drivers/iio/common/st_sensors/st_sensors_trigger.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * STMicroelectronics sensors trigger library driver
   4  *
   5  * Copyright 2012-2013 STMicroelectronics Inc.
   6  *
   7  * Denis Ciocca <denis.ciocca@st.com>
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/iio/iio.h>
  14 #include <linux/iio/trigger.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/regmap.h>
  17 #include <linux/iio/common/st_sensors.h>
  18 #include "st_sensors_core.h"
  19
  20 /**
  21  * st_sensors_new_samples_available() - check if more samples came in
  22  * @indio_dev: IIO device reference.
  23  * @sdata: Sensor data.
  24  *
  25  * returns:
  26  * 0 - no new samples available
  27  * 1 - new samples available
  28  * negative - error or unknown
  29  */
  30 static int st_sensors_new_samples_available(struct iio_dev *indio_dev,
  31                                             struct st_sensor_data *sdata)
  32 {
  33         int ret, status;
  34
  35         /* How would I know if I can't check it? */
  36         if (!sdata->sensor_settings->drdy_irq.stat_drdy.addr)
  37                 return -EINVAL;
  38
  39         /* No scan mask, no interrupt */
  40         if (!indio_dev->active_scan_mask)
  41                 return 0;
  42
  43         ret = regmap_read(sdata->regmap,
  44                           sdata->sensor_settings->drdy_irq.stat_drdy.addr,
  45                           &status);
  46         if (ret < 0) {
  47                 dev_err(sdata->dev, "error checking samples available\n");
  48                 return ret;
  49         }
  50
  51         if (status & sdata->sensor_settings->drdy_irq.stat_drdy.mask)
  52                 return 1;
  53
  54         return 0;
  55 }
  56
  57 /**
  58  * st_sensors_irq_handler() - top half of the IRQ-based triggers
  59  * @irq: irq number
  60  * @p: private handler data
  61  */
  62 static irqreturn_t st_sensors_irq_handler(int irq, void *p)
  63 {
  64         struct iio_trigger *trig = p;
  65         struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
  66         struct st_sensor_data *sdata = iio_priv(indio_dev);
  67
  68         /* Get the time stamp as close in time as possible */
  69         sdata->hw_timestamp = iio_get_time_ns(indio_dev);
  70         return IRQ_WAKE_THREAD;
  71 }
  72
  73 /**
  74  * st_sensors_irq_thread() - bottom half of the IRQ-based triggers
  75  * @irq: irq number
  76  * @p: private handler data
  77  */
  78 static irqreturn_t st_sensors_irq_thread(int irq, void *p)
  79 {
  80         struct iio_trigger *trig = p;
  81         struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
  82         struct st_sensor_data *sdata = iio_priv(indio_dev);
  83
  84         /*
  85          * If this trigger is backed by a hardware interrupt and we have a
  86          * status register, check if this IRQ came from us. Notice that
  87          * we will process also if st_sensors_new_samples_available()
  88          * returns negative: if we can't check status, then poll
  89          * unconditionally.
  90          */
  91         if (sdata->hw_irq_trigger &&
  92             st_sensors_new_samples_available(indio_dev, sdata)) {
  93                 iio_trigger_poll_chained(p);
  94         } else {
  95                 dev_dbg(sdata->dev, "spurious IRQ\n");
  96                 return IRQ_NONE;
  97         }
  98
  99         /*
 100          * If we have proper level IRQs the handler will be re-entered if
 101          * the line is still active, so return here and come back in through
 102          * the top half if need be.
 103          */
 104         if (!sdata->edge_irq)
 105                 return IRQ_HANDLED;
 106
 107         /*
 108          * If we are using edge IRQs, new samples arrived while processing
 109          * the IRQ and those may be missed unless we pick them here, so poll
 110          * again. If the sensor delivery frequency is very high, this thread
 111          * turns into a polled loop handler.
 112          */
 113         while (sdata->hw_irq_trigger &&
 114                st_sensors_new_samples_available(indio_dev, sdata)) {
 115                 dev_dbg(sdata->dev, "more samples came in during polling\n");
 116                 sdata->hw_timestamp = iio_get_time_ns(indio_dev);
 117                 iio_trigger_poll_chained(p);
 118         }
 119
 120         return IRQ_HANDLED;
 121 }
 122
 123 int st_sensors_allocate_trigger(struct iio_dev *indio_dev,
 124                                 const struct iio_trigger_ops *trigger_ops)
 125 {
 126         struct st_sensor_data *sdata = iio_priv(indio_dev);
 127         unsigned long irq_trig;
 128         int err;
 129
 130         sdata->trig = iio_trigger_alloc("%s-trigger", indio_dev->name);
 131         if (sdata->trig == NULL) {
 132                 dev_err(&indio_dev->dev, "failed to allocate iio trigger.\n");
 133                 return -ENOMEM;
 134         }
 135
 136         iio_trigger_set_drvdata(sdata->trig, indio_dev);
 137         sdata->trig->ops = trigger_ops;
 138         sdata->trig->dev.parent = sdata->dev;
 139
 140         irq_trig = irqd_get_trigger_type(irq_get_irq_data(sdata->irq));
 141         /*
 142          * If the IRQ is triggered on falling edge, we need to mark the
 143          * interrupt as active low, if the hardware supports this.
