hw/m48t08.c - third_party/qemu - Git at Google

 /*
  * QEMU M48T08 NVRAM emulation for Sparc platform
  *
  * Copyright (c) 2003-2004 Jocelyn Mayer
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
 #include "vl.h"
 #include "m48t08.h"

 //#define DEBUG_NVRAM

 #if defined(DEBUG_NVRAM)
 #define NVRAM_PRINTF(fmt, args...) do { printf(fmt , ##args); } while (0)
 #else
 #define NVRAM_PRINTF(fmt, args...) do { } while (0)
 #endif

 #define NVRAM_MAX_MEM 0xfff0

 struct m48t08_t {
     /* Hardware parameters */
     int mem_index;
     uint32_t mem_base;
     uint16_t size;
     /* RTC management */
     time_t   time_offset;
     time_t   stop_time;
     /* NVRAM storage */
     uint8_t  lock;
     uint16_t addr;
     uint8_t *buffer;
 };

 /* Fake timer functions */
 /* Generic helpers for BCD */
 static inline uint8_t toBCD (uint8_t value)
 {
     return (((value / 10) % 10) << 4) | (value % 10);
 }

 static inline uint8_t fromBCD (uint8_t BCD)
 {
     return ((BCD >> 4) * 10) + (BCD & 0x0F);
 }

 /* RTC management helpers */
 static void get_time (m48t08_t *NVRAM, struct tm *tm)
 {
     time_t t;

     t = time(NULL) + NVRAM->time_offset;
 #ifdef _WIN32
     memcpy(tm,localtime(&t),sizeof(*tm));
 #else
     localtime_r (&t, tm) ;
 #endif
 }

 static void set_time (m48t08_t *NVRAM, struct tm *tm)
 {
     time_t now, new_time;

     new_time = mktime(tm);
     now = time(NULL);
     NVRAM->time_offset = new_time - now;
 }

 /* Direct access to NVRAM */
 void m48t08_write (m48t08_t *NVRAM, uint32_t val)
 {
     struct tm tm;
     int tmp;

     if (NVRAM->addr > NVRAM_MAX_MEM && NVRAM->addr < 0x2000)
 	NVRAM_PRINTF("%s: 0x%08x => 0x%08x\n", __func__, NVRAM->addr, val);
     switch (NVRAM->addr) {
     case 0x1FF8:
         /* control */
 	NVRAM->buffer[0x1FF8] = (val & ~0xA0) | 0x90;
         break;
     case 0x1FF9:
         /* seconds (BCD) */
 	tmp = fromBCD(val & 0x7F);
 	if (tmp >= 0 && tmp <= 59) {
 	    get_time(NVRAM, &tm);
 	    tm.tm_sec = tmp;
 	    set_time(NVRAM, &tm);
 	}
 	if ((val & 0x80) ^ (NVRAM->buffer[0x1FF9] & 0x80)) {
 	    if (val & 0x80) {
 		NVRAM->stop_time = time(NULL);
 	    } else {
 		NVRAM->time_offset += NVRAM->stop_time - time(NULL);
 		NVRAM->stop_time = 0;
 	    }
 	}
 	NVRAM->buffer[0x1FF9] = val & 0x80;
         break;
     case 0x1FFA:
         /* minutes (BCD) */
 	tmp = fromBCD(val & 0x7F);
 	if (tmp >= 0 && tmp <= 59) {
 	    get_time(NVRAM, &tm);
 	    tm.tm_min = tmp;
 	    set_time(NVRAM, &tm);
 	}
         break;
     case 0x1FFB:
         /* hours (BCD) */
 	tmp = fromBCD(val & 0x3F);
 	if (tmp >= 0 && tmp <= 23) {
 	    get_time(NVRAM, &tm);
 	    tm.tm_hour = tmp;
 	    set_time(NVRAM, &tm);
 	}
         break;
     case 0x1FFC:
         /* day of the week / century */
 	tmp = fromBCD(val & 0x07);
 	get_time(NVRAM, &tm);
 	tm.tm_wday = tmp;
 	set_time(NVRAM, &tm);
         NVRAM->buffer[0x1FFC] = val & 0x40;
         break;
     case 0x1FFD:
         /* date */
 	tmp = fromBCD(val & 0x1F);
 	if (tmp != 0) {
 	    get_time(NVRAM, &tm);
 	    tm.tm_mday = tmp;
 	    set_time(NVRAM, &tm);
 	}
         break;
     case 0x1FFE:
         /* month */
 	tmp = fromBCD(val & 0x1F);
 	if (tmp >= 1 && tmp <= 12) {
 	    get_time(NVRAM, &tm);
 	    tm.tm_mon = tmp - 1;
 	    set_time(NVRAM, &tm);
 	}
         break;
     case 0x1FFF:
         /* year */
 	tmp = fromBCD(val);
 	if (tmp >= 0 && tmp <= 99) {
 	    get_time(NVRAM, &tm);
 	    tm.tm_year = fromBCD(val);
 	    set_time(NVRAM, &tm);
 	}
         break;
     default:
         /* Check lock registers state */
         if (NVRAM->addr >= 0x20 && NVRAM->addr <= 0x2F && (NVRAM->lock & 1))
             break;
         if (NVRAM->addr >= 0x30 && NVRAM->addr <= 0x3F && (NVRAM->lock & 2))
             break;
         if (NVRAM->addr < NVRAM_MAX_MEM ||
 	    (NVRAM->addr > 0x1FFF && NVRAM->addr < NVRAM->size)) {
             NVRAM->buffer[NVRAM->addr] = val & 0xFF;
 	}
         break;
     }
 }

