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MSC exclusive access support. #8814

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1 change: 1 addition & 0 deletions extmod/vfs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,7 @@
#define MP_BLOCKDEV_IOCTL_BLOCK_COUNT (4)
#define MP_BLOCKDEV_IOCTL_BLOCK_SIZE (5)
#define MP_BLOCKDEV_IOCTL_BLOCK_ERASE (6)
#define MP_BLOCKDEV_IOCTL_STATUS (7)

// At the moment the VFS protocol just has import_stat, but could be extended to other methods
typedef struct _mp_vfs_proto_t {
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26 changes: 20 additions & 6 deletions extmod/vfs_fat_diskio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -114,6 +114,7 @@ DRESULT disk_ioctl(
[GET_SECTOR_COUNT] = MP_BLOCKDEV_IOCTL_BLOCK_COUNT,
[GET_SECTOR_SIZE] = MP_BLOCKDEV_IOCTL_BLOCK_SIZE,
[IOCTL_INIT] = MP_BLOCKDEV_IOCTL_INIT,
[IOCTL_STATUS] = MP_BLOCKDEV_IOCTL_STATUS,
};
uint8_t bp_op = op_map[cmd & 7];
mp_obj_t ret = mp_const_none;
Expand Down Expand Up @@ -147,16 +148,29 @@ DRESULT disk_ioctl(
*((DWORD *)buff) = 1; // erase block size in units of sector size
return RES_OK;

case IOCTL_INIT:
case IOCTL_STATUS: {
DSTATUS stat;
case IOCTL_INIT: {
DSTATUS stat = 0;
if (ret != mp_const_none && MP_OBJ_SMALL_INT_VALUE(ret) != 0) {
// error initialising
stat = STA_NOINIT;
} else if (vfs->blockdev.writeblocks[0] == MP_OBJ_NULL) {
stat = STA_PROTECT;
} else {
stat = 0;
// IOCTL_INIT only returns non 0 for all errors/flags. To return
// a more accurate disk state, IOCTL_STATUS is called again here.
ret = mp_vfs_blockdev_ioctl(&vfs->blockdev, MP_BLOCKDEV_IOCTL_STATUS, 0);
if (vfs->blockdev.writeblocks[0] == MP_OBJ_NULL ||
(ret != mp_const_none && MP_OBJ_SMALL_INT_VALUE(ret) != 0)) {
stat = STA_PROTECT;
}
}
*((DSTATUS *)buff) = stat;
return RES_OK;
}

case IOCTL_STATUS: {
DSTATUS stat = 0;
if (vfs->blockdev.writeblocks[0] == MP_OBJ_NULL ||
(ret != mp_const_none && MP_OBJ_SMALL_INT_VALUE(ret) != 0)) {
stat = STA_PROTECT;
}
*((DSTATUS *)buff) = stat;
return RES_OK;
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7 changes: 6 additions & 1 deletion ports/rp2/main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -82,7 +82,6 @@ int main(int argc, char **argv) {

#if MICROPY_HW_ENABLE_USBDEV
bi_decl(bi_program_feature("USB REPL"))
tusb_init();
#endif

#if MICROPY_PY_THREAD
Expand Down Expand Up @@ -147,6 +146,12 @@ int main(int argc, char **argv) {
pyexec_frozen_module("_boot.py");
#endif

#if MICROPY_HW_ENABLE_USBDEV
if (!tusb_inited()) {
tusb_init();
}
#endif

// Execute user scripts.
int ret = pyexec_file_if_exists("boot.py");
if (ret & PYEXEC_FORCED_EXIT) {
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1 change: 1 addition & 0 deletions ports/rp2/mpconfigport.h
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Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,7 @@
#if MICROPY_HW_USB_MSC
#define MICROPY_FATFS_USE_LABEL (1)
#define MICROPY_FATFS_MULTI_PARTITION (1)
#define MICROPY_HW_USB_MSC_EXCLUSIVE_ACCESS (1)
// Set FatFS block size to flash sector size to avoid caching
// the flash sector in memory to support smaller block sizes.
#define MICROPY_FATFS_MAX_SS (FLASH_SECTOR_SIZE)
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13 changes: 9 additions & 4 deletions ports/rp2/msc_disk.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,8 @@
#define FLASH_BASE_ADDR (PICO_FLASH_SIZE_BYTES - MICROPY_HW_FLASH_STORAGE_BYTES)
#define FLASH_MMAP_ADDR (XIP_BASE + FLASH_BASE_ADDR)

static bool ejected = false;
bool tud_msc_ejected = true;
extern void tud_msc_remount(void);

// Invoked when received SCSI_CMD_INQUIRY
// Application fill vendor id, product id and revision with string up to 8, 16, 4 characters respectively
Expand All @@ -51,12 +52,13 @@ void tud_msc_inquiry_cb(uint8_t lun, uint8_t vendor_id[8], uint8_t product_id[16
strncpy((char *)vendor_id, vid, 8);
strncpy((char *)product_id, pid, 16);
strncpy((char *)product_rev, rev, 4);
tud_msc_ejected = false;
}

