circuitpython/stm/storage.c

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C
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#include <stdint.h>
#include "std.h"
#include "misc.h"
#include "led.h"
#include "flash.h"
#include "storage.h"
#define BLOCK_SIZE (512)
#define CACHE_MEM_START_ADDR (0x10000000) // CCM data RAM, 64k
#define FLASH_PART1_START_BLOCK (0x100)
#define FLASH_PART1_NUM_BLOCKS (224) // 16k+16k+16k+64k=112k
#define FLASH_MEM_START_ADDR (0x08004000) // sector 1, 16k
static bool is_initialised = false;
static uint32_t cache_flash_sector_id;
static uint32_t cache_flash_sector_start;
static uint32_t cache_flash_sector_size;
static bool cache_dirty;
static void cache_flush() {
if (cache_dirty) {
// sync the cache RAM buffer by writing it to the flash page
flash_write(cache_flash_sector_start, (const uint32_t*)CACHE_MEM_START_ADDR, cache_flash_sector_size / 4);
cache_dirty = false;
// indicate a clean cache with LED off
led_state(PYB_LED_R1, 0);
}
}
static uint8_t *cache_get_addr_for_write(uint32_t flash_addr) {
uint32_t flash_sector_start;
uint32_t flash_sector_size;
uint32_t flash_sector_id = flash_get_sector_info(flash_addr, &flash_sector_start, &flash_sector_size);
if (cache_flash_sector_id != flash_sector_id) {
cache_flush();
memcpy((void*)CACHE_MEM_START_ADDR, (const void*)flash_sector_start, flash_sector_size);
cache_flash_sector_id = flash_sector_id;
cache_flash_sector_start = flash_sector_start;
cache_flash_sector_size = flash_sector_size;
}
cache_dirty = true;
// indicate a dirty cache with LED on
led_state(PYB_LED_R1, 1);
return (uint8_t*)CACHE_MEM_START_ADDR + flash_addr - flash_sector_start;
}
void storage_init() {
if (!is_initialised) {
cache_flash_sector_id = 0;
cache_dirty = false;
is_initialised = true;
}
}
void storage_flush() {
cache_flush();
}
static void build_partition(uint8_t *buf, int boot, int type, uint32_t start_block, uint32_t num_blocks) {
buf[0] = boot;
if (num_blocks == 0) {
buf[1] = 0;
buf[2] = 0;
buf[3] = 0;
} else {
buf[1] = 0xff;
buf[2] = 0xff;
buf[3] = 0xff;
}
buf[4] = type;
if (num_blocks == 0) {
buf[5] = 0;
buf[6] = 0;
buf[7] = 0;
} else {
buf[5] = 0xff;
buf[6] = 0xff;
buf[7] = 0xff;
}
buf[8] = start_block;
buf[9] = start_block >> 8;
buf[10] = start_block >> 16;
buf[11] = start_block >> 24;
buf[12] = num_blocks;
buf[13] = num_blocks >> 8;
buf[14] = num_blocks >> 16;
buf[15] = num_blocks >> 24;
}
bool storage_read_block(uint8_t *dest, uint32_t block) {
//printf("RD %u\n", block);
if (block == 0) {
// fake the MBR so we can decide on our own partition table
for (int i = 0; i < 446; i++) {
dest[i] = 0;
}
build_partition(dest + 446, 0, 0x01 /* FAT12 */, FLASH_PART1_START_BLOCK, FLASH_PART1_NUM_BLOCKS);
build_partition(dest + 462, 0, 0, 0, 0);
build_partition(dest + 478, 0, 0, 0, 0);
build_partition(dest + 494, 0, 0, 0, 0);
dest[510] = 0x55;
dest[511] = 0xaa;
return true;
} else if (FLASH_PART1_START_BLOCK <= block && block < FLASH_PART1_START_BLOCK + FLASH_PART1_NUM_BLOCKS) {
// non-MBR block, just copy straight from flash
uint8_t *src = (uint8_t*)FLASH_MEM_START_ADDR + (block - FLASH_PART1_START_BLOCK) * BLOCK_SIZE;
memcpy(dest, src, BLOCK_SIZE);
return true;
} else {
// bad block number
return false;
}
}
bool storage_write_block(const uint8_t *src, uint32_t block) {
//printf("WR %u\n", block);
if (block == 0) {
// can't write MBR, but pretend we did
return true;
} else if (FLASH_PART1_START_BLOCK <= block && block < FLASH_PART1_START_BLOCK + FLASH_PART1_NUM_BLOCKS) {
// non-MBR block, copy to cache
uint32_t flash_addr = FLASH_MEM_START_ADDR + (block - FLASH_PART1_START_BLOCK) * BLOCK_SIZE;
uint8_t *dest = cache_get_addr_for_write(flash_addr);
memcpy(dest, src, BLOCK_SIZE);
return true;
} else {
// bad block number
return false;
}
}