 uint32_t m48t08_read (m48t08_t *NVRAM)
 {
     struct tm tm;
     uint32_t retval = 0xFF;

     switch (NVRAM->addr) {
     case 0x1FF8:
         /* control */
 	goto do_read;
     case 0x1FF9:
         /* seconds (BCD) */
         get_time(NVRAM, &tm);
         retval = (NVRAM->buffer[0x1FF9] & 0x80) | toBCD(tm.tm_sec);
         break;
     case 0x1FFA:
         /* minutes (BCD) */
         get_time(NVRAM, &tm);
         retval = toBCD(tm.tm_min);
         break;
     case 0x1FFB:
         /* hours (BCD) */
         get_time(NVRAM, &tm);
         retval = toBCD(tm.tm_hour);
         break;
     case 0x1FFC:
         /* day of the week / century */
         get_time(NVRAM, &tm);
         retval = NVRAM->buffer[0x1FFC] | tm.tm_wday;
         break;
     case 0x1FFD:
         /* date */
         get_time(NVRAM, &tm);
         retval = toBCD(tm.tm_mday);
         break;
     case 0x1FFE:
         /* month */
         get_time(NVRAM, &tm);
         retval = toBCD(tm.tm_mon + 1);
         break;
     case 0x1FFF:
         /* year */
         get_time(NVRAM, &tm);
         retval = toBCD(tm.tm_year);
         break;
     default:
         /* Check lock registers state */
         if (NVRAM->addr >= 0x20 && NVRAM->addr <= 0x2F && (NVRAM->lock & 1))
             break;
         if (NVRAM->addr >= 0x30 && NVRAM->addr <= 0x3F && (NVRAM->lock & 2))
             break;
         if (NVRAM->addr < NVRAM_MAX_MEM ||
 	    (NVRAM->addr > 0x1FFF && NVRAM->addr < NVRAM->size)) {
 	do_read:
             retval = NVRAM->buffer[NVRAM->addr];
 	}
         break;
     }
     if (NVRAM->addr > NVRAM_MAX_MEM + 1 && NVRAM->addr < 0x2000)
 	NVRAM_PRINTF("0x%08x <= 0x%08x\n", NVRAM->addr, retval);

     return retval;
 }

 void m48t08_set_addr (m48t08_t *NVRAM, uint32_t addr)
 {
     NVRAM->addr = addr;
 }

 void m48t08_toggle_lock (m48t08_t *NVRAM, int lock)
 {
     NVRAM->lock ^= 1 << lock;
 }

 static void nvram_writeb (void *opaque, target_phys_addr_t addr, uint32_t value)
 {
     m48t08_t *NVRAM = opaque;

