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#include <stddef.h>
#include "bios.h"
#include "pflash.h"
#include "stdio.h"
#define CLEAR_STATUS_CMD 0x50
#define READ_STATUS_CMD 0x70
#define QUERY_CMD 0x98
#define READ_ARRAY_CMD 0xff
static void *pflash_detect(uint8_t *top_addr)
{
volatile uint8_t *p = top_addr;
uint8_t save;
int i, blocks, sector_len;
/* The low byte of the address is part of the command, so it must be 0. */
if ((uintptr_t)p & 256)
panic();
p -= 256;
for (i = 0; i < 256; i++)
if (p[i] != CLEAR_STATUS_CMD)
break;
if (i == 256)
return NULL;
save = p[i];
p[i] = CLEAR_STATUS_CMD;
if (p[i] == CLEAR_STATUS_CMD) {
/* behaves as RAM */
p[i] = save;
return NULL;
}
p[i] = READ_STATUS_CMD;
if (p[i] != 0) {
/* doesn't behave as flash */
return NULL;
}
/* 0x2d-0x2e: blocks_per_device - 1, little endian */
/* 0x2f-0x30: sector_len / 256 */
p[i] = QUERY_CMD;
blocks = p[0x2d] + (p[0x2e] << 8) + 1;
sector_len = (p[0x2f] + (p[0x30] << 8)) << 8;
p[i] = READ_ARRAY_CMD;
return top_addr - blocks * sector_len;
}
void *pflash_base(int n, size_t *size)
{
uint8_t *top = NULL;
uint8_t *prev;
while (n-- >= 0) {
prev = top;
top = pflash_detect(top);
if (!top)
return NULL;
*size = prev - top;
}
return top;
}
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