atmel-samd: Fix running off of the new VFS filesystem including

an issue at startup leading to safe mode and mass storage support
not working.

5 files changed, 56 insertions, 50 deletions

diff --git a/atmel-samd/access_vfs.c b/atmel-samd/access_vfs.c
index 72b56526b..5dc47a7a1 100644
--- a/atmel-samd/access_vfs.c
+++ b/atmel-samd/access_vfs.c
@@ -42,6 +42,17 @@
 
 #define VFS_INDEX 0
 
+static fs_user_mount_t* get_vfs(int index) {
+    mp_vfs_mount_t* current_mount = MP_STATE_VM(vfs_mount_table);
+    for (uint8_t i = 0; current_mount != NULL; i++) {
+        if (i == VFS_INDEX) {
+            return (fs_user_mount_t *) current_mount->obj;
+        }
+        current_mount = current_mount->next;
+    }
+    return NULL;
+}
+
 //! This function tests memory state, and starts memory initialization
 //! @return                            Ctrl_status
 //!   It is ready                ->    CTRL_GOOD
@@ -50,12 +61,9 @@
 //!   An error occurred          ->    CTRL_FAIL
 Ctrl_status vfs_test_unit_ready(void)
 {
-    mp_vfs_mount_t* current_mount = MP_STATE_VM(vfs_mount_table);
-    for (uint8_t i = 0; current_mount != NULL; i++) {
-        if (i == VFS_INDEX) {
-            return CTRL_GOOD;
-        }
-        current_mount = current_mount->next;
+    fs_user_mount_t* current_mount = get_vfs(VFS_INDEX);
+    if (current_mount != NULL) {
+        return CTRL_GOOD;
     }
     return CTRL_NO_PRESENT;
 }
@@ -69,7 +77,9 @@ Ctrl_status vfs_test_unit_ready(void)
 //!   An error occurred          ->    CTRL_FAIL
 Ctrl_status vfs_read_capacity(uint32_t *last_valid_sector)
 {
-    if (disk_ioctl(VFS_INDEX, GET_SECTOR_COUNT, last_valid_sector) != RES_OK) {
+    fs_user_mount_t * vfs = get_vfs(VFS_INDEX);
+    if (vfs == NULL ||
+        disk_ioctl(vfs, GET_SECTOR_COUNT, last_valid_sector) != RES_OK) {
         return CTRL_FAIL;
     }
     // Subtract one from the sector count to get the last valid sector.
@@ -83,20 +93,9 @@ Ctrl_status vfs_read_capacity(uint32_t *last_valid_sector)
 //!
 bool vfs_wr_protect(void)
 {
-    mp_vfs_mount_t* current_mount = MP_STATE_VM(vfs_mount_table);
-    for (uint8_t i = 0; current_mount != NULL; i++) {
-        if (i == VFS_INDEX) {
-            break;
-        }
-        current_mount = current_mount->next;
-    }
-    if (current_mount == NULL) {
-        return true;
-    }
-    fs_user_mount_t *vfs = (fs_user_mount_t *) current_mount->obj;
-
+    fs_user_mount_t * vfs = get_vfs(VFS_INDEX);
     // This is used to determine the writeability of the disk from USB.
-    if (vfs->writeblocks[0] == MP_OBJ_NULL ||
+    if (vfs == NULL || vfs->writeblocks[0] == MP_OBJ_NULL ||
         (vfs->flags & FSUSER_USB_WRITEABLE) == 0) {
         return true;
     }
@@ -112,11 +111,6 @@ bool vfs_removal(void)
 	return true;
 }
 
