linux-kernel - Re: [PATCHv3 2/5] arm: mvebu: support for SMP on 98DX3336 SoC

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Message-ID: <20170106063602.GM17126@codeaurora.org>
Date:   Thu, 5 Jan 2017 22:36:02 -0800
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Chris Packham <chris.packham@...iedtelesis.co.nz>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jason Cooper <jason@...edaemon.net>,
        Andrew Lunn <andrew@...n.ch>,
        Gregory Clement <gregory.clement@...e-electrons.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Chris Brand <chris.brand@...adcom.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jayachandran C <jchandra@...adcom.com>,
        Juri Lelli <juri.lelli@....com>,
        Magnus Damm <damm+renesas@...nsource.se>,
        Thierry Reding <treding@...dia.com>,
        Sudeep Holla <sudeep.holla@....com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv3 2/5] arm: mvebu: support for SMP on 98DX3336 SoC

On 01/06, Chris Packham wrote:
> diff --git a/arch/arm/mach-mvebu/platsmp.c b/arch/arm/mach-mvebu/platsmp.c
> index 46c742d3bd41..3c9ab9a008ad 100644
> --- a/arch/arm/mach-mvebu/platsmp.c
> +++ b/arch/arm/mach-mvebu/platsmp.c
> @@ -182,5 +182,48 @@ const struct smp_operations armada_xp_smp_ops __initconst = {
>  #endif
>  };
>  
> +static int mv98dx3236_boot_secondary(unsigned int cpu, struct task_struct *idle)
> +{
> +	int ret, hw_cpu;
> +
> +	pr_info("Booting CPU %d\n", cpu);

Doesn't the core already print something when bringing up CPUs?
This message seems redundant.

> +
> +	hw_cpu = cpu_logical_map(cpu);
> +	set_secondary_cpu_clock(hw_cpu);
> +	mv98dx3236_resume_set_cpu_boot_addr(hw_cpu,
> +					    armada_xp_secondary_startup);
> +
> +	/*
> +	 * This is needed to wake up CPUs in the offline state after
> +	 * using CPU hotplug.
> +	 */
> +	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
> +
> +	/*
> +	 * This is needed to take secondary CPUs out of reset on the
> +	 * initial boot.
> +	 */
> +	ret = mvebu_cpu_reset_deassert(hw_cpu);
> +	if (ret) {
> +		pr_warn("unable to boot CPU: %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +struct smp_operations mv98dx3236_smp_ops __initdata = {

static const __initconst?

> +	.smp_init_cpus		= armada_xp_smp_init_cpus,
> +	.smp_prepare_cpus	= armada_xp_smp_prepare_cpus,
> +	.smp_boot_secondary	= mv98dx3236_boot_secondary,
> +	.smp_secondary_init     = armada_xp_secondary_init,
> +#ifdef CONFIG_HOTPLUG_CPU
> +	.cpu_die		= armada_xp_cpu_die,
> +	.cpu_kill               = armada_xp_cpu_kill,
> +#endif
> +};
> +
>  CPU_METHOD_OF_DECLARE(armada_xp_smp, "marvell,armada-xp-smp",
>  		      &armada_xp_smp_ops);
> +CPU_METHOD_OF_DECLARE(mv98dx3236_smp, "marvell,98dx3236-smp",
> +		      &mv98dx3236_smp_ops);
> diff --git a/arch/arm/mach-mvebu/pmsu-98dx3236.c b/arch/arm/mach-mvebu/pmsu-98dx3236.c
> new file mode 100644
> index 000000000000..1052674dd439
> --- /dev/null
> +++ b/arch/arm/mach-mvebu/pmsu-98dx3236.c
> @@ -0,0 +1,52 @@
> +/**
> + * CPU resume support for 98DX3236 internal CPU (a.k.a. MSYS).
> + */
> +
> +#define pr_fmt(fmt) "mv98dx3236-resume: " fmt
> +
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/of_address.h>
> +#include <linux/io.h>
> +#include "common.h"
> +
> +static void __iomem *mv98dx3236_resume_base;
> +#define MV98DX3236_CPU_RESUME_CTRL_OFFSET	0x08
> +#define MV98DX3236_CPU_RESUME_ADDR_OFFSET	0x04
> +
> +static const struct of_device_id of_mv98dx3236_resume_table[] = {
> +	{.compatible = "marvell,98dx3336-resume-ctrl",},
> +	{ /* end of list */ },
> +};
> +
> +void mv98dx3236_resume_set_cpu_boot_addr(int hw_cpu, void *boot_addr)
> +{
> +	WARN_ON(hw_cpu != 1);
> +
> +	writel(0, mv98dx3236_resume_base + MV98DX3236_CPU_RESUME_CTRL_OFFSET);
> +	writel(virt_to_phys(boot_addr), mv98dx3236_resume_base +
> +	       MV98DX3236_CPU_RESUME_ADDR_OFFSET);
> +}
> +
> +static int __init mv98dx3236_resume_init(void)
> +{
> +	struct device_node *np;
> +	void __iomem *base;
> +
> +	np = of_find_matching_node(NULL, of_mv98dx3236_resume_table);
> +	if (!np)
> +		return 0;

Is there any reason we can't just look for this node from the
smp_ops and map it if it isn't mapped yet? Seems simpler than a
whole new file and initcall.

> +
> +	base = of_io_request_and_map(np, 0, of_node_full_name(np));
> +	if (IS_ERR(base)) {
> +		pr_err("unable to map registers\n");

Doesn't of_io_request_and_map() spit out an error on failure
already?

> +		of_node_put(np);

This could be done before the if statement and then the duplicate
statement deleted.

> +		return PTR_ERR(mv98dx3236_resume_base);

Should be PTR_ERR(base)?

> +	}
> +
> +	mv98dx3236_resume_base = base;
> +	of_node_put(np);
> +	return 0;
> +}

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