text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Mediatek GNSS receiver driver
   *
   * Copyright (C) 2018 Johan Hovold <johan@kernel.org>
   */
  
  #include <linux/errno.h>
  #include <linux/gnss.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 mtk_data {
  	struct regulator *vbackup;
  	struct regulator *vcc;
  };
  
  static int mtk_set_active(struct gnss_serial *gserial)
  {
  	struct mtk_data *data = gnss_serial_get_drvdata(gserial);
  	int ret;
  
  	ret = regulator_enable(data->vcc);
  	if (ret)
  		return ret;
  
  	return 0;
  }
  
  static int mtk_set_standby(struct gnss_serial *gserial)
  {
  	struct mtk_data *data = gnss_serial_get_drvdata(gserial);
  	int ret;
  
  	ret = regulator_disable(data->vcc);
  	if (ret)
  		return ret;
  
  	return 0;
  }
  
  static int mtk_set_power(struct gnss_serial *gserial,
  			 enum gnss_serial_pm_state state)
  {
  	switch (state) {
  	case GNSS_SERIAL_ACTIVE:
  		return mtk_set_active(gserial);
  	case GNSS_SERIAL_OFF:
  	case GNSS_SERIAL_STANDBY:
  		return mtk_set_standby(gserial);
  	}
  
  	return -EINVAL;
  }
  
  static const struct gnss_serial_ops mtk_gserial_ops = {
  	.set_power = mtk_set_power,
  };
  
  static int mtk_probe(struct serdev_device *serdev)
  {
  	struct gnss_serial *gserial;
  	struct mtk_data *data;
  	int ret;
  
  	gserial = gnss_serial_allocate(serdev, sizeof(*data));
  	if (IS_ERR(gserial)) {
  		ret = PTR_ERR(gserial);
  		return ret;
  	}
  
  	gserial->ops = &mtk_gserial_ops;
  
  	gserial->gdev->type = GNSS_TYPE_MTK;
  
  	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;
  	}
  
  	data->vbackup = devm_regulator_get_optional(&serdev->dev, "vbackup");
  	if (IS_ERR(data->vbackup)) {
  		ret = PTR_ERR(data->vbackup);
  		if (ret == -ENODEV)
  			data->vbackup = NULL;
  		else
  			goto err_free_gserial;
  	}
  
  	if (data->vbackup) {
  		ret = regulator_enable(data->vbackup);
  		if (ret)
  			goto err_free_gserial;
  	}
  
  	ret = gnss_serial_register(gserial);
  	if (ret)
  		goto err_disable_vbackup;
  
  	return 0;
  
  err_disable_vbackup:
  	if (data->vbackup)
  		regulator_disable(data->vbackup);
  err_free_gserial:
  	gnss_serial_free(gserial);
  
  	return ret;
  }
  
  static void mtk_remove(struct serdev_device *serdev)
  {
  	struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
  	struct mtk_data *data = gnss_serial_get_drvdata(gserial);
  
  	gnss_serial_deregister(gserial);
  	if (data->vbackup)
  		regulator_disable(data->vbackup);
  	gnss_serial_free(gserial);
  };
  
  #ifdef CONFIG_OF
  static const struct of_device_id mtk_of_match[] = {
  	{ .compatible = "globaltop,pa6h" },
  	{},
  };
  MODULE_DEVICE_TABLE(of, mtk_of_match);
  #endif
  
  static struct serdev_device_driver mtk_driver = {
  	.driver	= {
  		.name		= "gnss-mtk",
  		.of_match_table	= of_match_ptr(mtk_of_match),
  		.pm		= &gnss_serial_pm_ops,
  	},
  	.probe	= mtk_probe,
  	.remove	= mtk_remove,
  };
  module_serdev_device_driver(mtk_driver);
  
  MODULE_AUTHOR("Loys Ollivier <lollivier@baylibre.com>");
  MODULE_DESCRIPTION("Mediatek GNSS receiver driver");
  MODULE_LICENSE("GPL v2");
  