[PATCH v2 2/6] gpio: brcmstb: Add interrupt support
linus.walleij at linaro.org
Tue Jun 2 06:33:41 PDT 2015
On Fri, May 29, 2015 at 4:14 AM, Gregory Fong <gregory.0xf0 at gmail.com> wrote:
> Create an irq_chip for each GIO block. Uses chained IRQ handling since
> known uses of this block have a BCM7120 L2 interrupt controller as a
> parent. Supports interrupts for all GPIOs.
> In the IRQ handler, we check for raised IRQs for invalid GPIOs and warn
> (ratelimited) if they're encountered.
> Signed-off-by: Gregory Fong <gregory.0xf0 at gmail.com>
> - since imask member of bank struct was removed, just read and write from mask
> reg and don't maintain a shadow
> - warn on invalid IRQs
> - move some irq setup to a separate function since probe is getting unwieldy
This patch basically painfully reimplements GPIOLIB_IRQCHIP.
Is there a reason for not using that generic mechanism?
> +static int brcmstb_gpio_to_irq(struct gpio_chip *gc, unsigned gc_offset)
> + struct brcmstb_gpio_priv *priv = brcmstb_gpio_gc_to_priv(gc);
> + /* gc_offset is relative to this gpio_chip; want real offset */
> + int offset = gc_offset + (gc->base - priv->gpio_base);
> + if (offset >= priv->num_gpios)
> + return -ENXIO;
> + return irq_create_mapping(priv->irq_domain, offset);
It is a no-no to rely on .to_irq() to be called before using an IRQ
from a GPIO chip.
The gpiochip and irq_chip APIs are orthogonal, and a user may
request an interrupt from the irqchip without calling .to_irq() on any
GPIO line first.
This should only use irq_find_mapping().
irq_create_mapping() needs to be called on all available
offsets during probe.
If the module is removable or at error path it also needs
to call irq_dispose_mapping() on all lines. Also this is handled
by GPIOLIB_IRQCHIP, and that is why it should always be
used, if possible.
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