     addr -= NVRAM->mem_base;
     if (addr < NVRAM_MAX_MEM)
         NVRAM->buffer[addr] = value;
 }

 static void nvram_writew (void *opaque, target_phys_addr_t addr, uint32_t value)
 {
     m48t08_t *NVRAM = opaque;

     addr -= NVRAM->mem_base;
     if (addr < NVRAM_MAX_MEM) {
         NVRAM->buffer[addr] = value >> 8;
         NVRAM->buffer[addr + 1] = value;
     }
 }

 static void nvram_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
 {
     m48t08_t *NVRAM = opaque;

     addr -= NVRAM->mem_base;
     if (addr < NVRAM_MAX_MEM) {
         NVRAM->buffer[addr] = value >> 24;
         NVRAM->buffer[addr + 1] = value >> 16;
         NVRAM->buffer[addr + 2] = value >> 8;
         NVRAM->buffer[addr + 3] = value;
     }
 }

 static uint32_t nvram_readb (void *opaque, target_phys_addr_t addr)
 {
     m48t08_t *NVRAM = opaque;
     uint32_t retval = 0;

     addr -= NVRAM->mem_base;
     if (addr < NVRAM_MAX_MEM)
         retval = NVRAM->buffer[addr];

     return retval;
 }

 static uint32_t nvram_readw (void *opaque, target_phys_addr_t addr)
 {
     m48t08_t *NVRAM = opaque;
     uint32_t retval = 0;

     addr -= NVRAM->mem_base;
     if (addr < NVRAM_MAX_MEM) {
         retval = NVRAM->buffer[addr] << 8;
         retval |= NVRAM->buffer[addr + 1];
     }

     return retval;
 }

 static uint32_t nvram_readl (void *opaque, target_phys_addr_t addr)
 {
     m48t08_t *NVRAM = opaque;
     uint32_t retval = 0;

     addr -= NVRAM->mem_base;
     if (addr < NVRAM_MAX_MEM) {
         retval = NVRAM->buffer[addr] << 24;
         retval |= NVRAM->buffer[addr + 1] << 16;
         retval |= NVRAM->buffer[addr + 2] << 8;
         retval |= NVRAM->buffer[addr + 3];
     }

     return retval;
 }

 static CPUWriteMemoryFunc *nvram_write[] = {
     &nvram_writeb,
     &nvram_writew,
     &nvram_writel,
 };

 static CPUReadMemoryFunc *nvram_read[] = {
     &nvram_readb,
     &nvram_readw,
     &nvram_readl,
 };

 /* Initialisation routine */
 m48t08_t *m48t08_init(uint32_t mem_base, uint16_t size, uint8_t *macaddr)
 {
     m48t08_t *s;
     int i;
     unsigned char tmp = 0;

     s = qemu_mallocz(sizeof(m48t08_t));
     if (!s)
 	return NULL;
     s->buffer = qemu_mallocz(size);
     if (!s->buffer) {
         qemu_free(s);
         return NULL;
     }
     s->size = size;
     s->mem_base = mem_base;
     s->addr = 0;
     if (mem_base != 0) {
         s->mem_index = cpu_register_io_memory(0, nvram_read, nvram_write, s);
         cpu_register_physical_memory(mem_base, 0x4000, s->mem_index);
     }
     s->lock = 0;

     i = 0x1fd8;
     s->buffer[i++] = 0x01;
     s->buffer[i++] = 0x80; /* Sun4m OBP */
     memcpy(&s->buffer[i], macaddr, 6);

     /* Calculate checksum */
     for (i = 0x1fd8; i < 0x1fe7; i++) {
 	tmp ^= s->buffer[i];
     }
     s->buffer[0x1fe7] = tmp;
     return s;
 }

