LXR linux/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 than a full
  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 <linux/iio/iio.h>
  26#include <linux/iio/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 const struct iio_trigger_ops iio_gpio_trigger_ops = {
  51        .owner = THIS_MODULE,
  52};
  53
  54static int iio_gpio_trigger_probe(struct platform_device *pdev)
  55{
  56        struct iio_gpio_trigger_info *trig_info;
  57        struct iio_trigger *trig, *trig2;
  58        unsigned long irqflags;
  59        struct resource *irq_res;
  60        int irq, ret = 0, irq_res_cnt = 0;
  61
  62        do {
  63                irq_res = platform_get_resource(pdev,
  64                                IORESOURCE_IRQ, irq_res_cnt);
  65
  66                if (irq_res == NULL) {
  67                        if (irq_res_cnt == 0)
  68                                dev_err(&pdev->dev, "No GPIO IRQs specified");
  69                        break;
  70                }
  71                irqflags = (irq_res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED;
  72
  73                for (irq = irq_res->start; irq <= irq_res->end; irq++) {
  74
  75                        trig = iio_trigger_alloc("irqtrig%d", irq);
  76                        if (!trig) {
  77                                ret = -ENOMEM;
  78                                goto error_free_completed_registrations;
  79                        }
  80
  81                        trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
  82                        if (!trig_info) {
  83                                ret = -ENOMEM;
  84                                goto error_put_trigger;
  85                        }
  86                        trig->private_data = trig_info;
  87                        trig_info->irq = irq;
  88                        trig->ops = &iio_gpio_trigger_ops;
  89                        ret = request_irq(irq, iio_gpio_trigger_poll,
  90                                          irqflags, trig->name, trig);
  91                        if (ret) {
  92                                dev_err(&pdev->dev,
  93                                        "request IRQ-%d failed", irq);
  94                                goto error_free_trig_info;
  95                        }
  96
  97                        ret = iio_trigger_register(trig);
  98                        if (ret)
  99                                goto error_release_irq;
 100
 101                        list_add_tail(&trig->alloc_list,
 102                                        &iio_gpio_trigger_list);
 103                }
 104
 105                irq_res_cnt++;
 106        } while (irq_res != NULL);
 107
 108
 109        return 0;
 110
 111/* First clean up the partly allocated trigger */
 112error_release_irq:
 113        free_irq(irq, trig);
 114error_free_trig_info:
 115        kfree(trig_info);
 116error_put_trigger:
 117        iio_trigger_put(trig);
 118error_free_completed_registrations:
 119        /* The rest should have been added to the iio_gpio_trigger_list */
 120        list_for_each_entry_safe(trig,
 121                                 trig2,
 122                                 &iio_gpio_trigger_list,
 123                                 alloc_list) {
 124                trig_info = trig->private_data;
 125                free_irq(gpio_to_irq(trig_info->irq), trig);
 126                kfree(trig_info);
 127                iio_trigger_unregister(trig);
 128        }
 129
 130        return ret;
 131}
 132
 133static int iio_gpio_trigger_remove(struct platform_device *pdev)
 134{
 135        struct iio_trigger *trig, *trig2;
 136        struct iio_gpio_trigger_info *trig_info;
 137
 138        mutex_lock(&iio_gpio_trigger_list_lock);
 139        list_for_each_entry_safe(trig,
 140                                 trig2,
 141                                 &iio_gpio_trigger_list,
 142                                 alloc_list) {
 143                trig_info = trig->private_data;
 144                iio_trigger_unregister(trig);
 145                free_irq(trig_info->irq, trig);
 146                kfree(trig_info);
 147                iio_trigger_put(trig);
 148        }
 149        mutex_unlock(&iio_gpio_trigger_list_lock);
 150
 151        return 0;
 152}
 153
 154static struct platform_driver iio_gpio_trigger_driver = {
 155        .probe = iio_gpio_trigger_probe,
 156        .remove = iio_gpio_trigger_remove,
 157        .driver = {
 158                .name = "iio_gpio_trigger",
 159                .owner = THIS_MODULE,
 160        },
 161};
 162
 163module_platform_driver(iio_gpio_trigger_driver);
 164
 165MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 166MODULE_DESCRIPTION("Example gpio trigger for the iio subsystem");
 167MODULE_LICENSE("GPL v2");
 168