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 } 37