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; Implementation of the USB protocol for device enumeration.

; Manage a USB device when it becomes ready for USB commands:

; configure, enumerate, load the corresponding driver(s),

; pass device information to the driver.

; =============================================================================

; ================================= Constants =================================

; =============================================================================

; USB standard request codes

USB_GET_STATUS        = 0

USB_CLEAR_FEATURE     = 1

USB_SET_FEATURE       = 3

USB_SET_ADDRESS       = 5

USB_GET_DESCRIPTOR    = 6

USB_SET_DESCRIPTOR    = 7

USB_GET_CONFIGURATION = 8

USB_SET_CONFIGURATION = 9

USB_GET_INTERFACE     = 10

USB_SET_INTERFACE     = 11

USB_SYNCH_FRAME       = 12

; USB standard descriptor types

USB_DEVICE_DESCR             = 1

USB_CONFIG_DESCR             = 2

USB_STRING_DESCR             = 3

USB_INTERFACE_DESCR          = 4

USB_ENDPOINT_DESCR           = 5

USB_DEVICE_QUALIFIER_DESCR   = 6

USB_OTHER_SPEED_CONFIG_DESCR = 7

USB_INTERFACE_POWER_DESCR    = 8

; Possible speeds of USB devices

USB_SPEED_FS = 0 ; full-speed

USB_SPEED_LS = 1 ; low-speed

USB_SPEED_HS = 2 ; high-speed

; Compile-time setting. If set, the code will dump all descriptors as they are

; read to the debug board.

USB_DUMP_DESCRIPTORS = 1

; =============================================================================

; ================================ Structures =================================

; =============================================================================

; USB descriptors. See USB specification for detailed explanations.

; First two bytes of every descriptor have the same meaning.

struct usb_descr

bLength                 db      ?

; Size of this descriptor in bytes

bDescriptorType         db      ?

; One of USB_*_DESCR constants.

ends

; USB device descriptor

struct usb_device_descr usb_descr

bcdUSB                  dw      ?

; USB Specification Release number in BCD, e.g. 110h = USB 1.1

bDeviceClass            db      ?

; USB Device Class Code

bDeviceSubClass         db      ?

; USB Device Subclass Code

bDeviceProtocol         db      ?

; USB Device Protocol Code

bMaxPacketSize0         db      ?

; Maximum packet size for zero endpoint

idVendor                dw      ?

; Vendor ID

idProduct               dw      ?

; Product ID

bcdDevice               dw      ?

; Device release number in BCD

iManufacturer           db      ?

; Index of string descriptor describing manufacturer

iProduct                db      ?

; Index of string descriptor describing product

iSerialNumber           db      ?

; Index of string descriptor describing serial number

bNumConfigurations      db      ?

; Number of possible configurations

ends

; USB configuration descriptor

struct usb_config_descr usb_descr

wTotalLength            dw      ?

; Total length of data returned for this configuration

bNumInterfaces          db      ?

; Number of interfaces in this configuration

bConfigurationValue     db      ?

; Value for SET_CONFIGURATION control request

iConfiguration          db      ?

; Index of string descriptor describing this configuration

bmAttributes            db      ?

; Bit 6 is SelfPowered, bit 5 is RemoteWakeupSupported,

; bit 7 must be 1, other bits must be 0

bMaxPower               db      ?

; Maximum power consumption from the bus in 2mA units

ends

; USB interface descriptor

struct usb_interface_descr usb_descr

; The following two fields work in pair. Sometimes one interface can work

; in different modes; e.g. videostream from web-cameras requires different

; bandwidth depending on resolution/quality/compression settings.

; Each mode of each interface has its own descriptor with its own endpoints

; following; all descriptors for one interface have the same bInterfaceNumber,

; and different bAlternateSetting.

; By default, any interface operates in mode with bAlternateSetting = 0.

; Often this is the only mode. If there are another modes, the active mode

; is selected by SET_INTERFACE(bAlternateSetting) control request.

bInterfaceNumber        db      ?

bAlternateSetting       db      ?

bNumEndpoints           db      ?

; Number of endpoints used by this interface, excluding zero endpoint

bInterfaceClass         db      ?

; USB Interface Class Code

bInterfaceSubClass      db      ?

; USB Interface Subclass Code

bInterfaceProtocol      db      ?

; USB Interface Protocol Code

iInterface              db      ?

; Index of string descriptor describing this interface

ends

; USB endpoint descriptor

struct usb_endpoint_descr usb_descr

bEndpointAddress        db      ?

; Lower 4 bits form endpoint number,

; upper bit is 0 for OUT endpoints and 1 for IN endpoints,

; other bits must be zero

bmAttributes            db      ?

; Lower 2 bits form transfer type, one of *_PIPE,

; other bits must be zero for non-isochronous endpoints;

; refer to the USB specification for meaning in isochronous case

wMaxPacketSize          dw      ?

; Lower 11 bits form maximum packet size,

; next two bits specify the number of additional transactions per microframe

; for high-speed periodic endpoints, other bits must be zero.

bInterval               db      ?

