linux/drivers/iio/accel/cros_ec_accel_legacy.c
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   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 */
  39static const int cros_ec_legacy_sample_freq[] = { 10, 0 };
  40
  41static 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
  74static 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
 119static 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 */
 144static 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
 162static 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
 199static 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
 206static 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);
 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
 241static struct platform_driver cros_ec_accel_platform_driver = {
 242        .driver = {
 243                .name   = DRV_NAME,
 244        },
 245        .probe          = cros_ec_accel_legacy_probe,
 246};
 247module_platform_driver(cros_ec_accel_platform_driver);
 248
 249MODULE_DESCRIPTION("ChromeOS EC legacy accelerometer driver");
 250MODULE_AUTHOR("Gwendal Grignou <gwendal@chromium.org>");
 251MODULE_LICENSE("GPL v2");
 252MODULE_ALIAS("platform:" DRV_NAME);
 253