Get property of driver's parent (or ancestor) - macos

I have a driver for a USB-attached custom SCSI device which implements some vendor-specific commands. Each USB device hosts more than one SCSI LUN. This is working quite happily, but there is a problem with grouping SCSI LUNs according to device, as from the IOSCSILogicalUnitNub level down (which my driver inherits from), there are no identifying features which link the LUNs together (there are SCSI Logical Unit Numbers, but these collide for every new device; they all have a unit 0x0).
I'd like to do something like link them all according to the USB locationID field (or any other unique key), but I don't know how to get at the parent USB devices given only the io_service_t of the matching SCSI drivers. This would also be better to be done on the application side, rather than in the driver, as the application needs to keep track of which service has which LUNs and was opened by which instance of the handler.
The hierarchy in the IO Registry is:
MyUSB-SCSI Device#fd130000
|-IOUSBCompositeDriver
|-Mass Storage Class Interface#0 (has location ID 0xfd130000)
|-IOUSBMassStorageClass
|-IOSCSILogicalUnitNub#0 (has SCSI LUN number, unique in this device, but not globally)
| |-com_Company_driver_MyDriver (my driver)
| |-IOBlockStorageServices
| |-Manuf Device Media (these are strings from the device firmware)
| |-IOMediaBSDClient
|
|-IOSCSILogicalUnitNub#0
|-com_Company_driver_MyDriver
|-IOBlockStorageServices
|-Manuf Device Media
|-IOMediaBSDClient

If your device's io_service_t is in the variable _device, then the code would look like:
CFTypeRef _thing_you_want = IORegistryEntrySearchCFProperty(_device, kIOServicePlane, CFSTR("locationID"), NULL, kIORegistryIterateParents);
Go here for more info:
http://developer.apple.com/library/mac/#documentation/devicedrivers/conceptual/AccessingHardware/AH_IOKitLib_API/AH_IOKitLib_API.html

Related

How to identify a HID after it's moved to a different port on Windows

I'm on Windows and am trying to store calibration data for game controllers connected via USB and am trying to find a value which uniquely identifies them in a port independent way.
There is the HidD_GetSerialNumberString function but i've read here that it's uncommon for devices to have serial numbers and indeed when i try to read one f.e. from a PS4 controller HidD_GetSerialNumberString returns FALSE and GetLastError returns ERROR_INVALID_PARAMETER.
Is there any other data available which can be accessed to achieve this?
You can try to use instance ID for your HID device (call CM_Get_Device_Interface_Property with device interface path and DEVPKEY_Device_InstanceId property and use string after last & char). It should be unique and persistent per system restarts. But it is not guaranteed if serial number is not provided (in this case instance ID will be different if device is plugged into different usb port)...
More info on this here: https://stackoverflow.com/a/56885175/1795050

What happens when we press a key on Windows?

