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- /*
- * Driver for older Chrome OS EC accelerometer
- *
- * Copyright 2017 Google, Inc
- *
- * This software is licensed under the terms of the GNU General Public
- * License version 2, as published by the Free Software Foundation, and
- * may be copied, distributed, and modified under those terms.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * This driver uses the memory mapper cros-ec interface to communicate
- * with the Chrome OS EC about accelerometer data.
- * Accelerometer access is presented through iio sysfs.
- */
- #include <linux/delay.h>
- #include <linux/device.h>
- #include <linux/iio/buffer.h>
- #include <linux/iio/iio.h>
- #include <linux/iio/kfifo_buf.h>
- #include <linux/iio/trigger_consumer.h>
- #include <linux/iio/triggered_buffer.h>
- #include <linux/kernel.h>
- #include <linux/mfd/cros_ec.h>
- #include <linux/mfd/cros_ec_commands.h>
- #include <linux/module.h>
- #include <linux/slab.h>
- #include <linux/sysfs.h>
- #include <linux/platform_device.h>
- #define DRV_NAME "cros-ec-accel-legacy"
- /*
- * Sensor scale hard coded at 10 bits per g, computed as:
- * g / (2^10 - 1) = 0.009586168; with g = 9.80665 m.s^-2
- */
- #define ACCEL_LEGACY_NSCALE 9586168
- /* Indices for EC sensor values. */
- enum {
- X,
- Y,
- Z,
- MAX_AXIS,
- };
- /* State data for cros_ec_accel_legacy iio driver. */
- struct cros_ec_accel_legacy_state {
- struct cros_ec_device *ec;
- /*
- * Array holding data from a single capture. 2 bytes per channel
- * for the 3 channels plus the timestamp which is always last and
- * 8-bytes aligned.
- */
- s16 capture_data[8];
- s8 sign[MAX_AXIS];
- u8 sensor_num;
- };
- static int ec_cmd_read_u8(struct cros_ec_device *ec, unsigned int offset,
- u8 *dest)
- {
- return ec->cmd_readmem(ec, offset, 1, dest);
- }
- static int ec_cmd_read_u16(struct cros_ec_device *ec, unsigned int offset,
- u16 *dest)
- {
- __le16 tmp;
- int ret = ec->cmd_readmem(ec, offset, 2, &tmp);
- *dest = le16_to_cpu(tmp);
- return ret;
- }
- /**
- * read_ec_until_not_busy() - Read from EC status byte until it reads not busy.
- * @st: Pointer to state information for device.
- *
- * This function reads EC status until its busy bit gets cleared. It does not
- * wait indefinitely and returns -EIO if the EC status is still busy after a
- * few hundreds milliseconds.
- *
- * Return: 8-bit status if ok, -EIO on error
- */
- static int read_ec_until_not_busy(struct cros_ec_accel_legacy_state *st)
- {
- struct cros_ec_device *ec = st->ec;
- u8 status;
- int attempts = 0;
- ec_cmd_read_u8(ec, EC_MEMMAP_ACC_STATUS, &status);
- while (status & EC_MEMMAP_ACC_STATUS_BUSY_BIT) {
- /* Give up after enough attempts, return error. */
- if (attempts++ >= 50)
- return -EIO;
- /* Small delay every so often. */
- if (attempts % 5 == 0)
- msleep(25);
- ec_cmd_read_u8(ec, EC_MEMMAP_ACC_STATUS, &status);
- }
- return status;
- }
- /**
- * read_ec_accel_data_unsafe() - Read acceleration data from EC shared memory.
- * @st: Pointer to state information for device.
- * @scan_mask: Bitmap of the sensor indices to scan.
- * @data: Location to store data.
- *
- * This is the unsafe function for reading the EC data. It does not guarantee
- * that the EC will not modify the data as it is being read in.
- */
- static void read_ec_accel_data_unsafe(struct cros_ec_accel_legacy_state *st,
- unsigned long scan_mask, s16 *data)
- {
- int i = 0;
- int num_enabled = bitmap_weight(&scan_mask, MAX_AXIS);
- /* Read all sensors enabled in scan_mask. Each value is 2 bytes. */
- while (num_enabled--) {
- i = find_next_bit(&scan_mask, MAX_AXIS, i);
- ec_cmd_read_u16(st->ec,
- EC_MEMMAP_ACC_DATA +
- sizeof(s16) *
- (1 + i + st->sensor_num * MAX_AXIS),
- data);
- *data *= st->sign[i];
- i++;
- data++;
- }
- }
- /**
- * read_ec_accel_data() - Read acceleration data from EC shared memory.
- * @st: Pointer to state information for device.
