text: /*
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 2001, 2002, 2004 Ralf Baechle
   */
  #include <linux/init.h>
  #include <linux/console.h>
  #include <linux/kdev_t.h>
  #include <linux/major.h>
  #include <linux/termios.h>
  #include <linux/sched.h>
  #include <linux/tty.h>
  
  #include <linux/serial.h>
  #include <linux/serial_core.h>
  #include <asm/serial.h>
  #include <asm/io.h>
  
  /* SUPERIO uart register map */
  struct yo_uartregs {
  	union {
  		volatile u8	rbr;	/* read only, DLAB == 0 */
  		volatile u8	thr;	/* write only, DLAB == 0 */
  		volatile u8	dll;	/* DLAB == 1 */
  	} u1;
  	union {
  		volatile u8	ier;	/* DLAB == 0 */
  		volatile u8	dlm;	/* DLAB == 1 */
  	} u2;
  	union {
  		volatile u8	iir;	/* read only */
  		volatile u8	fcr;	/* write only */
  	} u3;
  	volatile u8	iu_lcr;
  	volatile u8	iu_mcr;
  	volatile u8	iu_lsr;
  	volatile u8	iu_msr;
  	volatile u8	iu_scr;
  } yo_uregs_t;
  
  #define iu_rbr u1.rbr
  #define iu_thr u1.thr
  #define iu_dll u1.dll
  #define iu_ier u2.ier
  #define iu_dlm u2.dlm
  #define iu_iir u3.iir
  #define iu_fcr u3.fcr
  
  #define ssnop()		__asm__ __volatile__("sll	$0, $0, 1\n");
  #define ssnop_4()	do { ssnop(); ssnop(); ssnop(); ssnop(); } while (0)
  
  #define IO_BASE_64	0x9000000000000000ULL
  
  static unsigned char readb_outer_space(unsigned long long phys)
  {
  	unsigned long long vaddr = IO_BASE_64 | phys;
  	unsigned char res;
  	unsigned int sr;
  
  	sr = read_c0_status();
  	write_c0_status((sr | ST0_KX) & ~ ST0_IE);
  	ssnop_4();
  
  	__asm__ __volatile__ (
  	"	.set	mips3		\n"
  	"	ld	%0, %1		\n"
  	"	lbu	%0, (%0)	\n"
  	"	.set	mips0		\n"
  	: "=r" (res)
  	: "m" (vaddr));
  
  	write_c0_status(sr);
  	ssnop_4();
  
  	return res;
  }
  
  static void writeb_outer_space(unsigned long long phys, unsigned char c)
  {
  	unsigned long long vaddr = IO_BASE_64 | phys;
  	unsigned long tmp;
  	unsigned int sr;
  
  	sr = read_c0_status();
  	write_c0_status((sr | ST0_KX) & ~ ST0_IE);
  	ssnop_4();
  
  	__asm__ __volatile__ (
  	"	.set	mips3		\n"
  	"	ld	%0, %1		\n"
  	"	sb	%2, (%0)	\n"
  	"	.set	mips0		\n"
  	: "=&r" (tmp)
  	: "m" (vaddr), "r" (c));
  
  	write_c0_status(sr);
  	ssnop_4();
  }
  
  void prom_putchar(char c)
  {
  	unsigned long lsr = 0xfd000008ULL + offsetof(struct yo_uartregs, iu_lsr);
  	unsigned long thr = 0xfd000008ULL + offsetof(struct yo_uartregs, iu_thr);
  
  	while ((readb_outer_space(lsr) & 0x20) == 0);
  	writeb_outer_space(thr, c);
  }
  