First of all, I would say to you that I write this question from nothing because I have attempt to find good documentation but nothing stand out...
What happens when we squeeze a key?
I think this is complex but I hope you can help me.
What I search to know : all (but especially the program start on the host machine and how the key electric signal is encoded and send...)
The eXtensible Host Controller (xHC) has a Periodic Transfer Ring. Windows programs this ring to trigger a transfer every time an interval in milliseconds has passed. The right interval is specified in the USB descriptor returned by the USB device. When the transfer occurs, the xHC puts a Transfer Event TRB on the event ring and triggers an MSI-X interrupt which bypasses the IOAPIC as some kind of inter-processor interrupt. If Windows detects some change in the keys pressed, it will send a message to the application which currently has focus (calling the window's procedure) with the key pressed in one of the argument.
I don't know about electrical signals but I know the eXtensible Host Controller is the USB controller responsible to interact with USB on modern Windows systems. Since Windows nowadays requires an x64 processor, the xHC must be present on your motherboard. The xHC is a PCI-Express device which is compliant with the PCI-Express specification.
To find an xHC, you:
Find the RSDP ACPI table in RAM;
This table will be found by the UEFI firmware which acts as some kind of small operating-system (OS) during boot of the computer. Then, the OS developers will write a small UEFI application named bootx64.efi that they will place on a FAT32 partition on the hard-disk. They will place this app in the /boot/efi directory. The UEFI firmware will directly launch that application on boot of the computer which allows to have an OS which doesn't require user input to be launched (similarly to how it used to work with the legacy BIOS fetching the first sector of the hard-disk and executing the instructions found there).
The UEFI application is compiled in practice with either EDK2 or gnu-efi. These compilers are aware of the UEFI environment and specification. They thus compile the code to system calls that are present during boot and available for the UEFI application written by the OS developers. The System Tables (often the ACPI tables) are given as an argument to the "main" function (often called UefiMain) called by the UEFI firmware in the UEFI application. The code of the application can thus simply use these arguments to find the RSDP table and pass it to the OS.
Find the MCFG ACPI table using the RSDP;
The chain of table is RSDP -> XSDT -> MCFG. Once the OS found the MCFG, this table specifies the base address of the PCI configuration space. To interact with PCI devices you use memory mapped IO (MMIO). You write to some position in RAM and it will instead write to the registers of the PCI devices. The MCFG thus specifies the base address at which you will start finding MMIO registers for the different PCI devices that are plugged into the computer.
Iterate on the PCI devices and look at their IDs until you find an xHC.
To iterate on the PCI devices, the PCI convention specifies a formula which is the following:
UINT64 physical_address = base_address + ((bus - first_bus) << 20 | device << 15 | function << 12);
The base_address is for a specific segment group. Each segment group can have 256 buses (suitable for large servers or large computers with lots of components). There can be up to 65536 segment groups and each can have up to 256 PCI buses. Each PCI bus can have up to 32 devices plugged onto it and each device can have up to 8 functions. Each function can also be a PCI bridge. This is quite straightforward to understand because the terminology is clear. The bus here is an actual serial bus that the PCI devices (like a network card, a graphics card, an xHC, an AHCI, etc.) use to communicate with RAM. The function is a functionality of the PCI device like controlling USB devices, hard-disks, HDMI screens (for graphics cards), etc. The PCI bridge bridges a PCI bus to another PCI bus. It means you can have almost an infinite amount of devices with the PCI specification because the bridges allow to extend the tree of devices by adding other PCI host controllers.
Meanwhile, the bus is simply a number between 0 and 255. The first bus is specified in the MCFG ACPI table for a specific segment group. The device is a number between 0 and 31 and the function is a number between 0 and 7. This formula returns a physical address which points to a conventional configuration space (it is the same for all functions) which has specific registers. These registers are used to determine what is the type of device and to load a proper driver for it. Each function of each device thus gets a configuration space.
For the xHC, there will be only one function and the IDs returned by its configuration space will be 0x0C for the class ID and 0x03 for the subclass ID (https://wiki.osdev.org/EXtensible_Host_Controller_Interface).
Once you found an xHC, it gets rather complex. You need to initialize it and get the USB devices which are plugged in the computer at the current moment. You need to take several steps to get the xHC operational. For this part, I'll leave you to read the xHCI specification which (on chapter 4) specifies exactly the steps which need to be taken (https://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/extensible-host-controler-interface-usb-xhci.pdf).
For the keyboard portion I'll leave you to read one of my answer on the stackexchange for computer science: https://cs.stackexchange.com/questions/141870/when-are-a-controllers-registers-loaded-and-ready-to-inform-an-i-o-operation/141918#141918.
Some good links:
https://wiki.osdev.org/Universal_Serial_Bus
https://wiki.osdev.org/PCI

