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    Subject[PATCH 13/14] IIO: Proof of concept gpio trigger
    Date
    Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>

    Simple example of how a gpio trigger driver would work.
    Things to be added include interupt type control (high, low).
    ---
    drivers/iio/trigger/Kconfig | 6 +
    drivers/iio/trigger/Makefile | 2 +-
    drivers/iio/trigger/iio-trig-gpio.c | 203 +++++++++++++++++++++++++++++++++++
    include/linux/iio/gpio_trigger.h | 6 +
    4 files changed, 216 insertions(+), 1 deletions(-)
    create mode 100644 drivers/iio/trigger/iio-trig-gpio.c
    create mode 100644 include/linux/iio/gpio_trigger.h

    diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
    index 0c73ccc..e7e1b6e 100644
    --- a/drivers/iio/trigger/Kconfig
    +++ b/drivers/iio/trigger/Kconfig
    @@ -10,3 +10,9 @@ config IIO_PERIODIC_RTC_TRIGGER
    help
    Provides support for using periodic capable real time
    clocks as IIO triggers.
    +
    +config IIO_GPIO_TRIGGER
    + tristate "GPIO trigger"
    + depends on IIO && IIO_TRIGGER && GENERIC_GPIO
    + help
    + Provides support for using GPIO pins as IIO triggers.
    \ No newline at end of file
    diff --git a/drivers/iio/trigger/Makefile b/drivers/iio/trigger/Makefile
    index 4ae55b9..e5f96d2 100644
    --- a/drivers/iio/trigger/Makefile
    +++ b/drivers/iio/trigger/Makefile
    @@ -2,4 +2,4 @@
    # Makefile for triggers not associated with iio-devices
    #
    obj-$(CONFIG_IIO_PERIODIC_RTC_TRIGGER) += iio-trig-periodic-rtc.o
    -
    +obj-$(CONFIG_IIO_GPIO_TRIGGER) += iio-trig-gpio.o
    \ No newline at end of file
    diff --git a/drivers/iio/trigger/iio-trig-gpio.c b/drivers/iio/trigger/iio-trig-gpio.c
    new file mode 100644
    index 0000000..80c7a54
    --- /dev/null
    +++ b/drivers/iio/trigger/iio-trig-gpio.c
    @@ -0,0 +1,203 @@
    +/*
    + * Industrial I/O - gpio based trigger support
    + *
    + * Copyright (c) 2008 Jonathan Cameron
    + *
    + * This program is free software; you can redistribute it and/or modify it
    + * under the terms of the GNU General Public License version 2 as published by
    + * the Free Software Foundation.
    + *
    + * Currently this is more of a functioning proof of concept that a fully
    + * fledged trigger driver.
    + *
    + * TODO:
    + *
    + * Add board config elements to allow specification of startup settings.
    + * Add configuration settings (irq type etc)
    + */
    +
    +#include <linux/kernel.h>
    +#include <linux/module.h>
    +#include <linux/platform_device.h>
    +#include <linux/interrupt.h>
    +#include <linux/gpio.h>
    +
    +#include <linux/iio/iio.h>
    +#include <linux/iio/trigger.h>
    +#include <linux/iio/gpio_trigger.h>
    +
    +LIST_HEAD(iio_gpio_trigger_list);
    +DEFINE_MUTEX(iio_gpio_trigger_list_lock);
    +
    +struct iio_gpio_trigger_info {
    + struct mutex in_use;
    + int gpio;
    +};
    +/*
    + * Need to reference count these triggers and only enable gpio interrupts
    + * as appropriate.
    + */
    +
    +/* So what functionality do we want in here?... */
    +/* set high / low as interrupt type? */
    +
    +static irqreturn_t iio_gpio_trigger_poll(int irq, void *private)
    +{
    + iio_trigger_poll(private);
    + return IRQ_HANDLED;
    +}
    +
    +DEVICE_ATTR(name, S_IRUGO, iio_trigger_read_name, NULL);
    +
    +static struct attribute *iio_gpio_trigger_attrs[] = {
    + &dev_attr_name.attr,
    + NULL,
    +};
    +
    +static const struct attribute_group iio_gpio_trigger_attr_group = {
    + .attrs = iio_gpio_trigger_attrs,
    +};
    +
    +static int iio_gpio_trigger_probe(struct platform_device *dev)
    +{
    + struct iio_gpio_trigger_pdata *pdata = dev->dev.platform_data;
    + struct iio_gpio_trigger_info *trig_info;
    + struct iio_trigger *trig, *trig2;
    + int i, irq, ret = 0;
    + if (!pdata) {
    + printk(KERN_ERR "No IIO gpio trigger platform data found\n");
    + goto error_ret;
    + }