; Interval for polling endpoint for data transfers.

; Isochronous and high-speed interrupt endpoints: poll every 2^(bInterval-1)

; (micro)frames

; Full/low-speed interrupt endpoints: poll every bInterval frames

; High-speed bulk/control OUT endpoints: maximum NAK rate

ends

; =============================================================================

; =================================== Code ====================================

; =============================================================================

; When a new device is ready to be configured, a controller-specific code

; calls usb_new_device.

; The sequence of further actions:

; * open pipe for the zero endpoint (usb_new_device);

;   maximum packet size is not known yet, but it must be at least 8 bytes,

;   so it is safe to send packets with <= 8 bytes

; * issue SET_ADDRESS control request (usb_new_device)

; * set the new device address in the pipe (usb_set_address_callback)

; * notify a controller-specific code that initialization of other ports

;   can be started (usb_set_address_callback)

; * issue GET_DESCRIPTOR control request for first 8 bytes of device descriptor

;   (usb_after_set_address)

; * first 8 bytes of device descriptor contain the true packet size for zero

;   endpoint, so set the true packet size (usb_get_descr8_callback)

; * first 8 bytes of a descriptor contain the full size of this descriptor,

;   issue GET_DESCRIPTOR control request for the full device descriptor

;   (usb_after_set_endpoint_size)

; * issue GET_DESCRIPTOR control request for first 8 bytes of configuration

;   descriptor (usb_get_descr_callback)

; * issue GET_DESCRIPTOR control request for full configuration descriptor

;   (usb_know_length_callback)

; * issue SET_CONFIGURATION control request (usb_set_config_callback)

; * parse configuration descriptor, load the corresponding driver(s),

;   pass the configuration descriptor to the driver and let the driver do

;   the further work (usb_got_config_callback)

; This function is called from controller-specific part

; when a new device is ready to be configured.

; in: ecx -> pseudo-pipe, part of usb_pipe

; in: esi -> usb_controller

; in: [esi+usb_controller.ResettingHub] is the pointer to usb_hub for device,

;     NULL if the device is connected to the root hub

; in: [esi+usb_controller.ResettingPort] is the port for the device, zero-based

; in: [esi+usb_controller.ResettingSpeed] is the speed of the device, one of

;     USB_SPEED_xx.

; out: eax = 0 <=> failed, the caller should disable the port.

proc usb_new_device

        push    ebx edi         ; save used registers to be stdcall

; 1. Allocate resources. Any device uses the following resources:

; - device address in the bus

; - memory for device data

; - pipe for zero endpoint

; If some allocation fails, we must undo our actions. Closing the pipe

; is a hard task, so we avoid it and open the pipe as the last resource.

; The order for other two allocations is quite arbitrary.

; 1a. Allocate a bus address.

        push    ecx

        call    usb_set_address_request

        pop     ecx

; 1b. If failed, just return zero.

        test    eax, eax

        jz      .nothing

; 1c. Allocate memory for device data.

; For now, we need sizeof.usb_device_data and extra 8 bytes for GET_DESCRIPTOR

; input and output, see usb_after_set_address. Later we will reallocate it

; to actual size needed for descriptors.

        push    sizeof.usb_device_data + 8

        pop     eax

        push    ecx

        call    malloc

        pop     ecx

; 1d. If failed, free the bus address and return zero.

        test    eax, eax

        jz      .nomemory

; 1e. Open pipe for endpoint zero.

; For now, we do not know the actual maximum packet size;

; for full-speed devices it can be any of 8, 16, 32, 64 bytes,

; low-speed devices must have 8 bytes, high-speed devices must have 64 bytes.

; Thus, we must use some fake "maximum packet size" until the actual size

; will be known. However, the maximum packet size must be at least 8, and

; initial stages of the configuration process involves only packets of <= 8

; bytes, they will be transferred correctly as long as

; the fake "maximum packet size" is also at least 8.

; Thus, any number >= 8 is suitable for actual hardware.

; However, software emulation of EHCI in VirtualBox assumes that high-speed

; control transfers are those originating from pipes with max packet size = 64,

; even on early stages of the configuration process. This is incorrect,

; but we have no specific preferences, so let VirtualBox be happy and use 64

; as the fake "maximum packet size".

        push    eax

; We will need many zeroes.

; "push edi" is one byte, "push 0" is two bytes; save space, use edi.

        xor     edi, edi

        stdcall usb_open_pipe, ecx, edi, 64, edi, edi

; Put pointer to pipe into ebx. "xchg eax,reg" is one byte, mov is two bytes.

        xchg    eax, ebx

        pop     eax

; 1f. If failed, free the memory, the bus address and return zero.

        test    ebx, ebx

        jz      .freememory

; 2. Store pointer to device data in the pipe structure.

        mov     [ebx+usb_pipe.DeviceData], eax

; 3. Init device data, using usb_controller.Resetting* variables.

        mov     [eax+usb_device_data.NumPipes], 1

        mov     [eax+usb_device_data.ConfigDataSize], edi

        mov     [eax+usb_device_data.Interfaces], edi

        movzx   ecx, [esi+usb_controller.ResettingPort]

; Note: the following write zeroes

; usb_device_data.DeviceDescrSize, usb_device_data.NumInterfaces,

; usb_device_data.Speed.

        mov     dword [eax+usb_device_data.Port], ecx

        mov     dl, [esi+usb_controller.ResettingSpeed]

        mov     [eax+usb_device_data.Speed], dl

        mov     edx, [esi+usb_controller.ResettingHub]

        mov     [eax+usb_device_data.Hub], edx

; 4. Store pointer to the config pipe in the hub data.

