From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [v2 5/9] clocksource: tegra: Enable ARM arch_timer with TSC
Date: Tue, 08 Jan 2013 15:41:42 -0700 [thread overview]
Message-ID: <50ECA0A6.4090307@wwwdotorg.org> (raw)
In-Reply-To: <50EC444B.5060206@arm.com>
On 01/08/2013 09:07 AM, Marc Zyngier wrote:
> On 08/01/13 12:47, Hiroshi Doyu wrote:
>> Add platform enabler for ARM arch_timer(TSC). TSC is more fine grained
>> timer than TMR0. If it's available, it will be used for clock source
>> and sched_clock. Otherwise, TMR0 is used. In any case TMR0 is
>> necessary for clock event.
>> diff --git a/drivers/clocksource/tegra20_timer.c b/drivers/clocksource/tegra20_timer.c
>> +/* FIXME: only secure mode is supported. */
>
> And this is a bug, as far as I'm concerned.
>
>> +static int tegra_arch_timer_init(void)
>> + clk = clk_get_sys("clk_m", NULL);
>> + if (IS_ERR(clk)) {
>> + freq = 12000000;
>> + pr_warn("Unable to get timer clock. Assuming 12Mhz input clock.\n");
>> + } else {
>> + freq = clk_get_rate(clk);
>> + clk_put(clk);
>> + }
>> + writel_relaxed(freq, tsc_base + TSC_CNTFID0);
>> +
>> + /* CNTFRQ */
>> + asm("mcr p15, 0, %0, c14, c0, 0\n" : : "r" (freq));
>> + asm("mrc p15, 0, %0, c14, c0, 0\n" : "=r" (val));
>> + BUG_ON(val != freq);
>
> No, not again! Like I said last year, this won't fly. So instead of
> trying to work around a broken firmware, let's do the right thing.
OK, so I understand you want to firmware/bootloader/... to write the
value into that register instead, so this all works in non-secure mode
(which sounds like a fine objection), but ...
>> +
>> + val = readl_relaxed(tsc_base + TSC_CNTCR);
>> + val |= TSC_CNTCR_ENABLE | TSC_CNTCR_HDBG;
>> + writel_relaxed(val, tsc_base + TSC_CNTCR);
>> +
>> + err = arch_timer_of_register();
>
> What about adding an optional property to the binding, pointing to the
> required clock? That would solve the above problem in a sensible way,
> and your kernel wouldn't go bust.
... I'm not sure how the comment about adding a clock to the DT binding
is related to that. Sorry for not following the plot!
next prev parent reply other threads:[~2013-01-08 22:41 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-08 12:47 [v2 0/9] ARM: Initial support for Tegra 114 SoC Hiroshi Doyu
2013-01-08 12:47 ` [v2 1/9] ARM: tegra: fuse: Add chipid TEGRA114 0x35 Hiroshi Doyu
2013-01-08 12:47 ` [v2 2/9] HACK: ARM: tegra: Use CLK_IGNORE_UNUSED for Tegra 114 SoC Hiroshi Doyu
2013-01-08 22:52 ` Stephen Warren
2013-01-08 12:47 ` [v2 3/9] ARM: tegra: # of CPU cores detection w/ & w/o HAVE_ARM_SCU Hiroshi Doyu
2013-01-08 14:26 ` Russell King - ARM Linux
2013-01-09 5:46 ` Hiroshi Doyu
2013-01-09 6:07 ` Joseph Lo
2013-01-09 6:25 ` Hiroshi Doyu
2013-01-08 14:28 ` Mark Rutland
2013-01-08 14:53 ` Hiroshi Doyu
2013-01-08 16:21 ` Mark Rutland
2013-01-08 17:11 ` Lorenzo Pieralisi
2013-01-09 11:46 ` Hiroshi Doyu
2013-01-09 15:17 ` Lorenzo Pieralisi
2013-01-10 12:58 ` Hiroshi Doyu
2013-01-10 13:47 ` Lorenzo Pieralisi
2013-01-10 14:03 ` Hiroshi Doyu
2013-01-10 14:33 ` Lorenzo Pieralisi
2013-01-10 14:59 ` Hiroshi Doyu
2013-01-10 16:54 ` Stephen Warren
2013-01-11 10:11 ` Lorenzo Pieralisi
2013-01-11 11:56 ` Hiroshi Doyu
2013-01-08 19:32 ` Stephen Warren
2013-01-09 5:49 ` Hiroshi Doyu
2013-01-09 11:34 ` Lorenzo Pieralisi
2013-01-09 16:17 ` Stephen Warren
2013-01-09 18:07 ` Lorenzo Pieralisi
2013-01-10 6:53 ` Hiroshi Doyu
2013-01-10 6:31 ` Hiroshi Doyu
2013-01-10 9:51 ` Lorenzo Pieralisi
2013-01-08 12:47 ` [v2 4/9] clocksource: tegra: Reorganize funcs by clock functionarities Hiroshi Doyu
2013-01-08 12:47 ` [v2 5/9] clocksource: tegra: Enable ARM arch_timer with TSC Hiroshi Doyu
2013-01-08 16:07 ` Marc Zyngier
2013-01-08 22:41 ` Stephen Warren [this message]
2013-01-09 6:00 ` Hiroshi Doyu
2013-01-09 6:40 ` Stephen Warren
2013-01-09 6:55 ` Hiroshi Doyu
2013-01-09 5:57 ` Hiroshi Doyu
2013-01-09 7:43 ` Santosh Shilimkar
2013-01-09 9:01 ` Marc Zyngier
2013-01-10 15:03 ` Hiroshi Doyu
2013-01-10 15:10 ` Marc Zyngier
2013-01-08 12:47 ` [v2 6/9] ARM: dt: tegra114: Add new SoC base, Tegra 114 SoC Hiroshi Doyu
2013-01-08 22:49 ` Stephen Warren
2013-01-10 12:35 ` Hiroshi Doyu
2013-01-08 12:47 ` [v2 7/9] ARM: dt: tegra114: Add new board, Dalmore Hiroshi Doyu
2013-01-08 12:47 ` [v2 8/9] ARM: dt: tegra114: Add new board, Pluto Hiroshi Doyu
2013-01-08 12:47 ` [v2 9/9] ARM: tegra: Add initial support for Tegra 114 SoC Hiroshi Doyu
2013-01-08 22:52 ` Stephen Warren
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