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Tom Rini83d290c2018-05-06 17:58:06 -04001# SPDX-License-Identifier: GPL-2.0+
Zhikang Zhang982388e2017-08-03 02:30:57 -07002#
3# Copyright (C) 2017 NXP Semiconductors
4# Copyright (C) 2017 Bin Meng <bmeng.cn@gmail.com>
Zhikang Zhang982388e2017-08-03 02:30:57 -07005
6What is NVMe
7============
8
9NVM Express (NVMe) is a register level interface that allows host software to
10communicate with a non-volatile memory subsystem. This interface is optimized
11for enterprise and client solid state drives, typically attached to the PCI
12express interface. It is a scalable host controller interface designed to
13address the needs of enterprise and client systems that utilize PCI express
14based solid state drives (SSD). The interface provides optimized command
15submission and completion paths. It includes support for parallel operation by
16supporting up to 64K I/O queues with up to 64K commands per I/O queue.
17
18The device is comprised of some number of controllers, where each controller
19is comprised of some number of namespaces, where each namespace is comprised
20of some number of logical blocks. A namespace is a quantity of non-volatile
21memory that is formatted into logical blocks. An NVMe namespace is equivalent
22to a SCSI LUN. Each namespace is operated as an independent "device".
23
24How it works
25------------
26There is an NVMe uclass driver (driver name "nvme"), an NVMe host controller
27driver (driver name "nvme") and an NVMe namespace block driver (driver name
28"nvme-blk"). The host controller driver is supposed to probe the hardware and
29do necessary initialization to put the controller into a ready state at which
30it is able to scan all available namespaces attached to it. Scanning namespace
31is triggered by the NVMe uclass driver and the actual work is done in the NVMe
32namespace block driver.
33
34Status
35------
36It only support basic block read/write functions in the NVMe driver.
37
38Config options
39--------------
40CONFIG_NVME Enable NVMe device support
Zhikang Zhang0adc38b2017-08-03 02:30:59 -070041CONFIG_CMD_NVME Enable basic NVMe commands
42
43Usage in U-Boot
44---------------
45To use an NVMe hard disk from U-Boot shell, a 'nvme scan' command needs to
46be executed for all NVMe hard disks attached to the NVMe controller to be
47identified.
48
49To list all of the NVMe hard disks, try:
50
Bin Mengfceadc12017-08-22 08:15:17 -070051 => nvme info
Zhikang Zhang0adc38b2017-08-03 02:30:59 -070052 Device 0: Vendor: 0x8086 Rev: 8DV10131 Prod: CVFT535600LS400BGN
53 Type: Hard Disk
54 Capacity: 381554.0 MB = 372.6 GB (781422768 x 512)
55
56and print out detailed information for controller and namespaces via:
57
Bin Mengfceadc12017-08-22 08:15:17 -070058 => nvme detail
Zhikang Zhang0adc38b2017-08-03 02:30:59 -070059
60Raw block read/write to can be done via the 'nvme read/write' commands:
61
62 => nvme read a0000000 0 11000
63
64 => tftp 80000000 /tftpboot/kernel.itb
65 => nvme write 80000000 0 11000
66
67Of course, file system command can be used on the NVMe hard disk as well:
68
69 => fatls nvme 0:1
70 32376967 kernel.itb
71 22929408 100m
72
73 2 file(s), 0 dir(s)
74
75 => fatload nvme 0:1 a0000000 /kernel.itb
76 => bootm a0000000
Bin Meng7088a362017-08-03 02:31:03 -070077
78Testing NVMe with QEMU x86
79--------------------------
80QEMU supports NVMe emulation and we can test NVMe driver with QEMU x86 running
81U-Boot. Please see README.x86 for how to build u-boot.rom image for QEMU x86.
82
83Example command line to call QEMU x86 below with emulated NVMe device:
84$ ./qemu-system-i386 -drive file=nvme.img,if=none,id=drv0 -device nvme,drive=drv0,serial=QEMUNVME0001 -bios u-boot.rom