Texas Instruments OMAP5912 Reference Manual page 1504

USB OTG Controller
Table 67. OTG Control Register (OTG_CTRL) (Continued)
Bit Name
15 DRIVER_SEL
14:13 Reserved
12 A_SETB_HNPEN
11 A_BUSREQ
212 Universal Serial Bus (USB)
Description
Active controller/driver software. When OTG is enabled (OTG_EN = 1), this
read-only bit determines which OMAP5912 USB controller (and therefore
software driver) has ownership of the OTG link. When HNP occurs, the
OTG controller updates this bit and issues a driver change interrupt. When
OTG is disabled (OTG_EN = 0), this bit has no meaning. When a write
changes OTG_EN from 0 to 1, this bit is updated to reflect the value of
OTG_CTRL.ID.
0: Host driver has control of the OTG link.
1: Device driver has control of the OTG link.
This bit is set to 1 by soft reset or hardware reset.
Reserved
B-device HNP indication (when acting as default-A device). When OTG is
enabled (OTG_EN = 1) and OMAP5912 acts as a default-A device
(OTG_CTRL.ID=0), this bit must be programmed to reflect whether or not
the B-device has been enabled to issue HNP. This bit has no effect when
OMAP5912 acts as a default-B device (OTG_CTRL.ID=1) or when OTG is
disabled (OTG_EN = 0).
0: The B-device has not been enabled to issue HNP. The OMAP5912 OTG
controller does not respond to HNP issued by the B-device.
1: The B-device has been enabled to issue HNP. The OMAP5912 OTG
controller responds to HNP issued by the B-device.
This bit is cleared 0 by soft reset or hardware reset.
Bus request (when acting as default-A device). When OTG is enabled
(OTG_EN = 1) and OMAP5912 is acting as a default-A device
(OTG_CTRL.ID = 0), system software must set this bit when it wishes to
begin an OTG session. When acting as the OTG A-device, system
software can suspend the appropriate USB host controller port and then
clear this bit to allow HNP requests from the B-device. If no HNP occurs,
system software can set this bit to resume ownership of the OTG link by
the OMAP5912 USB host controller. This bit has no effect if OTG_EN = 0
or if OTG_CTRL.ID = 1.
0: A-device does not request host role on the bus. Depending on OTG
state machine state, either the session can end or the default-B device can
issue an HNP.
1: A-device requests host role on the bus. OTG state machine begins a
session (if the OTG session is ended) or attempts to return to ownership of
the OTG link to the OMAP5912 USB host controller as soon as possible.
This bit is cleared 0 by soft reset, hardware reset, or when the
A_REQ_TMROUT interrupt is set.
SPRU761A