; Config pipe serves as device identifier.

; Root hubs use the array inside usb_controller structure,

; non-root hubs use the array immediately after usb_hub structure.

        test    edx, edx

        jz      .roothub

        mov     edx, [edx+usb_hub.ConnectedDevicesPtr]

        mov     [edx+ecx*4], ebx

        jmp     @f

.roothub:

        mov     [esi+usb_controller.DevicesByPort+ecx*4], ebx

@@:

        call    usb_reinit_pipe_list

; 5. Issue SET_ADDRESS control request, using buffer filled in step 1a.

; Use the return value from usb_control_async as our return value;

; if it is zero, then something has failed.

        lea     eax, [esi+usb_controller.SetAddressBuffer]

        stdcall usb_control_async, ebx, eax, edi, edi, usb_set_address_callback, edi, edi

.nothing:

; 6. Return.

        pop     edi ebx         ; restore used registers to be stdcall

        ret

; Handlers of failures in steps 1b, 1d, 1f.

.freememory:

        call    free

        jmp     .freeaddr

.nomemory:

        dbgstr 'No memory for device data'

.freeaddr:

        mov     ecx, dword [esi+usb_controller.SetAddressBuffer+2]

        bts     [esi+usb_controller.ExistingAddresses], ecx

        xor     eax, eax

        jmp     .nothing

endp

; Helper procedure for usb_new_device.

; Allocates a new USB address and fills usb_controller.SetAddressBuffer

; with data for SET_ADDRESS(allocated_address) request.

; out: eax = 0 <=> failed

; Destroys edi.

proc usb_set_address_request

; There are 128 bits, one for each possible address.

; Note: only the USB thread works with usb_controller.ExistingAddresses,

; so there is no need for synchronization.

; We must find a bit set to 1 and clear it.

; 1. Find the first dword which has a nonzero bit = which is nonzero.

        mov     ecx, 128/32

        lea     edi, [esi+usb_controller.ExistingAddresses]

        xor     eax, eax

        repz scasd

; 2. If all dwords are zero, return an error.

        jz      .error

; 3. The dword at [edi-4] is nonzero. Find the lowest nonzero bit.

        bsf     eax, [edi-4]

; Now eax = bit number inside the dword at [edi-4].

; 4. Clear the bit.

        btr     [edi-4], eax

; 5. Generate the address by edi = memory address and eax = bit inside dword.

; Address = eax + 8 * (edi-4 - (esi+usb_controller.ExistingAddress)).

        sub     edi, esi

        lea     edi, [eax+(edi-4-usb_controller.ExistingAddresses)*8]

; 6. Store the allocated address in SetAddressBuffer and fill remaining fields.

; Note that usb_controller is zeroed at allocation, so only command byte needs

; to be filled.

        mov     byte [esi+usb_controller.SetAddressBuffer+1], USB_SET_ADDRESS

        mov     dword [esi+usb_controller.SetAddressBuffer+2], edi

; 7. Return non-zero value in eax.

        inc     eax

.nothing:

        ret

.error:

        dbgstr 'cannot allocate USB address'

        xor     eax, eax

        jmp     .nothing

endp

; This procedure is called by USB stack when SET_ADDRESS request initiated by

; usb_new_device is completed, either successfully or unsuccessfully.

; Note that USB stack uses esi = pointer to usb_controller.

proc usb_set_address_callback stdcall, pipe:dword, status:dword, buffer:dword, length:dword, calldata:dword

        push    ebx     ; save ebx to be stdcall

; Load data to registers for further references.

        mov     ebx, [pipe]

        mov     ecx, dword [esi+usb_controller.SetAddressBuffer+2]

        mov     eax, [esi+usb_controller.HardwareFunc]

; 1. Check whether the device has accepted new address. If so, proceed to 2.

; Otherwise, go to 3.

        cmp     [status], 0

        jnz     .error

; 2. Address accepted.

; 2a. The controller-specific structure for the control pipe still uses

; zero address. Call the controller-specific function to change it to

; the actual address.

; Note that the hardware could cache the controller-specific structure,

; so setting the address could take some time until the cache is evicted.

; Thus, the call is asynchronous; meet us in usb_after_set_address when it will

; be safe to continue.

        dbgstr 'address set in device'

        call    [eax+usb_hardware_func.SetDeviceAddress]

; 2b. If the port is in non-root hub, clear 'reset in progress' flag.

