drivers/gnss/ubx.c

// SPDX-License-Identifier: GPL-2.0
/*
 * u-blox GNSS receiver driver
 *
 * Copyright (C) 2018 Johan Hovold <johan@kernel.org>
 */

#include <linux/errno.h>
#include <linux/gnss.h>
#include <linux/gpio/consumer.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regulator/consumer.h>
#include <linux/serdev.h>

#include "serial.h"

struct ubx_data {
	struct regulator *vcc;
};

static int ubx_set_active(struct gnss_serial *gserial)
{
	struct ubx_data *data = gnss_serial_get_drvdata(gserial);
	int ret;

	ret = regulator_enable(data->vcc);
	if (ret)
		return ret;

	return 0;
}

static int ubx_set_standby(struct gnss_serial *gserial)
{
	struct ubx_data *data = gnss_serial_get_drvdata(gserial);
	int ret;

	ret = regulator_disable(data->vcc);
	if (ret)
		return ret;

	return 0;
}

static int ubx_set_power(struct gnss_serial *gserial,
				enum gnss_serial_pm_state state)
{
	switch (state) {
	case GNSS_SERIAL_ACTIVE:
		return ubx_set_active(gserial);
	case GNSS_SERIAL_OFF:
	case GNSS_SERIAL_STANDBY:
		return ubx_set_standby(gserial);
	}

	return -EINVAL;
}

static const struct gnss_serial_ops ubx_gserial_ops = {
	.set_power = ubx_set_power,
};

static int ubx_probe(struct serdev_device *serdev)
{
	struct gnss_serial *gserial;
	struct gpio_desc *reset;
	struct ubx_data *data;
	int ret;

	gserial = gnss_serial_allocate(serdev, sizeof(*data));
	if (IS_ERR(gserial)) {
		ret = PTR_ERR(gserial);
		return ret;
	}

	gserial->ops = &ubx_gserial_ops;

	gserial->gdev->type = GNSS_TYPE_UBX;

	data = gnss_serial_get_drvdata(gserial);

	data->vcc = devm_regulator_get(&serdev->dev, "vcc");
	if (IS_ERR(data->vcc)) {
		ret = PTR_ERR(data->vcc);
		goto err_free_gserial;
	}

	ret = devm_regulator_get_enable_optional(&serdev->dev, "v-bckp");
	if (ret < 0 && ret != -ENODEV)
		goto err_free_gserial;

	/* Deassert reset */
	reset = devm_gpiod_get_optional(&serdev->dev, "reset", GPIOD_OUT_LOW);
	if (IS_ERR(reset)) {
		ret = PTR_ERR(reset);
		goto err_free_gserial;
	}

	ret = gnss_serial_register(gserial);
	if (ret)
		goto err_free_gserial;

	return 0;

err_free_gserial:
	gnss_serial_free(gserial);

	return ret;
}

static void ubx_remove(struct serdev_device *serdev)
{
	struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);

	gnss_serial_deregister(gserial);
	gnss_serial_free(gserial);
}

#ifdef CONFIG_OF
static const struct of_device_id ubx_of_match[] = {
	{ .compatible = "u-blox,neo-6m" },
	{ .compatible = "u-blox,neo-8" },
	{ .compatible = "u-blox,neo-m8" },
	{},
};
MODULE_DEVICE_TABLE(of, ubx_of_match);
#endif

static struct serdev_device_driver ubx_driver = {
	.driver	= {
		.name		= "gnss-ubx",
		.of_match_table	= of_match_ptr(ubx_of_match),
		.pm		= &gnss_serial_pm_ops,
	},
	.probe	= ubx_probe,
	.remove	= ubx_remove,
};
module_serdev_device_driver(ubx_driver);

MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
MODULE_DESCRIPTION("u-blox GNSS receiver driver");
MODULE_LICENSE("GPL v2");