From f248076c0dad45b7e50f27096e1aac6a617665db Mon Sep 17 00:00:00 2001 From: Paul Walmsley Date: Thu, 23 Apr 2009 21:11:10 -0600 Subject: OMAP2/3 GPTIMER: allow system tick GPTIMER to be changed in board-*.c files Add a function omap2_gp_clockevent_set_gptimer() for board-*.c files to use in .init_irq functions to configure the system tick GPTIMER. 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. But on HS devices, it may not be available for Linux use. It appears that most boards are fine with GPTIMER1, but BeagleBoard should use GPTIMER12 when using a 32KiHz timer source, due to hardware bugs in revisions B4 and below. Modify board-omap3beagle.c to use GPTIMER12. This patch originally used a Kbuild config option to select the GPTIMER, but was changed to allow this to be specified in board-*.c files, per Tony's request. Kalle Vallo found a bug in an earlier version of this patch - thanks Kalle. Tested on Beagle rev B4 ES2.1, with and without CONFIG_OMAP_32K_TIMER, and 3430SDP. Signed-off-by: Paul Walmsley Signed-off-by: Tony Lindgren Cc: Kalle Valo --- arch/arm/mach-omap2/timer-gp.c | 48 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 45 insertions(+), 3 deletions(-) (limited to 'arch/arm/mach-omap2/timer-gp.c') diff --git a/arch/arm/mach-omap2/timer-gp.c b/arch/arm/mach-omap2/timer-gp.c index 9fc13a2cc3f4..7835048041eb 100644 --- a/arch/arm/mach-omap2/timer-gp.c +++ b/arch/arm/mach-omap2/timer-gp.c @@ -3,6 +3,8 @@ * * OMAP2 GP timer support. * + * Copyright (C) 2009 Nokia Corporation + * * Update to use new clocksource/clockevent layers * Author: Kevin Hilman, MontaVista Software, Inc. * Copyright (C) 2007 MontaVista Software, Inc. @@ -36,8 +38,13 @@ #include #include +/* MAX_GPTIMER_ID: number of GPTIMERs on the chip */ +#define MAX_GPTIMER_ID 12 + static struct omap_dm_timer *gptimer; static struct clock_event_device clockevent_gpt; +static u8 __initdata gptimer_id = 1; +static u8 __initdata inited; static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id) { @@ -95,20 +102,53 @@ static struct clock_event_device clockevent_gpt = { .set_mode = omap2_gp_timer_set_mode, }; +/** + * omap2_gp_clockevent_set_gptimer - set which GPTIMER is used for clockevents + * @id: GPTIMER to use (1..MAX_GPTIMER_ID) + * + * Define the GPTIMER that the system should use for the tick timer. + * Meant to be called from board-*.c files in the event that GPTIMER1, the + * default, is unsuitable. Returns -EINVAL on error or 0 on success. + */ +int __init omap2_gp_clockevent_set_gptimer(u8 id) +{ + if (id < 1 || id > MAX_GPTIMER_ID) + return -EINVAL; + + BUG_ON(inited); + + gptimer_id = id; + + return 0; +} + static void __init omap2_gp_clockevent_init(void) { u32 tick_rate; + int src; + + inited = 1; - gptimer = omap_dm_timer_request_specific(1); + gptimer = omap_dm_timer_request_specific(gptimer_id); BUG_ON(gptimer == NULL); #if defined(CONFIG_OMAP_32K_TIMER) - omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_32_KHZ); + src = OMAP_TIMER_SRC_32_KHZ; #else - omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_SYS_CLK); + src = OMAP_TIMER_SRC_SYS_CLK; + WARN(gptimer_id == 12, "WARNING: GPTIMER12 can only use the " + "secure 32KiHz clock source\n"); #endif + + if (gptimer_id != 12) + WARN(IS_ERR_VALUE(omap_dm_timer_set_source(gptimer, src)), + "timer-gp: omap_dm_timer_set_source() failed\n"); + tick_rate = clk_get_rate(omap_dm_timer_get_fclk(gptimer)); + pr_info("OMAP clockevent source: GPTIMER%d at %u Hz\n", + gptimer_id, tick_rate); + omap2_gp_timer_irq.dev_id = (void *)gptimer; setup_irq(omap_dm_timer_get_irq(gptimer), &omap2_gp_timer_irq); omap_dm_timer_set_int_enable(gptimer, OMAP_TIMER_INT_OVERFLOW); @@ -125,6 +165,8 @@ static void __init omap2_gp_clockevent_init(void) clockevents_register_device(&clockevent_gpt); } +/* Clocksource code */ + #ifdef CONFIG_OMAP_32K_TIMER /* * When 32k-timer is enabled, don't use GPTimer for clocksource -- cgit v1.2.3