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Linux/drivers/staging/iio/trigger/iio-trig-periodic-rtc.c

  1 /* The industrial I/O periodic RTC trigger driver
  2  *
  3  * Copyright (c) 2008 Jonathan Cameron
  4  *
  5  * This program is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 as published by
  7  * the Free Software Foundation.
  8  *
  9  * This is a heavily rewritten version of the periodic timer system in
 10  * earlier version of industrialio.  It supplies the same functionality
 11  * but via a trigger rather than a specific periodic timer system.
 12  */
 13 
 14 #include <linux/platform_device.h>
 15 #include <linux/kernel.h>
 16 #include <linux/module.h>
 17 #include <linux/slab.h>
 18 #include <linux/rtc.h>
 19 #include <linux/iio/iio.h>
 20 #include <linux/iio/trigger.h>
 21 
 22 static LIST_HEAD(iio_prtc_trigger_list);
 23 static DEFINE_MUTEX(iio_prtc_trigger_list_lock);
 24 
 25 struct iio_prtc_trigger_info {
 26         struct rtc_device *rtc;
 27         int frequency;
 28         struct rtc_task task;
 29         bool state;
 30 };
 31 
 32 static int iio_trig_periodic_rtc_set_state(struct iio_trigger *trig, bool state)
 33 {
 34         struct iio_prtc_trigger_info *trig_info = iio_trigger_get_drvdata(trig);
 35         int ret;
 36 
 37         if (trig_info->frequency == 0 && state)
 38                 return -EINVAL;
 39         dev_dbg(&trig_info->rtc->dev, "trigger frequency is %d\n",
 40                         trig_info->frequency);
 41         ret = rtc_irq_set_state(trig_info->rtc, &trig_info->task, state);
 42         if (ret == 0)
 43                 trig_info->state = state;
 44 
 45         return ret;
 46 }
 47 
 48 static ssize_t iio_trig_periodic_read_freq(struct device *dev,
 49                                            struct device_attribute *attr,
 50                                            char *buf)
 51 {
 52         struct iio_trigger *trig = to_iio_trigger(dev);
 53         struct iio_prtc_trigger_info *trig_info = iio_trigger_get_drvdata(trig);
 54 
 55         return sprintf(buf, "%u\n", trig_info->frequency);
 56 }
 57 
 58 static ssize_t iio_trig_periodic_write_freq(struct device *dev,
 59                                             struct device_attribute *attr,
 60                                             const char *buf,
 61                                             size_t len)
 62 {
 63         struct iio_trigger *trig = to_iio_trigger(dev);
 64         struct iio_prtc_trigger_info *trig_info = iio_trigger_get_drvdata(trig);
 65         int val;
 66         int ret;
 67 
 68         ret = kstrtoint(buf, 10, &val);
 69         if (ret)
 70                 goto error_ret;
 71 
 72         if (val > 0) {
 73                 ret = rtc_irq_set_freq(trig_info->rtc, &trig_info->task, val);
 74                 if (ret == 0 && trig_info->state && trig_info->frequency == 0)
 75                         ret = rtc_irq_set_state(trig_info->rtc, &trig_info->task, 1);
 76         } else if (val == 0) {
 77                 ret = rtc_irq_set_state(trig_info->rtc, &trig_info->task, 0);
 78         } else
 79                 ret = -EINVAL;
 80         if (ret)
 81                 goto error_ret;
 82 
 83         trig_info->frequency = val;
 84 
 85         return len;
 86 
 87 error_ret:
 88         return ret;
 89 }
 90 
 91 static DEVICE_ATTR(frequency, S_IRUGO | S_IWUSR,
 92             iio_trig_periodic_read_freq,
 93             iio_trig_periodic_write_freq);
 94 
 95 static struct attribute *iio_trig_prtc_attrs[] = {
 96         &dev_attr_frequency.attr,
 97         NULL,
 98 };
 99 
100 static const struct attribute_group iio_trig_prtc_attr_group = {
101         .attrs = iio_trig_prtc_attrs,
102 };
103 
104 static const struct attribute_group *iio_trig_prtc_attr_groups[] = {
105         &iio_trig_prtc_attr_group,
106         NULL
107 };
108 
109 static void iio_prtc_trigger_poll(void *private_data)
110 {
111         iio_trigger_poll(private_data);
112 }
113 
114 static const struct iio_trigger_ops iio_prtc_trigger_ops = {
115         .owner = THIS_MODULE,
116         .set_trigger_state = &iio_trig_periodic_rtc_set_state,
117 };
