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 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");
 174