target/linux/ar71xx/files/arch/mips/ar71xx/early_printk.c

   1 /*
   2  *  Atheros AR7xxx/AR9xxx SoC early printk support
   3  *
   4  *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
   5  *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify it
   8  *  under the terms of the GNU General Public License version 2 as published
   9  *  by the Free Software Foundation.
  10  */
  11
  12 #include <linux/errno.h>
  13 #include <linux/io.h>
  14 #include <linux/serial_reg.h>
  15 #include <asm/addrspace.h>
  16
  17 #include <asm/mach-ar71xx/ar71xx.h>
  18
  19 static void __iomem *prom_uart_base;
  20 static void (*_putchar)(unsigned char);
  21
  22 #define UART_READ(r) \
  23         __raw_readl(prom_uart_base + 4 * (r))
  24
  25 #define UART_WRITE(r, v) \
  26         __raw_writel((v), prom_uart_base + 4 * (r))
  27
  28 static void prom_putchar_ar71xx(unsigned char ch)
  29 {
  30         while (((UART_READ(UART_LSR)) & UART_LSR_THRE) == 0)
  31                 ;
  32         UART_WRITE(UART_TX, ch);
  33         while (((UART_READ(UART_LSR)) & UART_LSR_THRE) == 0)
  34                 ;
  35 }
  36
  37 static void prom_putchar_ar933x(unsigned char ch)
  38 {
  39         while (((UART_READ(0)) & 0x200) == 0)
  40                 ;
  41         UART_WRITE(0, 0x200 | ch);
  42         while (((UART_READ(0)) & 0x200) == 0)
  43                 ;
  44 }
  45
  46 static int prom_putchar_init(void)
  47 {
  48         if (_putchar)
  49                 return 0;
  50
  51         switch(ar71xx_soc) {
  52         case AR71XX_SOC_AR7130:
  53         case AR71XX_SOC_AR7141:
  54         case AR71XX_SOC_AR7161:
  55         case AR71XX_SOC_AR7240:
  56         case AR71XX_SOC_AR7241:
  57         case AR71XX_SOC_AR7242:
  58         case AR71XX_SOC_AR9130:
  59         case AR71XX_SOC_AR9132:
  60         case AR71XX_SOC_AR9341:
  61         case AR71XX_SOC_AR9342:
  62         case AR71XX_SOC_AR9344:
  63                 prom_uart_base = (void __iomem *) KSEG1ADDR(AR71XX_UART_BASE);
  64                 _putchar = prom_putchar_ar71xx;
  65                 break;
  66
  67         case AR71XX_SOC_AR9330:
  68         case AR71XX_SOC_AR9331:
  69                 prom_uart_base = (void __iomem *) KSEG1ADDR(AR933X_UART_BASE);
  70                 _putchar = prom_putchar_ar933x;
  71                 break;
  72
  73         default:
  74                 return -ENODEV;
  75         }
  76
  77         return 0;
  78 }
  79
  80 void prom_putchar(unsigned char ch)
  81 {
  82         if (prom_putchar_init())
  83                 return;
  84
  85         _putchar(ch);
  86 }