// Invoked when received Test Unit Ready command.
// return true allowing host to read/write this LUN e.g SD card inserted
bool tud_msc_test_unit_ready_cb(uint8_t lun) {
if (ejected) {
if (tud_msc_ejected) {
tud_msc_set_sense(lun, SCSI_SENSE_NOT_READY, 0x3a, 0x00);
return false;
}
Expand All @@ -77,10 +79,13 @@ bool tud_msc_start_stop_cb(uint8_t lun, uint8_t power_condition, bool start, boo
if (load_eject) {
if (start) {
// load disk storage
ejected = false;
tud_msc_ejected = false;
} else {
// unload disk storage
ejected = true;
tud_msc_ejected = true;
#if MICROPY_HW_USB_MSC_EXCLUSIVE_ACCESS
tud_msc_remount();
#endif
}
}
return true;
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8 changes: 8 additions & 0 deletions ports/rp2/rp2_flash.c
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,8 @@
#define MICROPY_HW_FLASH_STORAGE_BASE (PICO_FLASH_SIZE_BYTES - MICROPY_HW_FLASH_STORAGE_BYTES)
#endif

extern bool tud_msc_ejected;

static_assert(MICROPY_HW_FLASH_STORAGE_BYTES <= PICO_FLASH_SIZE_BYTES, "MICROPY_HW_FLASH_STORAGE_BYTES too big");
static_assert(MICROPY_HW_FLASH_STORAGE_BASE + MICROPY_HW_FLASH_STORAGE_BYTES <= PICO_FLASH_SIZE_BYTES, "MICROPY_HW_FLASH_STORAGE_BYTES too big");

Expand Down Expand Up @@ -137,6 +139,12 @@ STATIC mp_obj_t rp2_flash_ioctl(mp_obj_t self_in, mp_obj_t cmd_in, mp_obj_t arg_
// TODO check return value
return MP_OBJ_NEW_SMALL_INT(0);
}
case MP_BLOCKDEV_IOCTL_STATUS:
#if MICROPY_HW_USB_MSC
return MP_OBJ_NEW_SMALL_INT(!tud_msc_ejected);
#else
return MP_OBJ_NEW_SMALL_INT(false);
#endif
default:
return mp_const_none;
}
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26 changes: 26 additions & 0 deletions shared/runtime/tinyusb_helpers.c
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Expand Up @@ -52,3 +52,29 @@ void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts) {
}

#endif

#if MICROPY_HW_USB_MSC_EXCLUSIVE_ACCESS
#include "tusb.h"
#include "extmod/vfs.h"
static mp_sched_node_t mp_remount_sched_node;

STATIC void tud_msc_remount_task(mp_sched_node_t *node) {
mp_vfs_mount_t *vfs = NULL;
for (vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
if (vfs->len == 1) {
nlr_buf_t nlr;
if (nlr_push(&nlr) == 0) {
mp_vfs_umount(vfs->obj);
nlr_pop();
}
mp_obj_t path = mp_obj_new_str(vfs->str, strlen(vfs->str));
mp_vfs_mount_and_chdir_protected(vfs->obj, path);
break;
}
}
}

void tud_msc_remount(void) {
mp_sched_schedule_node(&mp_remount_sched_node, tud_msc_remount_task);
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At which state will tud_msc_remount be called? Only when the device is ejected? Or is it possible that the PC may remount the drive? I cannot do that with my Linux box. If the board has always go through a power cycle, then it's fine.

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Assuming that a board with MSC support will start in locally write protected mode. What happens if the board is running stand-alone? Can it tell that there is no MSC mounted? Then the drive must be mounted write enabled.

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It gets called when the device is ejected. It may be possible to remount a safely-removed/ejected drive, but I think that disconnects power from the port anyway, I will have to test to confirm. However, I think that's a very unlikely case that shouldn't be handled, not sure if it should remount as read-only after giving write access to the device.

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@robert-hh robert-hh Jun 25, 2022 •
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I'm chewing on the timing issue. At the moment, the board starts with write enabled, to be able to create a file system, if it does not exist. Then it mounts the flash drive, which must be write protected if MSC is used. It could decide based on the status of the IOCTL_STATUS call. But how long does that status change take?

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OK. So the tud_msc_start_stop_cb() is only called on eject. The ud_msc_inquiry_cb() is called on start, as well as the tud_msc_capacity_cb(). So we could use these as indicator, that a PC is attempting to connect.
The tud_msc_test_unit_ready_cb() is called regularly.

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With the softreboot the file is gone. test without the soft reboot.
But I found a possible reason at my set-up: In tud_msc_remount_task() you have a check for len == 1. That is the length of the mount point name. On my set-up, the length is 6. So the remount never happens.
Changing the it to len == 6, the code is executed, and I can single-step it in the debugger. Then I see a strange phenomenon: while single stepping though unmount, remount, .., the PC still shows: "Unmount in progress, please do not remove the drive". Only after the remount function is finished, this message disappears. So it looks like in addition to the non-matching length check, the remount at the board was too early.

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So it looks like in addition to the non-matching length check, the remount at the board was too early.

maybe a false alarm: The PC/USB simple code waits for tud_msc_start_stop_cb() to finish.

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Yes maybe because you're single stepping the function. The remount is scheduled, so this function returns immediately. Anyway, the mount point of the MSC filesystem should be defined somewhere, or even better if it's detected dynamically somehow, but I'm not sure how to do that.

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I single stepped in the tud_msc_remount_task() function. So I know it is called.
At the moment, the internal flash is the first mounted file system. I do not know if we can reliably assume that this is always the case.

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If we do not find a good solution, we could at least defer opening the file system for write until the next soft boot. That's at least safe.

}
#endif