; In any case, proceed to 4.

        mov     eax, [esi+usb_controller.ResettingHub]

        test    eax, eax

        jz      .return

        and     [eax+usb_hub.Actions], not HUB_RESET_IN_PROGRESS

.return:

; 4. Address configuration done, we can proceed with other ports.

; Call the worker function for that.

        call    usb_test_pending_port

.nothing:

        pop     ebx     ; restore ebx to be stdcall

        ret

.error:

; 3. Device error: device not responding, disconnect etc.

        DEBUGF 1,'K : error %d in SET_ADDRESS, USB device disabled\n',[status]

; 3a. The address has not been accepted. Mark it as free.

        bts     dword [esi+usb_controller.ExistingAddresses], ecx

; 3b. Disable the port with bad device.

; For the root hub, call the controller-specific function and go to 6.

; For non-root hubs, let the hub code do its work and return (the request

; could take some time, the hub code is responsible for proceeding).

        cmp     [esi+usb_controller.ResettingHub], 0

        jz      .roothub

        mov     eax, [esi+usb_controller.ResettingHub]

        call    usb_hub_disable_resetting_port

        jmp     .nothing

.roothub:

        movzx   ecx, [esi+usb_controller.ResettingPort]

        call    [eax+usb_hardware_func.PortDisable]

        jmp     .return

endp

; This procedure is called from usb_subscription_done when the hardware cache

; is cleared after request from usb_set_address_callback.

; in: ebx -> usb_pipe

proc usb_after_set_address

        dbgstr 'address set for controller'

; Issue control transfer GET_DESCRIPTOR(DEVICE_DESCR) for first 8 bytes.

; Remember, we still do not know the actual packet size;

; 8-bytes-request is safe.

; usb_new_device has allocated 8 extra bytes besides sizeof.usb_device_data;

; use them for both input and output.

        mov     eax, [ebx+usb_pipe.DeviceData]

        add     eax, usb_device_data.DeviceDescriptor

        mov     dword [eax], \

                80h + \         ; device-to-host, standard, device-wide

                (USB_GET_DESCRIPTOR shl 8) + \  ; request

                (0 shl 16) + \  ; descriptor index: there is only one

                (USB_DEVICE_DESCR shl 24)       ; descriptor type

        mov     dword [eax+4], 8 shl 16         ; data length

        stdcall usb_control_async, ebx, eax, eax, 8, usb_get_descr8_callback, eax, 0

        ret

endp

; This procedure is called by USB stack when GET_DESCRIPTOR(DEVICE_DESCR)

; request initiated by usb_after_set_address is completed, either successfully

; or unsuccessfully.

; Note that USB stack uses esi = pointer to usb_controller.

proc usb_get_descr8_callback stdcall, pipe:dword, status:dword, buffer:dword, length:dword, calldata:dword

;       mov     eax, [buffer]

;       DEBUGF 1,'K : descr8: l=%x; %x %x %x %x %x %x %x %x\n',[length],\

;               [eax]:2,[eax+1]:2,[eax+2]:2,[eax+3]:2,[eax+4]:2,[eax+5]:2,[eax+6]:2,[eax+7]:2

        push    edi ebx         ; save used registers to be stdcall

        mov     ebx, [pipe]

; 1. Check whether the operation was successful.

; If not, say something to the debug board and stop the initialization.

        cmp     [status], 0

        jnz     .error

; 2. Length of descriptor must be at least sizeof.usb_device_descr bytes.

; If not, say something to the debug board and stop the initialization.

        mov     eax, [ebx+usb_pipe.DeviceData]

        cmp     [eax+usb_device_data.DeviceDescriptor+usb_device_descr.bLength], sizeof.usb_device_descr

        jb      .error

; 3. Now first 8 bytes of device descriptor are known;

; set DeviceDescrSize accordingly.

        mov     [eax+usb_device_data.DeviceDescrSize], 8

; 4. The controller-specific structure for the control pipe still uses

; the fake "maximum packet size". Call the controller-specific function to

; change it to the actual packet size from the device.

; Note that the hardware could cache the controller-specific structure,

; so changing it could take some time until the cache is evicted.

; Thus, the call is asynchronous; meet us in usb_after_set_endpoint_size

; when it will be safe to continue.

        movzx   ecx, [eax+usb_device_data.DeviceDescriptor+usb_device_descr.bMaxPacketSize0]

        mov     eax, [esi+usb_controller.HardwareFunc]

        call    [eax+usb_hardware_func.SetEndpointPacketSize]

.nothing:

; 5. Return.

        pop     ebx edi         ; restore used registers to be stdcall

        ret

.error:

        dbgstr 'error with USB device descriptor'

        jmp     .nothing

endp

; This procedure is called from usb_subscription_done when the hardware cache

; is cleared after request from usb_get_descr8_callback.

; in: ebx -> usb_pipe

proc usb_after_set_endpoint_size

; 1. Reallocate memory for device data:

; add memory for now-known size of device descriptor and extra 8 bytes

; for further actions.

