flash.c

// This file is part of the CircuitPython project: https://circuitpython.org
//
// SPDX-FileCopyrightText: Copyright (c) 2018 Scott Shawcroft
//
// SPDX-License-Identifier: MIT
#include "supervisor/flash.h"

#include "extmod/vfs_fat.h"
#include "py/runtime.h"
#include "lib/oofatfs/diskio.h"
#include "lib/oofatfs/ff.h"
#include "supervisor/flash.h"
#include "supervisor/shared/tick.h"

#define VFS_INDEX 0

#define PART1_START_BLOCK (0x1)

// there is a singleton Flash object
const mp_obj_type_t supervisor_flash_type;
static const mp_obj_base_t supervisor_flash_obj = {&supervisor_flash_type};

static mp_obj_t supervisor_flash_obj_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
    // check arguments
    mp_arg_check_num(n_args, n_kw, 0, 0, false);

    // return singleton object
    return (mp_obj_t)&supervisor_flash_obj;
}


static bool flash_ioctl(mp_obj_t self_in, size_t cmd, size_t arg, mp_int_t *out_value) {
    if (out_value != NULL) {
        *out_value = 0;
    }

    mp_vfs_blockdev_t *self = (mp_vfs_blockdev_t *)self_in;
    switch (cmd) {
        case MP_BLOCKDEV_IOCTL_INIT:
            supervisor_flash_init();
            break;
        case MP_BLOCKDEV_IOCTL_DEINIT:
            supervisor_flash_flush();
            break; // TODO properly
        case MP_BLOCKDEV_IOCTL_SYNC:
            supervisor_flash_flush();
            break;
        case MP_BLOCKDEV_IOCTL_BLOCK_COUNT:
            *out_value = PART1_START_BLOCK;
            #if CIRCUITPY_SAVES_PARTITION_SIZE > 0
            if (self->size > 0) {
                *out_value += self->size / self->block_size;
            } else {
                *out_value += supervisor_flash_get_block_count() - (self->offset / self->block_size);
            }
            #else
            *out_value += supervisor_flash_get_block_count();
            #endif
            break;
        case MP_BLOCKDEV_IOCTL_BLOCK_SIZE:
            *out_value = self->block_size;
            break;
        default:
            return false;
    }
    return true;
}

static mp_obj_t supervisor_flash_obj_ioctl(mp_obj_t self, mp_obj_t cmd_in, mp_obj_t arg_in) {
    mp_int_t cmd = mp_obj_get_int(cmd_in);
    mp_int_t arg = mp_obj_get_int(arg_in);
    mp_int_t out_value;
    if (flash_ioctl(self, cmd, arg, &out_value)) {
        return MP_OBJ_NEW_SMALL_INT(out_value);
    }
    return mp_const_none;
}
static MP_DEFINE_CONST_FUN_OBJ_3(supervisor_flash_obj_ioctl_obj, supervisor_flash_obj_ioctl);

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;
}

static mp_uint_t flash_read_blocks(mp_obj_t self_in, uint8_t *dest, uint32_t block_num, uint32_t num_blocks) {
    if (block_num == 0) {
        // fake the MBR so we can decide on our own partition table

        for (int i = 0; i < 446; i++) {
            dest[i] = 0;
        }

        mp_int_t block_count;
        flash_ioctl(self_in, MP_BLOCKDEV_IOCTL_BLOCK_COUNT, 0, &block_count);

        // Specifying "Big FAT12/16 CHS" allows mounting by Android
        build_partition(dest + 446, 0, 0x06 /* Big FAT12/16 CHS */, PART1_START_BLOCK, block_count - PART1_START_BLOCK);
        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;
        if (num_blocks > 1) {
            dest += 512;
            num_blocks -= 1;
            block_num += 1;
            // Fall through and do a read from flash.
        } else {
            return 0; // Done and ok.
        }
    }
    block_num -= PART1_START_BLOCK;
    #if CIRCUITPY_SAVES_PARTITION_SIZE > 0
    mp_vfs_blockdev_t *self = (mp_vfs_blockdev_t *)self_in;
    block_num += self->offset / self->block_size;
    #endif
    return supervisor_flash_read_blocks(dest, block_num, num_blocks);
}

static volatile bool filesystem_dirty = false;

