arch/mips/pic32/pic32mzda/early_console.c

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