• Simon Arlott's avatar
    ARM: bcm2835: add system timer · ee4af569
    Simon Arlott authored
    The System Timer peripheral provides four 32-bit timer channels and a
    single 64-bit free running counter. Each channel has an output compare
    register, which is compared against the 32 least significant bits of the
    free running counter values, and generates an interrupt.
    
    Timer 3 is used as the Linux timer.
    
    The BCM2835 also contains an SP804-based timer module. However, it
    apparently has significant differences from the standard SP804 IP block,
    and Broadcom's documentation recommends using the system timer instead.
    
    This patch was extracted from git://github.com/lp0/linux.git branch
    rpi-split as of 2012/09/08, and modified as follows:
    
    * s/bcm2708/bcm2835/.
    * Modified device tree vendor prefix.
    * Moved to drivers/clocksource/. This looks like the desired location for
      such code now.
    * Added DT binding docs.
    * Moved struct sys_timer bcm2835_timer into time.c to encapsulate it more.
    * Simplified bcm2835_time_init() to find one matching node and operate on
      it, rather than looping over all matching nodes. This seems more
      consistent with other clocksource code.
    * Simplified bcm2835_time_init() using of_iomap().
    * Renamed struct bcm2835_timer.index to match_mask to better represent its
      purpose.
    * s/printk(PR_INFO/pr_info(/
    Signed-off-by: default avatarChris Boot <bootc@bootc.net>
    Signed-off-by: default avatarSimon Arlott <simon@fire.lp0.eu>
    Signed-off-by: default avatarDom Cobley <popcornmix@gmail.com>
    Signed-off-by: default avatarDom Cobley <dc4@broadcom.com>
    Signed-off-by: default avatarStephen Warren <swarren@wwwdotorg.org>
    Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
    ee4af569
brcm,bcm2835-system-timer.txt 751 Bytes