• Paul Walmsley's avatar
    OMAP2/3 GPTIMER: allow system tick GPTIMER to be changed in board-*.c files · f248076c
    Paul Walmsley authored
    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 <kalle.valo@nokia.com> 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: default avatarPaul Walmsley <paul@pwsan.com>
    Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
    Cc: Kalle Valo <kalle.valo@nokia.com>
    f248076c
clock34xx.h 82.2 KB