 #if 0
 struct idprom
 {
         unsigned char   id_format;      /* Format identifier (always 0x01) */
         unsigned char   id_machtype;    /* Machine type */
         unsigned char   id_ethaddr[6];  /* Hardware ethernet address */
         long            id_date;        /* Date of manufacture */
         unsigned int    id_sernum:24;   /* Unique serial number */
         unsigned char   id_cksum;       /* Checksum - xor of the data bytes */
         unsigned char   reserved[16];
 };
 #endif
	/*
	* QEMU M48T08 NVRAM emulation for Sparc platform
	*
	* Copyright (c) 2003-2004 Jocelyn Mayer
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/
	#include "vl.h"
	#include "m48t08.h"

	//#define DEBUG_NVRAM

	#if defined(DEBUG_NVRAM)
	#define NVRAM_PRINTF(fmt, args...) do { printf(fmt , ##args); } while (0)
	#else
	#define NVRAM_PRINTF(fmt, args...) do { } while (0)
	#endif

	#define NVRAM_MAX_MEM 0xfff0

	struct m48t08_t {
	/* Hardware parameters */
	int mem_index;
	uint32_t mem_base;
	uint16_t size;
	/* RTC management */
	time_t time_offset;
	time_t stop_time;
	/* NVRAM storage */
	uint8_t lock;
	uint16_t addr;
	uint8_t *buffer;
	};

	/* Fake timer functions */
	/* Generic helpers for BCD */
	static inline uint8_t toBCD (uint8_t value)
	{
	return (((value / 10) % 10) << 4) \| (value % 10);
	}

	static inline uint8_t fromBCD (uint8_t BCD)
	{
	return ((BCD >> 4) * 10) + (BCD & 0x0F);
	}

	/* RTC management helpers */
	static void get_time (m48t08_t NVRAM, struct tm tm)
	{
	time_t t;

	t = time(NULL) + NVRAM->time_offset;
	#ifdef _WIN32
	memcpy(tm,localtime(&t),sizeof(*tm));
	#else
	localtime_r (&t, tm) ;
	#endif
	}

	static void set_time (m48t08_t NVRAM, struct tm tm)
	{
	time_t now, new_time;

	new_time = mktime(tm);
	now = time(NULL);
	NVRAM->time_offset = new_time - now;
	}

	/* Direct access to NVRAM */
	void m48t08_write (m48t08_t *NVRAM, uint32_t val)
	{
	struct tm tm;
	int tmp;

	if (NVRAM->addr > NVRAM_MAX_MEM && NVRAM->addr < 0x2000)
	NVRAM_PRINTF("%s: 0x%08x => 0x%08x\n", __func__, NVRAM->addr, val);
	switch (NVRAM->addr) {
	case 0x1FF8:
	/* control */
	NVRAM->buffer[0x1FF8] = (val & ~0xA0) \| 0x90;
	break;
	case 0x1FF9:
	/* seconds (BCD) */
	tmp = fromBCD(val & 0x7F);
	if (tmp >= 0 && tmp <= 59) {
	get_time(NVRAM, &tm);
	tm.tm_sec = tmp;
	set_time(NVRAM, &tm);
	}
	if ((val & 0x80) ^ (NVRAM->buffer[0x1FF9] & 0x80)) {
	if (val & 0x80) {
	NVRAM->stop_time = time(NULL);
	} else {
	NVRAM->time_offset += NVRAM->stop_time - time(NULL);
	NVRAM->stop_time = 0;
	}
	}
	NVRAM->buffer[0x1FF9] = val & 0x80;
	break;
	case 0x1FFA:
	/* minutes (BCD) */
	tmp = fromBCD(val & 0x7F);
	if (tmp >= 0 && tmp <= 59) {
	get_time(NVRAM, &tm);
	tm.tm_min = tmp;
	set_time(NVRAM, &tm);
	}
	break;
	case 0x1FFB:
	/* hours (BCD) */
	tmp = fromBCD(val & 0x3F);
	if (tmp >= 0 && tmp <= 23) {
	get_time(NVRAM, &tm);
	tm.tm_hour = tmp;
	set_time(NVRAM, &tm);
	}
	break;
	case 0x1FFC:
	/* day of the week / century */
	tmp = fromBCD(val & 0x07);
	get_time(NVRAM, &tm);
	tm.tm_wday = tmp;
	set_time(NVRAM, &tm);
	NVRAM->buffer[0x1FFC] = val & 0x40;
	break;
	case 0x1FFD:
	/* date */
	tmp = fromBCD(val & 0x1F);
	if (tmp != 0) {
	get_time(NVRAM, &tm);
	tm.tm_mday = tmp;
	set_time(NVRAM, &tm);
	}
	break;
	case 0x1FFE:
	/* month */
	tmp = fromBCD(val & 0x1F);
	if (tmp >= 1 && tmp <= 12) {
	get_time(NVRAM, &tm);
	tm.tm_mon = tmp - 1;
	set_time(NVRAM, &tm);
	}
	break;
	case 0x1FFF:
	/* year */
	tmp = fromBCD(val);
	if (tmp >= 0 && tmp <= 99) {
	get_time(NVRAM, &tm);
	tm.tm_year = fromBCD(val);
	set_time(NVRAM, &tm);
	}
	break;
	default:
	/* Check lock registers state */
	if (NVRAM->addr >= 0x20 && NVRAM->addr <= 0x2F && (NVRAM->lock & 1))
	break;
	if (NVRAM->addr >= 0x30 && NVRAM->addr <= 0x3F && (NVRAM->lock & 2))
	break;
	if (NVRAM->addr < NVRAM_MAX_MEM \|\|
	(NVRAM->addr > 0x1FFF && NVRAM->addr < NVRAM->size)) {
	NVRAM->buffer[NVRAM->addr] = val & 0xFF;
	}
	break;
	}
	}

