text: /*
   *  Atheros AR7XXX/AR9XXX SoC early printk support
   *
   *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
   *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
   *
   *  This program is free software; you can redistribute it and/or modify it
   *  under the terms of the GNU General Public License version 2 as published
   *  by the Free Software Foundation.
   */
  
  #include <linux/io.h>
  #include <linux/errno.h>
  #include <linux/serial_reg.h>
  #include <asm/addrspace.h>
  
  #include <asm/mach-ath79/ath79.h>
  #include <asm/mach-ath79/ar71xx_regs.h>
  #include <asm/mach-ath79/ar933x_uart.h>
  
  static void (*_prom_putchar) (unsigned char);
  
  static inline void prom_putchar_wait(void __iomem *reg, u32 mask, u32 val)
  {
  	u32 t;
  
  	do {
  		t = __raw_readl(reg);
  		if ((t & mask) == val)
  			break;
  	} while (1);
  }
  
  #define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
  
  static void prom_putchar_ar71xx(unsigned char ch)
  {
  	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
  
  	prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
  	__raw_writel(ch, base + UART_TX * 4);
  	prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
  }
  
  static void prom_putchar_ar933x(unsigned char ch)
  {
  	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));
  
  	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
  			  AR933X_UART_DATA_TX_CSR);
  	__raw_writel(AR933X_UART_DATA_TX_CSR | ch, base + AR933X_UART_DATA_REG);
  	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
  			  AR933X_UART_DATA_TX_CSR);
  }
  
  static void prom_putchar_dummy(unsigned char ch)
  {
  	/* nothing to do */
  }
  
  static void prom_putchar_init(void)
  {
  	void __iomem *base;
  	u32 id;
  
  	base = (void __iomem *)(KSEG1ADDR(AR71XX_RESET_BASE));
  	id = __raw_readl(base + AR71XX_RESET_REG_REV_ID);
  	id &= REV_ID_MAJOR_MASK;
  
  	switch (id) {
  	case REV_ID_MAJOR_AR71XX:
  	case REV_ID_MAJOR_AR7240:
  	case REV_ID_MAJOR_AR7241:
  	case REV_ID_MAJOR_AR7242:
  	case REV_ID_MAJOR_AR913X:
  	case REV_ID_MAJOR_AR9341:
  	case REV_ID_MAJOR_AR9342:
  	case REV_ID_MAJOR_AR9344:
  	case REV_ID_MAJOR_QCA9556:
  	case REV_ID_MAJOR_QCA9558:
  		_prom_putchar = prom_putchar_ar71xx;
  		break;
  
  	case REV_ID_MAJOR_AR9330:
  	case REV_ID_MAJOR_AR9331:
  		_prom_putchar = prom_putchar_ar933x;
  		break;
  
  	default:
  		_prom_putchar = prom_putchar_dummy;
  		break;
  	}
  }
  
  void prom_putchar(unsigned char ch)
  {
  	if (!_prom_putchar)
  		prom_putchar_init();
  
  	_prom_putchar(ch);
  }
  