; 1a. Allocate new memory.

        mov     eax, [ebx+usb_pipe.DeviceData]

        movzx   eax, [eax+usb_device_data.DeviceDescriptor+usb_device_descr.bLength]

; save length for step 2

        push    eax

        add     eax, sizeof.usb_device_data + 8

        call    malloc

; 1b. If failed, say something to the debug board and stop the initialization.

        test    eax, eax

        jz      .nomemory

; 1c. Copy data from old memory to new memory and switch the pointer in usb_pipe.

        push    eax

        push    esi edi

        mov     esi, [ebx+usb_pipe.DeviceData]

        mov     [ebx+usb_pipe.DeviceData], eax

        mov     edi, eax

        mov     eax, esi

repeat sizeof.usb_device_data / 4

        movsd

end repeat

        pop     edi esi

        call    usb_reinit_pipe_list

; 1d. Free the old memory.

; Note that free destroys ebx.

        push    ebx

        call    free

        pop     ebx

        pop     eax

; 2. Issue control transfer GET_DESCRIPTOR(DEVICE) for full descriptor.

; restore length saved in step 1a

        pop     edx

        add     eax, sizeof.usb_device_data

        mov     dword [eax], \

                80h + \         ; device-to-host, standard, device-wide

                (USB_GET_DESCRIPTOR shl 8) + \  ; request

                (0 shl 16) + \  ; descriptor index: there is only one

                (USB_DEVICE_DESCR shl 24)       ; descriptor type

        and     dword [eax+4], 0

        mov     [eax+6], dl     ; data length

        stdcall usb_control_async, ebx, eax, eax, edx, usb_get_descr_callback, eax, 0

; 3. Return.

        ret

.nomemory:

        dbgstr 'No memory for device data'

        ret

endp

; This procedure is called by USB stack when GET_DESCRIPTOR(DEVICE)

; request initiated by usb_after_set_endpoint_size is completed,

; either successfully or unsuccessfully.

proc usb_get_descr_callback stdcall, pipe:dword, status:dword, buffer:dword, length:dword, calldata:dword

; Note: the prolog is the same as in usb_get_descr8_callback.

        push    edi ebx         ; save used registers to be stdcall

; 1. Check whether the operation was successful.

; If not, say something to the debug board and stop the initialization.

        cmp     [status], 0

        jnz     usb_get_descr8_callback.error

; The full descriptor is known, dump it if specified by compile-time option.

if USB_DUMP_DESCRIPTORS

        mov     eax, [buffer]

        mov     ecx, [length]

        sub     ecx, 8

        jbe     .skipdebug

        DEBUGF 1,'K : device descriptor:'

@@:

        DEBUGF 1,' %x',[eax]:2

        inc     eax

        dec     ecx

        jnz     @b

        DEBUGF 1,'\n'

.skipdebug:

end if

; 2. Check that bLength is the same as was in the previous request.

; If not, say something to the debug board and stop the initialization.

; It is important, because usb_after_set_endpoint_size has allocated memory

; according to the old bLength. Note that [length] for control transfers

; includes 8 bytes of setup packet, so data length = [length] - 8.

        mov     eax, [buffer]

        movzx   ecx, [eax+usb_device_descr.bLength]

        add     ecx, 8

        cmp     [length], ecx

        jnz     usb_get_descr8_callback.error

; Amuse the user if she is watching the debug board.

        mov     cl, [eax+usb_device_descr.bNumConfigurations]

        DEBUGF 1,'K : found USB device with ID %x:%x, %d configuration(s)\n',\

                [eax+usb_device_descr.idVendor]:4,\

                [eax+usb_device_descr.idProduct]:4,\

                cl

; 3. If there are no configurations, stop the initialization.

        cmp     [eax+usb_device_descr.bNumConfigurations], 0

        jz      .nothing

; 4. Copy length of device descriptor to device data structure.

        movzx   edx, [eax+usb_device_descr.bLength]

        mov     [eax+usb_device_data.DeviceDescrSize-usb_device_data.DeviceDescriptor], dl

; 5. Issue control transfer GET_DESCRIPTOR(CONFIGURATION). We do not know

; the full length of that descriptor, so start with first 8 bytes, they contain

; the full length.

; usb_after_set_endpoint_size has allocated 8 extra bytes after the

; device descriptor, use them for both input and output.

        add     eax, edx

        mov     dword [eax], \

                80h + \         ; device-to-host, standard, device-wide

                (USB_GET_DESCRIPTOR shl 8) + \  ; request

                (0 shl 16) + \  ; descriptor index: there is only one

                (USB_CONFIG_DESCR shl 24)       ; descriptor type

        mov     dword [eax+4], 8 shl 16         ; data length

        stdcall usb_control_async, [pipe], eax, eax, 8, usb_know_length_callback, eax, 0

.nothing:

; 6. Return.

        pop     ebx edi         ; restore used registers to be stdcall

        ret

endp

; This procedure is called by USB stack when GET_DESCRIPTOR(CONFIGURATION)

; request initiated by usb_get_descr_callback is completed,

; either successfully or unsuccessfully.

proc usb_know_length_callback stdcall, pipe:dword, status:dword, buffer:dword, length:dword, calldata:dword

        push    ebx             ; save used registers to be stdcall

; 1. Check whether the operation was successful.

