mb1232.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * mb1232.c - Support for MaxBotix I2CXL-MaxSonar-EZ series ultrasonic
 *   ranger with i2c interface
 * actually tested with mb1232 type
 *
 * Copyright (c) 2019 Andreas Klinger <ak@it-klinger.de>
 *
 * For details about the device see:
 * https://www.maxbotix.com/documents/I2CXL-MaxSonar-EZ_Datasheet.pdf
 */

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/of_irq.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>

/* registers of MaxSonar device */
#define MB1232_RANGE_COMMAND	0x51	/* Command for reading range */
#define MB1232_ADDR_UNLOCK_1	0xAA	/* Command 1 for changing address */
#define MB1232_ADDR_UNLOCK_2	0xA5	/* Command 2 for changing address */

struct mb1232_data {
	struct i2c_client	*client;

	struct mutex		lock;

	/*
	 * optionally a gpio can be used to announce when ranging has
	 * finished
	 * since we are just using the falling trigger of it we request
	 * only the interrupt for announcing when data is ready to be read
	 */
	struct completion	ranging;
	int			irqnr;
	/* Ensure correct alignment of data to push to IIO buffer */
	struct {
		s16 distance;
		s64 ts __aligned(8);
	} scan;
};

static irqreturn_t mb1232_handle_irq(int irq, void *dev_id)
{
	struct iio_dev *indio_dev = dev_id;
	struct mb1232_data *data = iio_priv(indio_dev);

	complete(&data->ranging);

	return IRQ_HANDLED;
}

static s16 mb1232_read_distance(struct mb1232_data *data)
{
	struct i2c_client *client = data->client;
	int ret;
	s16 distance;
	__be16 buf;

	mutex_lock(&data->lock);

	reinit_completion(&data->ranging);

	ret = i2c_smbus_write_byte(client, MB1232_RANGE_COMMAND);
	if (ret < 0) {
		dev_err(&client->dev, "write command - err: %d\n", ret);
		goto error_unlock;
	}

	if (data->irqnr >= 0) {
		/* it cannot take more than 100 ms */
		ret = wait_for_completion_killable_timeout(&data->ranging,
									HZ/10);
		if (ret < 0)
			goto error_unlock;
		else if (ret == 0) {
			ret = -ETIMEDOUT;
			goto error_unlock;
		}
	} else {
		/* use simple sleep if announce irq is not connected */
		msleep(15);
	}

	ret = i2c_master_recv(client, (char *)&buf, sizeof(buf));
	if (ret < 0) {
		dev_err(&client->dev, "i2c_master_recv: ret=%d\n", ret);
		goto error_unlock;
	}

	distance = __be16_to_cpu(buf);
	/* check for not returning misleading error codes */
	if (distance < 0) {
		dev_err(&client->dev, "distance=%d\n", distance);
		ret = -EINVAL;
		goto error_unlock;
	}

	mutex_unlock(&data->lock);

	return distance;

error_unlock:
	mutex_unlock(&data->lock);

	return ret;
}

static irqreturn_t mb1232_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct mb1232_data *data = iio_priv(indio_dev);

	data->scan.distance = mb1232_read_distance(data);
	if (data->scan.distance < 0)
		goto err;

	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
					   pf->timestamp);

err:
	iio_trigger_notify_done(indio_dev->trig);
	return IRQ_HANDLED;
}

static int mb1232_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *channel, int *val,
			    int *val2, long mask)
{
	struct mb1232_data *data = iio_priv(indio_dev);
	int ret;

	if (channel->type != IIO_DISTANCE)
		return -EINVAL;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		ret = mb1232_read_distance(data);
		if (ret < 0)
			return ret;
		*val = ret;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		/* 1 LSB is 1 cm */
		*val = 0;
		*val2 = 10000;
		return IIO_VAL_INT_PLUS_MICRO;
	default:
		return -EINVAL;
	}
}

static const struct iio_chan_spec mb1232_channels[] = {
	{
		.type = IIO_DISTANCE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				      BIT(IIO_CHAN_INFO_SCALE),
		.scan_index = 0,
		.scan_type = {
			.sign = 's',
			.realbits = 16,
			.storagebits = 16,
			.endianness = IIO_CPU,
		},
	},
	IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct iio_info mb1232_info = {
	.read_raw = mb1232_read_raw,
};

static int mb1232_probe(struct i2c_client *client,
					 const struct i2c_device_id *id)
{
	struct iio_dev *indio_dev;
	struct mb1232_data *data;
	int ret;
	struct device *dev = &client->dev;

	if (!i2c_check_functionality(client->adapter,
					I2C_FUNC_SMBUS_READ_BYTE |
					I2C_FUNC_SMBUS_WRITE_BYTE))
		return -ENODEV;

	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
	if (!indio_dev)
		return -ENOMEM;

	data = iio_priv(indio_dev);
	i2c_set_clientdata(client, indio_dev);
	data->client = client;

	indio_dev->info = &mb1232_info;
	indio_dev->name = id->name;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = mb1232_channels;
	indio_dev->num_channels = ARRAY_SIZE(mb1232_channels);

	mutex_init(&data->lock);

	init_completion(&data->ranging);

	data->irqnr = irq_of_parse_and_map(dev->of_node, 0);
	if (data->irqnr <= 0) {
		/* usage of interrupt is optional */
		data->irqnr = -1;
	} else {
		ret = devm_request_irq(dev, data->irqnr, mb1232_handle_irq,
				IRQF_TRIGGER_FALLING, id->name, indio_dev);
		if (ret < 0) {
			dev_err(dev, "request_irq: %d\n", ret);
			return ret;
		}
	}

	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
			iio_pollfunc_store_time, mb1232_trigger_handler, NULL);
	if (ret < 0) {
		dev_err(dev, "setup of iio triggered buffer failed\n");
		return ret;
	}

	return devm_iio_device_register(dev, indio_dev);
}

static const struct of_device_id of_mb1232_match[] = {
	{ .compatible = "maxbotix,mb1202", },
	{ .compatible = "maxbotix,mb1212", },
	{ .compatible = "maxbotix,mb1222", },
	{ .compatible = "maxbotix,mb1232", },
	{ .compatible = "maxbotix,mb1242", },
	{ .compatible = "maxbotix,mb7040", },
	{ .compatible = "maxbotix,mb7137", },
	{},
};

MODULE_DEVICE_TABLE(of, of_mb1232_match);

static const struct i2c_device_id mb1232_id[] = {
	{ "maxbotix-mb1202", },
	{ "maxbotix-mb1212", },
	{ "maxbotix-mb1222", },
	{ "maxbotix-mb1232", },
	{ "maxbotix-mb1242", },
	{ "maxbotix-mb7040", },
	{ "maxbotix-mb7137", },
	{ }
};
MODULE_DEVICE_TABLE(i2c, mb1232_id);

static struct i2c_driver mb1232_driver = {
	.driver = {
		.name	= "maxbotix-mb1232",
		.of_match_table	= of_mb1232_match,
	},
	.probe = mb1232_probe,
	.id_table = mb1232_id,
};
module_i2c_driver(mb1232_driver);

MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
MODULE_DESCRIPTION("Maxbotix I2CXL-MaxSonar i2c ultrasonic ranger driver");
MODULE_LICENSE("GPL");