USB = Universal Serial Bus
UDC = USB Device Client
OTG = 'On The Go'
ULPI = Low Pin Interface
UTMI = USB2.0 Tranceiver Macrocell Interface
UTMI+ = UTMI + OTG
O

OTG -> Can switch between being host and client.
UTMI: Interface between PXA and USB chip on the board.
ULPI = UTMI+ in less pins. = LPI for USB, LPI is more general.


USB2 pin numbers on 24-pin connector:
VCC: 11 verified
D-: 10
D+: 9
GND: 8 

+5V: 5

1	Main charge +5v
2	
3	
4	
5 	+5v	Vbus-Host
6	d+
7	d-
8 	GND Client
9 	D+ Client
10	D- Client
11	Vbus Client
12
13
 

Main charge +5v: 1
2 <--> 24
3 <--> +5v charge 



It seems that:
GPIO18 is input, is VBUS detect: 1=off, 0=on
GPIO20 is output: 1= D+ pulled high when VBUS on, 0=D+ not pulled high
Hmmm, maybe not

Ok, so there is the quicklogic chip aswell. 
GPIOS used by usbflash.S: (maybe non-usb)
Inputs: 0, 113, 9, 101, 70, 93, 18
Output: 20, 6, 125, 111, 17, 2, 82

GPIOs used by qlusb20fn.dll.S:
Output: 119, 94

GPIOs used by ohci2.dll.S:
90 (IO), 8 (O ?I?), 10 (O), 9 (I)

All up:
In:
0	
113
9	called "bOpen" in ohci2.dll, is cable detect for something - 24pin connector detect, can't work out which actual pin
101	CF1 detect
70	CF2 detect
93	
18	'vbus detect'

Out:
20	Seems to actually be quicklogic low power mode related - see qlpowermanager.dll.1.S
6
125	Also seems to be quicklogic enable related, PXA locks if 0x00000000 read with this off
111	Seems to be Quicklogic enable, 0x00000000 reads 0's with this off
17
2
82	Is set to 1 for mini-usb connector, 0 for 24-pin (see qlpowermanager.dll.1.S:check_mini_usb())
119
94
8	Appears to be USB host VBus
10	USB Host Related

Both:
90	From usbflash.S, looks like 'Reset USB'





Default GPIO settings according to usbflash.S:setupGPIOS()
Inputs: 0, 113, 9, 101, 70, 93, 18
Output: 20, 6, 125, 111, 17, 2, 82
High: 20, 6, 125, 111
Set 17 high if [0xbc00059e] == 0x0103

GPIO	reg:value	in windows, usb ready
0	000:00000001	1
113	100:00020000	1
9	000:00000200	0
101	100:00000010	0
70	008:00000040	0
93	008:20000000	1
18	000:00040000	1
20	000:00100000	1
6	000:00000040	0
125	100:20000000	1
111	100:00008000	1
17	000:00020000	1
2	000:00000004	0
82	008:00040000	0

From haret boot into linux with no U2D configed in, the pull/down behaviour seems to work.
However.. if gpio111 is set low, it dies and never recovers.

UDC cable insert/remove while watching GPIOS:

000/00000200 = 9
008/00040000 = 82
000/00000500 = 10,8
100/00000100 = 104

Plug in (no usb):
9_2 off
82 off
10,8 on,on

104 on
...
104 off

UDC Cable Out:
9 on		MMC2 Data 0
82 on		??
10 off		MMC2 Data 1
8 off		MMC1 Command
104 on		WM9713 Power
...
104 off		WM9713 Power

100/00020000 = 113
000/00040000 = 18

USB In, power only:
113 IRQ
113 off
113 on
18 IRQ
18 off
113 IRQ
113 off
113 on

power:
113
91