From: James Hogan <james.hogan@imgtec.com>
To: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
Arnd Bergmann <arnd@arndb.de>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2 22/44] metag: Time keeping
Date: Fri, 4 Jan 2013 12:21:53 +0000 [thread overview]
Message-ID: <50E6C961.40009@imgtec.com> (raw)
In-Reply-To: <50E6A987.207@synopsys.com>
On 04/01/13 10:05, Vineet Gupta wrote:
> Hi James,
>
> On Wednesday 05 December 2012 09:38 PM, James Hogan wrote:
>
>> +static unsigned int hwtimer_freq = HARDWARE_FREQ;
>> +static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);
>> +static DEFINE_PER_CPU(char [11], local_clockevent_name);
>
>> +void __cpuinit local_timer_setup(unsigned int cpu)
>> +{
>> + unsigned int txdivtime;
>> + struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
>> + char *name = per_cpu(local_clockevent_name, cpu);
>> +
>> + txdivtime = TBI_GETREG(TXDIVTIME);
>> +
>> + txdivtime &= ~TXDIVTIME_DIV_BITS;
>> + txdivtime |= (HARDWARE_DIV & TXDIVTIME_DIV_BITS);
>> +
>> + TBI_SETREG(TXDIVTIME, txdivtime);
>> +
>> + sprintf(name, "META %d", cpu);
>> + clk->name = name;
>> + clk->features = CLOCK_EVT_FEAT_ONESHOT,
>> +
>> + clk->rating = 200,
>> + clk->shift = 12,
>> + clk->irq = TBID_SIGNUM_TRT,
>> + clk->set_mode = metag_timer_set_mode,
>> + clk->set_next_event = metag_timer_set_next_event,
>> +
>> + clk->mult = div_sc(hwtimer_freq, NSEC_PER_SEC, clk->shift);
>> + clk->max_delta_ns = clockevent_delta2ns(0x7fffffff, clk);
>> + clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
>> + clk->cpumask = cpumask_of(cpu);
>> +
>> + clockevents_register_device(clk);
>> +
>> + /*
>> + * For all non-boot CPUs we need to synchronize our free
>> + * running clock (TXTIMER) with the boot CPU's clock.
>> + *
>> + * While this won't be accurate, it should be close enough.
>> + */
>> + if (cpu) {
>> + unsigned int thread0 = cpu_2_hwthread_id[0];
>> + unsigned long val;
>> +
>> + val = core_reg_read(TXUCT_ID, TXTIMER_REGNUM, thread0);
>> +
>> + asm volatile("MOV TXTIMER, %0\n" : : "r" (val));
>> + }
>> +}
>> +
>> +void __init time_init(void)
>> +{
>> + /*
>> + * On Meta 2 SoCs, the actual frequency of the timer is based on the
>> + * Meta core clock speed divided by an integer, so it is only
>> + * approximately 1MHz. Calculating the real frequency here drastically
>> + * reduces clock skew on these SoCs.
>> + */
>> +#ifdef CONFIG_METAG_META21
>> + hwtimer_freq = get_coreclock() / (metag_in32(EXPAND_TIMER_DIV) + 1);
>> +#endif
>> + clocksource_register_hz(&clocksource_metag, hwtimer_freq);
>> +
>> + setup_irq(TBID_SIGNUM_TRT, &metag_timer_irq);
>> +
>> + local_timer_setup(smp_processor_id());
>> +}
>
> I have a kludge in ARC port in this subsystem - which I hope you could help clear.
>
> ARC also has a local timer device used for clockevent on each CPU. A one-time
> setup_irq() with IRQF_PERCPU - would indeed setup the generic IRQ subsystem - for
> making registration effective for all CPUs. However don't you need some per-cpu
> magic - say enabling the IRQ at cpu or embedded interrupt controller level -
> assuming you starts off with all IRQs disabled (which ARC Linux does).
Hi Vineet,
For Meta this is done in secondary_start_kernel in
arch/metag/kernel/smp.c (see
https://github.com/jahogan/metag-linux/blob/metag-core/arch/metag/kernel/smp.c#L276).
It uses tbi_startup_interrupt which is also called by the irq_startup
callback for the root irq_chip.
> So we end up using different APIs - request_percpu_irq() as equivalent of
> setup_irq() on boot-cpu only and then each CPU calling enable_percpu_irq() to do
> the local magic. request_percpu_irq() in turn requires an apriori call to
> irq_set_percpu_devid().
For Meta we could probably do something similar if we moved it's root
irq_startup irq_chip callback code into irq_enable or irq_unmask.
Cheers
James
>
> https://lkml.org/lkml/2012/11/7/128
>
> Do don't seem to be requiring all of this hence I'm wondering how it works for you!
