USB Host Controller Access to System Memory
14-86
14.6.3.2
LBVAtoMPUVA()—Local Bus Virtual Address to MPU Virtual Address Conversion
Function
This function converts a local bus virtual address to a MPU virtual address.
This function is used when the host controller driver must traverse the ED and
TD linked lists in system memory, or in traversing the done TD list.
This function must understand both the MPU MMU and local bus MMU
programming and local bus virtual address restrictions. This routine is general-
ly implemented in a two step process—local bus virtual address to physical
address, then physical address to MPU virtual address. Those two steps are
described in section 14.6.3.4, LBVAtoPA()—Local Bus Virtual Address to
Physical Address Conversion Function and section 14.6.3.6,
PAtoMPUVA()—Physical Address to MPU Virtual Address Conversion
Function.
Take care when converting null pointers. The OHCI USB host controller uses
null pointers to indicate the end of lists. Some convention must be used to
indicate an MPU null pointer and properly convert a local bus virtual address
of 0x000000 to that MPU null pointer value.
14.6.3.3
MPUVAtoPA()—MPU Virtual Address to Physical Address Conversion Function
This function converts an MPU virtual address to the equivalent system physi-
cal address. This function must understand the way that the system software
has configured the MPU MMU. This function must provide a conversion that
has a result that is identical to the conversion done in hardware by the MPU
MMU.
14.6.3.4
LBVAtoPA()—Local Bus Virtual Address to Physical Address Conversion Function
This function converts a local bus virtual address to the equivalent system
physical address. This function must understand the way that the system soft-
ware has configured the local bus MMU. This function must provide a conver-
sion that has a result that is identical to the conversion done in hardware by
the local bus MMU.
This function must also understand the OMAP5910 local bus limitation that
requires local bus virtual addresses to be in the range 0x30000000 to
0x3FFFFFFF.