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         /* Timestamp not currently provided */
  46         iio_trigger_poll(private, 0);
  47         return IRQ_HANDLED;
  48 }
  49
  50 static DEVICE_ATTR(name, S_IRUGO, iio_trigger_read_name, NULL);
  51
  52 static struct attribute *iio_gpio_trigger_attrs[] = {
  53         &dev_attr_name.attr,
  54         NULL,
  55 };
  56
  57 static const struct attribute_group iio_gpio_trigger_attr_group = {
  58         .attrs = iio_gpio_trigger_attrs,
  59 };
  60
  61 static int iio_gpio_trigger_probe(struct platform_device *pdev)
  62 {
  63         struct iio_gpio_trigger_info *trig_info;
  64         struct iio_trigger *trig, *trig2;
  65         unsigned long irqflags;
  66         struct resource *irq_res;
  67         int irq, ret = 0, irq_res_cnt = 0;
  68
  69         do {
  70                 irq_res = platform_get_resource(pdev,
  71                                 IORESOURCE_IRQ, irq_res_cnt);
  72
  73                 if (irq_res == NULL) {
  74                         if (irq_res_cnt == 0)
  75                                 dev_err(&pdev->dev, "No GPIO IRQs specified");
  76                         break;
  77                 }
  78                 irqflags = (irq_res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED;
  79
  80                 for (irq = irq_res->start; irq <= irq_res->end; irq++) {
  81
  82                         trig = iio_allocate_trigger();
  83                         if (!trig) {
  84                                 ret = -ENOMEM;
  85                                 goto error_free_completed_registrations;
  86                         }
  87
  88                         trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
  89                         if (!trig_info) {
  90                                 ret = -ENOMEM;
  91                                 goto error_put_trigger;
  92                         }
  93                         trig->control_attrs = &iio_gpio_trigger_attr_group;
  94                         trig->private_data = trig_info;
  95                         trig_info->irq = irq;
  96                         trig->owner = THIS_MODULE;
  97                         trig->name = kasprintf(GFP_KERNEL, "irqtrig%d", irq);
  98                         if (trig->name == NULL) {
  99                                 ret = -ENOMEM;
 100                                 goto error_free_trig_info;
 101                         }
 102                         ret = request_irq(irq, iio_gpio_trigger_poll,
 103                                           irqflags, trig->name, trig);
 104                         if (ret) {
 105                                 dev_err(&pdev->dev,
 106                                         "request IRQ-%d failed", irq);
 107                                 goto error_free_name;
 108                         }
 109
 110                         ret = iio_trigger_register(trig);
 111                         if (ret)
 112                                 goto error_release_irq;
 113
 114                         list_add_tail(&trig->alloc_list,
 115                                         &iio_gpio_trigger_list);
 116                 }
 117
 118                 irq_res_cnt++;
 119         } while (irq_res != NULL);
 120
 121
 122         return 0;
 123
 124 /* First clean up the partly allocated trigger */
 125 error_release_irq:
 126         free_irq(irq, trig);
 127 error_free_name:
 128         kfree(trig->name);
 129 error_free_trig_info:
 130         kfree(trig_info);
 131 error_put_trigger:
 132         iio_put_trigger(trig);
 133 error_free_completed_registrations:
 134         /* The rest should have been added to the iio_gpio_trigger_list */
 135         list_for_each_entry_safe(trig,
 136                                  trig2,
 137                                  &iio_gpio_trigger_list,
 138                                  alloc_list) {
 139                 trig_info = trig->private_data;
 140                 free_irq(gpio_to_irq(trig_info->irq), trig);
 141                 kfree(trig->name);
 142                 kfree(trig_info);
 143                 iio_trigger_unregister(trig);
 144         }
 145
 146         return ret;
 147 }
 148
 149 static int iio_gpio_trigger_remove(struct platform_device *pdev)
 150 {
 151         struct iio_trigger *trig, *trig2;
 152         struct iio_gpio_trigger_info *trig_info;
 153
 154         mutex_lock(&iio_gpio_trigger_list_lock);
 155         list_for_each_entry_safe(trig,
 156                                  trig2,
 157                                  &iio_gpio_trigger_list,
 158                                  alloc_list) {
 159                 trig_info = trig->private_data;
 160                 iio_trigger_unregister(trig);
 161                 free_irq(trig_info->irq, trig);
 162                 kfree(trig->name);
 163                 kfree(trig_info);
 164                 iio_put_trigger(trig);
 165         }
 166         mutex_unlock(&iio_gpio_trigger_list_lock);
 167
 168         return 0;
 169 }
 170
 171 static struct platform_driver iio_gpio_trigger_driver = {
 172         .probe = iio_gpio_trigger_probe,
 173         .remove = iio_gpio_trigger_remove,
 174         .driver = {
 175                 .name = "iio_gpio_trigger",
 176                 .owner = THIS_MODULE,
 177         },
 178 };
 179
 180 static int __init iio_gpio_trig_init(void)
 181 {
 182         return platform_driver_register(&iio_gpio_trigger_driver);
 183 }
 184 module_init(iio_gpio_trig_init);
 185
 186 static void __exit iio_gpio_trig_exit(void)
 187 {
 188         platform_driver_unregister(&iio_gpio_trigger_driver);
 189 }
 190 module_exit(iio_gpio_trig_exit);
 191
 192 MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
 193 MODULE_DESCRIPTION("Example gpio trigger for the iio subsystem");
 194 MODULE_LICENSE("GPL v2");