/drivers/staging/iio/trigger/iio-trig-gpio.c

  1/*
  2 * Industrial I/O - gpio based trigger support
  3 *
  4 * Copyright (c) 2008 Jonathan Cameron
  5 *
  6 * This program is free software; you can redistribute it and/or modify it
  7 * under the terms of the GNU General Public License version 2 as published by
  8 * the Free Software Foundation.
  9 *
 10 * Currently this is more of a functioning proof of concept that a fully
 11 * fledged trigger driver.
 12 *
 13 * TODO:
 14 *
 15 * Add board config elements to allow specification of startup settings.
 16 */
 17
 18#include <linux/kernel.h>
 19#include <linux/module.h>
 20#include <linux/platform_device.h>
 21#include <linux/interrupt.h>
 22#include <linux/gpio.h>
 23#include <linux/slab.h>
 24
 25#include "../iio.h"
 26#include "../trigger.h"
 27
 28static LIST_HEAD(iio_gpio_trigger_list);
 29static DEFINE_MUTEX(iio_gpio_trigger_list_lock);
 30
 31struct iio_gpio_trigger_info {
 32	struct mutex in_use;
 33	unsigned int irq;
 34};
 35/*
 36 * Need to reference count these triggers and only enable gpio interrupts
 37 * as appropriate.
 38 */
 39
 40/* So what functionality do we want in here?... */
 41/* set high / low as interrupt type? */
 42
 43static irqreturn_t iio_gpio_trigger_poll(int irq, void *private)
 44{
 45	/* Timestamp not currently provided */
 46	iio_trigger_poll(private, 0);
 47	return IRQ_HANDLED;
 48}
 49
 50static int iio_gpio_trigger_probe(struct platform_device *pdev)
 51{
 52	struct iio_gpio_trigger_info *trig_info;
 53	struct iio_trigger *trig, *trig2;
 54	unsigned long irqflags;
 55	struct resource *irq_res;
 56	int irq, ret = 0, irq_res_cnt = 0;
 57
 58	do {
 59		irq_res = platform_get_resource(pdev,
 60				IORESOURCE_IRQ, irq_res_cnt);
 61
 62		if (irq_res == NULL) {
 63			if (irq_res_cnt == 0)
 64				dev_err(&pdev->dev, "No GPIO IRQs specified");
 65			break;
 66		}
 67		irqflags = (irq_res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED;
 68
 69		for (irq = irq_res->start; irq <= irq_res->end; irq++) {
 70
 71			trig = iio_allocate_trigger("irqtrig%d", irq);
 72			if (!trig) {
 73				ret = -ENOMEM;
 74				goto error_free_completed_registrations;
 75			}
 76
 77			trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
 78			if (!trig_info) {
 79				ret = -ENOMEM;
 80				goto error_put_trigger;
 81			}
 82			trig->private_data = trig_info;
 83			trig_info->irq = irq;
 84			trig->owner = THIS_MODULE;
 85			ret = request_irq(irq, iio_gpio_trigger_poll,
 86					  irqflags, trig->name, trig);
 87			if (ret) {
 88				dev_err(&pdev->dev,
 89					"request IRQ-%d failed", irq);
 90				goto error_free_trig_info;
 91			}
 92
 93			ret = iio_trigger_register(trig);
 94			if (ret)
 95				goto error_release_irq;
 96
 97			list_add_tail(&trig->alloc_list,
 98					&iio_gpio_trigger_list);
 99		}
100
101		irq_res_cnt++;
102	} while (irq_res != NULL);
103
104
105	return 0;
106
107/* First clean up the partly allocated trigger */
108error_release_irq:
109	free_irq(irq, trig);
110error_free_trig_info:
111	kfree(trig_info);
112error_put_trigger:
113	iio_put_trigger(trig);
114error_free_completed_registrations:
115	/* The rest should have been added to the iio_gpio_trigger_list */
116	list_for_each_entry_safe(trig,
117				 trig2,
118				 &iio_gpio_trigger_list,
119				 alloc_list) {
120		trig_info = trig->private_data;
121		free_irq(gpio_to_irq(trig_info->irq), trig);
122		kfree(trig_info);
123		iio_trigger_unregister(trig);
124	}
125
126	return ret;
127}
128
129static int iio_gpio_trigger_remove(struct platform_device *pdev)
130{
131	struct iio_trigger *trig, *trig2;
132	struct iio_gpio_trigger_info *trig_info;
133
134	mutex_lock(&iio_gpio_trigger_list_lock);
135	list_for_each_entry_safe(trig,
136				 trig2,
137				 &iio_gpio_trigger_list,
138				 alloc_list) {
139		trig_info = trig->private_data;
140		iio_trigger_unregister(trig);
141		free_irq(trig_info->irq, trig);
142		kfree(trig_info);
143		iio_put_trigger(trig);
144	}
145	mutex_unlock(&iio_gpio_trigger_list_lock);
146
147	return 0;
148}
149
150static struct platform_driver iio_gpio_trigger_driver = {
151	.probe = iio_gpio_trigger_probe,
152	.remove = iio_gpio_trigger_remove,
153	.driver = {
154		.name = "iio_gpio_trigger",
155		.owner = THIS_MODULE,
156	},
157};
158
159static int __init iio_gpio_trig_init(void)
160{
161	return platform_driver_register(&iio_gpio_trigger_driver);
162}
163module_init(iio_gpio_trig_init);
164
165static void __exit iio_gpio_trig_exit(void)
166{
167	platform_driver_unregister(&iio_gpio_trigger_driver);
168}
169module_exit(iio_gpio_trig_exit);
170
171MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
172MODULE_DESCRIPTION("Example gpio trigger for the iio subsystem");
173MODULE_LICENSE("GPL v2");