-bool vfs_unload(bool unload)
-{
-	return unload;
-}
-
 // TODO(tannewt): Transfer more than a single sector at a time if we need more
 // speed.
 //! This function transfers the memory data to the USB MSC interface
@@ -132,9 +126,10 @@ bool vfs_unload(bool unload)
 //!
 Ctrl_status vfs_usb_read_10(uint32_t addr, volatile uint16_t nb_sector)
 {
+    fs_user_mount_t * vfs = get_vfs(VFS_INDEX);
     uint8_t sector_buffer[FILESYSTEM_BLOCK_SIZE];
     for (uint16_t sector = 0; sector < nb_sector; sector++) {
-        DRESULT result = disk_read(VFS_INDEX, sector_buffer, addr + sector, 1);
+        DRESULT result = disk_read(vfs, sector_buffer, addr + sector, 1);
         if (result == RES_PARERR) {
             return CTRL_NO_PRESENT;
         }
@@ -161,13 +156,17 @@ Ctrl_status vfs_usb_read_10(uint32_t addr, volatile uint16_t nb_sector)
 //!
 Ctrl_status vfs_usb_write_10(uint32_t addr, volatile uint16_t nb_sector)
 {
+    if (vfs_wr_protect()) {
+        return CTRL_FAIL;
+    }
+    fs_user_mount_t * vfs = get_vfs(VFS_INDEX);
     uint8_t sector_buffer[FILESYSTEM_BLOCK_SIZE];
     for (uint16_t sector = 0; sector < nb_sector; sector++) {
         if (!udi_msc_trans_block(false, sector_buffer, FILESYSTEM_BLOCK_SIZE, NULL)) {
             return CTRL_FAIL; // transfer aborted
         }
         uint32_t sector_address = addr + sector;
-        DRESULT result = disk_write(VFS_INDEX, sector_buffer, sector_address, 1);
+        DRESULT result = disk_write(vfs, sector_buffer, sector_address, 1);
         if (result == RES_PARERR) {
             return CTRL_NO_PRESENT;
         }
@@ -176,18 +175,6 @@ Ctrl_status vfs_usb_write_10(uint32_t addr, volatile uint16_t nb_sector)
         }
         // Since by getting here we assume the mount is read-only to MicroPython
         // lets update the cached FatFs sector if its the one we just wrote.
-        mp_vfs_mount_t* current_mount = MP_STATE_VM(vfs_mount_table);
-        for (uint8_t i = 0; current_mount != NULL; i++) {
-            if (i == VFS_INDEX) {
-                break;
-            }
-            current_mount = current_mount->next;
-        }
-        if (current_mount == NULL) {
-            return CTRL_NO_PRESENT;
-        }
-        fs_user_mount_t *vfs = (fs_user_mount_t *) current_mount->obj;
-
         #if _MAX_SS != _MIN_SS
         if (vfs->ssize == FILESYSTEM_BLOCK_SIZE) {
         #else
diff --git a/atmel-samd/access_vfs.h b/atmel-samd/access_vfs.h
index 07af89e22..c1cd635fc 100644
--- a/atmel-samd/access_vfs.h
+++ b/atmel-samd/access_vfs.h
@@ -36,7 +36,6 @@ Ctrl_status vfs_test_unit_ready(void);
 Ctrl_status vfs_read_capacity(uint32_t *u32_nb_sector);
 bool        vfs_wr_protect(void);
 bool        vfs_removal(void);
-bool        vfs_unload(bool);
 Ctrl_status vfs_usb_read_10(uint32_t addr, uint16_t nb_sector);
 Ctrl_status vfs_usb_write_10(uint32_t addr, uint16_t nb_sector);
 
diff --git a/atmel-samd/main.c b/atmel-samd/main.c
index 1f3c3405c..1a0ee9dca 100644
--- a/atmel-samd/main.c
+++ b/atmel-samd/main.c
@@ -104,10 +104,7 @@ void init_flash_fs(void) {
     } else if (res != FR_OK) {
         return;
     }
-    mp_vfs_mount_t *vfs = m_new_obj_maybe(mp_vfs_mount_t);
-    if (vfs == NULL) {
-        return;
-    }
+    mp_vfs_mount_t *vfs = &mp_vfs_mount_flash;
     vfs->str = "/";
     vfs->len = 1;
     vfs->obj = MP_OBJ_FROM_PTR(vfs_fat);
@@ -584,9 +581,6 @@ int main(void) {
     mp_stack_ctrl_init();
     mp_stack_set_limit((char*)&_estack - (char*)&_ebss - 1024);
 
