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qemu/hw/eeprom93xx.c
aurel32 7ab2589cbb hw/eeprom93xx.c: support 93xx EEPROMs with more than 255 words 
In the head of eeprom93xx.c we promise to support chips with 256 words,
but store the size in an unsigned byte. This patch replaces this with an
16 bit variable and changes the load/store code accordingly (introducing a
new version).

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6918 c046a42c-6fe2-441c-8c8c-71466251a162
2009-03-28 23:14:52 +00:00

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/*
* QEMU EEPROM 93xx emulation
*
* Copyright (c) 2006-2007 Stefan Weil
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/* Emulation for serial EEPROMs:
* NMC93C06 256-Bit (16 x 16)
* NMC93C46 1024-Bit (64 x 16)
* NMC93C56 2028 Bit (128 x 16)
* NMC93C66 4096 Bit (256 x 16)
* Compatible devices include FM93C46 and others.
*
* Other drivers use these interface functions:
* eeprom93xx_new - add a new EEPROM (with 16, 64 or 256 words)
* eeprom93xx_free - destroy EEPROM
* eeprom93xx_read - read data from the EEPROM
* eeprom93xx_write - write data to the EEPROM
* eeprom93xx_data - get EEPROM data array for external manipulation
*
* Todo list:
* - No emulation of EEPROM timings.
*/
#include <assert.h>
#include "hw.h"
#include "eeprom93xx.h"
/* Debug EEPROM emulation. */
//~ #define DEBUG_EEPROM
#ifdef DEBUG_EEPROM
#define logout(fmt, args...) fprintf(stderr, "EEPROM\t%-24s" fmt, __func__, ##args)
#else
#define logout(fmt, args...) ((void)0)
#endif
#define EEPROM_INSTANCE 0
#define OLD_EEPROM_VERSION 20061112
#define EEPROM_VERSION (OLD_EEPROM_VERSION + 1)
#if 0
typedef enum {
eeprom_read = 0x80, /* read register xx */
eeprom_write = 0x40, /* write register xx */
eeprom_erase = 0xc0, /* erase register xx */
eeprom_ewen = 0x30, /* erase / write enable */
eeprom_ewds = 0x00, /* erase / write disable */
eeprom_eral = 0x20, /* erase all registers */
eeprom_wral = 0x10, /* write all registers */
eeprom_amask = 0x0f,
eeprom_imask = 0xf0
} eeprom_instruction_t;
#endif
#ifdef DEBUG_EEPROM
static const char *opstring[] = {
"extended", "write", "read", "erase"
};
#endif
struct _eeprom_t {
uint8_t tick;
uint8_t address;
uint8_t command;
uint8_t writeable;
uint8_t eecs;
uint8_t eesk;
uint8_t eedo;
uint8_t addrbits;
uint16_t size;
uint16_t data;
uint16_t contents[0];
};
/* Code for saving and restoring of EEPROM state. */
static void eeprom_save(QEMUFile *f, void *opaque)
{
/* Save EEPROM data. */
unsigned address;
eeprom_t *eeprom = (eeprom_t *)opaque;
qemu_put_byte(f, eeprom->tick);
qemu_put_byte(f, eeprom->address);
qemu_put_byte(f, eeprom->command);
qemu_put_byte(f, eeprom->writeable);
qemu_put_byte(f, eeprom->eecs);
qemu_put_byte(f, eeprom->eesk);
qemu_put_byte(f, eeprom->eedo);
qemu_put_byte(f, eeprom->addrbits);
qemu_put_be16(f, eeprom->size);
qemu_put_be16(f, eeprom->data);
for (address = 0; address < eeprom->size; address++) {
qemu_put_be16(f, eeprom->contents[address]);
}
}
static int eeprom_load(QEMUFile *f, void *opaque, int version_id)
{
/* Load EEPROM data from saved data if version and EEPROM size
of data and current EEPROM are identical. */
eeprom_t *eeprom = (eeprom_t *)opaque;
int result = -EINVAL;
if (version_id >= OLD_EEPROM_VERSION) {
unsigned address;
int size = eeprom->size;
eeprom->tick = qemu_get_byte(f);
eeprom->address = qemu_get_byte(f);
eeprom->command = qemu_get_byte(f);
eeprom->writeable = qemu_get_byte(f);
eeprom->eecs = qemu_get_byte(f);
eeprom->eesk = qemu_get_byte(f);
eeprom->eedo = qemu_get_byte(f);
eeprom->addrbits = qemu_get_byte(f);
if (version_id == OLD_EEPROM_VERSION) {
eeprom->size = qemu_get_byte(f);
qemu_get_byte(f);
} else {
eeprom->size = qemu_get_be16(f);
}
if (eeprom->size == size) {
eeprom->data = qemu_get_be16(f);
for (address = 0; address < eeprom->size; address++) {
eeprom->contents[address] = qemu_get_be16(f);
}
result = 0;
}
}
return result;
}
void eeprom93xx_write(eeprom_t *eeprom, int eecs, int eesk, int eedi)
{
uint8_t tick = eeprom->tick;
uint8_t eedo = eeprom->eedo;
uint16_t address = eeprom->address;
uint8_t command = eeprom->command;
logout("CS=%u SK=%u DI=%u DO=%u, tick = %u\n",
