User`s guide

2 Overview of a BSP

2.3 Components of a BSP

romInit.s

This assembly file contains the romInit( ) routine, which is the entry point for

bootstrapping, plus any romInit( ) subroutines. The romInit( ) routine must be the

first routine in the text segment of romInit.s.

At power-up (cold start) the processor begins execution at romInit( ). For warm

starts, the processor begins execution at romInit( ) plus a small offset (see

sysToMonitor( ) in sysLib.c). Most hardware and device initialization is

performed later in the boot sequence by sysHwInit( ), which is located in sysLib.c.

The job of romInit( ) is to perform the minimal setup needed to transfer control to

romStart( ), located in target/config/all/bootInit.c. The minimal setup includes:

■

Initializing the processor (this code is specific to the processor but not the

board, and thus can be copied from a reference BSP):

– Mask processor interrupts

– Set the initial stack pointer to

STACK_ADRS (defined in configAll.h)

– Disable processor caches

■

Initializing access to target DRAM as needed for the following (this code is

board-specific):

– Wait states

–Refresh rate

– Chip-selects

– Disabling secondary (L2) caches (if needed)

At the end of the initialization sequence, romInit( ) jumps to romStart( ) in

bootInit.c, passing the start type. The start type is

BOOT_COLD for a cold boot, or

the parameter passed from sysToMonitor( ) on a warm boot.

For more information, see romInit.s in a reference BSP or the template romInit.s

file in the template BSP. Also see 2.3.7 Hardware Considerations, p.42.

sysLib.c

The sysLib.c file contains the routines that directly or indirectly initialize all

hardware device drivers. The principal routines for initializing the hardware

drivers are sysHwInit( ) and sysHwInit2( ), but additional driver initialization

routines are called by usrRoot( ), such as sysClkConnect( ), which calls