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    SubjectRe: [PATCH 1/3] irq: If an IRQ is a GPIO, request and configure it
    On 08/04/2011 06:00 PM, Stephen Warren wrote:
    > Many IRQs are associated with GPIO pins. When the pin is used as an IRQ,
    > it can't be used as anything else; it should be requested. Enhance the
    > core interrupt code to call gpio_request() and gpio_direction_input() for
    > any IRQ that is also a GPIO. This prevents duplication of these calls in
    > each driver that uses an IRQ.
    >
    > Signed-off-by: Stephen Warren <swarren@nvidia.com>
    > ---
    > kernel/irq/manage.c | 23 +++++++++++++++++++++--
    > 1 files changed, 21 insertions(+), 2 deletions(-)
    >
    > diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
    > index 0a7840a..6e2db72 100644
    > --- a/kernel/irq/manage.c
    > +++ b/kernel/irq/manage.c
    > @@ -7,6 +7,7 @@
    > * This file contains driver APIs to the irq subsystem.
    > */
    >
    > +#include <linux/gpio.h>
    > #include <linux/irq.h>
    > #include <linux/kthread.h>
    > #include <linux/module.h>
    > @@ -875,7 +876,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
    > struct irqaction *old, **old_ptr;
    > const char *old_name = NULL;
    > unsigned long flags, thread_mask = 0;
    > - int ret, nested, shared = 0;
    > + int ret, nested, shared = 0, gpio = -1;
    > cpumask_var_t mask;
    >
    > if (!desc)
    > @@ -978,6 +979,16 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
    > old = *old_ptr;
    > } while (old);
    > shared = 1;
    > + } else {
    > + gpio = irq_to_gpio(irq);

    If you read the documentation for gpio, it is not recommended to use
    irq_to_gpio. There's only a handful of users. Part of the problem is it
    is platform specific and the gpio core cannot convert irq to gpio
    number. Here is the relevant section:

    Non-error values returned from irq_to_gpio() would most commonly be used
    with gpio_get_value(), for example to initialize or update driver state
    when the IRQ is edge-triggered. Note that some platforms don't support
    this reverse mapping, so you should avoid using it.

    Rob

    > + if (gpio_is_valid(gpio)) {
    > + ret = gpio_request(gpio, new->name);
    > + if (ret < 0)
    > + goto out_mask;
    > + ret = gpio_direction_input(gpio);
    > + if (ret < 0)
    > + goto out_mask;
    > + }
    > }
    >
    > /*
    > @@ -1083,6 +1094,8 @@ mismatch:
    > ret = -EBUSY;
    >
    > out_mask:
    > + if (gpio_is_valid(gpio))
    > + gpio_free(gpio);
    > raw_spin_unlock_irqrestore(&desc->lock, flags);
    > free_cpumask_var(mask);
    >
    > @@ -1127,6 +1140,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
    > struct irq_desc *desc = irq_to_desc(irq);
    > struct irqaction *action, **action_ptr;
    > unsigned long flags;
    > + int gpio;
    >
    > WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
    >
    > @@ -1165,8 +1179,13 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
    > #endif
    >
    > /* If this was the last handler, shut down the IRQ line: */
    > - if (!desc->action)
    > + if (!desc->action) {
    > irq_shutdown(desc);
    > + /* If the IRQ line is a GPIO, it's no longer in use */
    > + gpio = irq_to_gpio(irq);
    > + if (gpio_is_valid(gpio))
    > + gpio_free(gpio);
    > + }
    >
    > #ifdef CONFIG_SMP
    > /* make sure affinity_hint is cleaned up */



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