iris/source/usb-mass-storage.ccp

#pypp 0
// Iris: micro-kernel for a capability-based operating system.
// source/usb-mass-storage.ccp: USB mass storage device driver.
// Copyright 2009-2010 Bas Wijnen <wijnen@debian.org>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#include "iris.hh"
#include "devices.hh"
#define ARCH
#include "arch.hh"

#if 0
States and expected interrupts:

IDLE: after reset or csw.
	IN interrupt: csw received, do nothing.
	OUT interrupt: cbw; handle
		-> IDLE (no data; csw sent)
		-> CSW (data sent in one packet)
		-> TX (more than one packet to send)
		-> RX (receive packets)
TX: transmitting data.
	IN interrupt: host received data; send more.
		-> TX (more to send)
		-> CSW (last data has now been sent)
RX: receiving data.
	OUT interrupt: host sent data; handle.
		-> RX (more to receive)
		-> IDLE (done receiving; send csw)
CSW: waiting to transmit csw.
	IN interrupt: TX is done; send csw
		-> IDLE
#endif

extern "C":
	void *memset (char *s, int c, unsigned long n):
		Iris::debug ("memset called: %x %x->%x\n", s, n, c)
		for unsigned i = 0; i < n; ++i:
			s[i] = c
		return s

class Udc:
	typedef unsigned char u8
	typedef unsigned short u16
	typedef unsigned int u32
	typedef u8 string
	// The ugly stuff is because pypp doesn't support __attribute__.
	/**/struct Setup {
		u8 request_type;
		u8 request;
		u16 value;
		u16 index;
		u16 length;
	 } __attribute__ ((packed))
	/**/struct Device {
		static u8 const Type = 1;
		u8 length;
		u8 type;
		u16 usb_version;
		u8 dev_class;
		u8 subclass;
		u8 protocol;
		u8 max_packet_size0;
		u16 vendor;
		u16 product;
		u16 dev_version;
		string s_manufacturer;
		string s_product;
		string s_serial;
		u8 num_configurations;
	 } __attribute__ ((packed))
	/**/struct Configuration {
		static u8 const Type = 2;
		u8 length;
		u8 type;
		u16 total_length;
		u8 num_interfaces;
		u8 configuration_value;
		u8 configuration;
		u8 attributes;
		u8 max_power;
	 } __attribute__ ((packed))
	/**/struct Interface {
		static u8 const Type = 4;
		u8 length;
		u8 type;
		u8 interface;
		u8 alternate;
		u8 num_endpoints;
		u8 iface_class;
		u8 subclass;
		u8 protocol;
		string name;
	 } __attribute__ ((packed))
	/**/struct Endpoint {
		static u8 const Type = 5;
		u8 length;
		u8 type;
		u8 address;
		u8 attributes;
		u16 max_packet_size;
		u8 interval;
	 } __attribute__ ((packed))
	/**/struct Device_Qualifier {
		static u8 const Type = 6;
		u8 length;
		u8 type;
		u16 version;
		u8 dev_class;
		u8 subclass;
		u8 protocol;
		u8 max_packet_size0;
		u8 num_configurations;
		u8 reserved;
	 } __attribute__ ((packed))
	/**/struct Langs {
		static u8 const Type = 3;
		u8 length;
		u8 type;
		u8 lang;
	 } __attribute__ ((packed))
	template <unsigned size> struct String {
		static u8 const Type = 3;
		u8 length;
		u8 type;
		u16 data[size];
