drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c

   1 /*
   2 * Copyright (C) 2012 Invensense, Inc.
   3 *
   4 * This software is licensed under the terms of the GNU General Public
   5 * License version 2, as published by the Free Software Foundation, and
   6 * may be copied, distributed, and modified under those terms.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 * GNU General Public License for more details.
  12 */
  13
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/i2c.h>
  17 #include <linux/err.h>
  18 #include <linux/delay.h>
  19 #include <linux/sysfs.h>
  20 #include <linux/jiffies.h>
  21 #include <linux/irq.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/kfifo.h>
  24 #include <linux/poll.h>
  25 #include "inv_mpu_iio.h"
  26
  27 int inv_reset_fifo(struct iio_dev *indio_dev)
  28 {
  29         int result;
  30         u8 d;
  31         struct inv_mpu6050_state  *st = iio_priv(indio_dev);
  32
  33         /* disable interrupt */
  34         result = inv_mpu6050_write_reg(st, st->reg->int_enable, 0);
  35         if (result) {
  36                 dev_err(&st->client->dev, "int_enable failed %d\n", result);
  37                 return result;
  38         }
  39         /* disable the sensor output to FIFO */
  40         result = inv_mpu6050_write_reg(st, st->reg->fifo_en, 0);
  41         if (result)
  42                 goto reset_fifo_fail;
  43         /* disable fifo reading */
  44         result = inv_mpu6050_write_reg(st, st->reg->user_ctrl, 0);
  45         if (result)
  46                 goto reset_fifo_fail;
  47
  48         /* reset FIFO*/
  49         result = inv_mpu6050_write_reg(st, st->reg->user_ctrl,
  50                                         INV_MPU6050_BIT_FIFO_RST);
  51         if (result)
  52                 goto reset_fifo_fail;
  53         /* enable interrupt */
  54         if (st->chip_config.accl_fifo_enable ||
  55             st->chip_config.gyro_fifo_enable) {
  56                 result = inv_mpu6050_write_reg(st, st->reg->int_enable,
  57                                         INV_MPU6050_BIT_DATA_RDY_EN);
  58                 if (result)
  59                         return result;
  60         }
  61         /* enable FIFO reading and I2C master interface*/
  62         result = inv_mpu6050_write_reg(st, st->reg->user_ctrl,
  63                                         INV_MPU6050_BIT_FIFO_EN);
  64         if (result)
  65                 goto reset_fifo_fail;
  66         /* enable sensor output to FIFO */
  67         d = 0;
  68         if (st->chip_config.gyro_fifo_enable)
  69                 d |= INV_MPU6050_BITS_GYRO_OUT;
  70         if (st->chip_config.accl_fifo_enable)
  71                 d |= INV_MPU6050_BIT_ACCEL_OUT;
  72         result = inv_mpu6050_write_reg(st, st->reg->fifo_en, d);
  73         if (result)
  74                 goto reset_fifo_fail;
  75
  76         return 0;
  77
  78 reset_fifo_fail:
  79         dev_err(&st->client->dev, "reset fifo failed %d\n", result);
  80         result = inv_mpu6050_write_reg(st, st->reg->int_enable,
  81                                         INV_MPU6050_BIT_DATA_RDY_EN);
  82
  83         return result;
  84 }
  85
  86 static void inv_clear_kfifo(struct inv_mpu6050_state *st)
  87 {
  88         unsigned long flags;
  89
  90         /* take the spin lock sem to avoid interrupt kick in */
  91         spin_lock_irqsave(&st->time_stamp_lock, flags);
  92         kfifo_reset(&st->timestamps);
  93         spin_unlock_irqrestore(&st->time_stamp_lock, flags);
  94 }
  95
  96 /**
  97  * inv_mpu6050_irq_handler() - Cache a timestamp at each data ready interrupt.
