UFS Layer | SCSI Layer

[PranabNandy]

Hi Team,
Can we add SCSI layer and UFS layer to access storage devices?
I am planning to add these layers.
Can you please share your opinion in this?
@travisg I would like to hear your thoughts
Thanks

[PranabNandy]

+----------------------+
|   Filesystem (ext4)  |
+----------------------+
|   Block Layer        |
+----------------------+
|   SCSI Layer         | 
+----------------------+
|   UFS Layer          |
+----------------------+
|   UFS Host Controller|
+----------------------+

1. Design Goals

No dynamic complexity
No full SCSI stack (like Linux)
Only essential commands:

• INQUIRY
• TEST UNIT READY
• READ CAPACITY (10/16)
• READ (10)
• WRITE (10) (optional)
• REQUEST SENSE

2. Core Data Structures

struct scsi_cmd {
    uint8_t  opcode;
    uint8_t  lun;
    uint32_t lba;
    uint32_t transfer_len;
    void    *buf;
    uint8_t  direction; // READ / WRITE / NONE
};
struct scsi_device {
    uint8_t lun;
    uint32_t block_size;
    uint64_t capacity;
    void *ufs_handle;
};
struct scsi_sense {
    uint8_t key;
    uint8_t asc;
    uint8_t ascq;
};

[travisg]

Oh that looks excellent, I'm very interested in this. There's some desire to also use the SCSI bits for virtio-scsi and probably usb mass storage at some point, so this is a great thing to have.

[PranabNandy]

Hi @travisg
Thanks for confirming.
Now I will start working on it.