1 /*
2 * Copyright (C) 2018 bzt (bztsrc@github)
3 *
4 * Permission is hereby granted, free of charge, to any person
5 * obtaining a copy of this software and associated documentation
6 * files (the "Software"), to deal in the Software without
7 * restriction, including without limitation the rights to use, copy,
8 * modify, merge, publish, distribute, sublicense, and/or sell copies
9 * of the Software, and to permit persons to whom the Software is
10 * furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
19 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
20 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
22 * DEALINGS IN THE SOFTWARE.
23 *
24 */
25
26 #include "gpio.h"
27
28 /* Auxilary mini UART registers */
29 #define AUX_ENABLE ((volatile unsigned int*)(MMIO_BASE+0x00215004))
30 #define AUX_MU_IO ((volatile unsigned int*)(MMIO_BASE+0x00215040))
31 #define AUX_MU_IER ((volatile unsigned int*)(MMIO_BASE+0x00215044))
32 #define AUX_MU_IIR ((volatile unsigned int*)(MMIO_BASE+0x00215048))
33 #define AUX_MU_LCR ((volatile unsigned int*)(MMIO_BASE+0x0021504C))
34 #define AUX_MU_MCR ((volatile unsigned int*)(MMIO_BASE+0x00215050))
35 #define AUX_MU_LSR ((volatile unsigned int*)(MMIO_BASE+0x00215054))
36 #define AUX_MU_MSR ((volatile unsigned int*)(MMIO_BASE+0x00215058))
37 #define AUX_MU_SCRATCH ((volatile unsigned int*)(MMIO_BASE+0x0021505C))
38 #define AUX_MU_CNTL ((volatile unsigned int*)(MMIO_BASE+0x00215060))
39 #define AUX_MU_STAT ((volatile unsigned int*)(MMIO_BASE+0x00215064))
40 #define AUX_MU_BAUD ((volatile unsigned int*)(MMIO_BASE+0x00215068))
41
42 /**
43 * Set baud rate and characteristics (115200 8N1) and map to GPIO
44 */
uart_init()45 void uart_init()
46 {
47 register unsigned int r;
48
49 /* initialize UART */
50 *AUX_ENABLE |=1; // enable UART1, AUX mini uart
51 *AUX_MU_CNTL = 0;
52 *AUX_MU_LCR = 3; // 8 bits
53 *AUX_MU_MCR = 0;
54 *AUX_MU_IER = 0;
55 *AUX_MU_IIR = 0xc6; // disable interrupts
56 *AUX_MU_BAUD = 270; // 115200 baud
57 /* map UART1 to GPIO pins */
58 r=*GPFSEL1;
59 r&=~((7<<12)|(7<<15)); // gpio14, gpio15
60 r|=(2<<12)|(2<<15); // alt5
61 *GPFSEL1 = r;
62 *GPPUD = 0; // enable pins 14 and 15
63 r=150; while(r--) { asm volatile("nop"); }
64 *GPPUDCLK0 = (1<<14)|(1<<15);
65 r=150; while(r--) { asm volatile("nop"); }
66 *GPPUDCLK0 = 0; // flush GPIO setup
67 *AUX_MU_CNTL = 3; // enable Tx, Rx
68 }
69
70 /**
71 * Send a character
72 */
uart_send(unsigned int c)73 void uart_send(unsigned int c) {
74 /* wait until we can send */
75 do{asm volatile("nop");}while(!(*AUX_MU_LSR&0x20));
76 /* write the character to the buffer */
77 *AUX_MU_IO=c;
78 }
79
80 /**
81 * Receive a character
82 */
uart_getc()83 char uart_getc() {
84 char r;
85 /* wait until something is in the buffer */
86 do{asm volatile("nop");}while(!(*AUX_MU_LSR&0x01));
87 /* read it and return */
88 r=(char)(*AUX_MU_IO);
89 /* convert carrige return to newline */
90 return r=='\r'?'\n':r;
91 }
92
93 /**
94 * Display a string
95 */
uart_puts(char * s)96 void uart_puts(char *s) {
97 while(*s) {
98 /* convert newline to carrige return + newline */
99 if(*s=='\n')
100 uart_send('\r');
101 uart_send(*s++);
102 }
103 }
104