gnss: add driver for u-blox receivers

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gnss/Kconfig b/drivers/gnss/Kconfig
index f8ee54f99a8d84a2c24cc3f90410189d3b3bf7d9..784b8c0367d99a080abc0a8ed99a8e75af132ace 100644 (file)
--- 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 171aba71684db0b4cc7a82d63b929b26a1bfe4e5..d9295b20b7bcdd1af4fa9afa1b7971632b48a6c7 100644 (file)
--- 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 (file)
index 0000000..ecddfb3
--- /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");