118 
119 static int iio_trig_periodic_rtc_probe(struct platform_device *dev)
120 {
121         char **pdata = dev->dev.platform_data;
122         struct iio_prtc_trigger_info *trig_info;
123         struct iio_trigger *trig, *trig2;
124 
125         int i, ret;
126 
127         for (i = 0;; i++) {
128                 if (pdata[i] == NULL)
129                         break;
130                 trig = iio_trigger_alloc("periodic%s", pdata[i]);
131                 if (!trig) {
132                         ret = -ENOMEM;
133                         goto error_free_completed_registrations;
134                 }
135                 list_add(&trig->alloc_list, &iio_prtc_trigger_list);
136 
137                 trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
138                 if (!trig_info) {
139                         ret = -ENOMEM;
140                         goto error_put_trigger_and_remove_from_list;
141                 }
142                 iio_trigger_set_drvdata(trig, trig_info);
143                 trig->ops = &iio_prtc_trigger_ops;
144                 /* RTC access */
145                 trig_info->rtc = rtc_class_open(pdata[i]);
146                 if (trig_info->rtc == NULL) {
147                         ret = -EINVAL;
148                         goto error_free_trig_info;
149                 }
150                 trig_info->task.func = iio_prtc_trigger_poll;
151                 trig_info->task.private_data = trig;
152                 ret = rtc_irq_register(trig_info->rtc, &trig_info->task);
153                 if (ret)
154                         goto error_close_rtc;
155                 trig->dev.groups = iio_trig_prtc_attr_groups;
156                 ret = iio_trigger_register(trig);
157                 if (ret)
158                         goto error_unregister_rtc_irq;
159         }
160         return 0;
161 error_unregister_rtc_irq:
162         rtc_irq_unregister(trig_info->rtc, &trig_info->task);
163 error_close_rtc:
164         rtc_class_close(trig_info->rtc);
165 error_free_trig_info:
166         kfree(trig_info);
167 error_put_trigger_and_remove_from_list:
168         list_del(&trig->alloc_list);
169         iio_trigger_put(trig);
170 error_free_completed_registrations:
171         list_for_each_entry_safe(trig,
172                                  trig2,
173                                  &iio_prtc_trigger_list,
174                                  alloc_list) {
175                 trig_info = iio_trigger_get_drvdata(trig);
176                 rtc_irq_unregister(trig_info->rtc, &trig_info->task);
177                 rtc_class_close(trig_info->rtc);
178                 kfree(trig_info);
179                 iio_trigger_unregister(trig);
180         }
181         return ret;
182 }
183 
184 static int iio_trig_periodic_rtc_remove(struct platform_device *dev)
185 {
186         struct iio_trigger *trig, *trig2;
187         struct iio_prtc_trigger_info *trig_info;
188 
189         mutex_lock(&iio_prtc_trigger_list_lock);
190         list_for_each_entry_safe(trig,
191                                  trig2,
192                                  &iio_prtc_trigger_list,
193                                  alloc_list) {
194                 trig_info = iio_trigger_get_drvdata(trig);
195                 rtc_irq_unregister(trig_info->rtc, &trig_info->task);
196                 rtc_class_close(trig_info->rtc);
197                 kfree(trig_info);
198                 iio_trigger_unregister(trig);
199         }
200         mutex_unlock(&iio_prtc_trigger_list_lock);
201         return 0;
202 }
203 
204 static struct platform_driver iio_trig_periodic_rtc_driver = {
205         .probe = iio_trig_periodic_rtc_probe,
206         .remove = iio_trig_periodic_rtc_remove,
207         .driver = {
208                 .name = "iio_prtc_trigger",
209                 .owner = THIS_MODULE,
210         },
211 };
212 
213 module_platform_driver(iio_trig_periodic_rtc_driver);
214 
215 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
216 MODULE_DESCRIPTION("Periodic realtime clock trigger for the iio subsystem");
217 MODULE_LICENSE("GPL v2");
218 

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