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 */
 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, iio_get_masklength(indio_dev)) {
 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);
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 (!strcmp(indio_dev->label, "accel-display")) {
234		state->sign[CROS_EC_SENSOR_X] = -1;
235		state->sign[CROS_EC_SENSOR_Z] = -1;
236	}
237
238	return cros_ec_sensors_core_register(dev, indio_dev, NULL);
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);