diff options
Diffstat (limited to 'recipes/linux/linux-omap-2.6.26/beagleboard/01-make_tick_gptimer_configurable')
| -rw-r--r-- | recipes/linux/linux-omap-2.6.26/beagleboard/01-make_tick_gptimer_configurable | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/recipes/linux/linux-omap-2.6.26/beagleboard/01-make_tick_gptimer_configurable b/recipes/linux/linux-omap-2.6.26/beagleboard/01-make_tick_gptimer_configurable new file mode 100644 index 0000000000..bcf0fa79f8 --- /dev/null +++ b/recipes/linux/linux-omap-2.6.26/beagleboard/01-make_tick_gptimer_configurable @@ -0,0 +1,58 @@ +OMAP2/3 GPTIMER: allow system tick GPTIMER to be configurable at build + +From: Paul Walmsley <paul@pwsan.com> + +Add Kbuild code to allow the builder to select which GPTIMER block to use +for the Linux clockevents timer. Practical choices at this point are +GPTIMER1 or GPTIMER12. Both of these timers are in the WKUP powerdomain, +and so are unaffected by chip power management. GPTIMER1 can use sys_clk +as a source, for applications where a high-resolution timer is more important +than power management. GPTIMER12 has the special property that it has +the secure 32kHz oscillator as its source clock, which may be less prone +to glitches than the off-chip 32kHz oscillator. + +At this point, it appears that most boards are fine with GPTIMER1, +but Beagle should use GPTIMER12. +--- + + arch/arm/mach-omap2/Kconfig | 16 ++++++++++++++++ + arch/arm/mach-omap2/timer-gp.c | 2 +- + 2 files changed, 17 insertions(+), 1 deletions(-) + +diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig +index bb6d695..0002cb6 100644 +--- a/arch/arm/mach-omap2/Kconfig ++++ b/arch/arm/mach-omap2/Kconfig +@@ -122,3 +122,19 @@ config MACH_OMAP3EVM + config MACH_OMAP3_BEAGLE + bool "OMAP3 BEAGLE board" + depends on ARCH_OMAP3 && ARCH_OMAP34XX ++ ++config OMAP_TICK_GPTIMER ++ int "GPTIMER used for system tick timer" ++ depends on ARCH_OMAP2 || ARCH_OMAP3 ++ range 1 12 ++ default 1 ++ help ++ Linux uses one of the twelve on-board OMAP GPTIMER blocks to generate ++ system tick interrupts. The twelve GPTIMERs have slightly ++ different powerdomain, source clock, and security properties ++ (mostly documented in the OMAP3 TRMs) that can affect the selection ++ of which GPTIMER to use. The historical default is GPTIMER1. ++ If CONFIG_OMAP_32K_TIMER is selected, Beagle may require GPTIMER12 ++ due to hardware sensitivity to glitches on the OMAP 32kHz clock ++ input. ++ +diff --git a/arch/arm/mach-omap2/timer-gp.c b/arch/arm/mach-omap2/timer-gp.c +index 557603f..ec80af5 100644 +--- a/arch/arm/mach-omap2/timer-gp.c ++++ b/arch/arm/mach-omap2/timer-gp.c +@@ -99,7 +99,7 @@ static void __init omap2_gp_clockevent_init(void) + { + u32 tick_rate; + +- gptimer = omap_dm_timer_request_specific(1); ++ gptimer = omap_dm_timer_request_specific(CONFIG_OMAP_TICK_GPTIMER); + BUG_ON(gptimer == NULL); + + #if defined(CONFIG_OMAP_32K_TIMER) |