; If not, say something to the debug board and stop the initialization.

        cmp     [status], 0

        jnz     .error

; 2. Get the total length of data associated with config descriptor and store

; it in device data structure. The total length must be at least

; sizeof.usb_config_descr bytes; if not, say something to the debug board and

; stop the initialization.

        mov     eax, [buffer]

        mov     edx, [pipe]

        movzx   ecx, [eax+usb_config_descr.wTotalLength]

        mov     eax, [edx+usb_pipe.DeviceData]

        cmp     ecx, sizeof.usb_config_descr

        jb      .error

        mov     [eax+usb_device_data.ConfigDataSize], ecx

; 3. Reallocate memory for device data:

; include usb_device_data structure, device descriptor,

; config descriptor with all associated data, and extra bytes

; sufficient for 8 bytes control packet and for one usb_interface_data struc.

; Align extra bytes to dword boundary.

if sizeof.usb_interface_data > 8

.extra_size = sizeof.usb_interface_data

else

.extra_size = 8

end if

; 3a. Allocate new memory.

        movzx   edx, [eax+usb_device_data.DeviceDescrSize]

        lea     eax, [ecx+edx+sizeof.usb_device_data+.extra_size+3]

        and     eax, not 3

        push    eax

        call    malloc

        pop     edx

; 3b. If failed, say something to the debug board and stop the initialization.

        test    eax, eax

        jz      .nomemory

; 3c. Copy data from old memory to new memory and switch the pointer in usb_pipe.

        push    eax

        mov     ebx, [pipe]

        push    esi edi

        mov     esi, [ebx+usb_pipe.DeviceData]

        mov     edi, eax

        mov     [ebx+usb_pipe.DeviceData], eax

        mov     eax, esi

        movzx   ecx, [esi+usb_device_data.DeviceDescrSize]

        sub     edx, .extra_size

        mov     [esi+usb_device_data.Interfaces], edx

        add     ecx, sizeof.usb_device_data + 8

        mov     edx, ecx

        shr     ecx, 2

        and     edx, 3

        rep movsd

        mov     ecx, edx

        rep movsb

        pop     edi esi

        call    usb_reinit_pipe_list

; 3d. Free old memory.

        call    free

        pop     eax

; 4. Issue control transfer GET_DESCRIPTOR(DEVICE) for full descriptor.

        movzx   ecx, [eax+usb_device_data.DeviceDescrSize]

        mov     edx, [eax+usb_device_data.ConfigDataSize]

        lea     eax, [eax+ecx+sizeof.usb_device_data]

        mov     dword [eax], \

                80h + \         ; device-to-host, standard, device-wide

                (USB_GET_DESCRIPTOR shl 8) + \  ; request

                (0 shl 16) + \  ; descriptor index: there is only one

                (USB_CONFIG_DESCR shl 24)       ; descriptor type

        and     dword [eax+4], 0

        mov     word [eax+6], dx        ; data length

        stdcall usb_control_async, [pipe], eax, eax, edx, usb_set_config_callback, eax, 0

.nothing:

; 5. Return.

        pop     ebx             ; restore used registers to be stdcall

        ret

.error:

        dbgstr 'error with USB configuration descriptor'

        jmp     .nothing

.nomemory:

        dbgstr 'No memory for device data'

        jmp     .nothing

endp

; This procedure is called by USB stack when GET_DESCRIPTOR(CONFIGURATION)

; request initiated by usb_know_length_callback is completed,

; either successfully or unsuccessfully.

proc usb_set_config_callback stdcall, pipe:dword, status:dword, buffer:dword, length:dword, calldata:dword

; Note that the prolog is the same as in usb_know_length_callback.

        push    ebx             ; save used registers to be stdcall

; 1. Check whether the operation was successful.

; If not, say something to the debug board and stop the initialization.

        xor     ecx, ecx

        mov     ebx, [pipe]

        cmp     [status], ecx

        jnz     usb_know_length_callback.error

; The full descriptor is known, dump it if specified by compile-time option.

if USB_DUMP_DESCRIPTORS

        mov     eax, [buffer]

        mov     ecx, [length]

        sub     ecx, 8

        jbe     .skip_debug

        DEBUGF 1,'K : config descriptor:'

@@:

        DEBUGF 1,' %x',[eax]:2

        inc     eax

        dec     ecx

        jnz     @b

        DEBUGF 1,'\n'

.skip_debug:

        xor     ecx, ecx

end if

; 2. Issue control transfer SET_CONFIGURATION to activate this configuration.

; Usually this is the only configuration.

