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 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 */
 108 error_release_irq:
 109         free_irq(irq, trig);
 110 error_free_trig_info:
 111         kfree(trig_info);
 112 error_put_trigger:
 113         iio_put_trigger(trig);
 114 error_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
 129 static 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
 150 static 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
 159 static int __init iio_gpio_trig_init(void)
 160 {
 161         return platform_driver_register(&iio_gpio_trigger_driver);
 162 }
 163 module_init(iio_gpio_trig_init);
 164
 165 static void __exit iio_gpio_trig_exit(void)
 166 {
 167         platform_driver_unregister(&iio_gpio_trigger_driver);
 168 }
 169 module_exit(iio_gpio_trig_exit);
 170
 171 MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
 172 MODULE_DESCRIPTION("Example gpio trigger for the iio subsystem");
 173 MODULE_LICENSE("GPL v2");