Overview
D-2
D.1
Overview
DSP/BIOS has been enhanced to provide seamless support for the
General Purpose Timers (GP Timers) and Level 2 Interrupt Controller
(L2IC) present within the OMAP 2420. The CLK module functionality is
now driven by GP Timers. The HWI module APIs can define and
manipulate level 2 interrupts in addition to level 1 interrupts.
The OMAP 2420 is the first in a series of next generation "OMAP 4"
devices. This series may also be referred to as OMAP24xx devices.
Documentation for the OMAP 2420 is provided in the
OMAP 2410/2420
Technical Reference Manual
(SWPU064).
D.2
OMAP 2420 and the CLK Module
A number of changes and enhancements have been made to the
DSP/BIOS CLK module to enable the use of OMAP 2420 General
Purpose (GP) timers. The OMAP 2420 has 12 General Purpose (GP)
timers. Four timers (5, 6, 7, and 8) are designed to be used by the DSP.
D.2.1
Static Configuration
For OMAP 2420, the high- and low-resolution DSP/BIOS clocks are
completely independent of each other. It is possible to disable the low-
resolution CLK while still supporting the high-resolution CLK features,
and vice versa.
The following CLK module properties have differences for OMAP 2420:
❏
TIMERSELECT.
This property may be set to “Timer 5” or “Timer 6”
to set the GP timer used for the low-resolution time. The GP Timer 7
is used for the high-resolution time. Timer 5 (the default) runs at 32
kHz. Timers 6 and 7 run at 12 MHz. For example:
bios.CLK.TIMERSELECT = “Timer 5”;
❏
TIMERS_BASE.
This property points to the address of GP timer 5
within the DSP address space. This location is set by the DSP MMU
configuration shown in Section D.2.2,
. The
locations of timers 6 and 7 are determined by adding 0x0400 and
0x0800 respectively to the base address. For example, the following
statement informs DSP/BIOS that the GP Timer 5 is mapped to IO
address 0x7000, the GP Timer 6 is mapped to IO address 0x7400,
and the GP Timer 7 is mapped to IO address 0x7800.
bios.CLK.TIMERS_BASE = 0x7000;