  98  */
  99 irqreturn_t inv_mpu6050_irq_handler(int irq, void *p)
 100 {
 101         struct iio_poll_func *pf = p;
 102         struct iio_dev *indio_dev = pf->indio_dev;
 103         struct inv_mpu6050_state *st = iio_priv(indio_dev);
 104         s64 timestamp;
 105
 106         timestamp = iio_get_time_ns();
 107         kfifo_in_spinlocked(&st->timestamps, &timestamp, 1,
 108                                 &st->time_stamp_lock);
 109
 110         return IRQ_WAKE_THREAD;
 111 }
 112
 113 /**
 114  * inv_mpu6050_read_fifo() - Transfer data from hardware FIFO to KFIFO.
 115  */
 116 irqreturn_t inv_mpu6050_read_fifo(int irq, void *p)
 117 {
 118         struct iio_poll_func *pf = p;
 119         struct iio_dev *indio_dev = pf->indio_dev;
 120         struct inv_mpu6050_state *st = iio_priv(indio_dev);
 121         size_t bytes_per_datum;
 122         int result;
 123         u8 data[INV_MPU6050_OUTPUT_DATA_SIZE];
 124         u16 fifo_count;
 125         s64 timestamp;
 126
 127         mutex_lock(&indio_dev->mlock);
 128         if (!(st->chip_config.accl_fifo_enable |
 129                 st->chip_config.gyro_fifo_enable))
 130                 goto end_session;
 131         bytes_per_datum = 0;
 132         if (st->chip_config.accl_fifo_enable)
 133                 bytes_per_datum += INV_MPU6050_BYTES_PER_3AXIS_SENSOR;
 134
 135         if (st->chip_config.gyro_fifo_enable)
 136                 bytes_per_datum += INV_MPU6050_BYTES_PER_3AXIS_SENSOR;
 137
 138         /*
 139          * read fifo_count register to know how many bytes inside FIFO
 140          * right now
 141          */
 142         result = i2c_smbus_read_i2c_block_data(st->client,
 143                                        st->reg->fifo_count_h,
 144                                        INV_MPU6050_FIFO_COUNT_BYTE, data);
 145         if (result != INV_MPU6050_FIFO_COUNT_BYTE)
 146                 goto end_session;
 147         fifo_count = be16_to_cpup((__be16 *)(&data[0]));
 148         if (fifo_count < bytes_per_datum)
 149                 goto end_session;
 150         /* fifo count can't be odd number, if it is odd, reset fifo*/
 151         if (fifo_count & 1)
 152                 goto flush_fifo;
 153         if (fifo_count >  INV_MPU6050_FIFO_THRESHOLD)
 154                 goto flush_fifo;
 155         /* Timestamp mismatch. */
 156         if (kfifo_len(&st->timestamps) >
 157                 fifo_count / bytes_per_datum + INV_MPU6050_TIME_STAMP_TOR)
 158                         goto flush_fifo;
 159         while (fifo_count >= bytes_per_datum) {
 160                 result = i2c_smbus_read_i2c_block_data(st->client,
 161                                                        st->reg->fifo_r_w,
 162                                                        bytes_per_datum, data);
 163                 if (result != bytes_per_datum)
 164                         goto flush_fifo;
 165
 166                 result = kfifo_out(&st->timestamps, &timestamp, 1);
 167                 /* when there is no timestamp, put timestamp as 0 */
 168                 if (0 == result)
 169                         timestamp = 0;
 170
 171                 result = iio_push_to_buffers_with_timestamp(indio_dev, data,
 172                         timestamp);
 173                 if (result)
 174                         goto flush_fifo;
 175                 fifo_count -= bytes_per_datum;
 176         }
 177
 178 end_session:
 179         mutex_unlock(&indio_dev->mlock);
 180         iio_trigger_notify_done(indio_dev->trig);
 181
 182         return IRQ_HANDLED;
 183
 184 flush_fifo:
 185         /* Flush HW and SW FIFOs. */
 186         inv_reset_fifo(indio_dev);
 187         inv_clear_kfifo(st);
 188         mutex_unlock(&indio_dev->mlock);
 189         iio_trigger_notify_done(indio_dev->trig);
 190
 191         return IRQ_HANDLED;
 192 }