	 } __attribute__ ((packed))
	/**/struct CBW {
		u32 sig;
		u32 tag;
		u32 length;
		u8 flags;
		u8 lun;
		u8 size;
		u8 data[16];
		enum Code {
			TEST_UNIT_READY = 0x00,
			REQUEST_SENSE = 0x03,
			FORMAT_UNIT = 0x04,
			INQUIRY = 0x12,
			RESERVE6 = 0x16,
			RELEASE6 = 0x17,
			SEND_DIAGNOSTIC = 0x1d,
			READ_CAPACITY = 0x25,
			READ10 = 0x28,
			WRITE10 = 0x2a,
			RESERVE10 = 0x56,
			RELEASE10 = 0x57
		 };
	 } __attribute__ ((packed))
	static unsigned const max_packet_size0 = 64
	static unsigned const max_packet_size_bulk = 64
	enum Requests:
		GET_STATUS = 0
		CLEAR_FEATURE = 1
		SET_FEATURE = 3
		SET_ADDRESS = 5
		GET_DESCRIPTOR = 6
		SET_DESCRIPTOR = 7
		GET_CONFIGURATION = 8
		SET_CONFIGURATION = 9
		GET_INTERFACE = 10
		SET_INTERFACE = 11
		SYNCH_FRAME = 12
	enum Storage_requests:
		BULK_ONLY_RESET = 0xff
		GET_MAX_LUN = 0xfe
	enum Request_types:
		STANDARD_TO_DEVICE = 0
		CLASS_TO_DEVICE = 0x20
		VENDOR_TO_DEVICE = 0x40
		STANDARD_TO_INTERFACE = 1
		CLASS_TO_INTERFACE = 0x21
		VENDOR_TO_INTERFACE = 0x41
		STANDARD_TO_ENDPOINT = 2
		CLASS_TO_ENDPOINT = 0x22
		VENDOR_TO_ENDPOINT = 0x42
		STANDARD_FROM_DEVICE = 0x80
		CLASS_FROM_DEVICE = 0xa0
		VENDOR_FROM_DEVICE = 0xc0
		STANDARD_FROM_INTERFACE = 0x81
		CLASS_FROM_INTERFACE = 0xa1
		VENDOR_FROM_INTERFACE = 0xc1
		STANDARD_FROM_ENDPOINT = 0x82
		CLASS_FROM_ENDPOINT = 0xa2
		VENDOR_FROM_ENDPOINT = 0xc2
	enum Endpoint_types:
		CONTROL = 0
		ISOCHRONOUS = 1
		BULK = 2
		INTERRUPT = 3
	enum Endpoint_features:
		ENDPOINT_HALT = 0
	/**/struct my_config {
		Configuration config;
		Interface interface;
		Endpoint endpoint[2];
	 } __attribute__ ((packed))
	static Device device_descriptor
	//static Device_Qualifier device_qualifier_descriptor
	static my_config config_descriptor; //, other_config_descriptor
	static String <1> s_langs
	static String <6> s_manufacturer
	static String <16> s_product
	static String <12> s_serial
	char configuration
	unsigned get_descriptor (unsigned type, unsigned idx, unsigned len)
	unsigned handle_setup (Setup *s)
	void irq_usb ()
	void irq_in0 ()
	void irq_out ()
	void send_csw ()
	unsigned big_endian (unsigned src)
	bool handle_interrupt (bool usb, bool in)
	void stall (unsigned error)
	bool stalling[3]
	unsigned residue
	unsigned status
	unsigned tag
	unsigned block_bits
	Iris::WBlock block
	Iris::Page buffer_page
	// A random address to map the buffer.
	static unsigned const buffer = 0x15000
	public:
	void init (Iris::WBlock b)
	void log (unsigned c)
	void interrupt ()
	void send (unsigned ep, char const *data, unsigned length, unsigned maxlength)
	void send_padded (char const *data, unsigned length, unsigned maxlength)

Udc::Device Udc::device_descriptor
Udc::my_config Udc::config_descriptor
Udc::String <1> Udc::s_langs
Udc::String <6> Udc::s_manufacturer
Udc::String <16> Udc::s_product
Udc::String <12> Udc::s_serial