 144          */
 145         switch(irq_trig) {
 146         case IRQF_TRIGGER_FALLING:
 147         case IRQF_TRIGGER_LOW:
 148                 if (!sdata->sensor_settings->drdy_irq.addr_ihl) {
 149                         dev_err(&indio_dev->dev,
 150                                 "falling/low specified for IRQ but hardware supports only rising/high: will request rising/high\n");
 151                         if (irq_trig == IRQF_TRIGGER_FALLING)
 152                                 irq_trig = IRQF_TRIGGER_RISING;
 153                         if (irq_trig == IRQF_TRIGGER_LOW)
 154                                 irq_trig = IRQF_TRIGGER_HIGH;
 155                 } else {
 156                         /* Set up INT active low i.e. falling edge */
 157                         err = st_sensors_write_data_with_mask(indio_dev,
 158                                 sdata->sensor_settings->drdy_irq.addr_ihl,
 159                                 sdata->sensor_settings->drdy_irq.mask_ihl, 1);
 160                         if (err < 0)
 161                                 goto iio_trigger_free;
 162                         dev_info(&indio_dev->dev,
 163                                  "interrupts on the falling edge or active low level\n");
 164                 }
 165                 break;
 166         case IRQF_TRIGGER_RISING:
 167                 dev_info(&indio_dev->dev,
 168                          "interrupts on the rising edge\n");
 169                 break;
 170         case IRQF_TRIGGER_HIGH:
 171                 dev_info(&indio_dev->dev,
 172                          "interrupts active high level\n");
 173                 break;
 174         default:
 175                 /* This is the most preferred mode, if possible */
 176                 dev_err(&indio_dev->dev,
 177                         "unsupported IRQ trigger specified (%lx), enforce rising edge\n", irq_trig);
 178                 irq_trig = IRQF_TRIGGER_RISING;
 179         }
 180
 181         /* Tell the interrupt handler that we're dealing with edges */
 182         if (irq_trig == IRQF_TRIGGER_FALLING ||
 183             irq_trig == IRQF_TRIGGER_RISING)
 184                 sdata->edge_irq = true;
 185         else
 186                 /*
 187                  * If we're not using edges (i.e. level interrupts) we
 188                  * just mask off the IRQ, handle one interrupt, then
 189                  * if the line is still low, we return to the
 190                  * interrupt handler top half again and start over.
 191                  */
 192                 irq_trig |= IRQF_ONESHOT;
 193
 194         /*
 195          * If the interrupt pin is Open Drain, by definition this
 196          * means that the interrupt line may be shared with other
 197          * peripherals. But to do this we also need to have a status
 198          * register and mask to figure out if this sensor was firing
 199          * the IRQ or not, so we can tell the interrupt handle that
 200          * it was "our" interrupt.
 201          */
 202         if (sdata->int_pin_open_drain &&
 203             sdata->sensor_settings->drdy_irq.stat_drdy.addr)
 204                 irq_trig |= IRQF_SHARED;
 205
 206         err = request_threaded_irq(sdata->irq,
 207                                    st_sensors_irq_handler,
 208                                    st_sensors_irq_thread,
 209                                    irq_trig,
 210                                    sdata->trig->name,
 211                                    sdata->trig);
 212         if (err) {
 213                 dev_err(&indio_dev->dev, "failed to request trigger IRQ.\n");
 214                 goto iio_trigger_free;
 215         }
 216
 217         err = iio_trigger_register(sdata->trig);
 218         if (err < 0) {
 219                 dev_err(&indio_dev->dev, "failed to register iio trigger.\n");
 220                 goto iio_trigger_register_error;
 221         }
 222         indio_dev->trig = iio_trigger_get(sdata->trig);
 223
 224         return 0;
 225
 226 iio_trigger_register_error:
 227         free_irq(sdata->irq, sdata->trig);
 228 iio_trigger_free:
 229         iio_trigger_free(sdata->trig);
 230         return err;
 231 }
 232 EXPORT_SYMBOL(st_sensors_allocate_trigger);
 233
 234 void st_sensors_deallocate_trigger(struct iio_dev *indio_dev)
 235 {
 236         struct st_sensor_data *sdata = iio_priv(indio_dev);
 237
 238         iio_trigger_unregister(sdata->trig);
 239         free_irq(sdata->irq, sdata->trig);
 240         iio_trigger_free(sdata->trig);
 241 }
 242 EXPORT_SYMBOL(st_sensors_deallocate_trigger);
 243
 244 int st_sensors_validate_device(struct iio_trigger *trig,
 245                                struct iio_dev *indio_dev)
 246 {
 247         struct iio_dev *indio = iio_trigger_get_drvdata(trig);
 248
 249         if (indio != indio_dev)
 250                 return -EINVAL;
 251
 252         return 0;
 253 }
 254 EXPORT_SYMBOL(st_sensors_validate_device);
 255
 256 MODULE_AUTHOR("Denis Ciocca <denis.ciocca@st.com>");
 257 MODULE_DESCRIPTION("STMicroelectronics ST-sensors trigger");
 258 MODULE_LICENSE("GPL v2");