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 "../iio.h"
  26 #include "../trigger.h"
  27
  28 static LIST_HEAD(iio_gpio_trigger_list);
  29 static DEFINE_MUTEX(iio_gpio_trigger_list_lock);
  30
  31 struct 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
  43 static 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
  50 static const struct iio_trigger_ops iio_gpio_trigger_ops = {
  51         .owner = THIS_MODULE,
  52 };
  53
  54 static 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_allocate_trigger("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 */
 112 error_release_irq:
 113         free_irq(irq, trig);
 114 error_free_trig_info:
 115         kfree(trig_info);
 116 error_put_trigger:
 117         iio_put_trigger(trig);
 118 error_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
 133 static 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_put_trigger(trig);
 148         }
 149         mutex_unlock(&iio_gpio_trigger_list_lock);
 150
 151         return 0;
 152 }
 153
 154 static 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
 163 module_platform_driver(iio_gpio_trigger_driver);
 164
 165 MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
 166 MODULE_DESCRIPTION("Example gpio trigger for the iio subsystem");
 167 MODULE_LICENSE("GPL v2");