	uint32_t m48t08_read (m48t08_t *NVRAM)
	{
	struct tm tm;
	uint32_t retval = 0xFF;

	switch (NVRAM->addr) {
	case 0x1FF8:
	/* control */
	goto do_read;
	case 0x1FF9:
	/* seconds (BCD) */
	get_time(NVRAM, &tm);
	retval = (NVRAM->buffer[0x1FF9] & 0x80) \| toBCD(tm.tm_sec);
	break;
	case 0x1FFA:
	/* minutes (BCD) */
	get_time(NVRAM, &tm);
	retval = toBCD(tm.tm_min);
	break;
	case 0x1FFB:
	/* hours (BCD) */
	get_time(NVRAM, &tm);
	retval = toBCD(tm.tm_hour);
	break;
	case 0x1FFC:
	/* day of the week / century */
	get_time(NVRAM, &tm);
	retval = NVRAM->buffer[0x1FFC] \| tm.tm_wday;
	break;
	case 0x1FFD:
	/* date */
	get_time(NVRAM, &tm);
	retval = toBCD(tm.tm_mday);
	break;
	case 0x1FFE:
	/* month */
	get_time(NVRAM, &tm);
	retval = toBCD(tm.tm_mon + 1);
	break;
	case 0x1FFF:
	/* year */
	get_time(NVRAM, &tm);
	retval = toBCD(tm.tm_year);
	break;
	default:
	/* Check lock registers state */
	if (NVRAM->addr >= 0x20 && NVRAM->addr <= 0x2F && (NVRAM->lock & 1))
	break;
	if (NVRAM->addr >= 0x30 && NVRAM->addr <= 0x3F && (NVRAM->lock & 2))
	break;
	if (NVRAM->addr < NVRAM_MAX_MEM \|\|
	(NVRAM->addr > 0x1FFF && NVRAM->addr < NVRAM->size)) {
	do_read:
	retval = NVRAM->buffer[NVRAM->addr];
	}
	break;
	}
	if (NVRAM->addr > NVRAM_MAX_MEM + 1 && NVRAM->addr < 0x2000)
	NVRAM_PRINTF("0x%08x <= 0x%08x\n", NVRAM->addr, retval);

	return retval;
	}

	void m48t08_set_addr (m48t08_t *NVRAM, uint32_t addr)
	{
	NVRAM->addr = addr;
	}

	void m48t08_toggle_lock (m48t08_t *NVRAM, int lock)
	{
	NVRAM->lock ^= 1 << lock;
	}

	static void nvram_writeb (void *opaque, target_phys_addr_t addr, uint32_t value)
	{
	m48t08_t *NVRAM = opaque;

