Re: [Xen-devel] [PATCH ARM v7 09/13] mini-os: arm: time

[Thomas Leonard <talex5@xxxxxxxxx>]

On 8 September 2014 11:59, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Fri, 2014-08-08 at 16:47 +0100, Thomas Leonard wrote:
>
> Sorry for how long I took to get to this, travel and the resulting
> backlog conspired against me.

Hi Ian,

I'm on holiday for a few weeks now. Please feel free to apply any
minor changes if you don't want to wait. In any case, I'll take
another look at the end of Sep.

Regards,

>> +    __asm__ __volatile__("isb;mrrc p15, 1, %0, %1, c14":"=r"(c_lo), 
>> "=r"(c_hi));
>
> Is the isb really necessary here?

I don't think so.

>> +    return (((uint64_t) c_hi) << 32) + c_lo;
>> +}
>> +
>> +/* monotonic_clock(): returns # of nanoseconds passed since time_init()
>> + *        Note: This function is required to return accurate
>> + *        time even in the absence of multiple timer ticks.
>> + */
>> +uint64_t monotonic_clock(void)
>> +{
>> +    s_time_t time = ticks_to_ns(read_virtual_count() - cntvct_at_init);
>> +    //printk("monotonic_clock: %llu (%llu)\n", time, NSEC_TO_SEC(time));
>
> There's quite a few of these //printk(debug) statements in this patch...
>
>> +    return time;
>> +}
>> +
>> +int gettimeofday(struct timeval *tv, void *tz)
>> +{
>> +    uint64_t nsec = monotonic_clock();
>> +    nsec += shadow_ts.tv_nsec;
>> +
>> +    tv->tv_sec = shadow_ts.tv_sec;
>> +    tv->tv_sec += NSEC_TO_SEC(nsec);
>> +    tv->tv_usec = NSEC_TO_USEC(nsec % 1000000000UL);
>> +
>> +    return 0;
>> +}
>> +
>> +void set_vtimer_compare(uint64_t value) {
>> +    uint32_t x, y;
>> +
>> +    DEBUG("New CompareValue : %llx\n", value);
>> +    x = 0xFFFFFFFFULL & value;
>> +    y = (value >> 32) & 0xFFFFFFFF;
>> +
>> +    __asm__ __volatile__("mcrr p15, 3, %0, %1, c14"
>> +            ::"r"(x), "r"(y));
>
> I think you can use
>         "mcrr p15, 3, %0, %H0, c14" :: "r" (value)
> here.
>
>
>> +
>> +    __asm__ __volatile__("mov %0, #0x1\n"
>> +            "mcr p15, 0, %0, c14, c3, 1\n" /* Enable timer and unmask the 
>> output signal */
>> +            "isb":"=r"(x));
>
> x = 1 before this would avoid the mov inside the inline stuff as well as
> the strange looking use of an output register for a write.
>
>> +}
>> +
>> +void unset_vtimer_compare(void) {
>> +    uint32_t x;
>> +
>> +    __asm__ __volatile__("mov %0, #0x2\n"
>> +            "mcr p15, 0, %0, c14, c3, 1\n" /* Disable timer and mask the 
>> output signal */
>> +            "isb":"=r"(x));
>
> and again. You probably just want a write_timer_ctl(uiint.. val) type
> function.
>
>> +}
>> +
>> +void block_domain(s_time_t until)
>> +{
>> +    uint64_t until_count = ns_to_ticks(until) + cntvct_at_init;
>> +    ASSERT(irqs_disabled());
>> +    if (read_virtual_count() < until_count)
>> +    {
>> +        set_vtimer_compare(until_count);
>> +        //char buf[] = "sleep\n"; 
>> (void)HYPERVISOR_console_io(CONSOLEIO_write, strlen(buf), buf);
>> +        __asm__ __volatile__("wfi");
>> +        //char wake[] = "wake\n"; 
>> (void)HYPERVISOR_console_io(CONSOLEIO_write, strlen(wake), wake);
>
> More left over debug.
>
>> +        unset_vtimer_compare();
>> +
>> +        /* Give the IRQ handler a chance to handle whatever woke us up. */
>> +        local_irq_enable();
>> +        local_irq_disable();
>> +    }
>> +}
>
> Ian.
>



-- 
Dr Thomas Leonard        http://0install.net/
GPG: 9242 9807 C985 3C07 44A6  8B9A AE07 8280 59A5 3CC1
GPG: DA98 25AE CAD0 8975 7CDA  BD8E 0713 3F96 CA74 D8BA

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