void Udc::init (Iris::WBlock b):
	block = b
	block_bits = block.get_align_bits ()
	// Set up the buffer page.
	buffer_page = Iris::my_memory.create_page ()
	buffer_page.set_flags (Iris::Page::PAYING)
	Iris::my_memory.map (buffer_page, buffer)
	// Initialize the globals.  My method of compiling doesn't handle global constructors.
	device_descriptor = (Device){ sizeof (Device), Device::Type, 0x200, 0, 0, 0, max_packet_size0, 0xfffe, 0x0002, 0x100, 1, 2, 3, 1 }
	config_descriptor = (my_config){
		(Configuration){ sizeof (Configuration), Configuration::Type, sizeof (my_config), 1, 1, 0, 0xc0, 30 },
		(Interface){ sizeof (Interface), Interface::Type, 0, 0, 2, 0x8, 0x6, 0x50, 0 }, {
			(Endpoint){ sizeof (Endpoint), Endpoint::Type, 1, BULK, max_packet_size_bulk, 0 },
			(Endpoint){ sizeof (Endpoint), Endpoint::Type, 0x82, BULK, max_packet_size_bulk, 0 }
		}
	 }
	s_langs = (String <1>){ sizeof (String <1>), String <1>::Type, { 0x0409 } }
	s_manufacturer = (String <6>){ sizeof (String <6>), String <6>::Type, { 's', 'h', 'e', 'v', 'e', 'k' } }
	s_product = (String <16>){ sizeof (String <16>), String <16>::Type, { 'I', 'r', 'i', 's', ' ', 'o', 'n', ' ', 'N', 'a', 'n', 'o', 'N', 'o', 't', 'e' } }
	s_serial = (String <12>){ sizeof (String <12>), String <12>::Type, { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B' } }

	cpm_start_udc ()
	// Disconnect from the bus and don't try to get high-speed.
	UDC_POWER = 0
	UDC_TESTMODE = 0
	configuration = 0
	// Set max packet sizes.
	UDC_INDEX = 1
	UDC_OUTMAXP = max_packet_size_bulk
	UDC_OUTCSR = UDC_OUTCSR_CDT | UDC_OUTCSR_FF
	UDC_OUTCSR = UDC_OUTCSR_CDT | UDC_OUTCSR_FF
	UDC_INDEX = 2
	UDC_INMAXP = max_packet_size_bulk
	UDC_INCSRH = UDC_INCSRH_MODE
	UDC_INCSR = UDC_INCSR_CDT | UDC_INCSR_FF
	UDC_INCSR = UDC_INCSR_CDT | UDC_INCSR_FF
	// exit suspend mode by reading the interrupt register.
	unsigned i = UDC_INTRUSB
	// reset all pending endpoint interrupts.
	i = UDC_INTRIN
	i = UDC_INTROUT
	// enable interrupt on bus reset.
	UDC_INTRUSBE = UDC_INTR_RESET
	// enable interrupts on endpoint 0 and in endpoint 2
	UDC_INTRINE = 1 << 0 | 1 << 2
	// and on out endpoint 1.
	UDC_INTROUTE = 1 << 1
	// Wait a while.
	Iris::sleep (HZ / 10)
	// Connect to the host.
	UDC_POWER = UDC_POWER_SOFTCONN

	// Initialize cbw state
	status = 0
	residue = 0

void Udc::send (unsigned ep, char const *data, unsigned length, unsigned maxlength):
	if maxlength < length:
		length = maxlength
	unsigned i
	for i = 0; (length - i & ~3) > 0 && i < length; i += 4:
		UDC_FIFO (ep) = ((unsigned *)data)[i / 4]
		//kdebug_num (((unsigned *)data)[i / 4], 8)
		//kdebug (" ")
	for ; i < length; ++i:
		UDC_FIFO8 (ep) = data[i]
		//kdebug_num (data[i], 2)
		//kdebug (" ")

void Udc::send_padded (char const *data, unsigned length, unsigned maxlength):
	UDC_INDEX = 2
	if UDC_INCSR & UDC_INCSR_INPKTRDY:
		Iris::panic (0, "sending padded not possible because a packet is already waiting.\n")
	unsigned len = length < maxlength ? length : maxlength
	residue = maxlength - len
	len = (len + 3) & ~3
	send (2, data, len, maxlength)
	while len + 3 < maxlength:
		UDC_FIFO (2) = 0
		len += 4
		//kdebug_char ('-')
	while len < maxlength:
		UDC_FIFO8 (2) = 0
		++len
		//kdebug_char ('.')
	UDC_INCSR |= UDC_INCSR_INPKTRDY
	while true:
		Iris::register_interrupt (IRQ_UDC)
		Iris::wait_for_interrupt (IRQ_UDC)
		//kdebug ("interrupt pad\t")
		unsigned usb = UDC_INTRUSB
		unsigned in = UDC_INTRIN
		unsigned out = UDC_INTROUT
		if usb & 4 || in & 1:
			//kdebug ("general interrupt pad\t")
			if !handle_interrupt (usb & 4, in & 1):
				return
		if out & 2:
			Iris::panic (0, "out interrupt while waiting for in")
		if in & 4:
			break
	//kdebug ("done interrupt pad\n")

