1 /*
2 * This file and its contents are supplied under the terms of the
3 * Common Development and Distribution License ("CDDL"), version 1.0.
4 * You may only use this file in accordance with the terms of version
5 * 1.0 of the CDDL.
6 *
7 * A full copy of the text of the CDDL should have accompanied this
8 * source. A copy of the CDDL is also available via the Internet at
9 * http://www.illumos.org/license/CDDL.
10 */
11
12 /*
13 * Copyright 2013 (c) Joyent, Inc. All rights reserved.
14 */
15
16 /*
17 * A simple uart driver for the RPi.
18 */
19 #include <sys/types.h>
20
21 extern uint32_t arm_reg_read(uint32_t);
22 extern void arm_reg_write(uint32_t, uint32_t);
23
24 /*
25 * The primary serial console that we end up using is not in fact a normal UART,
26 * but is instead actually a mini-uart that shares interrupts and registers with
27 * the SPI masters as well. While the RPi also supports another more traditional
28 * UART, that isn't what we are actually hooking up to generally with the
29 * adafruit cable. We already wasted our time having to figure that out. -_-
30 */
31
32 #define AUX_BASE 0x20215000
33 #define AUX_ENABLES 0x4
34 #define AUX_MU_IO_REG 0x40
35 #define AUX_MU_IER_REG 0x44
36 #define AUX_MU_IIR_REG 0x48
37 #define AUX_MU_LCR_REG 0x4C
38 #define AUX_MU_MCR_REG 0x50
39 #define AUX_MU_LSR_REG 0x54
40 #define AUX_MU_CNTL_REG 0x60
41 #define AUX_MU_BAUD 0x68
42
43 #define AUX_MU_RX_READY 0x01
44 #define AUX_MU_TX_READY 0x20
45
46 /*
47 * For the mini UART, all we care about are pins 14 and 15 for the UART.
48 * Specifically, alt5 for GPIO14 is TXD1 and GPIO15 is RXD1. Those are
49 * controlled by FSEL1.
50 */
51 #define GPIO_BASE 0x20200000
52 #define GPIO_FSEL1 0x4
53 #define GPIO_PUD 0x94
54 #define GPIO_PUDCLK0 0x98
55
56 #define GPIO_SEL_ALT5 0x2
57 #define GPIO_UART_MASK 0xfffc0fff
58 #define GPIO_UART_TX_SHIFT 12
59 #define GPIO_UART_RX_SHIFT 15
60
61 #define GPIO_PUD_DISABLE 0x0
62 #define GPIO_PUDCLK_UART 0x0000c000
63
64 /*
65 * A simple nop
66 */
67 static void
68 bcm2835_miniuart_nop(void)
69 {
70 __asm__ volatile("mov r0, r0\n" : : :);
71 }
72
73 void
74 bcm2835_miniuart_init(void)
75 {
76 uint32_t v;
77 int i;
78
79 /* Enable the mini UAT */
80 arm_reg_write(AUX_BASE + AUX_ENABLES, 0x1);
81
82 /* Disable interrupts */
83 arm_reg_write(AUX_BASE + AUX_MU_IER_REG, 0x0);
84
85 /* Disable the RX and TX */
86 arm_reg_write(AUX_BASE + AUX_MU_CNTL_REG, 0x0);
87
88 /*
89 * Enable 8-bit word length. External sources tell us the PRM is buggy
90 * here and that even though bit 1 is reserved, we need to actually set
91 * it to get 8-bit words.
92 */
93 arm_reg_write(AUX_BASE + AUX_MU_LCR_REG, 0x3);
94
95 /* Set RTS high */
96 arm_reg_write(AUX_BASE + AUX_MU_MCR_REG, 0x0);
97
98 /* Disable interrupts */
99 arm_reg_write(AUX_BASE + AUX_MU_IER_REG, 0x0);
100
101 /* Set baud rate */
102 arm_reg_write(AUX_BASE + AUX_MU_IIR_REG, 0xc6);
103 arm_reg_write(AUX_BASE + AUX_MU_BAUD, 0x10e);
104
105 /* TODO: Factor out the gpio bits */
106 v = arm_reg_read(GPIO_BASE + GPIO_FSEL1);
107 v &= GPIO_UART_MASK;
108 v |= GPIO_SEL_ALT5 << GPIO_UART_RX_SHIFT;
109 v |= GPIO_SEL_ALT5 << GPIO_UART_TX_SHIFT;
110 arm_reg_write(GPIO_BASE + GPIO_FSEL1, v);
111
112 arm_reg_write(GPIO_BASE + GPIO_PUD, GPIO_PUD_DISABLE);
113 for (i = 0; i < 150; i++)
114 bcm2835_miniuart_nop();
115 arm_reg_write(GPIO_BASE + GPIO_PUDCLK0, GPIO_PUDCLK_UART);
116 for (i = 0; i < 150; i++)
117 bcm2835_miniuart_nop();
118 arm_reg_write(GPIO_BASE + GPIO_PUDCLK0, 0);
119
120 /* Finally, go back and enable RX and TX */
121 arm_reg_write(AUX_BASE + AUX_MU_CNTL_REG, 0x3);
122 }
123
124 void
125 bcm2835_miniuart_putc(uint8_t c)
126 {
127 for (;;) {
128 if (arm_reg_read(AUX_BASE + AUX_MU_LSR_REG) & AUX_MU_TX_READY)
129 break;
130 }
131 arm_reg_write(AUX_BASE + AUX_MU_IO_REG, c & 0x7f);
132 if (c == '\n')
133 bcm2835_miniuart_putc('\r');
134 }
135
136 uint8_t
137 bcm2835_miniuart_getc(void)
138 {
139 for (;;) {
140 if (arm_reg_read(AUX_BASE + AUX_MU_LSR_REG) & AUX_MU_RX_READY)
141 break;
142 }
143 return (arm_reg_read(AUX_BASE + AUX_MU_IO_REG) & 0x7f);
144 }
145
146 int
147 bcm2835_miniuart_isc(void)
148 {
149 return (arm_reg_read(AUX_BASE + AUX_MU_LSR_REG) & AUX_MU_RX_READY);
150 }