arch/mips/pic32/pic32mzda/early_console.c

   1 /*
   2  * Joshua Henderson <joshua.henderson@microchip.com>
   3  * Copyright (C) 2015 Microchip Technology Inc.  All rights reserved.
   4  *
   5  *  This program is free software; you can distribute it and/or modify it
   6  *  under the terms of the GNU General Public License (Version 2) as
   7  *  published by the Free Software Foundation.
   8  *
   9  *  This program is distributed in the hope it will be useful, but WITHOUT
  10  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  *  for more details.
  13  */
  14 #include <asm/mach-pic32/pic32.h>
  15 #include <asm/fw/fw.h>
  16
  17 #include "pic32mzda.h"
  18 #include "early_pin.h"
  19
  20 /* Default early console parameters */
  21 #define EARLY_CONSOLE_PORT      1
  22 #define EARLY_CONSOLE_BAUDRATE  115200
  23
  24 #define UART_ENABLE             BIT(15)
  25 #define UART_ENABLE_RX          BIT(12)
  26 #define UART_ENABLE_TX          BIT(10)
  27 #define UART_TX_FULL            BIT(9)
  28
  29 /* UART1(x == 0) - UART6(x == 5) */
  30 #define UART_BASE(x)    ((x) * 0x0200)
  31 #define U_MODE(x)       UART_BASE(x)
  32 #define U_STA(x)        (UART_BASE(x) + 0x10)
  33 #define U_TXR(x)        (UART_BASE(x) + 0x20)
  34 #define U_BRG(x)        (UART_BASE(x) + 0x40)
  35
  36 static void __iomem *uart_base;
  37 static char console_port = -1;
  38
  39 static int __init configure_uart_pins(int port)
  40 {
  41         switch (port) {
  42         case 1:
  43                 pic32_pps_input(IN_FUNC_U2RX, IN_RPB0);
  44                 pic32_pps_output(OUT_FUNC_U2TX, OUT_RPG9);
  45                 break;
  46         case 5:
  47                 pic32_pps_input(IN_FUNC_U6RX, IN_RPD0);
  48                 pic32_pps_output(OUT_FUNC_U6TX, OUT_RPB8);
  49                 break;
  50         default:
  51                 return -1;
  52         }
  53
  54         return 0;
  55 }
  56
  57 static void __init configure_uart(char port, int baud)
  58 {
  59         u32 pbclk;
  60
  61         pbclk = pic32_get_pbclk(2);
  62
  63         __raw_writel(0, uart_base + U_MODE(port));
  64         __raw_writel(((pbclk / baud) / 16) - 1, uart_base + U_BRG(port));
  65         __raw_writel(UART_ENABLE, uart_base + U_MODE(port));
  66         __raw_writel(UART_ENABLE_TX | UART_ENABLE_RX,
  67                      uart_base + PIC32_SET(U_STA(port)));
  68 }
  69
  70 static void __init setup_early_console(char port, int baud)
  71 {
  72         if (configure_uart_pins(port))
  73                 return;
  74
  75         console_port = port;
  76         configure_uart(console_port, baud);
  77 }
  78
  79 static char * __init pic32_getcmdline(void)
  80 {
  81         /*
  82          * arch_mem_init() has not been called yet, so we don't have a real
  83          * command line setup if using CONFIG_CMDLINE_BOOL.
  84          */
  85 #ifdef CONFIG_CMDLINE_OVERRIDE
  86         return CONFIG_CMDLINE;
  87 #else
  88         return fw_getcmdline();
  89 #endif
  90 }
  91
  92 static int __init get_port_from_cmdline(char *arch_cmdline)
  93 {
  94         char *s;
  95         int port = -1;
  96
  97         if (!arch_cmdline || *arch_cmdline == '\0')
  98                 goto _out;
  99
 100         s = strstr(arch_cmdline, "earlyprintk=");
 101         if (s) {
 102                 s = strstr(s, "ttyS");
 103                 if (s)
 104                         s += 4;
 105                 else
 106                         goto _out;
 107
 108                 port = (*s) - '0';
 109         }
 110
 111 _out:
 112         return port;
 113 }
 114
 115 static int __init get_baud_from_cmdline(char *arch_cmdline)
 116 {
 117         char *s;
 118         int baud = -1;
 119
 120         if (!arch_cmdline || *arch_cmdline == '\0')
 121                 goto _out;
 122
 123         s = strstr(arch_cmdline, "earlyprintk=");
 124         if (s) {
 125                 s = strstr(s, "ttyS");
 126                 if (s)
 127                         s += 6;
 128                 else
 129                         goto _out;
 130
 131                 baud = 0;
 132                 while (*s >= '0' && *s <= '9')
 133                         baud = baud * 10 + *s++ - '0';
 134         }
 135
 136 _out:
 137         return baud;
 138 }
 139
 140 void __init fw_init_early_console(char port)
 141 {
 142         char *arch_cmdline = pic32_getcmdline();
 143         int baud = -1;
 144
 145         uart_base = ioremap_nocache(PIC32_BASE_UART, 0xc00);
 146
 147         baud = get_baud_from_cmdline(arch_cmdline);
 148         if (port == -1)
 149                 port = get_port_from_cmdline(arch_cmdline);
 150
 151         if (port == -1)
 152                 port = EARLY_CONSOLE_PORT;
 153
 154         if (baud == -1)
 155                 baud = EARLY_CONSOLE_BAUDRATE;
 156
 157         setup_early_console(port, baud);
 158 }
 159
 160 int prom_putchar(char c)
 161 {
 162         if (console_port >= 0) {
 163                 while (__raw_readl(
 164                                 uart_base + U_STA(console_port)) & UART_TX_FULL)
 165                         ;
 166
 167                 __raw_writel(c, uart_base + U_TXR(console_port));
 168         }
 169
 170         return 1;
 171 }