[PATCH v2 5/8] gnss: add driver for u-blox receivers

Johan Hovold
2018-05-30T10:35:42Z

Add driver for serial-connected u-blox GNSS receivers.

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 u-blox 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 timepulse-support is not yet implemented.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/gnss/Kconfig | 13 ++++
drivers/gnss/Makefile | 3 +
drivers/gnss/ubx.c | 151 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 167 insertions(+)
create mode 100644 drivers/gnss/ubx.c

diff --git a/drivers/gnss/Kconfig b/drivers/gnss/Kconfig
index f8ee54f99a8d..784b8c0367d9 100644
--- a/drivers/gnss/Kconfig
+++ b/drivers/gnss/Kconfig
@@ -15,4 +15,17 @@ if GNSS
config GNSS_SERIAL
tristate

+config GNSS_UBX_SERIAL
+ tristate "u-blox GNSS receiver support"
+ depends on SERIAL_DEV_BUS
+ select GNSS_SERIAL
+ ---help---
+ Say Y here if you have a u-blox GNSS receiver which uses a serial
+ interface.
+
+ To compile this driver as a module, choose M here: the module will
+ be called gnss-ubx.
+
+ If unsure, say N.
+
endif # GNSS
diff --git a/drivers/gnss/Makefile b/drivers/gnss/Makefile
index 171aba71684d..d9295b20b7bc 100644
--- a/drivers/gnss/Makefile
+++ b/drivers/gnss/Makefile
@@ -8,3 +8,6 @@ gnss-y := core.o

obj-$(CONFIG_GNSS_SERIAL) += gnss-serial.o
gnss-serial-y := serial.o
+
+obj-$(CONFIG_GNSS_UBX_SERIAL) += gnss-ubx.o
+gnss-ubx-y := ubx.o
diff --git a/drivers/gnss/ubx.c b/drivers/gnss/ubx.c
new file mode 100644
index 000000000000..ecddfb362a6f
--- /dev/null
+++ b/drivers/gnss/ubx.c
@@ -0,0 +1,151 @@
+// 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/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 *v_bckp;
+ 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;
+}
+
+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 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;
+
+ 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->v_bckp = devm_regulator_get_optional(&serdev->dev, "v-bckp");
+ if (IS_ERR(data->v_bckp)) {
+ ret = PTR_ERR(data->v_bckp);
+ if (ret == -ENODEV)
+ data->v_bckp = NULL;
+ else
+ goto err_free_gserial;
+ }
+
+ if (data->v_bckp) {
+ ret = regulator_enable(data->v_bckp);
+ if (ret)
+ goto err_free_gserial;
+ }
+
+ ret = gnss_serial_register(gserial);
+ if (ret)
+ goto err_disable_v_bckp;
+
+ return 0;
+
+err_disable_v_bckp:
+ if (data->v_bckp)
+ regulator_disable(data->v_bckp);
+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);
+ struct ubx_data *data = gnss_serial_get_drvdata(gserial);
+
+ gnss_serial_deregister(gserial);
+ if (data->v_bckp)
+ regulator_disable(data->v_bckp);
+ gnss_serial_free(gserial);
+};
+
+#ifdef CONFIG_OF
+static const struct of_device_id ubx_of_match[] = {
+ { .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");
--
2.17.0