staging: fsl-mc: add support for the modalias sysfs attribute

In order to support uevent based module loading implement modalias support
for the fsl-mc bus driver. Aliases are based on vendor and object/device
id and are of the form "fsl-mc:vNdN".
Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fsl-mc/bus/mc-bus.c

@@ -82,10 +82,35 @@ static int fsl_mc_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
 	return 0;
 }
 
+static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev);
+
+	return sprintf(buf, "fsl-mc:v%08Xd%s\n", mc_dev->obj_desc.vendor,
+		       mc_dev->obj_desc.type);
+}
+static DEVICE_ATTR_RO(modalias);
+
+static struct attribute *fsl_mc_dev_attrs[] = {
+	&dev_attr_modalias.attr,
+	NULL,
+};
+
+static const struct attribute_group fsl_mc_dev_group = {
+	.attrs = fsl_mc_dev_attrs,
+};
+
+static const struct attribute_group *fsl_mc_dev_groups[] = {
+	&fsl_mc_dev_group,
+	NULL,
+};
+
 struct bus_type fsl_mc_bus_type = {
 	.name = "fsl-mc",
 	.match = fsl_mc_bus_match,
 	.uevent = fsl_mc_bus_uevent,
+	.dev_groups = fsl_mc_dev_groups,
 };
 EXPORT_SYMBOL_GPL(fsl_mc_bus_type);