); }
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*GPPUDCLK0 = 0; // flush GPIO setup
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*UART0_ICR = 0x7FF; // clear interrupts
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*UART0_IBRD = 2; // 115200 baud
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*UART0_FBRD = 0xB;
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*UART0_LCRH = 0b11<<5; // 8n1
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*UART0_CR = 0x301; // enable Tx, Rx, FIFO
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}
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/**
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* Send a character
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*/
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void uart_send(unsigned int c) {
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/* wait until we can send */
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do{asm volatile("nop");}while(*UART0_FR&0x20);
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/* write the carachter to the buffer */
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*UART0_DR=c;
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}
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/**
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* Receive a character
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*/
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char uart_getc() {
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char r;
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/* wait until something is in the buffer */
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do{asm volatile("nop");}while(*UART0_FR&0x10);
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/* read it and return */
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r=(char)(*UART0_DR);
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/* convert carrige return to newline */
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return r=='\r'?'\n':r;
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}
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/**
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* Display a string
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*/
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void uart_puts(char *s) {
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while(*s) {
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/* convert newline to carrige return + newline */
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if(*s=='\n')
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uart_send('\r');
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uart_send(*s++);
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}
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}
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/**
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* Display a binary value in hexadecimal
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*/
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void uart_hex(unsigned int d) {
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unsigned int n;
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int c;
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for(c=28;c>=0;c-=4) {
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// get highest tetrad
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n=(d>>c)&0xF;
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// 0-9 => '0'-'9', 10-15 => 'A'-'F'
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n+=n>9?0x37:0x30;
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uart_send(n);
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}
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}
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