Hi Renan,
The UEFI driver model uses a stack of several modular DXE drivers to translate
from lower level to higher level interfaces. As a baseline reference, this is
what the driver stack would look like for a UFS device on an Intel SoC:
+--------------------------+
| EFI_BLOCK_IO(2)_PROTOCOL | <-- Represents a generic Hard Drive
+--------------------------+
|
V
*-------------*
| ScsiDiskDxe |
*-------------*
|
V
+----------------------+
| EFI_SCSI_IO_PROTOCOL | <-- Represents a SCSI device on a SCSI Bus
+----------------------+
|
V
*------------*
| ScsiBusDxe |
*------------*
|
V
+---------------------------------+
| EFI_EXT_SCSI_PASS_THRU_PROTOCOL | <-- Represents a SCSI HBA (Host-Bus
Adapter)
+---------------------------------+
|
V
*----------------*
| UfsPassThruDxe |
*----------------*
|
V
+----------------------------------+
| EFI_UFS_HOST_CONTROLLER_PROTOCOL | <-- Represents a UFS Controller
+----------------------------------+
|
V
*-------------*
| UfsPciHcDxe |
*-------------*
|
V
+---------------------+
| EFI_PCI_IO_PROTOCOL | <-- Represents a PCI device on a PCI bus
+---------------------+
|
V
*-----------*
| PciBusDxe |
*-----------*
|
V
+---------------------------------+
| EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL | <-- Represents the PCIe root complex
+---------------------------------+
|
V
*---------------------------------------*
| MdeModulePkg/Bus/Pci/PciHostBridgeDxe | <-- Requires SoCs specific
PciHostBridgeLib
*---------------------------------------*
|
V
+----------------------+
| EFI_CPU_IO2_PROTOCOL | <-- Provides the access to memory mapped I/O
and legacy I/O ports
+----------------------+
|
V
*----------------------*
| UefiCpuPkg/CpuIo2Dxe | <-- The only x86 specific driver in this stack
*----------------------*
The important thing to note about this diagram is that the UfsPciHcDxe device
driver that is present in MdeModulePkg can only be used for UFS controllers
that the SoC exposes as a PCI bus attached UFS controller. If the SoC exposes
the UFS controller as a PCI device, this driver should work. However, if the
SoC does not expose the UFS controller as a PCI device, then a SoC specific
driver will be required to produce a device handle with an instance of
EFI_UFS_HOST_CONTROLLER_PROTOCOL. You mentioned that no PCI devices with class
01h and subclass 09h exist on this SoC, which means that a SoC specific driver
is needed.
After the EFI_UFS_HOST_CONTROLLER_PROTOCOL instance is created, everything
above EFI_UFS_HOST_CONTROLLER_PROTOCOL in the diagram above (including
UfsPassThruDxe) will work without code change. The drivers below
EFI_UFS_HOST_CONTROLLER_PROTOCOL will obviously be different.
Hope that Helps,
Nate
From: [email protected] <[email protected]> On Behalf Of renan.moraes2
via groups.io
Sent: Tuesday, January 26, 2021 9:24 AM
To: [email protected]
Subject: [edk2-devel] Questions/doubts about UFS device on UEFI
Good afternoon,
We are studying how to communicate with Universal Flash Storage (UFS) device on
UEFI environment. The first step is identify the UFS device, we are using the
system Lenovo Flex 5G (It has Snapdragon processor + UFS device).
We tried to identify the UFS device in three ways:
1 - Specific UEFI protocols (UFS_DEVICE_CONFIG_PROTOCOL /
UFS_HOST_CONTROLLER_PROTOCOL) -> None of these protocols could be found on our
test systems, we compiled the EDK II 2020 (edk2-stable202005) available drivers
(UfsPassThru and UfsPciHc) and loaded them. However, these drivers can't detect
the UFS device.
2 - Device Path -> Tried to identify by its type (Type 3 – Messaging Device
Path) and subtype (Sub-Type 25 – UFS), but could not find any matches.
3 - Pci bus -> Tried to identify by its class (01h - Mass Storage Controller)
and subclass (09h - Universal Flash Storage controller), but could not find any
matches.
We would like to know if there is an alternative UEFI UFS driver or other
methods to identify and communicate with this type of storage device.
Thank you in advance.
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