linux-kernel - Re: [PATCH] gpio: Emma Mobile GPIO driver V2

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Message-ID: <20120516072927.GN7988@linux-sh.org>
Date:	Wed, 16 May 2012 16:29:28 +0900
From:	Paul Mundt <lethal@...ux-sh.org>
To:	Magnus Damm <magnus.damm@...il.com>
Cc:	linux-kernel@...r.kernel.org, rjw@...k.pl,
	linus.walleij@...ricsson.com, arnd@...db.de,
	linux-sh@...r.kernel.org, horms@...ge.net.au,
	grant.likely@...retlab.ca, olof@...om.net
Subject: Re: [PATCH] gpio: Emma Mobile GPIO driver V2

On Wed, May 16, 2012 at 12:43:33AM +0900, Magnus Damm wrote:
> +static int __devinit em_gio_irq_domain_init(struct em_gio_priv *p)
> +{
> +	struct platform_device *pdev = p->pdev;
> +	struct gpio_em_config *pdata = pdev->dev.platform_data;
> +
> +	p->irq_base = irq_alloc_descs(pdata->irq_base, 0,
> +				      pdata->number_of_pins, numa_node_id());
> +	if (IS_ERR_VALUE(p->irq_base)) {
> +		dev_err(&pdev->dev, "cannot get irq_desc\n");
> +		return -ENXIO;
> +	}
> +	pr_debug("gio: hw base = %d, nr = %d, sw base = %d\n",
> +		 pdata->gpio_base, pdata->number_of_pins, p->irq_base);
> +
> +	p->irq_domain = irq_domain_add_legacy(pdev->dev.of_node,
> +					      pdata->number_of_pins,
> +					      p->irq_base, 0,
> +					      &em_gio_irq_domain_ops, p);
> +	if (!p->irq_domain) {
> +		irq_free_descs(p->irq_base, pdata->number_of_pins);
> +		return -ENXIO;
> +	}
> +
> +	return 0;
> +}
> +
There's no reason to use a legacy domain here, this is a pretty
straightforward candidate for a linear map. You can use ->to_irq() for
the irq_create_mapping() invocation and then later look up the IRQ with
irq_linear_revmap().

irq_domain_add_legacy() exists for existing static ranges, which there is
really no reason to be adding in new board/platform support. You don't
have to worry about virq overlap since irq_create_mapping() already wraps
on top of irq_alloc_desc_xxx() for lookup.

> +static void __devexit em_gio_irq_domain_cleanup(struct em_gio_priv *p)
> +{
> +	struct gpio_em_config *pdata = p->pdev->dev.platform_data;
> +
> +	irq_free_descs(p->irq_base, pdata->number_of_pins);
> +	/* FIXME: irq domain wants to be freed! */
> +}
> +
After which point you can iterate and dispose of the virq mappings with
irq_dispose_mapping(). The lack of irq domain teardown functionality does
need to be addressed though.
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