linux-kernel - Re: [PATCH v21 11/13] acpi/arm64: Add memory-mapped timer support in GTDT driver

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Message-ID: <20170317194055.GE15909@leverpostej>
Date:   Fri, 17 Mar 2017 19:40:55 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     fu.wei@...aro.org
Cc:     rjw@...ysocki.net, lenb@...nel.org, daniel.lezcano@...aro.org,
        tglx@...utronix.de, marc.zyngier@....com,
        lorenzo.pieralisi@....com, sudeep.holla@....com,
        hanjun.guo@...aro.org, linux-arm-kernel@...ts.infradead.org,
        linaro-acpi@...ts.linaro.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, rruigrok@...eaurora.org,
        harba@...eaurora.org, cov@...eaurora.org, timur@...eaurora.org,
        graeme.gregory@...aro.org, al.stone@...aro.org, jcm@...hat.com,
        wei@...hat.com, arnd@...db.de, catalin.marinas@....com,
        will.deacon@....com, Suravee.Suthikulpanit@....com,
        leo.duran@....com, wim@...ana.be, linux@...ck-us.net,
        linux-watchdog@...r.kernel.org, tn@...ihalf.com,
        christoffer.dall@...aro.org, julien.grall@....com
Subject: Re: [PATCH v21 11/13] acpi/arm64: Add memory-mapped timer support in
 GTDT driver

Hi,

On Tue, Feb 07, 2017 at 02:50:13AM +0800, fu.wei@...aro.org wrote:
> +static int __init gtdt_parse_timer_block(struct acpi_gtdt_timer_block *block,
> +					 struct arch_timer_mem *data)

Please s/data/timer_mem/ here, to match the rest of the timer code.

> +{
> +	int i, j;
> +	struct acpi_gtdt_timer_entry *frame;

So as to make it clear what this is, and to make things a litlte simpler
below, please s/frame/gtdt_frame/ here.

> +
> +	if (!block->timer_count) {
> +		pr_err(FW_BUG "GT block present, but frame count is zero.");
> +		return -ENODEV;
> +	}
> +
> +	if (block->timer_count > ARCH_TIMER_MEM_MAX_FRAMES) {
> +		pr_err(FW_BUG "GT block lists %d frames, ACPI spec only allows 8\n",
> +		       block->timer_count);
> +		return -EINVAL;
> +	}
> +
> +	data->cntctlbase = (phys_addr_t)block->block_address;
> +	/*
> +	 * According to "Table * CNTCTLBase memory map" of
> +	 * <ARM Architecture Reference Manual> for ARMv8,
> +	 * The size of the CNTCTLBase frame is 4KB(Offset 0x000 – 0xFFC).
> +	 */

As a general thing, please cite the version of the ARM ARM you're
referring to, as over time the internal numbering (and the headings)
change.

e.g.
	/*
	 * The CNTCTLBase frame is 4KB (register offsets 0x000 - 0xFFC).
	 * See ARM DDI 0487A.k_iss10775, page I1-5129, Table I1-3
	 * "CNTCTLBase memory map".
	 */

> +	data->size = SZ_4K;
> +
> +	frame = (void *)block + block->timer_offset;
> +	if (frame + block->timer_count != (void *)block + block->header.length)
> +		return -EINVAL;
> +
> +	/*
> +	 * Get the GT timer Frame data for every GT Block Timer
> +	 */
> +	for (i = 0, j = 0; i < block->timer_count; i++, frame++) {

With the gtdt_frame rename as above, here we can do:

	struct arch_timer_mem_frame *frame = &timer_mem->frame[j];

> +		if (frame->common_flags & ACPI_GTDT_GT_IS_SECURE_TIMER)
> +			continue;
> +
> +		if (!frame->base_address || !frame->timer_interrupt)
> +			return -EINVAL;
> +
> +		data->frame[j].phys_irq = map_gt_gsi(frame->timer_interrupt,
> +						     frame->timer_flags);

... allowing us to simplify lines like this.

Thanks,
Mark.