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d4584bbfcf
Add driver for serial-connected Mediatek-based GNSS receivers. These devices typically boot transmitting vendor specific NMEA output sequences. The serial port bit rate is read from the device tree "current-speed". Note that the driver uses the generic GNSS serial implementation and therefore essentially only manages power abstracted into three power states: ACTIVE, STANDBY, and OFF. For mediatek receivers with a main supply and no enable-gpios, this simply means that the main supply is disabled in STANDBY and OFF (the optional backup supply is kept enabled while the driver is bound). Note that the timepulse-support is left unimplemented. Signed-off-by: Loys Ollivier <lollivier@baylibre.com> [ johan: rename backup supply ] Signed-off-by: Johan Hovold <johan@kernel.org>
152 lines
3 KiB
C
152 lines
3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Mediatek GNSS receiver driver
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*
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* Copyright (C) 2018 Johan Hovold <johan@kernel.org>
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*/
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#include <linux/errno.h>
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#include <linux/gnss.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/regulator/consumer.h>
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#include <linux/serdev.h>
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#include "serial.h"
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struct mtk_data {
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struct regulator *vbackup;
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struct regulator *vcc;
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};
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static int mtk_set_active(struct gnss_serial *gserial)
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{
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struct mtk_data *data = gnss_serial_get_drvdata(gserial);
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int ret;
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ret = regulator_enable(data->vcc);
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if (ret)
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return ret;
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return 0;
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}
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static int mtk_set_standby(struct gnss_serial *gserial)
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{
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struct mtk_data *data = gnss_serial_get_drvdata(gserial);
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int ret;
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ret = regulator_disable(data->vcc);
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if (ret)
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return ret;
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return 0;
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}
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static int mtk_set_power(struct gnss_serial *gserial,
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enum gnss_serial_pm_state state)
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{
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switch (state) {
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case GNSS_SERIAL_ACTIVE:
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return mtk_set_active(gserial);
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case GNSS_SERIAL_OFF:
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case GNSS_SERIAL_STANDBY:
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return mtk_set_standby(gserial);
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}
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return -EINVAL;
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}
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static const struct gnss_serial_ops mtk_gserial_ops = {
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.set_power = mtk_set_power,
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};
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static int mtk_probe(struct serdev_device *serdev)
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{
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struct gnss_serial *gserial;
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struct mtk_data *data;
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int ret;
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gserial = gnss_serial_allocate(serdev, sizeof(*data));
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if (IS_ERR(gserial)) {
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ret = PTR_ERR(gserial);
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return ret;
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}
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gserial->ops = &mtk_gserial_ops;
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gserial->gdev->type = GNSS_TYPE_MTK;
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data = gnss_serial_get_drvdata(gserial);
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data->vcc = devm_regulator_get(&serdev->dev, "vcc");
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if (IS_ERR(data->vcc)) {
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ret = PTR_ERR(data->vcc);
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goto err_free_gserial;
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}
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data->vbackup = devm_regulator_get_optional(&serdev->dev, "vbackup");
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if (IS_ERR(data->vbackup)) {
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ret = PTR_ERR(data->vbackup);
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if (ret == -ENODEV)
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data->vbackup = NULL;
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else
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goto err_free_gserial;
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}
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if (data->vbackup) {
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ret = regulator_enable(data->vbackup);
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if (ret)
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goto err_free_gserial;
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}
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ret = gnss_serial_register(gserial);
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if (ret)
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goto err_disable_vbackup;
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return 0;
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err_disable_vbackup:
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if (data->vbackup)
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regulator_disable(data->vbackup);
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err_free_gserial:
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gnss_serial_free(gserial);
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return ret;
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}
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static void mtk_remove(struct serdev_device *serdev)
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{
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struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
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struct mtk_data *data = gnss_serial_get_drvdata(gserial);
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gnss_serial_deregister(gserial);
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if (data->vbackup)
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regulator_disable(data->vbackup);
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gnss_serial_free(gserial);
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};
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#ifdef CONFIG_OF
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static const struct of_device_id mtk_of_match[] = {
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{ .compatible = "globaltop,pa6h" },
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{},
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};
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MODULE_DEVICE_TABLE(of, mtk_of_match);
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#endif
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static struct serdev_device_driver mtk_driver = {
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.driver = {
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.name = "gnss-mtk",
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.of_match_table = of_match_ptr(mtk_of_match),
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.pm = &gnss_serial_pm_ops,
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},
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.probe = mtk_probe,
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.remove = mtk_remove,
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};
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module_serdev_device_driver(mtk_driver);
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MODULE_AUTHOR("Loys Ollivier <lollivier@baylibre.com>");
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MODULE_DESCRIPTION("Mediatek GNSS receiver driver");
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MODULE_LICENSE("GPL v2");
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