unsigned Udc::get_descriptor (unsigned type, unsigned idx, unsigned len):
	switch type:
		case Configuration::Type:
			if idx != 0:
				return false
			//Iris::debug ("get config descriptor\n")
			send (0, reinterpret_cast <char const *> (&config_descriptor), sizeof (config_descriptor), len)
			return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
		case Device::Type:
			if idx != 0:
				return false
			//Iris::debug ("get device descriptor\n")
			send (0, reinterpret_cast <char const *> (&device_descriptor), sizeof (device_descriptor), len)
			return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
		case Device_Qualifier::Type:
			//if idx != 0:
			//	return false
			//send (0, reinterpret_cast <char const *> (&device_qualifier_descriptor), sizeof (device_qualifier_descriptor), len)
			//return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
			//break
			return ~0
		// The 6 is an arbitrary number, except that String <6> is instantiated already.
		case String <6>::Type:
			switch idx:
				case 0:
					//Iris::debug ("get language descriptor\n")
					send (0, reinterpret_cast <char const *> (&s_langs), sizeof (s_langs), len)
					return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
				case 1:
					//Iris::debug ("get manufacturer descriptor\n")
					send (0, reinterpret_cast <char const *> (&s_manufacturer), sizeof (s_manufacturer), len)
					return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
				case 2:
					//Iris::debug ("get product descriptor\n")
					send (0, reinterpret_cast <char const *> (&s_product), sizeof (s_product), len)
					return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
				case 3:
					//Iris::debug ("get serial descriptor\n")
					send (0, reinterpret_cast <char const *> (&s_serial), sizeof (s_serial), len)
					return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
				default:
					return ~0
		default:
			return ~0

unsigned Udc::handle_setup (Setup *s):
	switch s->request_type:
		case STANDARD_TO_DEVICE:
			UDC_INDEX = 0
			UDC_CSR0 = UDC_CSR0_DATAEND | UDC_CSR0_SVDOUTPKTRDY
			switch s->request:
				case SET_ADDRESS:
					UDC_FADDR = s->value
					//Iris::debug ("set address %x\n", s->value)
					return 0
				case SET_CONFIGURATION:
					if s->value >= 2:
						return ~0
					configuration = s->value
					//Iris::debug ("set configuration %x\n", s->value)
					return 0
				case SET_INTERFACE:
					if s->value != 0:
						return ~0
					//Iris::debug ("set interface %x\n", s->value)
					return 0
				default:
					return ~0
		case STANDARD_FROM_DEVICE:
			UDC_INDEX = 0
			UDC_CSR0 = UDC_CSR0_DATAEND | UDC_CSR0_SVDOUTPKTRDY
			switch s->request:
				case GET_STATUS:
					//Iris::debug ("get status\t")
					send (0, "\0\0", 2, s->length)
					return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
				case GET_DESCRIPTOR:
					return get_descriptor ((s->value >> 8) & 0xff, s->value & 0xff, s->length)
				case GET_CONFIGURATION:
					//Iris::debug ("get configuration\t")
					send (0, &configuration, 1, s->length)
					return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
				case GET_INTERFACE:
					//Iris::debug ("get interface\t")
					send (0, "\0", 1, s->length)
					return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
				default:
					return ~0
		case STANDARD_TO_ENDPOINT:
			switch s->request:
				case CLEAR_FEATURE:
					switch s->value:
						case ENDPOINT_HALT:
							switch s->index:
								case 0x82:
									//Iris::debug ("in ep halt reset\n")
									UDC_INDEX = 2
									UDC_INCSR &= ~UDC_INCSR_SENDSTALL
									stalling[2] = false
									break
								case 1:
									//Iris::debug ("out ep halt reset\n")
									UDC_INDEX = 1
									UDC_OUTCSR &= ~UDC_OUTCSR_SENDSTALL
									stalling[1] = false
									break
								default:
									return ~0
							UDC_INDEX = 0
							UDC_CSR0 = UDC_CSR0_DATAEND | UDC_CSR0_SVDOUTPKTRDY
							return 0
						default:
							return ~0
				default:
					return ~0
		case CLASS_FROM_INTERFACE:
			UDC_INDEX = 0
			UDC_CSR0 = UDC_CSR0_DATAEND | UDC_CSR0_SVDOUTPKTRDY
			switch s->request:
				case GET_MAX_LUN:
					//Iris::debug ("get max lun\t")
					send (0, "\0", 1, s->length)
					return UDC_CSR0_INPKTRDY | UDC_CSR0_DATAEND
				default:
					return ~0
		case CLASS_TO_INTERFACE:
			UDC_INDEX = 0
			UDC_CSR0 = UDC_CSR0_DATAEND | UDC_CSR0_SVDOUTPKTRDY
			switch s->request:
				case BULK_ONLY_RESET:
					//Iris::debug ("bulk reset\n")
					return 0
				default:
					return ~0
		default:
			Iris::debug ("request: %x %x %x %x %x\n", s->request_type, s->request, s->index, s->length, s->value)
			return ~0

