linux-kernel - Re: [PATCH v4 2/5] irqchip: add virtual demultiplexer implementation

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Date:	Tue, 10 Feb 2015 15:48:38 +0000
From:	Mark Rutland <mark.rutland@....com>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <Pawel.Moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/5] irqchip: add virtual demultiplexer implementation

[...]

> +static int __init virt_irq_demux_of_init(struct device_node *node,
> +                                        struct device_node *parent)
> +{
> +       struct irq_chip_virt_demux *demux;
> +       unsigned int irq;
> +       u32 valid_irqs;
> +       int ret;
> +
> +       irq = irq_of_parse_and_map(node, 0);
> +       if (!irq) {
> +               pr_err("Failed to retrieve virt irq demuxer source\n");
> +               return -EINVAL;
> +       }
> +
> +       ret = of_property_read_u32(node, "irqs", &valid_irqs);
> +       if (ret) {
> +               pr_err("Invalid of missing 'irqs' property\n");
> +               return ret;
> +       }
> +
> +       demux = irq_alloc_virt_demux_chip(irq, valid_irqs,
> +                                         IRQ_NOREQUEST | IRQ_NOPROBE |
> +                                         IRQ_NOAUTOEN, 0);
> +       if (!demux) {
> +               pr_err("Failed to allocate virt irq demuxer struct\n");
> +               return -ENOMEM;
> +       }
> +
> +       demux->domain = irq_domain_add_linear(node, BITS_PER_LONG,
> +                                             &irq_virt_demux_domain_ops,
> +                                             demux);
> +       if (!demux->domain) {
> +               ret = -ENOMEM;
> +               goto err_free_demux;
> +       }
> +
> +       ret = irq_set_handler_data(irq, demux);
> +       if (ret) {
> +               pr_err("Failed to assign handler data\n");
> +               goto err_free_domain;
> +       }
> +
> +       irq_set_chained_handler_nostartup(irq, irq_virt_demux_handler);
> +
> +       return 0;
> +
> +err_free_domain:
> +       irq_domain_remove(demux->domain);
> +
> +err_free_demux:
> +       kfree(demux);
> +
> +       return ret;
> +}
> +IRQCHIP_DECLARE(virt_irq_demux, "virtual,irq-demux", virt_irq_demux_of_init);

As mentioned on the DT binding patch, I really don't think this should
be in the DT. It corresponds only to Linux internal details, not a piece
of hardware. If we need this internally, I don't see why it can't be
instanciated as required.

If we _must_ have this in the DT, I have concerns with the binding
w.r.t. the "irqs" property being a 32-bit bitmask (as opposed to say
being something like "num-irqs" which could be far larger, and is
easuier to read).

Thanks,
Mark.
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