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    SubjectRe: [PATCH v2 28/31] arm64: Generic timers support
    On 08/14/2012 01:52 PM, Catalin Marinas wrote:
    > From: Marc Zyngier <marc.zyngier@arm.com>
    >
    > This patch adds support for the ARM generic timers with A64 instructions
    > for accessing the timer registers. It uses the physical counter as the
    > clock source and the virtual counter as sched_clock.
    >
    > The timer frequency can be specified via DT or read from the CNTFRQ_EL0
    > register. The physical counter is also accessible from user space
    > allowing fast gettimeofday() implementation.

    [...]

    > +++ b/drivers/clocksource/arm_generic.c

    [...]

    > +static void arch_timer_reg_write(int reg, u32 val)
    > +{
    > + switch (reg) {
    > + case ARCH_TIMER_REG_CTRL:
    > + asm volatile("msr cntp_ctl_el0, %0" : : "r" (val));
    > + break;
    > + case ARCH_TIMER_REG_TVAL:
    > + asm volatile("msr cntp_tval_el0, %0" : : "r" (val));
    > + break;
    > + default:
    > + BUG();
    > + }
    > +
    > + isb();
    > +}

    Doesn't architecture-specific assembly need to go in the arch directory rather
    than the drivers directory?

    Christopher

    --
    Employee of Qualcomm Innovation Center, Inc.
    Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum


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