-    // Initialise the local flash filesystem after the gc in case we need to
-    // grab memory from it. Create it if needed, mount in on /flash, and set it
-    // as current dir.
     init_flash_fs();
 
     // Reset everything and prep MicroPython to run boot.py.
@@ -599,7 +593,7 @@ int main(void) {
 
     // If not in safe mode, run boot before initing USB and capture output in a
     // file.
-    if (safe_mode == NO_SAFE_MODE) {
+    if (safe_mode == NO_SAFE_MODE && MP_STATE_VM(vfs_mount_table) != NULL) {
         new_status_color(BOOT_RUNNING);
         #ifdef CIRCUITPY_BOOT_OUTPUT_FILE
         FIL file_pointer;
@@ -680,6 +674,10 @@ void gc_collect(void) {
     // pointers from CPU registers, and thus may function incorrectly.
     void *dummy;
     gc_collect_start();
+    // This collects root pointers from the first VFS entry which is statically
+    // allocated. This way we can do VFS operations prior to setting up the heap.
+    // This also means it can be done once on boot and not repeatedly.
+    gc_collect_root((void**)&mp_vfs_mount_flash, sizeof(mp_vfs_mount_t) / sizeof(mp_uint_t));
     // This naively collects all object references from an approximate stack
     // range.
     gc_collect_root(&dummy, ((mp_uint_t)&_estack - (mp_uint_t)&dummy) / sizeof(mp_uint_t));
@@ -687,11 +685,13 @@ void gc_collect(void) {
 }
 
 void NORETURN nlr_jump_fail(void *val) {
-    while (1);
+    HardFault_Handler();
+    while (true) {}
 }
 
 void NORETURN __fatal_error(const char *msg) {
-    while (1);
+    HardFault_Handler();
+    while (true) {}
 }
 
 #ifndef NDEBUG
diff --git a/atmel-samd/spi_flash.c b/atmel-samd/spi_flash.c
index 7f3c8984c..bf1f190c8 100644
--- a/atmel-samd/spi_flash.c
+++ b/atmel-samd/spi_flash.c
@@ -662,7 +662,10 @@ const mp_obj_type_t spi_flash_type = {
 };
 
 void flash_init_vfs(fs_user_mount_t *vfs) {
+    vfs->base.type = &mp_fat_vfs_type;
     vfs->flags |= FSUSER_NATIVE | FSUSER_HAVE_IOCTL;
+    vfs->fatfs.drv = vfs;
+    vfs->fatfs.part = 1; // flash filesystem lives on first partition
     vfs->readblocks[0] = (mp_obj_t)&spi_flash_obj_readblocks_obj;
     vfs->readblocks[1] = (mp_obj_t)&spi_flash_obj;
     vfs->readblocks[2] = (mp_obj_t)spi_flash_read_blocks; // native version
diff --git a/py/runtime.c b/py/runtime.c
index 5fe132ae7..504c17c15 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -29,6 +29,8 @@
 #include <string.h>
 #include <assert.h>
 
+#include "extmod/vfs.h"
+
 #include "py/mpstate.h"
 #include "py/nlr.h"
 #include "py/parsenum.h"
@@ -114,10 +116,25 @@ void mp_init(void) {
     #endif
 
     #if MICROPY_VFS
+    #if MICROPY_FATFS_NUM_PERSISTENT > 0
+    mp_vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table);
+    if (vfs != NULL) {
+        MP_STATE_VM(vfs_cur) = vfs;
+    }
+    // Skip forward until the vfs->next pointer is the first vfs that shouldn't
+    // persist.
+    uint8_t i = 1;
+    while (vfs != NULL && i < MICROPY_FATFS_NUM_PERSISTENT) {
+        vfs = vfs->next;
+        i++;
+    }
+    vfs->next = NULL;
+    #else
     // initialise the VFS sub-system
     MP_STATE_VM(vfs_cur) = NULL;
     MP_STATE_VM(vfs_mount_table) = NULL;
     #endif
+    #endif
 
     #if MICROPY_PY_THREAD_GIL
     mp_thread_mutex_init(&MP_STATE_VM(gil_mutex));