- * @scan_mask: Bitmap of the sensor indices to scan.
- * @data: Location to store data.
- *
- * This is the safe function for reading the EC data. It guarantees that
- * the data sampled was not modified by the EC while being read.
- *
- * Return: 0 if ok, -ve on error
- */
- static int read_ec_accel_data(struct cros_ec_accel_legacy_state *st,
- unsigned long scan_mask, s16 *data)
- {
- u8 samp_id = 0xff;
- u8 status = 0;
- int ret;
- int attempts = 0;
- /*
- * Continually read all data from EC until the status byte after
- * all reads reflects that the EC is not busy and the sample id
- * matches the sample id from before all reads. This guarantees
- * that data read in was not modified by the EC while reading.
- */
- while ((status & (EC_MEMMAP_ACC_STATUS_BUSY_BIT |
- EC_MEMMAP_ACC_STATUS_SAMPLE_ID_MASK)) != samp_id) {
- /* If we have tried to read too many times, return error. */
- if (attempts++ >= 5)
- return -EIO;
- /* Read status byte until EC is not busy. */
- ret = read_ec_until_not_busy(st);
- if (ret < 0)
- return ret;
- status = ret;
- /*
- * Store the current sample id so that we can compare to the
- * sample id after reading the data.
- */
- samp_id = status & EC_MEMMAP_ACC_STATUS_SAMPLE_ID_MASK;
- /* Read all EC data, format it, and store it into data. */
- read_ec_accel_data_unsafe(st, scan_mask, data);
- /* Read status byte. */
- ec_cmd_read_u8(st->ec, EC_MEMMAP_ACC_STATUS, &status);
- }
- return 0;
- }
- static int cros_ec_accel_legacy_read(struct iio_dev *indio_dev,
- struct iio_chan_spec const *chan,
- int *val, int *val2, long mask)
- {
- struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);
- s16 data = 0;
- int ret = IIO_VAL_INT;
- switch (mask) {
- case IIO_CHAN_INFO_RAW:
- ret = read_ec_accel_data(st, (1 << chan->scan_index), &data);
- if (ret)
- return ret;
- *val = data;
- return IIO_VAL_INT;
- case IIO_CHAN_INFO_SCALE:
- *val = 0;
- *val2 = ACCEL_LEGACY_NSCALE;
- return IIO_VAL_INT_PLUS_NANO;
- case IIO_CHAN_INFO_CALIBBIAS:
- /* Calibration not supported. */
- *val = 0;
- return IIO_VAL_INT;
- default:
- return -EINVAL;
- }
- }
- static int cros_ec_accel_legacy_write(struct iio_dev *indio_dev,
- struct iio_chan_spec const *chan,
- int val, int val2, long mask)
- {
- /*
- * Do nothing but don't return an error code to allow calibration
- * script to work.
- */
- if (mask == IIO_CHAN_INFO_CALIBBIAS)
- return 0;
- return -EINVAL;
- }
- static const struct iio_info cros_ec_accel_legacy_info = {
- .read_raw = &cros_ec_accel_legacy_read,
- .write_raw = &cros_ec_accel_legacy_write,
- };
- /**
- * cros_ec_accel_legacy_capture() - The trigger handler function
- * @irq: The interrupt number.
- * @p: Private data - always a pointer to the poll func.
- *
- * On a trigger event occurring, if the pollfunc is attached then this
- * handler is called as a threaded interrupt (and hence may sleep). It
- * is responsible for grabbing data from the device and pushing it into
- * the associated buffer.
- *
- * Return: IRQ_HANDLED
- */
- static irqreturn_t cros_ec_accel_legacy_capture(int irq, void *p)
- {
- struct iio_poll_func *pf = p;
- struct iio_dev *indio_dev = pf->indio_dev;
- struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);
- /* Clear capture data. */
- memset(st->capture_data, 0, sizeof(st->capture_data));
- /*
- * Read data based on which channels are enabled in scan mask. Note
- * that on a capture we are always reading the calibrated data.
- */
- read_ec_accel_data(st, *indio_dev->active_scan_mask, st->capture_data);
- iio_push_to_buffers_with_timestamp(indio_dev, (void *)st->capture_data,
- iio_get_time_ns(indio_dev));
- /*
- * Tell the core we are done with this trigger and ready for the
- * next one.
