linux-kernel - Re: [PATCH 17/20] clocksource / arch_timer: Use ACPI GTDT table to initialize arch timer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20140127112647.GC16516@e106331-lin.cambridge.arm.com>
Date:	Mon, 27 Jan 2014 11:26:47 +0000
From:	Mark Rutland <mark.rutland@....com>
To:	Hanjun Guo <hanjun.guo@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Will Deacon <Will.Deacon@....com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Olof Johansson <olof@...om.net>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Rob Herring <robh@...nel.org>, Arnd Bergmann <arnd@...db.de>,
	"patches@...aro.org" <patches@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
	Charles Garcia-Tobin <Charles.Garcia-Tobin@....com>,
	Amit Daniel Kachhap <amit.daniel@...sung.com>
Subject: Re: [PATCH 17/20] clocksource / arch_timer: Use ACPI GTDT table to
 initialize arch timer

On Fri, Jan 17, 2014 at 12:25:11PM +0000, Hanjun Guo wrote:
> ACPI GTDT (Generic Timer Description Table) contains information for
> arch timer initialization, this patch use this table to probe arm timer.
> 
> GTDT table is used for ARM/ARM64 only, please refer to chapter 5.2.24
> of ACPI 5.0 spec for detailed inforamtion
> 
> Signed-off-by: Amit Daniel Kachhap <amit.daniel@...sung.com>
> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
> ---
>  drivers/clocksource/arm_arch_timer.c |  100 +++++++++++++++++++++++++++++-----
>  1 file changed, 85 insertions(+), 15 deletions(-)

[...]

> +static void __init register_arch_interrupt(u32 interrupt, u32 flags,
> +					int *arch_timer_ppi)
> +{
> +	int trigger, polarity;
> +
> +	if (!interrupt || !arch_timer_ppi)
> +		return;
> +
> +	trigger = (flags & ACPI_GTDT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
> +			: ACPI_LEVEL_SENSITIVE;
> +
> +	polarity = (flags & ACPI_GTDT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
> +			: ACPI_ACTIVE_HIGH;
> +
> +	*arch_timer_ppi = acpi_register_gsi(NULL, interrupt, trigger,
> +						polarity);
> +}

Why does this take a pointer to the irq rather than returning the irq
(as with irq_of_parse_and_map)?

This looks awfully generic. Are the timer interrupts encoded specially
or is this useful for parsing other interrupts?

> +
> +static int __init acpi_parse_gtdt(struct acpi_table_header *table)
> +{
> +	struct acpi_table_gtdt *gtdt;
> +
> +	gtdt = (struct acpi_table_gtdt *)table;
> +	if (!gtdt)
> +		return -EINVAL;
> +
> +	arch_timer_rate = arch_timer_get_cntfrq();
> +
> +	if (!arch_timer_rate) {
> +		pr_warn("arch_timer: Could not get frequency from CNTFREG\n");

s/CNTFREG/CNTFREQ/

This is probably worth a pr_err at least, the system is unlikely to get
very far if the timers don't work.

Thanks,
Mark.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/