void Udc::irq_usb ():
	// Reset.
	// enable interrupts on endpoint 0 and in endpoint 2
	UDC_INTRINE = 1 << 0 | 1 << 2
	// and on out endpoint 1.
	UDC_INTROUTE = 1 << 1
	UDC_INDEX = 1
	// Do this twice to flush a double-buffered fifo completely.
	UDC_OUTMAXP = max_packet_size_bulk
	UDC_OUTCSR |= UDC_OUTCSR_CDT | UDC_OUTCSR_FF
	UDC_OUTCSR |= UDC_OUTCSR_CDT | UDC_OUTCSR_FF
	UDC_INDEX = 2
	UDC_INMAXP = max_packet_size_bulk
	UDC_INCSR |= UDC_INCSR_CDT
	//Iris::debug ("usb reset\n")

void Udc::irq_in0 ():
	// Interrupt on endpoint 0.
	UDC_INDEX = 0
	unsigned csr = UDC_CSR0
	if csr & UDC_CSR0_SENTSTALL:
		UDC_CSR0 = 0
		//Iris::debug ("stall done\t")
	if csr & UDC_CSR0_SETUPEND:
		UDC_CSR0 = UDC_CSR0_SVDSETUPEND
		//Iris::debug ("setup aborted\t")
	if !(csr & UDC_CSR0_OUTPKTRDY):
		//Iris::debug ("no packet 0: %x\n", csr)
		return
	union { unsigned d[2]; Setup s; } packet
	packet.d[0] = UDC_FIFO (0)
	packet.d[1] = UDC_FIFO (0)
	if !(packet.s.request_type & 0x80) && packet.s.length > 0:
		// More data will follow; unsupported.
		//Iris::debug ("packet on ep0 too long\n")
		UDC_CSR0 = UDC_CSR0_SENDSTALL
		return
	UDC_INDEX = 1
	UDC_OUTCSR |= UDC_OUTCSR_CDT
	UDC_INDEX = 2
	UDC_INCSR |= UDC_INCSR_CDT
	unsigned ret = handle_setup (&packet.s)
	UDC_INDEX = 0
	if ret == ~0:
		Iris::debug ("failed setup: %x %x %x %x %x\n", packet.s.request_type, packet.s.request, packet.s.index, packet.s.length, packet.s.value)
		UDC_CSR0 = UDC_CSR0_SENDSTALL
		return
	if ret:
		UDC_CSR0 = ret
	//kdebug ("done in0\n")

void Udc::send_csw ():
	UDC_INDEX = 2
	UDC_FIFO (2) = 0x53425355
	UDC_FIFO (2) = tag
	UDC_FIFO (2) = residue
	UDC_FIFO8 (2) = status
	UDC_INCSR |= UDC_INCSR_INPKTRDY
	status = 0
	residue = 0
	while true:
		Iris::register_interrupt (IRQ_UDC)
		Iris::wait_for_interrupt (IRQ_UDC)
		unsigned usb = UDC_INTRUSB
		unsigned in = UDC_INTRIN
		if usb & 4 || in & 1:
			if !handle_interrupt (usb & 4, in & 1):
				return
		if in & 4:
			break
		unsigned out = UDC_INTROUT
		if out & 2:
			Iris::panic (0, "out interrupt while waiting for in after csw")
	//kdebug ("sent csw\n")

