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 #include <asm/mach-ar71xx/ar933x_uart.h>
  19
  20 static void (*_prom_putchar) (unsigned char);
  21
  22 static inline void prom_putchar_wait(void __iomem *reg, u32 mask, u32 val)
  23 {
  24         u32 t;
  25
  26         do {
  27                 t = __raw_readl(reg);
  28                 if ((t & mask) == val)
  29                         break;
  30         } while (1);
  31 }
  32
  33 static void prom_putchar_ar71xx(unsigned char ch)
  34 {
  35         void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
  36
  37         prom_putchar_wait(base + UART_LSR * 4, UART_LSR_THRE, UART_LSR_THRE);
  38         __raw_writel(ch, base + UART_TX * 4);
  39         prom_putchar_wait(base + UART_LSR * 4, UART_LSR_THRE, UART_LSR_THRE);
  40 }
  41
  42 static void prom_putchar_ar933x(unsigned char ch)
  43 {
  44         void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));
  45
  46         prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
  47                           AR933X_UART_DATA_TX_CSR);
  48         __raw_writel(AR933X_UART_DATA_TX_CSR | ch, base + AR933X_UART_DATA_REG);
  49         prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
  50                           AR933X_UART_DATA_TX_CSR);
  51 }
  52
  53 static void prom_putchar_dummy(unsigned char ch)
  54 {
  55         /* nothing to do */
  56 }
  57
  58 static void prom_putchar_init(void)
  59 {
  60         void __iomem *base;
  61         u32 id;
  62
  63         base = (void __iomem *)(KSEG1ADDR(AR71XX_RESET_BASE));
  64         id = __raw_readl(base + AR71XX_RESET_REG_REV_ID);
  65         id &= REV_ID_MAJOR_MASK;
  66
  67         switch (id) {
  68         case REV_ID_MAJOR_AR71XX:
  69         case REV_ID_MAJOR_AR7240:
  70         case REV_ID_MAJOR_AR7241:
  71         case REV_ID_MAJOR_AR7242:
  72         case REV_ID_MAJOR_AR913X:
  73         case REV_ID_MAJOR_AR9341:
  74         case REV_ID_MAJOR_AR9342:
  75         case REV_ID_MAJOR_AR9344:
  76                 _prom_putchar = prom_putchar_ar71xx;
  77                 break;
  78
  79         case REV_ID_MAJOR_AR9330:
  80         case REV_ID_MAJOR_AR9331:
  81                 _prom_putchar = prom_putchar_ar933x;
  82                 break;
  83
  84         default:
  85                 _prom_putchar = prom_putchar_dummy;
  86                 break;
  87         }
  88 }
  89
  90 void prom_putchar(unsigned char ch)
  91 {
  92         if (!_prom_putchar)
  93                 prom_putchar_init();
  94
  95         _prom_putchar(ch);
  96 }