- */
- iio_trigger_notify_done(indio_dev->trig);
- return IRQ_HANDLED;
- }
- static char *cros_ec_accel_legacy_loc_strings[] = {
- [MOTIONSENSE_LOC_BASE] = "base",
- [MOTIONSENSE_LOC_LID] = "lid",
- [MOTIONSENSE_LOC_MAX] = "unknown",
- };
- static ssize_t cros_ec_accel_legacy_loc(struct iio_dev *indio_dev,
- uintptr_t private,
- const struct iio_chan_spec *chan,
- char *buf)
- {
- struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);
- return sprintf(buf, "%s\n",
- cros_ec_accel_legacy_loc_strings[st->sensor_num +
- MOTIONSENSE_LOC_BASE]);
- }
- static ssize_t cros_ec_accel_legacy_id(struct iio_dev *indio_dev,
- uintptr_t private,
- const struct iio_chan_spec *chan,
- char *buf)
- {
- struct cros_ec_accel_legacy_state *st = iio_priv(indio_dev);
- return sprintf(buf, "%d\n", st->sensor_num);
- }
- static const struct iio_chan_spec_ext_info cros_ec_accel_legacy_ext_info[] = {
- {
- .name = "id",
- .shared = IIO_SHARED_BY_ALL,
- .read = cros_ec_accel_legacy_id,
- },
- {
- .name = "location",
- .shared = IIO_SHARED_BY_ALL,
- .read = cros_ec_accel_legacy_loc,
- },
- { }
- };
- #define CROS_EC_ACCEL_LEGACY_CHAN(_axis) \
- { \
- .type = IIO_ACCEL, \
- .channel2 = IIO_MOD_X + (_axis), \
- .modified = 1, \
- .info_mask_separate = \
- BIT(IIO_CHAN_INFO_RAW) | \
- BIT(IIO_CHAN_INFO_CALIBBIAS), \
- .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SCALE), \
- .ext_info = cros_ec_accel_legacy_ext_info, \
- .scan_type = { \
- .sign = 's', \
- .realbits = 16, \
- .storagebits = 16, \
- }, \
- } \
- static struct iio_chan_spec ec_accel_channels[] = {
- CROS_EC_ACCEL_LEGACY_CHAN(X),
- CROS_EC_ACCEL_LEGACY_CHAN(Y),
- CROS_EC_ACCEL_LEGACY_CHAN(Z),
- IIO_CHAN_SOFT_TIMESTAMP(MAX_AXIS)
- };
- static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
- {
- struct device *dev = &pdev->dev;
- struct cros_ec_dev *ec = dev_get_drvdata(dev->parent);
- struct cros_ec_sensor_platform *sensor_platform = dev_get_platdata(dev);
- struct iio_dev *indio_dev;
- struct cros_ec_accel_legacy_state *state;
- int ret, i;
- if (!ec || !ec->ec_dev) {
- dev_warn(&pdev->dev, "No EC device found.\n");
- return -EINVAL;
- }
- if (!ec->ec_dev->cmd_readmem) {
- dev_warn(&pdev->dev, "EC does not support direct reads.\n");
- return -EINVAL;
- }
- indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*state));
- if (!indio_dev)
- return -ENOMEM;
- platform_set_drvdata(pdev, indio_dev);
- state = iio_priv(indio_dev);
- state->ec = ec->ec_dev;
- state->sensor_num = sensor_platform->sensor_num;
- indio_dev->dev.parent = dev;
- indio_dev->name = pdev->name;
- indio_dev->channels = ec_accel_channels;
- /*
- * Present the channel using HTML5 standard:
- * need to invert X and Y and invert some lid axis.
- */
- for (i = X ; i < MAX_AXIS; i++) {
- switch (i) {
- case X:
- ec_accel_channels[X].scan_index = Y;
- case Y:
- ec_accel_channels[Y].scan_index = X;
- case Z:
- ec_accel_channels[Z].scan_index = Z;
- }
- if (state->sensor_num == MOTIONSENSE_LOC_LID && i != Y)
- state->sign[i] = -1;
- else
- state->sign[i] = 1;
- }
- indio_dev->num_channels = ARRAY_SIZE(ec_accel_channels);
- indio_dev->dev.parent = &pdev->dev;
- indio_dev->info = &cros_ec_accel_legacy_info;
- indio_dev->modes = INDIO_DIRECT_MODE;
- ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
- cros_ec_accel_legacy_capture,
- NULL);
- if (ret)
- return ret;
- return devm_iio_device_register(dev, indio_dev);
- }
- static struct platform_driver cros_ec_accel_platform_driver = {
- .driver = {
- .name = DRV_NAME,
- },
- .probe = cros_ec_accel_legacy_probe,
- };
- module_platform_driver(cros_ec_accel_platform_driver);
- MODULE_DESCRIPTION("ChromeOS EC legacy accelerometer driver");
- MODULE_AUTHOR("Gwendal Grignou <gwendal@chromium.org>");
- MODULE_LICENSE("GPL");
- MODULE_ALIAS("platform:" DRV_NAME);
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