eecs, eesk, eedi, eedo, tick);
if (! eeprom->eecs && eecs) {
/* Start chip select cycle. */
logout("Cycle start, waiting for 1st start bit (0)\n");
tick = 0;
command = 0x0;
address = 0x0;
} else if (eeprom->eecs && ! eecs) {
/* End chip select cycle. This triggers write / erase. */
if (eeprom->writeable) {
uint8_t subcommand = address >> (eeprom->addrbits - 2);
if (command == 0 && subcommand == 2) {
/* Erase all. */
for (address = 0; address < eeprom->size; address++) {
eeprom->contents[address] = 0xffff;
}
} else if (command == 3) {
/* Erase word. */
eeprom->contents[address] = 0xffff;
} else if (tick >= 2 + 2 + eeprom->addrbits + 16) {
if (command == 1) {
/* Write word. */
eeprom->contents[address] &= eeprom->data;
} else if (command == 0 && subcommand == 1) {
/* Write all. */
for (address = 0; address < eeprom->size; address++) {
eeprom->contents[address] &= eeprom->data;
}
}
}
}
/* Output DO is tristate, read results in 1. */
eedo = 1;
} else if (eecs && ! eeprom->eesk && eesk) {
/* Raising edge of clock shifts data in. */
if (tick == 0) {
/* Wait for 1st start bit. */
if (eedi == 0) {
logout("Got correct 1st start bit, waiting for 2nd start bit (1)\n");
tick++;
} else {
logout("wrong 1st start bit (is 1, should be 0)\n");
tick = 2;
//~ assert(!"wrong start bit");
}
} else if (tick == 1) {
/* Wait for 2nd start bit. */
if (eedi != 0) {
logout("Got correct 2nd start bit, getting command + address\n");
tick++;
} else {
logout("1st start bit is longer than needed\n");
}
} else if (tick < 2 + 2) {
/* Got 2 start bits, transfer 2 opcode bits. */
tick++;
command <<= 1;
if (eedi) {
command += 1;
}
} else if (tick < 2 + 2 + eeprom->addrbits) {
/* Got 2 start bits and 2 opcode bits, transfer all address bits. */
tick++;
address = ((address << 1) | eedi);
if (tick == 2 + 2 + eeprom->addrbits) {
logout("%s command, address = 0x%02x (value 0x%04x)\n",
opstring[command], address, eeprom->contents[address]);
if (command == 2) {
eedo = 0;
}
address = address % eeprom->size;
if (command == 0) {
/* Command code in upper 2 bits of address. */
switch (address >> (eeprom->addrbits - 2)) {
case 0:
logout("write disable command\n");
eeprom->writeable = 0;
break;
case 1:
logout("write all command\n");
break;
case 2:
logout("erase all command\n");
break;
case 3:
logout("write enable command\n");
eeprom->writeable = 1;
break;
}
} else {
/* Read, write or erase word. */
eeprom->data = eeprom->contents[address];
}
}
} else if (tick < 2 + 2 + eeprom->addrbits + 16) {
/* Transfer 16 data bits. */
tick++;
if (command == 2) {
/* Read word. */
eedo = ((eeprom->data & 0x8000) != 0);
}
eeprom->data <<= 1;
eeprom->data += eedi;
} else {
logout("additional unneeded tick, not processed\n");
}
}
/* Save status of EEPROM. */
eeprom->tick = tick;
eeprom->eecs = eecs;
eeprom->eesk = eesk;
eeprom->eedo = eedo;
eeprom->address = address;
eeprom->command = command;
}
uint16_t eeprom93xx_read(eeprom_t *eeprom)
{
/* Return status of pin DO (0 or 1). */
logout("CS=%u DO=%u\n", eeprom->eecs, eeprom->eedo);
return (eeprom->eedo);
}
#if 0
void eeprom93xx_reset(eeprom_t *eeprom)
{
/* prepare eeprom */
logout("eeprom = 0x%p\n", eeprom);
eeprom->tick = 0;
eeprom->command = 0;
}
#endif
eeprom_t *eeprom93xx_new(uint16_t nwords)
{
/* Add a new EEPROM (with 16, 64 or 256 words). */
eeprom_t *eeprom;
uint8_t addrbits;
switch (nwords) {
case 16:
case 64:
addrbits = 6;
break;
case 128:
case 256:
addrbits = 8;
break;
default:
assert(!"Unsupported EEPROM size, fallback to 64 words!");
nwords = 64;
addrbits = 6;
}
eeprom = (eeprom_t *)qemu_mallocz(sizeof(*eeprom) + nwords * 2);
eeprom->size = nwords;
eeprom->addrbits = addrbits;
/* Output DO is tristate, read results in 1. */
eeprom->eedo = 1;
logout("eeprom = 0x%p, nwords = %u\n", eeprom, nwords);
register_savevm("eeprom", EEPROM_INSTANCE, EEPROM_VERSION,
eeprom_save, eeprom_load, eeprom);
return eeprom;
}
void eeprom93xx_free(eeprom_t *eeprom)
{
/* Destroy EEPROM. */
logout("eeprom = 0x%p\n", eeprom);
qemu_free(eeprom);
}
uint16_t *eeprom93xx_data(eeprom_t *eeprom)
{
/* Get EEPROM data array. */
return &eeprom->contents[0];
}
/* eof */
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