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flash_storage: add key-value flash storage support

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fallen authored and sbourdeauducq committed Apr 7, 2015
1 parent 110f7bc commit 13119eb9eeb38cbf712f16b06544940ba2b04ae6
Showing with 184 additions and 0 deletions.
  1. +173 −0 soc/runtime/flash_storage.c
  2. +11 −0 soc/runtime/flash_storage.h
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/*
* Yann Sionneau <ys@m-labs.hk>, 2015
*/
#include <spiflash.h>
#include <string.h>
#include <generated/flash_geometry.h>
#include <generated/mem.h>
#include <system.h>
#include "flash_storage.h"
#define STORAGE_ADDRESS ((char *)(FLASH_BOOT_ADDRESS + 128*1024))
#define STORAGE_SIZE SECTOR_SIZE
#define END_MARKER (0xFFFFFFFF)
#define min(a, b) (a>b?b:a)
#define max(a, b) (a>b?a:b)
#define goto_next_record(buff,addr) do { \
unsigned int key_size = strlen(&buff[addr])+1; \
if (key_size % 4) \
key_size += 4 - (key_size % 4); \
unsigned int *buflen_p = (unsigned int *)&buff[addr + key_size]; \
unsigned int buflen = *buflen_p; \
if (buflen % 4) \
buflen += 4 - (buflen % 4); \
addr += key_size + sizeof(int) + buflen; \
} while (0);
union seek {
unsigned int integer;
char bytes[4];
};
char sector_buff[STORAGE_SIZE];
static void write_at_offset(char *key, void *buffer, int buflen, unsigned int sector_offset);
static char key_exists(char *buff, char *key, char *end);
static char check_for_duplicates(char *buff);
static unsigned int try_to_flush_duplicates(void);
static char key_exists(char *buff, char *key, char *end)
{
unsigned int addr;
for(addr = 0; &buff[addr] < end && *(unsigned int*)&buff[addr] != END_MARKER;) {
if(strcmp(&buff[addr], key) == 0)
return 1;
goto_next_record(buff, addr);
}
return 0;
}
static char check_for_duplicates(char *buff)
{
unsigned int addr;
char *key_name;
for(addr = 0; addr < STORAGE_SIZE && *(unsigned int *)&buff[addr] != END_MARKER;) {
key_name = &buff[addr];
goto_next_record(buff, addr);
if(key_exists(&buff[addr], key_name, &buff[STORAGE_SIZE]))
return 1;
}
return 0;
}
static unsigned int try_to_flush_duplicates(void)
{
unsigned int addr, i, key_size, buflen;
char *key_name, *last_duplicate;
union seek *seeker = (union seek *)sector_buff;
memcpy(sector_buff, STORAGE_ADDRESS, STORAGE_SIZE);
if(check_for_duplicates(sector_buff)) {
erase_flash_sector((unsigned int)STORAGE_ADDRESS);
flush_cpu_dcache();
for(addr = 0; addr < STORAGE_SIZE && seeker[addr >> 2].integer != END_MARKER;) {
key_name = &sector_buff[addr];
key_size = strlen(key_name)+1;
if(key_size % 4)
key_size += 4 - (key_size % 4);
if(!key_exists((char *)STORAGE_ADDRESS, key_name, STORAGE_ADDRESS+STORAGE_SIZE)) {
last_duplicate = key_name;
for(i = addr; i < STORAGE_SIZE;) {
goto_next_record(sector_buff, i);
if(strcmp(&sector_buff[i], key_name) == 0)
last_duplicate = &sector_buff[i];
}
buflen = *(unsigned int *)&last_duplicate[key_size];
write(key_name, &last_duplicate[key_size+sizeof(int)], buflen);
}
goto_next_record(sector_buff, addr);
}
return 0;
} else
return 1;
}
static void write_at_offset(char *key, void *buffer, int buflen, unsigned int sector_offset)
{
int key_len = strlen(key) + 1;
int key_len_alignment = 0, buflen_alignment = 0;
unsigned char padding[3] = {0, 0, 0};
if(key_len % 4)
key_len_alignment = 4 - (key_len % 4);
if(buflen % 4)
buflen_alignment = 4 - (buflen % 4);
write_to_flash(sector_offset, (unsigned char *)key, key_len);
write_to_flash(sector_offset+key_len, padding, key_len_alignment);
write_to_flash(sector_offset+key_len+key_len_alignment, (unsigned char *)&buflen, sizeof(buflen));
write_to_flash(sector_offset+key_len+key_len_alignment+sizeof(buflen), buffer, buflen);
write_to_flash(sector_offset+key_len+key_len_alignment+sizeof(buflen)+buflen, padding, buflen_alignment);
}
void write(char *key, void *buffer, unsigned int buflen)
{
char *addr;
unsigned int key_size = strlen(key)+1;
unsigned int record_size = key_size + sizeof(int) + buflen;
for(addr = STORAGE_ADDRESS; addr < STORAGE_ADDRESS + STORAGE_SIZE - record_size; addr += 4) {
if(*(unsigned int *)addr == END_MARKER) {
write_at_offset(key, buffer, buflen, (unsigned int)addr);
flush_cpu_dcache();
break;
}
}
if(addr >= STORAGE_ADDRESS + STORAGE_SIZE - record_size) { // Flash is full? Try to flush duplicates.
if(try_to_flush_duplicates())
return; // No duplicates found, cannot write the new key-value record: sector is full.
// Now retrying to write, hoping enough flash was freed.
for(addr = STORAGE_ADDRESS; addr < STORAGE_ADDRESS + STORAGE_SIZE - record_size; addr += 4) {
if(*(unsigned int *)addr == END_MARKER) {
write_at_offset(key, buffer, buflen, (unsigned int)addr);
flush_cpu_dcache();
break;
}
}
}
}
unsigned int read(char *key, void *buffer, unsigned int buflen, unsigned int *remain)
{
unsigned int read_length = 0;
char *addr;
for(addr = STORAGE_ADDRESS; addr < (STORAGE_ADDRESS + STORAGE_SIZE) && (*addr != END_MARKER);) {
unsigned int key_len, value_len;
char *key_addr = addr;
key_len = strlen(addr) + 1;
if(key_len % 4)
key_len += 4 - (key_len % 4);
addr += key_len;
value_len = *(unsigned int *)addr;
addr += sizeof(value_len);
if(strcmp(key_addr, key) == 0) {
memcpy(buffer, addr, min(value_len, buflen));
read_length = min(value_len, buflen);
*remain = max(0, (int)value_len - (int)buflen);
}
addr += value_len;
if((int)addr % 4)
addr += 4 - ((int)addr % 4);
}
return read_length;
}
@@ -0,0 +1,11 @@
/*
* Yann Sionneau <ys@m-labs.hk>, 2015
*/
#ifndef __FLASH_STORAGE_H
#define __FLASH_STORAGE_H
void write(char *key, void *buffer, unsigned int buflen);
unsigned int read(char *key, void *buffer, unsigned int buflen, unsigned int *remain);
#endif /* __FLASH_STORAGE_H */

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