// SPDX-License-Identifier: GPL-2.0
/*
* Driver for older Chrome OS EC accelerometer
*
* Copyright 2017 Google, Inc
*
* 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/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_SCALE) | \
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;
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.
*/
ec_accel_channels[X].scan_index = Y;
ec_accel_channels[Y].scan_index = X;
ec_accel_channels[Z].scan_index = Z;
state->sign[Y] = 1;
if (state->sensor_num == MOTIONSENSE_LOC_LID)
state->sign[X] = state->sign[Z] = -1;
else
state->sign[X] = state->sign[Z] = 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 v2");
MODULE_ALIAS("platform:" DRV_NAME);
