1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Joshua Henderson <joshua.henderson@microchip.com>
4 * Copyright (C) 2015 Microchip Technology Inc. All rights reserved.
5 */
6 #include <linux/io.h>
7 #include <linux/platform_data/pic32.h>
8 #include <asm/fw/fw.h>
9 #include <asm/setup.h>
10
11 #include "pic32mzda.h"
12 #include "early_pin.h"
13
14 /* Default early console parameters */
15 #define EARLY_CONSOLE_PORT 1
16 #define EARLY_CONSOLE_BAUDRATE 115200
17
18 #define UART_ENABLE BIT(15)
19 #define UART_ENABLE_RX BIT(12)
20 #define UART_ENABLE_TX BIT(10)
21 #define UART_TX_FULL BIT(9)
22
23 /* UART1(x == 0) - UART6(x == 5) */
24 #define UART_BASE(x) ((x) * 0x0200)
25 #define U_MODE(x) UART_BASE(x)
26 #define U_STA(x) (UART_BASE(x) + 0x10)
27 #define U_TXR(x) (UART_BASE(x) + 0x20)
28 #define U_BRG(x) (UART_BASE(x) + 0x40)
29
30 static void __iomem *uart_base;
31 static int console_port = -1;
32
configure_uart_pins(int port)33 static int __init configure_uart_pins(int port)
34 {
35 switch (port) {
36 case 1:
37 pic32_pps_input(IN_FUNC_U2RX, IN_RPB0);
38 pic32_pps_output(OUT_FUNC_U2TX, OUT_RPG9);
39 break;
40 case 5:
41 pic32_pps_input(IN_FUNC_U6RX, IN_RPD0);
42 pic32_pps_output(OUT_FUNC_U6TX, OUT_RPB8);
43 break;
44 default:
45 return -1;
46 }
47
48 return 0;
49 }
50
configure_uart(int port,int baud)51 static void __init configure_uart(int port, int baud)
52 {
53 u32 pbclk;
54
55 pbclk = pic32_get_pbclk(2);
56
57 __raw_writel(0, uart_base + U_MODE(port));
58 __raw_writel(((pbclk / baud) / 16) - 1, uart_base + U_BRG(port));
59 __raw_writel(UART_ENABLE, uart_base + U_MODE(port));
60 __raw_writel(UART_ENABLE_TX | UART_ENABLE_RX,
61 uart_base + PIC32_SET(U_STA(port)));
62 }
63
setup_early_console(int port,int baud)64 static void __init setup_early_console(int port, int baud)
65 {
66 if (configure_uart_pins(port))
67 return;
68
69 console_port = port;
70 configure_uart(console_port, baud);
71 }
72
pic32_getcmdline(void)73 static char * __init pic32_getcmdline(void)
74 {
75 /*
76 * arch_mem_init() has not been called yet, so we don't have a real
77 * command line setup if using CONFIG_CMDLINE_BOOL.
78 */
79 #ifdef CONFIG_CMDLINE_OVERRIDE
80 return CONFIG_CMDLINE;
81 #else
82 return fw_getcmdline();
83 #endif
84 }
85
get_port_from_cmdline(char * arch_cmdline)86 static int __init get_port_from_cmdline(char *arch_cmdline)
87 {
88 char *s;
89 int port = -1;
90
91 if (!arch_cmdline || *arch_cmdline == '\0')
92 goto _out;
93
94 s = strstr(arch_cmdline, "earlyprintk=");
95 if (s) {
96 s = strstr(s, "ttyS");
97 if (s)
98 s += 4;
99 else
100 goto _out;
101
102 port = (*s) - '0';
103 }
104
105 _out:
106 return port;
107 }
108
get_baud_from_cmdline(char * arch_cmdline)109 static int __init get_baud_from_cmdline(char *arch_cmdline)
110 {
111 char *s;
112 int baud = -1;
113
114 if (!arch_cmdline || *arch_cmdline == '\0')
115 goto _out;
116
117 s = strstr(arch_cmdline, "earlyprintk=");
118 if (s) {
119 s = strstr(s, "ttyS");
120 if (s)
121 s += 6;
122 else
123 goto _out;
124
125 baud = 0;
126 while (*s >= '0' && *s <= '9')
127 baud = baud * 10 + *s++ - '0';
128 }
129
130 _out:
131 return baud;
132 }
133
fw_init_early_console(void)134 void __init fw_init_early_console(void)
135 {
136 char *arch_cmdline = pic32_getcmdline();
137 int baud, port;
138
139 uart_base = ioremap(PIC32_BASE_UART, 0xc00);
140
141 baud = get_baud_from_cmdline(arch_cmdline);
142 port = get_port_from_cmdline(arch_cmdline);
143
144 if (port == -1)
145 port = EARLY_CONSOLE_PORT;
146
147 if (baud == -1)
148 baud = EARLY_CONSOLE_BAUDRATE;
149
150 setup_early_console(port, baud);
151 }
152
prom_putchar(char c)153 void prom_putchar(char c)
154 {
155 if (console_port >= 0) {
156 while (__raw_readl(
157 uart_base + U_STA(console_port)) & UART_TX_FULL)
158 ;
159
160 __raw_writel(c, uart_base + U_TXR(console_port));
161 }
162 }
163