Freescale Semiconductor MPC5200B - Manual (Page 423)

MPC5200B Users Guide, Rev. 1
12-20 Freescale Semiconductor
Host Control (HC) Operational Registers
12.4.5.2 USB HC Rh Descriptor B Register—MBAR + 0x104C
This register is the second of two registers describing the Root Hub characteristics. These fields are written during initialization to correspond
with the system implementation. Reset values are implementation-specific.
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 lsb
R Reserved NOC
P
OCP
M
DT NPS PSM NDP
W
RESET: 0 0 0 1 0 0 1 0 0 0 0 0 0 0 1 0
Bits Name Description
0:7 POTPGT PowerOnToPowerGoodTime—specifies the duration HCD must wait before accessing a Root
Hub powered-on port. POTPGT is implementation-specific.
The time unit is 2ms. Duration is calculated as POTPGT x 2ms.
8:18 — Reserved
19 NOCP NoOverCurrentProtection—describes how the Root Hub port overcurrent status is reported.
When NOCP is cleared, OCPM specifies global or per-port reporting.
0 = Overcurrent status is reported collectively for all downstream ports.
1 = No overcurrent protection supported.
20 OCPM OverCurrentProtectionMode—describes how the Root Hub port overcurrent status is
reported.
At reset, OCPM should reflect the same mode as PowerSwitchingMode. OCPM is valid only
if NoOverCurrentProtection is cleared.
0 = Overcurrent status is reported collectively for all downstream ports.
1 = Overcurrent status is reported on a per-port basis.
21 DT DeviceType—specifies Root Hub is not a compound device. Root Hub is not permitted to be
a compound device. DT should always read/write 0.
22 NPS NoPowerSwitching—specifies whether power switching is supported or ports are always
powered. NPS is implementation specific. When this bit is cleared, PSM specifies global or
per-port switching.
0 = Ports are power switched.
1 = Ports are always powered on when HC is powered on.
23 PSM PowerSwitchingMode—specifies how the root hub port power switching is controlled. PSM is
implementation-specific and is only valid if the NoPowerSwitching field is cleared.
0 = All ports are powered at the same time.
1 = Each port is powered individually. This mode lets port power be controlled by either the
global switch or per-port switching.
• If PortPowerControlMask bit is set, port responds only to port power commands
(Set/ClearPor tPower).
• If port mask is cleared, port is controlled only by the global power switch
(Set/ClearGlobalPower).
24:31 NDP NumberDownstreamPorts—specifies the number of downstream ports supported by the Root
Hub. NDP is implementation-specific.
• Minimum number of ports is 1.
• Maximum number of ports (supported by OpenHCI) is 15.