drivers/iio/accel/cros_ec_accel_legacy.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Driver for older Chrome OS EC accelerometer
   4  *
   5  * Copyright 2017 Google, Inc
   6  *
   7  * This driver uses the memory mapper cros-ec interface to communicate
   8  * with the Chrome OS EC about accelerometer data or older commands.
   9  * Accelerometer access is presented through iio sysfs.
  10  */
  11
  12 #include <linux/delay.h>
  13 #include <linux/device.h>
  14 #include <linux/iio/buffer.h>
  15 #include <linux/iio/common/cros_ec_sensors_core.h>
  16 #include <linux/iio/iio.h>
  17 #include <linux/iio/kfifo_buf.h>
  18 #include <linux/iio/trigger_consumer.h>
  19 #include <linux/iio/triggered_buffer.h>
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/slab.h>
  23 #include <linux/platform_data/cros_ec_commands.h>
  24 #include <linux/platform_data/cros_ec_proto.h>
  25 #include <linux/platform_device.h>
  26
  27 #define DRV_NAME        "cros-ec-accel-legacy"
  28
  29 #define CROS_EC_SENSOR_LEGACY_NUM 2
  30 /*
  31  * Sensor scale hard coded at 10 bits per g, computed as:
  32  * g / (2^10 - 1) = 0.009586168; with g = 9.80665 m.s^-2
  33  */
  34 #define ACCEL_LEGACY_NSCALE 9586168
  35
  36 /*
  37  * Sensor frequency is hard-coded to 10Hz.
  38  */
  39 static const int cros_ec_legacy_sample_freq[] = { 10, 0 };
  40
  41 static int cros_ec_accel_legacy_read_cmd(struct iio_dev *indio_dev,
  42                                   unsigned long scan_mask, s16 *data)
  43 {
  44         struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
  45         int ret;
  46         unsigned int i;
  47         u8 sensor_num;
  48
  49         /*
  50          * Read all sensor data through a command.
  51          * Save sensor_num, it is assumed to stay.
  52          */
  53         sensor_num = st->param.info.sensor_num;
  54         st->param.cmd = MOTIONSENSE_CMD_DUMP;
  55         st->param.dump.max_sensor_count = CROS_EC_SENSOR_LEGACY_NUM;
  56         ret = cros_ec_motion_send_host_cmd(st,
  57                         sizeof(st->resp->dump) + CROS_EC_SENSOR_LEGACY_NUM *
  58                         sizeof(struct ec_response_motion_sensor_data));
  59         st->param.info.sensor_num = sensor_num;
  60         if (ret != 0) {
  61                 dev_warn(&indio_dev->dev, "Unable to read sensor data\n");
  62                 return ret;
  63         }
  64
  65         for_each_set_bit(i, &scan_mask, indio_dev->masklength) {
  66                 *data = st->resp->dump.sensor[sensor_num].data[i] *
  67                         st->sign[i];
  68                 data++;
  69         }
  70
  71         return 0;
  72 }
  73
  74 static int cros_ec_accel_legacy_read(struct iio_dev *indio_dev,
  75                                      struct iio_chan_spec const *chan,
  76                                      int *val, int *val2, long mask)
  77 {
  78         struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
  79         s16 data = 0;
  80         int ret;
  81         int idx = chan->scan_index;
  82
  83         mutex_lock(&st->cmd_lock);
  84
  85         switch (mask) {
  86         case IIO_CHAN_INFO_RAW:
  87                 ret = st->read_ec_sensors_data(indio_dev, 1 << idx, &data);
  88                 if (ret < 0)
  89                         break;
  90                 ret = IIO_VAL_INT;
  91                 *val = data;
  92                 break;
  93         case IIO_CHAN_INFO_SCALE:
  94                 WARN_ON(st->type != MOTIONSENSE_TYPE_ACCEL);
  95                 *val = 0;
  96                 *val2 = ACCEL_LEGACY_NSCALE;
  97                 ret = IIO_VAL_INT_PLUS_NANO;
  98                 break;
  99         case IIO_CHAN_INFO_CALIBBIAS:
 100                 /* Calibration not supported. */
 101                 *val = 0;
 102                 ret = IIO_VAL_INT;
 103                 break;
 104         case IIO_CHAN_INFO_SAMP_FREQ:
 105                 *val = cros_ec_legacy_sample_freq[0];
 106                 *val2 = cros_ec_legacy_sample_freq[1];
 107                 ret = IIO_VAL_INT_PLUS_MICRO;
 108                 break;
 109         default:
 110                 ret = cros_ec_sensors_core_read(st, chan, val, val2,
 111                                 mask);
 112                 break;
 113         }
 114         mutex_unlock(&st->cmd_lock);
 115
 116         return ret;
 117 }
 118
 119 static int cros_ec_accel_legacy_write(struct iio_dev *indio_dev,
 120                                       struct iio_chan_spec const *chan,
 121                                       int val, int val2, long mask)
 122 {
 123         /*
 124          * Do nothing but don't return an error code to allow calibration
 125          * script to work.
