arch/mips/ath79/early_printk.c

   1 /*
   2  *  Atheros AR71XX/AR724X/AR913X SoC early printk support
   3  *
   4  *  Copyright (C) 2008-2010 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/io.h>
  13 #include <linux/serial_reg.h>
  14 #include <asm/addrspace.h>
  15
  16 #include <asm/mach-ath79/ar71xx_regs.h>
  17
  18 static inline void prom_wait_thre(void __iomem *base)
  19 {
  20         u32 lsr;
  21
  22         do {
  23                 lsr = __raw_readl(base + UART_LSR * 4);
  24                 if (lsr & UART_LSR_THRE)
  25                         break;
  26         } while (1);
  27 }
  28
  29 void prom_putchar(unsigned char ch)
  30 {
  31         void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
  32
  33         prom_wait_thre(base);
  34         __raw_writel(ch, base + UART_TX * 4);
  35         prom_wait_thre(base);
  36 }