greybus: hd: add bus_id attribute

The greybus host device id can only be read by parsing the uevent if one
wants to identify a specific host device 'or' bus. This is 'lsgb' uses
today.

This change adds a bus_id attribute so libraries can identify multiple
host devices 'or' bus if they exist.

Testing Done:
Tested on Arche,
'cat /sys/bus/greybus/devices/greysbus1/bus_id'

Signed-off-by: Sandeep Patil <sspatil@google.com>
Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/hd.c b/drivers/staging/greybus/hd.c
index 762cc03..2863472 100644 (file)
--- a/drivers/staging/greybus/hd.c
+++ b/drivers/staging/greybus/hd.c
@@ -24,6 +24,21 @@ int gb_hd_output(struct gb_host_device *hd, void *req, u16 size, u8 cmd,
 }
 EXPORT_SYMBOL_GPL(gb_hd_output);
 
+static ssize_t bus_id_show(struct device *dev,
+                               struct device_attribute *attr, char *buf)
+{
+       struct gb_host_device *hd = to_gb_host_device(dev);
+
+       return sprintf(buf, "%d\n", hd->bus_id);
+}
+static DEVICE_ATTR_RO(bus_id);
+
+static struct attribute *bus_attrs[] = {
+       &dev_attr_bus_id.attr,
+       NULL
+};
+ATTRIBUTE_GROUPS(bus);
+
 static void gb_hd_release(struct device *dev)
 {
        struct gb_host_device *hd = to_gb_host_device(dev);
@@ -98,6 +113,7 @@ struct gb_host_device *gb_hd_create(struct gb_hd_driver *driver,
        hd->dev.parent = parent;
        hd->dev.bus = &greybus_bus_type;
        hd->dev.type = &greybus_hd_type;
+       hd->dev.groups = bus_groups;
        hd->dev.dma_mask = hd->dev.parent->dma_mask;
        device_initialize(&hd->dev);
        dev_set_name(&hd->dev, "greybus%d", hd->bus_id);