Re: [PATCH 2/2][resend] gpio: pcf857x: enable gpio_to_irq() support

[Paul Mundt <lethal@linux-sh.org>]

On Wed, Jun 13, 2012 at 09:58:26PM -0700, Kuninori Morimoto wrote:
> +static void pcf857x_nothing(struct irq_data *data)
> +{
> +	/* do nothing */
> +}
> +
> +static struct irq_chip pcf857x_irq_chip = {
> +	.name		= "pcf857x cascade",
> +	.irq_mask	= pcf857x_nothing,
> +	.irq_unmask	= pcf857x_nothing,
> +};
> +
Just use dummy_irq_chip.

> +static int pcf857x_irq_domain_init(struct pcf857x *gpio,
> +				   struct pcf857x_platform_data *pdata,
> +				   struct device *dev)
> +{
> +	int status;
> +
> +	/* create demuxed irq */
> +	gpio->irq_demux_base = irq_alloc_descs(-1, 0, gpio->chip.ngpio, 0);
> +	if (gpio->irq_demux_base < 0)
> +		return -ENODEV;
> +
> +	gpio->irq_domain = irq_domain_add_legacy(dev->of_node,
> +						 gpio->chip.ngpio,
> +						 gpio->irq_demux_base,
> +						 0,
> +						 &pcf857x_irq_domain_ops,
> +						 NULL);

Given that you don't actually care where the IRQs are mapped there's no
need to bother with a legacy domain here, you can just use a linear one
outright. At which point you can drop your separate irq_desc
allocation/management.