Client USB device driver query

How does an OS maps USB device with its device driver? I understand that in the interface descriptor of client USB firmware if no class type has been selected for the device then developer has to provide its own device driver.
I am keen to know how OS maps the pluggged USB device with its device driver? Does descriptors in the USB client firmware contains the file name of the custom device driver? Please let me know.
As a hobby, I have done quite a bit of work with the USB hardware, and had these same questions when I first started.
An OS can map a USB device any way it wants. However, to be more precise toward your question, a USB device will, and must return a class and interface code. Granted, that class code can be 0xFF for user-defined, where the device now must require a unique driver.
In my opinion, this is where the USB shines. All USB devices that return a valid class code specified within the USB specification, will and must follow a specific sequence of events and will "work right out of the box" as indicated. However, this doesn't mean that it cannot have extra capabilities.
For example. A pointing device, such as a mouse, will probably always follow the boot protocol when first plugged in. This is the protocol used and specified in the USB specification so that any OS that follows this protocol can use this pointing device. This protocol specifies a simple three (or more) byte packet for pointer input.
Byte Description
0 Button(s)
1 X Displacement
2 Y Displacement
3 (Device Specific) (optional)
Any pointing device that follows the USB specification most likely has this protocol and will use this protocol until told otherwise. This is so any USB capable OS can use the pointing device.
Every USB device also has a vendor, device, and protocol definition. Once the OS has found this device, it can search through its drivers for a driver that can support this device. That driver, once loaded, can then tell the device to now use a different protocol. i.e.: Return a different Input Report.
Here is an example. Let's say that you have a fancy gaming mouse with three directions of displacement (X, Y and Z), and six buttons. As the OS is booting, it probably has no idea how to use that mouse. Therefore, the manufacturer creates the mouse to use the boot protocol shown above until the driver can be loaded. Once the driver is loaded, which knows how to use the three direction displacements and all six buttons, it can tell the mouse, through a Control packet, maybe the SET INTERFACE command as well, to now start sending a different report, now using the full capabilities of the mouse.
So, as along as the device is USB specification accurate, and has a class code not of user defined (0xFF), the device will be recognized, even if it is a minimal use and/or is to show a statement that a driver is needed.
As for giving a file name of a custom device driver, this is all up to the device manufacturer. However, usually this is not that case. Usually, the OS will retrieve the DEVICE DESCRIPTOR which contains the manufacturer, device, protocol, and other fields. It will then match any driver to those fields. If it does not find a compatible driver, it will ask for one.
For example, one of the pointing devices I used with my research has the following few bytes of the 18-byte Device Descriptor:
Offset Field Value
0 Length 0x12
1 Type 0x01
2 Release Num 0x0110
4 Device Class 0x00
5 Sub Class 0x00
6 Protocol 0x00
7 MaxPacketSz 0x08
8 VendorID 0x04FC
10 Product ID 0x0003
...
Notice that it specifies the Vendor and the Product. Using these two values, a compatible driver can be found.
Now, notice that the class code is zero. This is not an error and is a perfectly valid class code, and simply means that the interface descriptor is to be used instead.
So, hopefully with this information, and specifically, the Manufacturer and Product codes within the DEVICE DESCRIPTOR, you can now see how an OS can find the correct driver for any device.

Programmatically determine NUMA node or PCI bus, device, function number of Direct3D9Ex device

I'm looking for a way to programmatically determine which NUMA node a particular Direct3D9Ex display adapter is connected to so that I can allocate memory for host to device transfers on that node.
I can use IDirect3D9Ex::GetAdapterIdentifier() to obtain a DeviceName of the form "\.\DISPLAY1".
I can use EnumDisplayDevices() to enumerate the display devices and match this DeviceName to a DeviceKey of the form "\Registry\Machine\System\CurrentControlSet\Control\Video{62E184AC-2614-4AA8-844C-47454B92C142}\0000".
I can use SetupDiEnumDeviceInfo() to enumerate devices and SetupDiGetDeviceProperty() to query properties including DEVPKEY_NAME (e.g. "NVIDIA GeForce GTX TITAN X"), DEVPKEY_Device_LocationInfo (e.g. "PCI bus 2, device 0, function 0") and DEVPKEY_Device_Numa_Node (e.g. 0) but I can't find anything to link one of these devices to either the DeviceName or DeviceKey in EnumDisplayDevices().
I can do equivalent thing is CUDA because cudaDeviceGetPCIBusId() provides the PCI bus, device and function information but I also need to do it in Direct3D9Ex (when CUDA is unavailable).
The other thing I've noticed is that in the registry under "HKLM\SYSTEM\CurrentControlSet\Enum\PCI\VEN_10DE&DEV_17C2&SUBSYS_113210DE&REV_A1" there is a key for each of my display devices and each one contains another key called "Device Parameters" with a value called "VideoID" of the form "{62E184AC-2614-4AA8-844C-47454B92C142}". Unfortunately applications are not supposed to read this part of the registry directly and I don't know how to obtain the same information through the SETUPAPI.

how to parse USB Device Instance ID (DIID)?

