[PATCH] gpio/mxs: support irqs triggered by both edges

[Grant Likely]

On Mon, 20 Feb 2012 14:52:05 +0100, Enrico Scholz <enrico.scholz at sigma-chemnitz.de> wrote:
> iMX28 silicon does not support irqs triggered by both gpio edges. Patch
> emulates this behavior by configuring such irqs as level triggered and
> by switching polarity in the interrupt handler.
> 
> Signed-off-by: Enrico Scholz <enrico.scholz at sigma-chemnitz.de>

That looks dodgy and hacky.  This will definitely miss interrupts if they
come in too fast.  I don't like this approach.  What do you need it for?

g.

> ---
>  drivers/gpio/gpio-mxs.c |   31 +++++++++++++++++++++++++++++--
>  1 files changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-mxs.c b/drivers/gpio/gpio-mxs.c
> index 385c58e..ab973be 100644
> --- a/drivers/gpio/gpio-mxs.c
> +++ b/drivers/gpio/gpio-mxs.c
> @@ -57,6 +57,7 @@ struct mxs_gpio_port {
>  	int id;
>  	int irq;
>  	int virtual_irq_start;
> +	unsigned long both_edge;
>  	struct bgpio_chip bgc;
>  };
>  
> @@ -68,9 +69,12 @@ static int mxs_gpio_set_irq_type(struct irq_data *d, unsigned int type)
>  	u32 pin_mask = 1 << (gpio & 31);
>  	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
>  	struct mxs_gpio_port *port = gc->private;
> +	int lvl;
>  	void __iomem *pin_addr;
>  	int edge;
>  
> +	clear_bit(gpio & 31, &port->both_edge);
> +
>  	switch (type) {
>  	case IRQ_TYPE_EDGE_RISING:
>  		edge = GPIO_INT_RISE_EDGE;
> @@ -84,6 +88,14 @@ static int mxs_gpio_set_irq_type(struct irq_data *d, unsigned int type)
>  	case IRQ_TYPE_LEVEL_HIGH:
>  		edge = GPIO_INT_HIGH_LEV;
>  		break;
> +	case IRQ_TYPE_EDGE_RISING | IRQ_TYPE_EDGE_FALLING:
> +		/* mx28 does not support triggering irq by both edges; emulate
> +		 * behavior by configuring irq as level triggered and update
> +		 * irq polarity in the irq handler */
> +		set_bit(gpio & 31, &port->both_edge);
> +		lvl  = readl(port->base + PINCTRL_DIN(port->id));
> +		edge = (lvl & pin_mask) ? GPIO_INT_LOW_LEV : GPIO_INT_HIGH_LEV;
> +		break;
>  	default:
>  		return -EINVAL;
>  	}
> @@ -114,11 +126,26 @@ static void mxs_gpio_irq_handler(u32 irq, struct irq_desc *desc)
>  	u32 irq_stat;
>  	struct mxs_gpio_port *port = irq_get_handler_data(irq);
>  	u32 gpio_irq_no_base = port->virtual_irq_start;
> +	void __iomem *base = port->base;
> +	u32 pol_msk;
>  
>  	desc->irq_data.chip->irq_ack(&desc->irq_data);
>  
> -	irq_stat = readl(port->base + PINCTRL_IRQSTAT(port->id)) &
> -			readl(port->base + PINCTRL_IRQEN(port->id));
> +	irq_stat = readl(base + PINCTRL_IRQSTAT(port->id)) &
> +			readl(base + PINCTRL_IRQEN(port->id));
> +
> +	/* handle irqs triggered by both edges */
> +	pol_msk = irq_stat & port->both_edge;
> +	if (pol_msk) {
> +		void __iomem *reg = base + PINCTRL_IRQPOL(port->id);
> +		u32 port_lvl = readl(base + PINCTRL_DIN(port->id));
> +
> +		/* \todo write into the TOGGLE register (without reading port
> +		 * level register); this requires a special unmask operation
> +		 * which updates the IRQPOL register */
> +		writel(pol_msk & port_lvl, reg + MXS_CLR);
> +		writel(pol_msk & ~port_lvl, reg + MXS_SET);
> +	}
>  
>  	while (irq_stat != 0) {
>  		int irqoffset = fls(irq_stat) - 1;
> -- 
> 1.7.7.6
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

-- 
Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies,Ltd.