Re: [PATCH 1/3] irq: If an IRQ is a GPIO, request and configure it
From: Rob Herring <hidden>
Date: 2011-08-05 01:55:10
Also in:
alsa-devel, linux-arm-kernel, linux-mmc, lkml
On 08/04/2011 06:00 PM, Stephen Warren wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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
quoted hunk ↗ jump to hunk
+ 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 */