linux-kernel - Re: [PATCH v3 05/13] irqchip: add initial support for ompic

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Message-ID: <86d15egupi.fsf@arm.com>
Date:   Mon, 23 Oct 2017 09:00:09 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Stafford Horne <shorne@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Openrisc <openrisc@...ts.librecores.org>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Rob Herring <robh@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jonas Bonn <jonas@...thpole.se>,
        "David S. Miller" <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v3 05/13] irqchip: add initial support for ompic

On Sun, Oct 22 2017 at 12:15:52 pm BST, Stafford Horne <shorne@...il.com> wrote:
> From: Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
>
> IPI driver for the Open Multi-Processor Interrupt Controller (ompic) as
> described in the Multi-core support section of the OpenRISC 1.2
> proposed architecture specification:
>
>   https://github.com/stffrdhrn/doc/raw/arch-1.2-proposal/openrisc-arch-1.2-rev0.pdf
>
> Each OpenRISC core contains a full interrupt controller which is used in
> the SMP architecture for interrupt balancing.  This IPI device, the
> ompic, is the only external device required for enabling SMP on
> OpenRISC.
>
> Pending ops are stored in a memory bit mask which can allow multiple
> pending operations to be set and serviced at a time. This is mostly
> borrowed from the alpha IPI implementation.
>
> Cc: Marc Zyngier <marc.zyngier@....com>
> Cc: Rob Herring <robh@...nel.org>
> Signed-off-by: Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
> [shorne@...il.com: converted ops to bitmask, wrote commit message]
> Signed-off-by: Stafford Horne <shorne@...il.com>
> ---
>
> Changes since v2
>  - Fixed some issues with missing static
>  - Fixed spelling issue with multi-core
>  - Added back #interrupt-cells
>
> Changes since v1
>  - Added openrisc, prefix
>  - Clarified 8 bytes per cpu
>  - Removed #interrupt-cells as this will not be an irq parent
>  - Changed ops to be percpu
>  - Added DTS and intialization failure validations
>
>
>  .../interrupt-controller/openrisc,ompic.txt        |  22 +++
>  MAINTAINERS                                        |   1 +
>  arch/openrisc/Kconfig                              |   1 +
>  drivers/irqchip/Kconfig                            |   3 +
>  drivers/irqchip/Makefile                           |   1 +
>  drivers/irqchip/irq-ompic.c                        | 205 +++++++++++++++++++++
>  6 files changed, 233 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/interrupt-controller/openrisc,ompic.txt
>  create mode 100644 drivers/irqchip/irq-ompic.c

[...]

> +static struct irqaction ompi_ipi_irqaction = {
> +	.handler =      ompic_ipi_handler,
> +	.flags =        IRQF_PERCPU,
> +	.name =         "ompic_ipi",
> +};
> +
> +static int __init ompic_of_init(struct device_node *node, struct device_node *parent)
> +{
> +	struct resource res;
> +	int irq;
> +	int ret;
> +
> +	/* Validate the DT */
> +	if (ompic_base) {
> +		pr_err("ompic: duplicate ompic's are not supported");
> +		return -EEXIST;
> +	}
> +
> +	if (of_address_to_resource(node, 0, &res)) {
> +		pr_err("ompic: reg property requires an address and size");
> +		return -EINVAL;
> +	}
> +
> +	if (resource_size(&res) < (num_possible_cpus() * OMPIC_CPUBYTES)) {
> +		pr_err("ompic: reg size, currently %d must be at least %d",
> +			resource_size(&res),
> +			(num_possible_cpus() * OMPIC_CPUBYTES));
> +		return -EINVAL;
> +	}
> +
> +	/* Setup the device */
> +	ompic_base = ioremap(res.start, resource_size(&res));
> +	if (IS_ERR(ompic_base)) {
> +		pr_err("ompic: unable to map registers");
> +		return PTR_ERR(ompic_base);
> +	}
> +
> +	irq = irq_of_parse_and_map(node, 0);
> +	if (irq <= 0) {
> +		pr_err("ompic: unable to parse device irq");
> +		ret = -EINVAL;
> +		goto out_unmap;
> +	}
> +
> +	ret = setup_irq(irq, &ompi_ipi_irqaction);
> +	if (ret)
> +		goto out_irq_disp;

Is there a particular reason why this cannot be turned request_irq()
call? setup_irq is something we try to avoid these days...

> +
> +	set_smp_cross_call(ompic_raise_softirq);
> +
> +	return 0;
> +
> +out_irq_disp:
> +	irq_dispose_mapping(irq);
> +out_unmap:
> +	iounmap(ompic_base);
> +	ompic_base = NULL;
> +	return ret;
> +}
> +IRQCHIP_DECLARE(ompic, "openrisc,ompic", ompic_of_init);

Otherwise looks good to me.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny.