diff options
Diffstat (limited to 'drivers/iio/accel/cros_ec_accel_legacy.c')
| -rw-r--r-- | drivers/iio/accel/cros_ec_accel_legacy.c | 422 |
1 files changed, 422 insertions, 0 deletions
diff --git a/drivers/iio/accel/cros_ec_accel_legacy.c b/drivers/iio/accel/cros_ec_accel_legacy.c new file mode 100644 index 000000000..c776a3509 --- /dev/null +++ b/drivers/iio/accel/cros_ec_accel_legacy.c @@ -0,0 +1,422 @@ +/* + * 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); |