; Use extra bytes allocated by usb_know_length_callback;

; offset from device data start is stored in Interfaces.

        mov     eax, [ebx+usb_pipe.DeviceData]

        mov     edx, [buffer]

        add     eax, [eax+usb_device_data.Interfaces]

        mov     dl, [edx+usb_config_descr.bConfigurationValue]

        mov     dword [eax], USB_SET_CONFIGURATION shl 8

        mov     dword [eax+4], ecx

        mov     byte [eax+2], dl

        stdcall usb_control_async, [pipe], eax, ecx, ecx, usb_got_config_callback, [buffer], ecx

        pop     ebx             ; restore used registers to be stdcall

        ret

endp

; This procedure is called by USB stack when SET_CONFIGURATION

; request initiated by usb_set_config_callback is completed,

; either successfully or unsuccessfully.

; If successfully, the device is configured and ready to work,

; pass the device to the corresponding driver(s).

proc usb_got_config_callback stdcall, pipe:dword, status:dword, buffer:dword, length:dword, calldata:dword

locals

InterfacesData  dd      ?

NumInterfaces   dd      ?

driver          dd      ?

endl

; 1. If there was an error, say something to the debug board and stop the

; initialization.

        cmp     [status], 0

        jz      @f

        dbgstr 'USB error in SET_CONFIGURATION'

        ret

@@:

        push    ebx edi         ; save used registers to be stdcall

; 2. Sanity checks: the total length must be the same as before (because we

; have allocated memory assuming the old value), length of config descriptor

; must be at least sizeof.usb_config_descr (we use fields from it),

; there must be at least one interface.

        mov     ebx, [pipe]

        mov     ebx, [ebx+usb_pipe.DeviceData]

        mov     eax, [calldata]

        mov     edx, [ebx+usb_device_data.ConfigDataSize]

        cmp     [eax+usb_config_descr.wTotalLength], dx

        jnz     .invalid

        cmp     [eax+usb_config_descr.bLength], 9

        jb      .invalid

        movzx   edx, [eax+usb_config_descr.bNumInterfaces]

        test    edx, edx

        jnz     @f

.invalid:

        dbgstr 'error: invalid configuration descriptor'

        jmp     .nothing

@@:

; 3. Store the number of interfaces in device data structure.

        mov     [ebx+usb_device_data.NumInterfaces], dl

; 4. If there is only one interface (which happens quite often),

; the memory allocated in usb_know_length_callback is sufficient.

; Otherwise (which also happens quite often), reallocate device data.

; 4a. Check whether there is only one interface. If so, skip this step.

        cmp     edx, 1

        jz      .has_memory

; 4b. Allocate new memory.

        mov     eax, [ebx+usb_device_data.Interfaces]

        lea     eax, [eax+edx*sizeof.usb_interface_data]

        call    malloc

; 4c. If failed, say something to the debug board and

; stop the initialization.

        test    eax, eax

        jnz     @f

        dbgstr 'No memory for device data'

        jmp     .nothing

@@:

; 4d. Copy data from old memory to new memory and switch the pointer in usb_pipe.

        push    eax

        push    esi

        mov     ebx, [pipe]

        mov     edi, eax

        mov     esi, [ebx+usb_pipe.DeviceData]

        mov     [ebx+usb_pipe.DeviceData], eax

        mov     eax, esi

        mov     ecx, [esi+usb_device_data.Interfaces]

        shr     ecx, 2

        rep movsd

        pop     esi

        call    usb_reinit_pipe_list

; 4e. Free old memory.

        call    free

        pop     ebx

.has_memory:

; 5. Initialize interfaces table: zero all contents.

        mov     edi, [ebx+usb_device_data.Interfaces]

        add     edi, ebx

        mov     [InterfacesData], edi

        movzx   ecx, [ebx+usb_device_data.NumInterfaces]

if sizeof.usb_interface_data <> 8

You have changed sizeof.usb_interface_data? Modify this place too.

end if

        add     ecx, ecx

        xor     eax, eax

        rep stosd

; No interfaces are found yet.

        mov     [NumInterfaces], eax

; 6. Get the pointer to config descriptor data.

; Note: if there was reallocation, [buffer] is not valid anymore,

; so calculate value based on usb_device_data.

        movzx   eax, [ebx+usb_device_data.DeviceDescrSize]

        lea     eax, [eax+ebx+sizeof.usb_device_data]

        mov     [calldata], eax

        mov     ecx, [ebx+usb_device_data.ConfigDataSize]

; 7. Loop over all descriptors,

; scan for interface descriptors with bAlternateSetting = 0,

; load the corresponding driver, call its AddDevice function.

.descriptor_loop:

; While in loop: eax points to the current descriptor,

; ecx = number of bytes left, the iteration starts only if ecx is nonzero,

; edx = size of the current descriptor.