 126          */
 127         if (mask == IIO_CHAN_INFO_CALIBBIAS)
 128                 return 0;
 129
 130         return -EINVAL;
 131 }
 132
 133 /**
 134  * cros_ec_accel_legacy_read_avail() - get available values
 135  * @indio_dev:          pointer to state information for device
 136  * @chan:       channel specification structure table
 137  * @vals:       list of available values
 138  * @type:       type of data returned
 139  * @length:     number of data returned in the array
 140  * @mask:       specifies which values to be requested
 141  *
 142  * Return:      an error code or IIO_AVAIL_LIST
 143  */
 144 static int cros_ec_accel_legacy_read_avail(struct iio_dev *indio_dev,
 145                                            struct iio_chan_spec const *chan,
 146                                            const int **vals,
 147                                            int *type,
 148                                            int *length,
 149                                            long mask)
 150 {
 151         switch (mask) {
 152         case IIO_CHAN_INFO_SAMP_FREQ:
 153                 *length = ARRAY_SIZE(cros_ec_legacy_sample_freq);
 154                 *vals = cros_ec_legacy_sample_freq;
 155                 *type = IIO_VAL_INT_PLUS_MICRO;
 156                 return IIO_AVAIL_LIST;
 157         }
 158
 159         return -EINVAL;
 160 }
 161
 162 static const struct iio_info cros_ec_accel_legacy_info = {
 163         .read_raw = &cros_ec_accel_legacy_read,
 164         .write_raw = &cros_ec_accel_legacy_write,
 165         .read_avail = &cros_ec_accel_legacy_read_avail,
 166 };
 167
 168 /*
 169  * Present the channel using HTML5 standard:
 170  * need to invert X and Y and invert some lid axis.
 171  */
 172 #define CROS_EC_ACCEL_ROTATE_AXIS(_axis)                                \
 173         ((_axis) == CROS_EC_SENSOR_Z ? CROS_EC_SENSOR_Z :               \
 174          ((_axis) == CROS_EC_SENSOR_X ? CROS_EC_SENSOR_Y :              \
 175           CROS_EC_SENSOR_X))
 176
 177 #define CROS_EC_ACCEL_LEGACY_CHAN(_axis)                                \
 178         {                                                               \
 179                 .type = IIO_ACCEL,                                      \
 180                 .channel2 = IIO_MOD_X + (_axis),                        \
 181                 .modified = 1,                                          \
 182                 .info_mask_separate =                                   \
 183                         BIT(IIO_CHAN_INFO_RAW) |                        \
 184                         BIT(IIO_CHAN_INFO_CALIBBIAS),                   \
 185                 .info_mask_shared_by_all =                              \
 186                         BIT(IIO_CHAN_INFO_SCALE) |                      \
 187                         BIT(IIO_CHAN_INFO_SAMP_FREQ),                   \
 188                 .info_mask_shared_by_all_available =                    \
 189                         BIT(IIO_CHAN_INFO_SAMP_FREQ),                   \
 190                 .ext_info = cros_ec_sensors_ext_info,                   \
 191                 .scan_type = {                                          \
 192                         .sign = 's',                                    \
 193                         .realbits = CROS_EC_SENSOR_BITS,                \
 194                         .storagebits = CROS_EC_SENSOR_BITS,             \
 195                 },                                                      \
 196                 .scan_index = CROS_EC_ACCEL_ROTATE_AXIS(_axis),         \
 197         }                                                               \
 198
 199 static const struct iio_chan_spec cros_ec_accel_legacy_channels[] = {
 200                 CROS_EC_ACCEL_LEGACY_CHAN(CROS_EC_SENSOR_X),
 201                 CROS_EC_ACCEL_LEGACY_CHAN(CROS_EC_SENSOR_Y),
 202                 CROS_EC_ACCEL_LEGACY_CHAN(CROS_EC_SENSOR_Z),
 203                 IIO_CHAN_SOFT_TIMESTAMP(CROS_EC_SENSOR_MAX_AXIS)
 204 };
 205
 206 static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
 207 {
 208         struct device *dev = &pdev->dev;
 209         struct iio_dev *indio_dev;
 210         struct cros_ec_sensors_core_state *state;
 211         int ret;
 212
 213         indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*state));
 214         if (!indio_dev)
 215                 return -ENOMEM;
 216
 217         ret = cros_ec_sensors_core_init(pdev, indio_dev, true,
 218                                         cros_ec_sensors_capture, NULL, false);
 219         if (ret)
 220                 return ret;
 221
 222         indio_dev->info = &cros_ec_accel_legacy_info;
 223         state = iio_priv(indio_dev);
 224
 225         if (state->ec->cmd_readmem != NULL)
 226                 state->read_ec_sensors_data = cros_ec_sensors_read_lpc;
 227         else
 228                 state->read_ec_sensors_data = cros_ec_accel_legacy_read_cmd;
 229
 230         indio_dev->channels = cros_ec_accel_legacy_channels;
 231         indio_dev->num_channels = ARRAY_SIZE(cros_ec_accel_legacy_channels);
 232         /* The lid sensor needs to be presented inverted. */
 233         if (state->loc == MOTIONSENSE_LOC_LID) {
 234                 state->sign[CROS_EC_SENSOR_X] = -1;
 235                 state->sign[CROS_EC_SENSOR_Z] = -1;
 236         }
 237
 238         return devm_iio_device_register(dev, indio_dev);
 239 }
 240
 241 static struct platform_driver cros_ec_accel_platform_driver = {
 242         .driver = {
 243                 .name   = DRV_NAME,
 244         },
 245         .probe          = cros_ec_accel_legacy_probe,
 246 };
 247 module_platform_driver(cros_ec_accel_platform_driver);
 248
 249 MODULE_DESCRIPTION("ChromeOS EC legacy accelerometer driver");
 250 MODULE_AUTHOR("Gwendal Grignou <gwendal@chromium.org>");
 251 MODULE_LICENSE("GPL v2");
 252 MODULE_ALIAS("platform:" DRV_NAME);