OMAP5910 Local Bus
14-100
14.7.10
LB IRQ Input Register (LB_IRQ_INPUT)
This register reports the status of local bus interrupts, including interrupts from
external sources (which are not used in OMAP5910) and the status of the
local bus abort interrupt.
This register has no effect on OMAP5910 USB host controller accesses
to system memory and is not affected by USB host controller accesses to
system memory.
Table 14–47. LB IRQ Input Register (LB_IRQ_INPUT)
Bit
Name
Description
Type
Reset
Value
31–5
Reserved
Reserved
R
0
4
ABORT_STAT
Local bus abort status
0: Local bus abort has occurred since last read of
LB_IRQ_INPUT.
1: Local bus abort has not occurred since last read of
LB_IRQ_INPUT.
Reading this register sets this bit to 1. Writes have no effect.
A local bus abort event causes an interrupt to the MPU level
1 interrupt handler if the LB_ABORT_MASK bit of the
LB_CLOCK_DIV register is set to 0.
Because the DMA controller, DSP, and MPU could
mistakenly attempt to access a local bus slave peripheral
address, it is recommended that system software trap the
local bus abort interrupt and signal a system error should one
occur.
R
1
3–0
IRQ_IN_STAT
Reserved for future expansion. These bits can be ignored.
R
0xF
14.7.11
Local Bus Initialization
Proper operation of the OMAP5910 local bus (for USB host controller access
to system memory) requires that the FUNC_MUX_CTRL_0 register be prop-
erly initialized. FUNC_MUX_CTRL_0 bits 1:0 must be set either to 00b or to
11b in order to support correct local bus activity.
The local bus clock rate must be chosen to provide a suitable clock to the USB
host controller. The local bus clock rate is controlled by the LB_CLOCK_DIV
register LB_CLK_DIV field and is generated by dividing the OMAP5910 trans-
fer controller clock by 2, 4, or 6. The local bus clock rate must be programmed
to provide a local bus clock frequency that is 50 MHz or slower.