gnss: add driver for mediatek receivers

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>
This commit is contained in:
Loys Ollivier 2019-02-13 16:09:29 +01:00 коммит произвёл Johan Hovold
Родитель 625239d4ad
Коммит d4584bbfcf
3 изменённых файлов: 168 добавлений и 0 удалений

Просмотреть файл

@ -15,6 +15,19 @@ if GNSS
config GNSS_SERIAL
tristate
config GNSS_MTK_SERIAL
tristate "Mediatek GNSS receiver support"
depends on SERIAL_DEV_BUS
select GNSS_SERIAL
help
Say Y here if you have a Mediatek-based GNSS receiver which uses a
serial interface.
To compile this driver as a module, choose M here: the module will
be called gnss-mtk.
If unsure, say N.
config GNSS_SIRF_SERIAL
tristate "SiRFstar GNSS receiver support"
depends on SERIAL_DEV_BUS

Просмотреть файл

@ -9,6 +9,9 @@ gnss-y := core.o
obj-$(CONFIG_GNSS_SERIAL) += gnss-serial.o
gnss-serial-y := serial.o
obj-$(CONFIG_GNSS_MTK_SERIAL) += gnss-mtk.o
gnss-mtk-y := mtk.o
obj-$(CONFIG_GNSS_SIRF_SERIAL) += gnss-sirf.o
gnss-sirf-y := sirf.o

152
drivers/gnss/mtk.c Normal file
Просмотреть файл

@ -0,0 +1,152 @@
// 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");