static mp_uint_t flash_write_blocks(mp_obj_t self_in, const uint8_t *src, uint32_t block_num, uint32_t num_blocks) {
    if (block_num == 0) {
        if (num_blocks > 1) {
            return 1; // error
        }
        // can't write MBR, but pretend we did
        return 0;
    } else {
        if (!filesystem_dirty) {
            // Turn on ticks so that we can flush after a period of time elapses.
            supervisor_enable_tick();
            filesystem_dirty = true;
        }
        block_num -= PART1_START_BLOCK;
        #if CIRCUITPY_SAVES_PARTITION_SIZE > 0
        mp_vfs_blockdev_t *self = (mp_vfs_blockdev_t *)self_in;
        block_num += self->offset / self->block_size;
        #endif
        return supervisor_flash_write_blocks(src, block_num, num_blocks);
    }
}

void PLACE_IN_ITCM(supervisor_flash_flush)(void) {
    #if INTERNAL_FLASH_FILESYSTEM
    port_internal_flash_flush();
    #else
    supervisor_external_flash_flush();
    #endif
    // Turn off ticks now that our filesystem has been flushed.
    if (filesystem_dirty) {
        supervisor_disable_tick();
    }
    filesystem_dirty = false;
}

static mp_obj_t supervisor_flash_obj_readblocks(mp_obj_t self, mp_obj_t block_num, mp_obj_t buf) {
    mp_buffer_info_t bufinfo;
    mp_get_buffer_raise(buf, &bufinfo, MP_BUFFER_WRITE);
    mp_uint_t ret = flash_read_blocks(self, bufinfo.buf, mp_obj_get_int(block_num), bufinfo.len / FILESYSTEM_BLOCK_SIZE);
    return MP_OBJ_NEW_SMALL_INT(ret);
}
static MP_DEFINE_CONST_FUN_OBJ_3(supervisor_flash_obj_readblocks_obj, supervisor_flash_obj_readblocks);

static mp_obj_t supervisor_flash_obj_writeblocks(mp_obj_t self, mp_obj_t block_num, mp_obj_t buf) {
    mp_buffer_info_t bufinfo;
    mp_get_buffer_raise(buf, &bufinfo, MP_BUFFER_READ);
    mp_uint_t ret = flash_write_blocks(self, bufinfo.buf, mp_obj_get_int(block_num), bufinfo.len / FILESYSTEM_BLOCK_SIZE);
    return MP_OBJ_NEW_SMALL_INT(ret);
}
static MP_DEFINE_CONST_FUN_OBJ_3(supervisor_flash_obj_writeblocks_obj, supervisor_flash_obj_writeblocks);

static const mp_rom_map_elem_t supervisor_flash_obj_locals_dict_table[] = {
    { MP_ROM_QSTR(MP_QSTR_readblocks), MP_ROM_PTR(&supervisor_flash_obj_readblocks_obj) },
    { MP_ROM_QSTR(MP_QSTR_writeblocks), MP_ROM_PTR(&supervisor_flash_obj_writeblocks_obj) },
    { MP_ROM_QSTR(MP_QSTR_ioctl), MP_ROM_PTR(&supervisor_flash_obj_ioctl_obj) },
};

static MP_DEFINE_CONST_DICT(supervisor_flash_obj_locals_dict, supervisor_flash_obj_locals_dict_table);

MP_DEFINE_CONST_OBJ_TYPE(
    supervisor_flash_type,
    MP_QSTR_Flash,
    MP_TYPE_FLAG_NONE,
    make_new, supervisor_flash_obj_make_new,
    locals_dict, &supervisor_flash_obj_locals_dict
    );

void supervisor_flash_init_vfs(fs_user_mount_t *vfs) {
    vfs->base.type = &mp_fat_vfs_type;
    vfs->blockdev.flags |= MP_BLOCKDEV_FLAG_NATIVE | MP_BLOCKDEV_FLAG_HAVE_IOCTL;
    vfs->blockdev.block_size = supervisor_flash_get_block_size();
    vfs->fatfs.drv = vfs;
    vfs->fatfs.part = 1; // flash filesystem lives on first fake partition
    vfs->blockdev.readblocks[0] = mp_const_none;
    vfs->blockdev.readblocks[1] = (mp_obj_t)&vfs->blockdev;
    vfs->blockdev.readblocks[2] = (mp_obj_t)flash_read_blocks; // native version
    vfs->blockdev.writeblocks[0] = mp_const_none;
    vfs->blockdev.writeblocks[1] = (mp_obj_t)&vfs->blockdev;
    vfs->blockdev.writeblocks[2] = (mp_obj_t)flash_write_blocks; // native version
    vfs->blockdev.u.ioctl[0] = mp_const_none;
    vfs->blockdev.u.ioctl[1] = (mp_obj_t)&vfs->blockdev;
    vfs->blockdev.u.ioctl[2] = (mp_obj_t)flash_ioctl; // native version
}