Partially implement proper flash storage.

1 files changed, 142 insertions, 0 deletions

diff --git a/stm/storage.c b/stm/storage.c
new file mode 100644
index 0000000000..56ade79773
--- /dev/null
+++ b/stm/storage.c
@@ -0,0 +1,142 @@
+#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() {
+    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;
+    }
+}