    + for (i = 0; i < pdata->num_gpios; i++) {
    +
    + trig = iio_allocate_trigger();
    + if (!trig) {
    + ret = -ENOMEM;
    + goto error_free_completed_registrations;
    + }
    +
    + trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
    + if (!trig_info) {
    + ret = -ENOMEM;
    + goto error_put_trigger;
    + }
    + trig->control_attrs = &iio_gpio_trigger_attr_group;
    + trig->private_data = trig_info;
    + trig_info->gpio = pdata->gpios[i];
    + trig->owner = THIS_MODULE;
    + trig->name = kmalloc(IIO_TRIGGER_NAME_LENGTH, GFP_KERNEL);
    + if (!trig->name) {
    + ret = -ENOMEM;
    + goto error_free_trig_info;
    + }
    + snprintf((char *)trig->name,
    + IIO_TRIGGER_NAME_LENGTH,
    + "gpiotrig%d",
    + pdata->gpios[i]);
    + ret = gpio_request(trig_info->gpio, trig->name);
    + if (ret)
    + goto error_free_name;
    +
    + ret = gpio_direction_input(trig_info->gpio);
    + if (ret)
    + goto error_release_gpio;
    +
    + irq = gpio_to_irq(trig_info->gpio);
    + if (irq < 0) {
    + ret = irq;
    + goto error_release_gpio;
    + }
    +
    + ret = request_irq(irq, iio_gpio_trigger_poll,
    + IRQF_TRIGGER_RISING,
    + trig->name,
    + trig);
    + if (ret)
    + goto error_release_gpio;
    +
    + ret = iio_trigger_register(trig);
    + if (ret)
    + goto error_release_irq;
    +
    + list_add_tail(&trig->alloc_list, &iio_gpio_trigger_list);
    +
    + }
    + return 0;
    +
    +/* First clean up the partly allocated trigger */
    +error_release_irq:
    + free_irq(irq, trig);
    +error_release_gpio:
    + gpio_free(trig_info->gpio);
    +error_free_name:
    + kfree(trig->name);
    +error_free_trig_info:
    + kfree(trig_info);
    +error_put_trigger:
    + iio_put_trigger(trig);
    +error_free_completed_registrations:
    + /* The rest should have been added to the iio_gpio_trigger_list */
    + list_for_each_entry_safe(trig,
    + trig2,
    + &iio_gpio_trigger_list,
    + alloc_list) {
    + trig_info = trig->private_data;
    + iio_trigger_unregister(trig);
    + free_irq(gpio_to_irq(trig_info->gpio), trig);
    + gpio_free(trig_info->gpio);
    + kfree(trig->name);
    + kfree(trig_info);
    + iio_put_trigger(trig);
    + }
    +
    +error_ret:
    + return ret;
    +}
    +
    +static int iio_gpio_trigger_remove(struct platform_device *dev)
    +{
    + struct iio_trigger *trig, *trig2;
    + struct iio_gpio_trigger_info *trig_info;
    +
    + mutex_lock(&iio_gpio_trigger_list_lock);
    + list_for_each_entry_safe(trig,
    + trig2,
    + &iio_gpio_trigger_list,
    + alloc_list) {
    + trig_info = trig->private_data;
    + iio_trigger_unregister(trig);
    + free_irq(gpio_to_irq(trig_info->gpio), trig);
    + gpio_free(trig_info->gpio);
    + kfree(trig->name);
    + kfree(trig_info);
    + iio_put_trigger(trig);
    + }
    + mutex_unlock(&iio_gpio_trigger_list_lock);
    +
    + return 0;
    +}
    +
    +static struct platform_driver iio_gpio_trigger_driver = {
    + .probe = iio_gpio_trigger_probe,
    + .remove = iio_gpio_trigger_remove,
    + .driver = {
    + .name = "iio_gpio_trigger",
    + .owner = THIS_MODULE,
    + },
    +};
    +
    +static int __init iio_gpio_trig_init(void)
    +{
    + return platform_driver_register(&iio_gpio_trigger_driver);
    +}
    +module_init(iio_gpio_trig_init);
    +
    +static void __exit iio_gpio_trig_exit(void)
    +{
    + platform_driver_unregister(&iio_gpio_trigger_driver);
    +}
    +module_exit(iio_gpio_trig_exit);
    +
    +MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
    +MODULE_DESCRIPTION("Example gpio trigger for the iio subsystem");
    +MODULE_LICENSE("GPL v2");
    diff --git a/include/linux/iio/gpio_trigger.h b/include/linux/iio/gpio_trigger.h
    new file mode 100644
    index 0000000..25be3da
    --- /dev/null
    +++ b/include/linux/iio/gpio_trigger.h
    @@ -0,0 +1,6 @@
    +
    +
    +struct iio_gpio_trigger_pdata {
    + int num_gpios;
    + int *gpios;
    +};
    --
    1.6.2


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