I want to know how "Device Instance ID" is made or how to parse it.
Take the following string as an example:
USB\VID_093A&PID_2700&MI_00\6&2703A67B&0&0000
As per my knowledge:
USB tells that this is a USB device
VID_093A indicates its vendor ID
similarly, PID_2700 is the product ID
However, I don't know about the rest.
MI is for multiple interfaces. A composite device has several interfaces.
6&2703A67B&0&0000 is the Instance ID.
The 6 at the beginning corresponds to the device node depth.
0 are root devices (e.g. volmgr, acpi_hal, they have Root\ prefix)
1 are acpi_hal devices (e.g. acpi (uses PNP0C08\0 instead of vid/pid/1), they have ACPI_HAL\ prefix)
2 are acpi devices (e.g. root pci bus controller (uses PNP0A08\0 instead of vid/pid/2), they have ACPI\ prefix)
3 are pci devices (e.g. xhci controller, they have PCI\ prefix)
4 are xhci devices (e.g. root hub, they have IUSB3\ prefix)
5+ are hub devices (e.g. usbccgp FDOs for composite devices, ubstor for storage etc., they have USB\ prefix)
6+ are usbstor devices (disk FDOs, USBSTOR\ prefix) or usbccgp composite interfaces (e.g. hidusb FDOs for input devices, USB\ prefix and have an MI)
7+ are endpoints (kbdhid FDOs for keyboards, mouhid FDOs for mice, HID\ prefix and have an MI)
The ID 2703A67B is an ID assigned by the parent. The xhci controller assigns the same one to all its root hubs; the separate hubs are identified by the value after the final ampersand, which is a simple incremental value. The root hub gives its child devices an ID that is the same across all devices and reboots; the separate devices are identified by the value after the final ampersand, again an incremental value. A composite device gives its children an ID that changes based on what hub/port it is plugged into; the separate interfaces are identified by the value after the final ampersand. An interface gives its children endpoints an ID that changes based on what hub/port it is plugged into; the separate endpoints are identified by the value after the final ampersand.
I can confirm that the ID that a hub assigns to its children changes if the hub is plugged into a different port on the root hub or a different hub altogether. I wrote '+' to indicate the presence of possible nested hubs. The PCI bus could also be nested and have a child bus (via PCIe to PCI bridge or PCIe root port aka. a PCIe to PCIe bridge), but I decided to leave that out. A root port is just a PCI device, basically a bridge/controller to a bus with only one slot (or more slots if the lanes are configured on the port to be split up), with a PCI\ prefix, and the child device will also have a PCI\ prefix.
By that token, the ID that the xHCI controller assigns probably depends on the PCI slot, and the ID the PCI bus controller assigns is probably dependent on what port the subordinate bus controller is connected to or whether it is the root controller.
This is why it installs drivers again when you insert a device into another port (unless it has a serial number). The drivers are considered installed when there is a registry entry for the DIID. The USB device will have a separate entry for each port and root hub combination they're plugged into. The composite device interfaces will have a separate entry for each port and root hub as well, as will the endpoints.
If the device has a serial number, which is uncommon, then the instance ID will be the serial number, and this will be the same regardless of where it is plugged into the system. If a composite device has a serial number instance ID then its interfaces probably have the same instance ID as that because the MI in the Device ID tells them apart. The endpoints are unlikely to have their own serial numbers and probably use the regular instance ID scheme.
Well, you really cant. This is the response from Microsoft regarding the same..
the device instance ID should be treated as opaque. if you want the VID/PID, query for the hardware and/or compa IDs and parse those. the hardware IDs are not considered opaque (but you still have to assume new hardware IDs will show up, so you need to detect the pattern you want to parse and have proactive code that handles other types of formats).
source: http://social.msdn.microsoft.com/Forums/en-US/4ff692bc-97c9-4943-b1ee-ec4f098e3b14/how-to-detect-sim-card-change-or-imsi-change-programatically-in-windows-phone-8?forum=wpdevelop
The Microsoft Device Instance ID page explains well how a Device Instance ID string is composed.
This page explains how a USB Identifier string (which composes the Device ID part of a Device Instance ID) is created.
Specifically, for your example:
USB\VID_093A&PID_2700&MI_00 is the Device ID, and
6&2703A67B&0&0000 is the Instance ID
Moreover, the Device ID tells you that:
USB\: this is a device under the USB enumerator
VID_093A: Pixart, Inc. manufactured this USB Device (you can find the USB Vendor ID list here)
PID_2700: this is the Product ID
MI_00: This is a Multiple Interface USB Device

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