void Udc::stall (unsigned error):
	unsigned index = UDC_INDEX
	if stalling[index]:
		Iris::debug ("already stalling!\n")
	if index == 1:
		UDC_OUTCSR |= UDC_OUTCSR_SENDSTALL
	else:
		UDC_INCSR |= UDC_INCSR_SENDSTALL
	stalling[index] = true
	while stalling[index]:
		//kdebug ("stalling\t")
		Iris::register_interrupt (IRQ_UDC)
		Iris::wait_for_interrupt (IRQ_UDC)
		//kdebug ("stalling interrupt\n")
		unsigned usb = UDC_INTRUSB
		unsigned in = UDC_INTRIN
		if in & 4:
			//kdebug ("stall has been sent to in endpoint\n")
			UDC_INDEX = 2
			UDC_INCSR &= ~UDC_INCSR_SENTSTALL
			//Iris::debug ("csr: %x\n", UDC_INCSR)
		if usb & 4 || in & 1:
			//kdebug ("stuff\n")
			if !handle_interrupt (usb & 4, in & 1):
				return
		unsigned out = UDC_INTROUT
		if out & 2:
			//kdebug ("stall has been sent to out endpoint\n")
			UDC_INDEX = 1
			UDC_OUTCSR &= ~UDC_OUTCSR_SENTSTALL
		UDC_INDEX = index
	if index == 2:
		status = error
		send_csw ()

unsigned Udc::big_endian (unsigned src):
	return src >> 24 | src >> 8 & 0xff00 | src << 8 & 0xff0000 | src << 24

