[PATCH v2 8/8] gnss: add device type support

Johan Hovold
2018-05-30T10:35:36Z

Add a "type" device attribute and a "GNSS_TYPE" uevent variable which
can be used to determine the type of a GNSS device. The currently
identified types reflect the protocol(s) supported by a device:

"NMEA" NMEA 0183
"SiRF" SiRF Binary
"UBX" UBX

Note that both SiRF and UBX type devices typically support a subset of
NMEA 0183 with vendor extensions (e.g. to allow switching to the vendor
protocol).

Signed-off-by: Johan Hovold <johan@kernel.org>
---
Documentation/ABI/testing/sysfs-class-gnss | 15 +++++++
MAINTAINERS | 1 +
drivers/gnss/core.c | 49 ++++++++++++++++++++++
drivers/gnss/sirf.c | 1 +
drivers/gnss/ubx.c | 2 +
include/linux/gnss.h | 9 ++++
6 files changed, 77 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-class-gnss

diff --git a/Documentation/ABI/testing/sysfs-class-gnss b/Documentation/ABI/testing/sysfs-class-gnss
new file mode 100644
index 000000000000..3bcdf8e2496a
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-gnss
@@ -0,0 +1,15 @@
+What: /sys/class/gnss/gnssN/type
+Date: May 2018
+KernelVersion: 4.18
+Contact: Johan Hovold <johan@kernel.org>
+Description:
+ The GNSS device type. The currently identified types reflect
+ the protocol(s) supported by the device:
+
+ "NMEA" NMEA 0183
+ "SiRF" SiRF Binary
+ "UBX" UBX
+
+ Note that also non-"NMEA" type devices typically support a
+ subset of NMEA 0183 with vendor extensions (e.g. to allow
+ switching to a vendor protocol).
diff --git a/MAINTAINERS b/MAINTAINERS
index fa219e80a1f8..e666bc28a102 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5965,6 +5965,7 @@ F: include/uapi/linux/gigaset_dev.h
GNSS SUBSYSTEM
M: Johan Hovold <johan@kernel.org>
S: Maintained
+F: Documentation/ABI/testing/sysfs-class-gnss
F: Documentation/devicetree/bindings/gnss/
F: drivers/gnss/
F: include/linux/gnss.h
diff --git a/drivers/gnss/core.c b/drivers/gnss/core.c
index 307894ca2725..f30ef8338b3a 100644
--- a/drivers/gnss/core.c
+++ b/drivers/gnss/core.c
@@ -330,6 +330,52 @@ int gnss_insert_raw(struct gnss_device *gdev, const unsigned char *buf,
}
EXPORT_SYMBOL_GPL(gnss_insert_raw);

+static const char * const gnss_type_names[GNSS_TYPE_COUNT] = {
+ [GNSS_TYPE_NMEA] = "NMEA",
+ [GNSS_TYPE_SIRF] = "SiRF",
+ [GNSS_TYPE_UBX] = "UBX",
+};
+
+static const char *gnss_type_name(struct gnss_device *gdev)
+{
+ const char *name = NULL;
+
+ if (gdev->type < GNSS_TYPE_COUNT)
+ name = gnss_type_names[gdev->type];
+
+ if (!name)
+ dev_WARN(&gdev->dev, "type name not defined\n");
+
+ return name;
+}
+
+static ssize_t type_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct gnss_device *gdev = to_gnss_device(dev);
+
+ return sprintf(buf, "%s\n", gnss_type_name(gdev));
+}
+static DEVICE_ATTR_RO(type);
+
+static struct attribute *gnss_attrs[] = {
+ &dev_attr_type.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(gnss);
+
+static int gnss_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+ struct gnss_device *gdev = to_gnss_device(dev);
+ int ret;
+
+ ret = add_uevent_var(env, "GNSS_TYPE=%s", gnss_type_name(gdev));
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
static int __init gnss_module_init(void)
{
int ret;
@@ -347,6 +393,9 @@ static int __init gnss_module_init(void)
goto err_unregister_chrdev;
}

+ gnss_class->dev_groups = gnss_groups;
+ gnss_class->dev_uevent = gnss_uevent;
+
pr_info("GNSS driver registered with major %d\n", MAJOR(gnss_first));

return 0;
diff --git a/drivers/gnss/sirf.c b/drivers/gnss/sirf.c
index 5fb0f730db48..79cb98950013 100644
--- a/drivers/gnss/sirf.c
+++ b/drivers/gnss/sirf.c
@@ -267,6 +267,7 @@ static int sirf_probe(struct serdev_device *serdev)
if (!gdev)
return -ENOMEM;

+ gdev->type = GNSS_TYPE_SIRF;
gdev->ops = &sirf_gnss_ops;
gnss_set_drvdata(gdev, data);

diff --git a/drivers/gnss/ubx.c b/drivers/gnss/ubx.c
index ecddfb362a6f..902b6854b7db 100644
--- a/drivers/gnss/ubx.c
+++ b/drivers/gnss/ubx.c
@@ -77,6 +77,8 @@ static int ubx_probe(struct serdev_device *serdev)

gserial->ops = &ubx_gserial_ops;

+ gserial->gdev->type = GNSS_TYPE_UBX;
+
data = gnss_serial_get_drvdata(gserial);

data->vcc = devm_regulator_get(&serdev->dev, "vcc");
diff --git a/include/linux/gnss.h b/include/linux/gnss.h
index e26aeac1e0e2..43546977098c 100644
--- a/include/linux/gnss.h
+++ b/include/linux/gnss.h
@@ -18,6 +18,14 @@

struct gnss_device;

+enum gnss_type {
+ GNSS_TYPE_NMEA = 0,
+ GNSS_TYPE_SIRF,
+ GNSS_TYPE_UBX,
+
+ GNSS_TYPE_COUNT
+};
+
struct gnss_operations {
int (*open)(struct gnss_device *gdev);
void (*close)(struct gnss_device *gdev);
@@ -30,6 +38,7 @@ struct gnss_device {
struct cdev cdev;
int id;

+ enum gnss_type type;
unsigned long flags;

struct rw_semaphore rwsem;
--
2.17.0