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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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