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
  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         iio_trigger_poll(private);
  46         return IRQ_HANDLED;
  47 }
  48
  49 static DEVICE_ATTR(name, S_IRUGO, iio_trigger_read_name, NULL);
  50
  51 static struct attribute *iio_gpio_trigger_attrs[] = {
  52         &dev_attr_name.attr,
  53         NULL,
  54 };
  55
  56 static const struct attribute_group iio_gpio_trigger_attr_group = {
  57         .attrs = iio_gpio_trigger_attrs,
  58 };
  59
  60 static int iio_gpio_trigger_probe(struct platform_device *pdev)
  61 {
  62         struct iio_gpio_trigger_info *trig_info;
  63         struct iio_trigger *trig, *trig2;
  64         unsigned long irqflags;
  65         struct resource *irq_res;
  66         int irq, ret = 0, irq_res_cnt = 0;
  67
  68         do {
  69                 irq_res = platform_get_resource(pdev,
  70                                 IORESOURCE_IRQ, irq_res_cnt);
  71
  72                 if (irq_res == NULL) {
  73                         if (irq_res_cnt == 0)
  74                                 dev_err(&pdev->dev, "No GPIO IRQs specified");
  75                         break;
  76                 }
  77                 irqflags = (irq_res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED;
  78
  79                 for (irq = irq_res->start; irq <= irq_res->end; irq++) {
  80
  81                         trig = iio_allocate_trigger();
  82                         if (!trig) {
  83                                 ret = -ENOMEM;
  84                                 goto error_free_completed_registrations;
  85                         }
  86
  87                         trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
  88                         if (!trig_info) {
  89                                 ret = -ENOMEM;
  90                                 goto error_put_trigger;
  91                         }
  92                         trig->control_attrs = &iio_gpio_trigger_attr_group;
  93                         trig->private_data = trig_info;
  94                         trig_info->irq = irq;
  95                         trig->owner = THIS_MODULE;
  96                         trig->name = kmalloc(IIO_TRIGGER_NAME_LENGTH,
  97                                         GFP_KERNEL);
  98                         if (!trig->name) {
  99                                 ret = -ENOMEM;
 100                                 goto error_free_trig_info;
 101                         }
 102                         snprintf((char *)trig->name,
 103                                  IIO_TRIGGER_NAME_LENGTH,
 104                                  "irqtrig%d", irq);
 105
 106                         ret = request_irq(irq, iio_gpio_trigger_poll,
 107                                           irqflags, trig->name, trig);
 108                         if (ret) {
 109                                 dev_err(&pdev->dev,
 110                                         "request IRQ-%d failed", irq);
 111                                 goto error_free_name;
 112                         }
 113
 114                         ret = iio_trigger_register(trig);
 115                         if (ret)
 116                                 goto error_release_irq;
 117
 118                         list_add_tail(&trig->alloc_list,
 119                                         &iio_gpio_trigger_list);
 120                 }
 121
 122                 irq_res_cnt++;
 123         } while (irq_res != NULL);
 124
 125
 126         return 0;
 127
 128 /* First clean up the partly allocated trigger */
 129 error_release_irq:
 130         free_irq(irq, trig);
 131 error_free_name:
 132         kfree(trig->name);
 133 error_free_trig_info:
 134         kfree(trig_info);
 135 error_put_trigger:
 136         iio_put_trigger(trig);
 137 error_free_completed_registrations:
 138         /* The rest should have been added to the iio_gpio_trigger_list */
 139         list_for_each_entry_safe(trig,
 140                                  trig2,
 141                                  &iio_gpio_trigger_list,
 142                                  alloc_list) {
 143                 trig_info = trig->private_data;
 144                 free_irq(gpio_to_irq(trig_info->irq), trig);
 145                 kfree(trig->name);
 146                 kfree(trig_info);
 147                 iio_trigger_unregister(trig);
 148         }
 149
 150         return ret;
 151 }
 152
 153 static int iio_gpio_trigger_remove(struct platform_device *pdev)
 154 {
 155         struct iio_trigger *trig, *trig2;
 156         struct iio_gpio_trigger_info *trig_info;
 157
 158         mutex_lock(&iio_gpio_trigger_list_lock);
 159         list_for_each_entry_safe(trig,
 160                                  trig2,
 161                                  &iio_gpio_trigger_list,
 162                                  alloc_list) {
 163                 trig_info = trig->private_data;
 164                 iio_trigger_unregister(trig);
 165                 free_irq(trig_info->irq, trig);
 166                 kfree(trig->name);
 167                 kfree(trig_info);
 168                 iio_put_trigger(trig);
 169         }
 170         mutex_unlock(&iio_gpio_trigger_list_lock);
 171
 172         return 0;
 173 }
 174
 175 static struct platform_driver iio_gpio_trigger_driver = {
 176         .probe = iio_gpio_trigger_probe,
 177         .remove = iio_gpio_trigger_remove,
 178         .driver = {
 179                 .name = "iio_gpio_trigger",
 180                 .owner = THIS_MODULE,
 181         },
 182 };
 183
 184 static int __init iio_gpio_trig_init(void)
 185 {
 186         return platform_driver_register(&iio_gpio_trigger_driver);
 187 }
 188 module_init(iio_gpio_trig_init);
 189
 190 static void __exit iio_gpio_trig_exit(void)
 191 {
 192         platform_driver_unregister(&iio_gpio_trigger_driver);
 193 }
 194 module_exit(iio_gpio_trig_exit);
 195
 196 MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
 197 MODULE_DESCRIPTION("Example gpio trigger for the iio subsystem");
 198 MODULE_LICENSE("GPL v2");