	addr -= NVRAM->mem_base;
	if (addr < NVRAM_MAX_MEM)
	NVRAM->buffer[addr] = value;
	}

	static void nvram_writew (void *opaque, target_phys_addr_t addr, uint32_t value)
	{
	m48t08_t *NVRAM = opaque;

	addr -= NVRAM->mem_base;
	if (addr < NVRAM_MAX_MEM) {
	NVRAM->buffer[addr] = value >> 8;
	NVRAM->buffer[addr + 1] = value;
	}
	}

	static void nvram_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
	{
	m48t08_t *NVRAM = opaque;

	addr -= NVRAM->mem_base;
	if (addr < NVRAM_MAX_MEM) {
	NVRAM->buffer[addr] = value >> 24;
	NVRAM->buffer[addr + 1] = value >> 16;
	NVRAM->buffer[addr + 2] = value >> 8;
	NVRAM->buffer[addr + 3] = value;
	}
	}

	static uint32_t nvram_readb (void *opaque, target_phys_addr_t addr)
	{
	m48t08_t *NVRAM = opaque;
	uint32_t retval = 0;

	addr -= NVRAM->mem_base;
	if (addr < NVRAM_MAX_MEM)
	retval = NVRAM->buffer[addr];

	return retval;
	}

	static uint32_t nvram_readw (void *opaque, target_phys_addr_t addr)
	{
	m48t08_t *NVRAM = opaque;
	uint32_t retval = 0;

	addr -= NVRAM->mem_base;
	if (addr < NVRAM_MAX_MEM) {
	retval = NVRAM->buffer[addr] << 8;
	retval \|= NVRAM->buffer[addr + 1];
	}

	return retval;
	}

	static uint32_t nvram_readl (void *opaque, target_phys_addr_t addr)
	{
	m48t08_t *NVRAM = opaque;
	uint32_t retval = 0;

	addr -= NVRAM->mem_base;
	if (addr < NVRAM_MAX_MEM) {
	retval = NVRAM->buffer[addr] << 24;
	retval \|= NVRAM->buffer[addr + 1] << 16;
	retval \|= NVRAM->buffer[addr + 2] << 8;
	retval \|= NVRAM->buffer[addr + 3];
	}

	return retval;
	}

	static CPUWriteMemoryFunc *nvram_write[] = {
	&nvram_writeb,
	&nvram_writew,
	&nvram_writel,
	};

	static CPUReadMemoryFunc *nvram_read[] = {
	&nvram_readb,
	&nvram_readw,
	&nvram_readl,
	};

	/* Initialisation routine */
	m48t08_t m48t08_init(uint32_t mem_base, uint16_t size, uint8_t macaddr)
	{
	m48t08_t *s;
	int i;
	unsigned char tmp = 0;

	s = qemu_mallocz(sizeof(m48t08_t));
	if (!s)
	return NULL;
	s->buffer = qemu_mallocz(size);
	if (!s->buffer) {
	qemu_free(s);
	return NULL;
	}
	s->size = size;
	s->mem_base = mem_base;
	s->addr = 0;
	if (mem_base != 0) {
	s->mem_index = cpu_register_io_memory(0, nvram_read, nvram_write, s);
	cpu_register_physical_memory(mem_base, 0x4000, s->mem_index);
	}
	s->lock = 0;

	i = 0x1fd8;
	s->buffer[i++] = 0x01;
	s->buffer[i++] = 0x80; /* Sun4m OBP */
	memcpy(&s->buffer[i], macaddr, 6);

	/* Calculate checksum */
	for (i = 0x1fd8; i < 0x1fe7; i++) {
	tmp ^= s->buffer[i];
	}
	s->buffer[0x1fe7] = tmp;
	return s;
	}

	#if 0
	struct idprom
	{
	unsigned char id_format; /* Format identifier (always 0x01) */
	unsigned char id_machtype; /* Machine type */
	unsigned char id_ethaddr[6]; /* Hardware ethernet address */
	long id_date; /* Date of manufacture */
	unsigned int id_sernum:24; /* Unique serial number */
	unsigned char id_cksum; /* Checksum - xor of the data bytes */
	unsigned char reserved[16];
	};
	#endif