void Udc::irq_out ():
	UDC_INDEX = 1
	unsigned csr = UDC_OUTCSR
	unsigned size = UDC_OUTCOUNT
	if !(csr & UDC_OUTCSR_OUTPKTRDY):
		// No packet, just a notification.
		//kdebug ("no packet\n")
		return
	if csr & UDC_OUTCSR_SENDSTALL:
		// When stalling, do nothing else.
		//kdebug ("not responding to out during stall\n")
		UDC_OUTCSR = csr & ~UDC_OUTCSR_SENTSTALL
		return
	// expect a new cbw.
	if size != 31:
		Iris::debug ("count %d != 31\n", size)
		stall (2)
		return
	union Cbw:
		unsigned u[8]
		char b[32]
		CBW cbw
	Cbw cbw
	for unsigned i = 0; i < 7; ++i:
		cbw.u[i] = UDC_FIFO (1)
	for unsigned i = 28; i < 31; ++i:
		cbw.b[i] = UDC_FIFO8 (1)
	UDC_OUTCSR = csr & ~UDC_OUTCSR_OUTPKTRDY
	tag = cbw.cbw.tag
	if cbw.cbw.sig != 0x43425355 || cbw.cbw.lun != 0 || cbw.cbw.size == 0 || cbw.cbw.size > 16:
		Iris::debug ("sig %x lun %d size %d\n", cbw.cbw.sig, cbw.cbw.lun, cbw.cbw.size)
		stall (2)
		return
	//kdebug ("bulk cbw\t")
	UDC_INDEX = 2
	bool to_host = cbw.cbw.flags & 0x80
	switch cbw.cbw.data[0]:
		case CBW::TEST_UNIT_READY:
			if to_host || cbw.cbw.length != 0:
				stall (2)
				return
			//Iris::debug ("sending ready response\t")
			send_csw ()
			break
		case CBW::REQUEST_SENSE:
			//Iris::debug ("sense requested\t")
			send_padded ("\xf0\x00\x05\x00\x00\x00\x00\x00", 8, cbw.cbw.length)
			send_csw ()
			break
		case CBW::FORMAT_UNIT:
			Iris::panic (0, "FORMAT_UNIT isn't implemented")
		case CBW::INQUIRY:
			if !to_host:
				stall (2)
				return
			//Iris::debug ("sending inquiry response\t")
			send_padded ("\x00\x00\x04\x02\x1f\x00\x00\x00shevek  iris usb stick  \x00\x00\x04\x02", 36, cbw.cbw.length)
			send_csw ()
			break
		case CBW::RESERVE6:
			Iris::panic (0, "RESERVE6 isn't implemented")
		case CBW::RELEASE6:
			Iris::panic (0, "RELEASE6 isn't implemented")
		case CBW::SEND_DIAGNOSTIC:
			Iris::panic (0, "SEND_DIAGNOSTIC isn't implemented")
		case CBW::READ_CAPACITY:
			if !to_host:
				stall (2)
				return
			unsigned capacity[2]
			capacity[0] = big_endian ((block.get_size ().value () >> block_bits) - 1)
			capacity[1] = big_endian (1 << block_bits)
			//Iris::debug ("sending capacity: %x * %x\t", capacity[0], capacity[1])
			send_padded ((char *)capacity, 8, cbw.cbw.length)
			send_csw ()
			break
		case CBW::READ10:
			unsigned lba = cbw.cbw.data[2] << 24 | cbw.cbw.data[3] << 16 | cbw.cbw.data[4] << 8 | cbw.cbw.data[5]
			unsigned blocks = cbw.cbw.data[7] << 8 | cbw.cbw.data[8]
			for unsigned i = 0; i < blocks; ++i:
				//Iris::debug ("reading block %d:", lba + i)
				// read block lba + i.
				buffer_page.set_flags (Iris::Page::FRAME)
				block.get_block (lba << block_bits, 1 << block_bits, 0, buffer_page)
				for unsigned p = 0; p < 1 << block_bits; p += max_packet_size_bulk:
					//Iris::debug (" %d", p)
					UDC_INDEX = 2
					for unsigned t = 0; t < max_packet_size_bulk; t += 4:
						UDC_FIFO (2) = ((unsigned *)buffer)[(p + t) >> 2]
					UDC_INCSR |= UDC_INCSR_INPKTRDY
					//Iris::debug ("\n")
					while true:
						Iris::register_interrupt (IRQ_UDC)
						Iris::wait_for_interrupt (IRQ_UDC)
						//kdebug ("interrupt read10\t")
						unsigned usb = UDC_INTRUSB
						unsigned in = UDC_INTRIN
						unsigned out = UDC_INTROUT
						if usb & 4 || in & 1:
							//kdebug ("general interrupt read10\t")
							if !handle_interrupt (usb & 4, in & 1):
								return
						if out & 2:
							Iris::panic (0, "out interrupt while waiting for in")
						if in & 4:
							break
			send_csw ()
			break
		case CBW::WRITE10:
			Iris::panic (0, "WRITE10 isn't implemented")
		case CBW::RESERVE10:
			Iris::panic (0, "RESERVE10 isn't implemented")
		case CBW::RELEASE10:
			Iris::panic (0, "RELEASE10 isn't implemented")
		default:
			Iris::debug ("cbw:")
			for unsigned i = 0; i < cbw.cbw.size; ++i:
				kdebug_char (' ')
				kdebug_num (cbw.cbw.data[i], 2)
			Iris::debug ("\n")
			residue = cbw.cbw.length
			stall (1)
			return
	// TODO.

bool Udc::handle_interrupt (bool usb, bool in):
	if usb:
		//Iris::debug ("usb\t")
		// reset.
		irq_usb ()
		return false
	if in:
		//Iris::debug ("control\t")
		// control request
		irq_in0 ()
		return true

void Udc::interrupt ():
	//Iris::debug ("interrupt\n")
	while true:
		unsigned usb = UDC_INTRUSB
		unsigned in = UDC_INTRIN
		bool action = false
		if in & 4:
			Iris::panic (0, "data request during idle\n")
		if usb & 4 || in & 1:
			handle_interrupt (usb & 4, in & 1)
			action = true
		unsigned out = UDC_INTROUT
		if out & 2:
			irq_out ()
			action = true
		if !action:
			// No more interrupts to handle; this is normal, because we're looping until this happens.
			//Iris::debug ("irq done\n")
			return

Iris::Num start ():
	map_udc ()
	map_gpio ()
	map_cpm ()
	Udc udc

	Iris::WBlock nand = Iris::my_parent.get_capability <Iris::WBlock> ()
	udc.init (nand)
	while true:
		Iris::register_interrupt (IRQ_UDC)
		Iris::wait ()
		udc.interrupt ()