; 7a. The first byte is always accessible; it contains the length of

; the current descriptor. Validate that the length is at least 2 bytes,

; and the entire descriptor is readable (the length is at most number of

; bytes left).

        movzx   edx, [eax+usb_descr.bLength]

        cmp     edx, sizeof.usb_descr

        jb      .invalid

        cmp     ecx, edx

        jb      .invalid

; 7b. Check descriptor type. Ignore all non-INTERFACE descriptor.

        cmp     byte [eax+usb_descr.bDescriptorType], USB_INTERFACE_DESCR

        jz      .interface

.next_descriptor:

; 7c. Advance pointer, decrease length left, if there is still something left,

; continue the loop.

        add     eax, edx

        sub     ecx, edx

        jnz     .descriptor_loop

.done:

.nothing:

        pop     edi ebx         ; restore used registers to be stdcall

        ret

.interface:

; 7d. Validate the descriptor length.

        cmp     edx, sizeof.usb_interface_descr

        jb      .next_descriptor

; 7e. If bAlternateSetting is nonzero, this descriptor actually describes

; another mode of already known interface and belongs to the already loaded

; driver; amuse the user and continue to 7c.

        cmp     byte [eax+usb_interface_descr.bAlternateSetting], 0

        jz      @f

        DEBUGF 1,'K : note: alternate setting with %x/%x/%x\n',\

                [eax+usb_interface_descr.bInterfaceClass]:2,\

                [eax+usb_interface_descr.bInterfaceSubClass]:2,\

                [eax+usb_interface_descr.bInterfaceProtocol]:2

        jmp     .next_descriptor

@@:

; 7f. Check that the new interface does not overflow allocated table.

        mov     edx, [NumInterfaces]

        inc     dl

        jz      .invalid

        cmp     dl, [ebx+usb_device_data.NumInterfaces]

        ja      .invalid

; 7g. We have found a new interface. Advance bookkeeping vars.

        mov     [NumInterfaces], edx

        add     [InterfacesData], sizeof.usb_interface_data

; 7h. Save length left and pointer to the current interface descriptor.

        push    ecx eax

; Amuse the user if she is watching the debug board.

        DEBUGF 1,'K : USB interface class/subclass/protocol = %x/%x/%x\n',\

                [eax+usb_interface_descr.bInterfaceClass]:2,\

                [eax+usb_interface_descr.bInterfaceSubClass]:2,\

                [eax+usb_interface_descr.bInterfaceProtocol]:2

; 7i. Select the correct driver based on interface class.

; For hubs, go to 7j. Otherwise, go to 7k.

; Note: this should be rewritten as table-based lookup when more drivers will

; be available.

        cmp     byte [eax+usb_interface_descr.bInterfaceClass], 9

        jz      .found_hub

        mov     edx, usb_hid_name

        cmp     byte [eax+usb_interface_descr.bInterfaceClass], 3

        jz      .load_driver

        mov     edx, usb_print_name

        cmp     byte [eax+usb_interface_descr.bInterfaceClass], 7

        jz      .load_driver

        mov     edx, usb_stor_name

        cmp     byte [eax+usb_interface_descr.bInterfaceClass], 8

        jz      .load_driver

        mov     edx, usb_other_name

        jmp     .load_driver

.found_hub:

; 7j. Hubs are a part of USB stack, thus, integrated into the kernel.

; Use the pointer to hub callbacks and go to 7m.

        mov     eax, usb_hub_pseudosrv - USBSRV.usb_func

        jmp     .driver_loaded

.load_driver:

; 7k. Load the corresponding driver.

        push    ebx esi edi

        stdcall get_service, edx

        pop     edi esi ebx

; 7l. If failed, say something to the debug board and go to 7p.

        test    eax, eax

        jnz     .driver_loaded

        dbgstr 'failed to load class driver'

        jmp     .next_descriptor2

.driver_loaded:

; 7m. Call AddDevice function of the driver.

; Note that top of stack contains a pointer to the current interface,

; saved by step 7h.

        mov     [driver], eax

        mov     eax, [eax+USBSRV.usb_func]

        pop     edx

        push    edx

; Note: usb_hub_init assumes that edx points to usb_interface_descr,

; ecx = length rest; if you change the code, modify usb_hub_init also.

        stdcall [eax+USBFUNC.add_device], [pipe], [calldata], edx

; 7n. If failed, say something to the debug board and go to 7p.

        test    eax, eax

        jnz     .store_data

        dbgstr 'USB device initialization failed'

        jmp     .next_descriptor2

.store_data:

; 7o. Store the returned value and the driver handle to InterfacesData.

; Note that step 7g has already advanced InterfacesData.

        mov     edx, [InterfacesData]

        mov     [edx+usb_interface_data.DriverData-sizeof.usb_interface_data], eax

        mov     eax, [driver]

        mov     [edx+usb_interface_data.DriverFunc-sizeof.usb_interface_data], eax

.next_descriptor2:

; 7p. Restore registers saved in step 7h, get the descriptor length and

; continue to 7c.

        pop     eax ecx

        movzx   edx, byte [eax+usb_descr.bLength]

        jmp     .next_descriptor

endp

; Driver names, see step 7i of usb_got_config_callback.

iglobal

usb_hid_name    db      'usbhid',0

usb_stor_name   db      'usbstor',0

usb_print_name  db      'usbprint',0

usb_other_name  db      'usbother',0

endg