arch/mips/ath79/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/io.h>
  13 #include <linux/errno.h>
  14 #include <linux/serial_reg.h>
  15 #include <asm/addrspace.h>
  16
  17 #include <asm/mach-ath79/ath79.h>
  18 #include <asm/mach-ath79/ar71xx_regs.h>
  19 #include <asm/mach-ath79/ar933x_uart.h>
  20
  21 static void (*_prom_putchar) (unsigned char);
  22
  23 static inline void prom_putchar_wait(void __iomem *reg, u32 mask, u32 val)
  24 {
  25         u32 t;
  26
  27         do {
  28                 t = __raw_readl(reg);
  29                 if ((t & mask) == val)
  30                         break;
  31         } while (1);
  32 }
  33
  34 static void prom_putchar_ar71xx(unsigned char ch)
  35 {
  36         void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
  37
  38         prom_putchar_wait(base + UART_LSR * 4, UART_LSR_THRE, UART_LSR_THRE);
  39         __raw_writel(ch, base + UART_TX * 4);
  40         prom_putchar_wait(base + UART_LSR * 4, UART_LSR_THRE, UART_LSR_THRE);
  41 }
  42
  43 static void prom_putchar_ar933x(unsigned char ch)
  44 {
  45         void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));
  46
  47         prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
  48                           AR933X_UART_DATA_TX_CSR);
  49         __raw_writel(AR933X_UART_DATA_TX_CSR | ch, base + AR933X_UART_DATA_REG);
  50         prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
  51                           AR933X_UART_DATA_TX_CSR);
  52 }
  53
  54 static void prom_putchar_dummy(unsigned char ch)
  55 {
  56         /* nothing to do */
  57 }
  58
  59 static void prom_putchar_init(void)
  60 {
  61         void __iomem *base;
  62         u32 id;
  63
  64         base = (void __iomem *)(KSEG1ADDR(AR71XX_RESET_BASE));
  65         id = __raw_readl(base + AR71XX_RESET_REG_REV_ID);
  66         id &= REV_ID_MAJOR_MASK;
  67
  68         switch (id) {
  69         case REV_ID_MAJOR_AR71XX:
  70         case REV_ID_MAJOR_AR7240:
  71         case REV_ID_MAJOR_AR7241:
  72         case REV_ID_MAJOR_AR7242:
  73         case REV_ID_MAJOR_AR913X:
  74                 _prom_putchar = prom_putchar_ar71xx;
  75                 break;
  76
  77         case REV_ID_MAJOR_AR9330:
  78         case REV_ID_MAJOR_AR9331:
  79                 _prom_putchar = prom_putchar_ar933x;
  80                 break;
  81
  82         default:
  83                 _prom_putchar = prom_putchar_dummy;
  84                 break;
  85         }
  86 }
  87
  88 void prom_putchar(unsigned char ch)
  89 {
  90         if (!_prom_putchar)
  91                 prom_putchar_init();
  92
  93         _prom_putchar(ch);
  94 }