>
> -Vineet
>
next prev parent reply other threads:[~2013-01-04 12:21 UTC|newest]
Thread overview: 125+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-05 16:08 [PATCH v2 00/44] Meta Linux Kernel Port James Hogan
2012-12-05 16:08 ` [PATCH v2 01/44] asm-generic/io.h: remove asm/cacheflush.h include James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 02/44] asm-generic/unistd.h: handle symbol prefixes in cond_syscall James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 03/44] Add CONFIG_HAVE_64BIT_ALIGNED_STRUCT for taskstats James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-08 3:43 ` H. Peter Anvin
2012-12-10 10:22 ` James Hogan
2012-12-10 12:55 ` Geert Uytterhoeven
2012-12-10 12:55 ` Geert Uytterhoeven
2012-12-17 9:51 ` James Hogan
2012-12-17 19:11 ` David Miller
2012-12-05 16:08 ` [PATCH v2 04/44] trace/ring_buffer: handle 64bit aligned structs James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-08 1:24 ` Steven Rostedt
2012-12-10 10:27 ` James Hogan
2012-12-10 10:27 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 05/44] Revert some of "binfmt_elf: cleanups" James Hogan
2012-12-05 16:08 ` James Hogan
[not found] ` <1354723742-6195-1-git-send-email-james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
2012-12-05 16:08 ` [PATCH v2 06/44] of/vendor-prefixes: add Imagination Technologies James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 22:28 ` Grant Likely
2012-12-05 22:28 ` Grant Likely
2012-12-06 9:24 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 07/44] metag: Add MAINTAINERS entry James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 08/44] metag: Headers for core arch constants James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 09/44] metag: Header for core memory mapped registers James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 10/44] metag: Boot James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 11/44] metag; TBX header James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 12/44] metag: TBX source James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 18:53 ` Joe Perches
2012-12-05 18:53 ` Joe Perches
2012-12-06 9:35 ` James Hogan
2012-12-06 12:59 ` Joe Perches
2012-12-06 15:03 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 13/44] metag: Cache/TLB handling James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 14/44] metag: Memory management James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 15/44] metag: Memory handling James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 16/44] metag: Huge TLB James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 17/44] metag: Highmem support James Hogan
2012-12-05 16:08 ` [PATCH v2 18/44] metag: TCM support James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 19/44] metag: Signal handling James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 17:16 ` Al Viro
2012-12-06 11:17 ` James Hogan
2012-12-06 22:09 ` [braindump][RFC] signals and syscall restarts (Re: [PATCH v2 19/44] metag: Signal handling) Al Viro
2012-12-08 7:44 ` Al Viro
2012-12-15 16:26 ` Jonas Bonn
2012-12-15 17:07 ` Al Viro
2012-12-08 18:14 ` Al Viro
2012-12-08 18:14 ` Al Viro
2012-12-12 9:44 ` James Hogan
2012-12-10 10:40 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 20/44] metag: Device tree James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 21/44] metag: ptrace James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 22/44] metag: Time keeping James Hogan
2013-01-04 10:05 ` Vineet Gupta
2013-01-04 12:21 ` James Hogan [this message]
2013-01-04 12:48 ` Vineet Gupta
2013-01-04 13:11 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 23/44] metag: Traps James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 17:40 ` Al Viro
2012-12-06 11:43 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 24/44] metag: IRQ handling James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 25/44] metag: System Calls James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 26/44] metag: Scheduling/Process management James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 27/44] metag: Module support James Hogan
2012-12-05 16:08 ` [PATCH v2 28/44] metag: Atomics, locks and bitops James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 29/44] metag: Basic documentation James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 30/44] metag: SMP support James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 31/44] metag: DMA James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 32/44] metag: Optimised library functions James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 33/44] metag: Stack unwinding James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 34/44] metag: Various other headers James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 35/44] mm: define VM_GROWSUP for CONFIG_METAG James Hogan
2012-12-05 16:08 ` [PATCH v2 36/44] Add metag to various Kconfig dependency lists James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 37/44] metag: Build infrastructure James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 38/44] metag: Perf James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 39/44] metag: ftrace support James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 40/44] scripts/checkstack.pl: Add metag support James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:08 ` [PATCH v2 41/44] metag: OProfile James Hogan
2012-12-05 16:08 ` James Hogan
2012-12-05 16:09 ` [PATCH v2 42/44] metag: Add JTAG Debug Adapter (DA) support James Hogan
2012-12-05 16:09 ` [PATCH v2 43/44] tty/metag_da: Add metag DA TTY driver James Hogan
2012-12-05 16:09 ` James Hogan
2012-12-05 17:24 ` Alan Cox
2013-01-04 14:11 ` James Hogan
2013-01-04 17:00 ` Alan Cox
2013-01-07 11:30 ` James Hogan
2013-01-07 11:54 ` Alan Cox
2012-12-05 16:09 ` [PATCH v2 44/44] fs: imgdafs: Add IMG DAFS filesystem for metag James Hogan
2012-12-05 17:11 ` [PATCH v2 00/44] Meta Linux Kernel Port Al Viro
2012-12-05 18:39 ` Al Viro
2012-12-18 16:09 ` James Hogan
2012-12-06 9:19 ` James Hogan
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