usb: typec: Make the attributes read-only when writing is not possible

This affects the read-writable attribute files. Before this
there was no way for the user to know is changing the value
supported or not.

>From now on those attribute files will be made read-only
unless the underlying driver supports changing of the value.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20200211112531.86510-2-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
index 7c44e93..a451ae1 100644 (file)
--- a/drivers/usb/typec/class.c
+++ b/drivers/usb/typec/class.c
@@ -432,7 +432,28 @@ static struct attribute *typec_altmode_attrs[] = {
        &dev_attr_vdo.attr,
        NULL
 };
-ATTRIBUTE_GROUPS(typec_altmode);
+
+static umode_t typec_altmode_attr_is_visible(struct kobject *kobj,
+                                            struct attribute *attr, int n)
+{
+       struct typec_altmode *adev = to_typec_altmode(kobj_to_dev(kobj));
+
+       if (attr == &dev_attr_active.attr)
+               if (!adev->ops || !adev->ops->activate)
+                       return 0444;
+
+       return attr->mode;
+}
+
+static struct attribute_group typec_altmode_group = {
+       .is_visible = typec_altmode_attr_is_visible,
+       .attrs = typec_altmode_attrs,
+};
+
+static const struct attribute_group *typec_altmode_groups[] = {
+       &typec_altmode_group,
+       NULL
+};
 
 static int altmode_id_get(struct device *dev)
 {
@@ -1305,7 +1326,47 @@ static struct attribute *typec_attrs[] = {
        &dev_attr_port_type.attr,
        NULL,
 };
-ATTRIBUTE_GROUPS(typec);
+
+static umode_t typec_attr_is_visible(struct kobject *kobj,
+                                    struct attribute *attr, int n)
+{
+       struct typec_port *port = to_typec_port(kobj_to_dev(kobj));
+
+       if (attr == &dev_attr_data_role.attr) {
+               if (port->cap->data != TYPEC_PORT_DRD ||
+                   !port->ops || !port->ops->dr_set)
+                       return 0444;
+       } else if (attr == &dev_attr_power_role.attr) {
+               if (port->cap->type != TYPEC_PORT_DRP ||
+                   !port->cap->pd_revision ||
+                   !port->ops || !port->ops->pr_set)
+                       return 0444;
+       } else if (attr == &dev_attr_vconn_source.attr) {
+               if (!port->cap->pd_revision ||
+                   !port->ops || !port->ops->vconn_set)
+                       return 0444;
+       } else if (attr == &dev_attr_preferred_role.attr) {
+               if (port->cap->type != TYPEC_PORT_DRP ||
+                   !port->ops || !port->ops->try_role)
+                       return 0444;
+       } else if (attr == &dev_attr_port_type.attr) {
+               if (port->cap->type != TYPEC_PORT_DRP ||
+                   !port->ops || !port->ops->port_type_set)
+                       return 0444;
+       }
+
+       return attr->mode;
+}
+
+static struct attribute_group typec_group = {
+       .is_visible = typec_attr_is_visible,
+       .attrs = typec_attrs,
+};
+
+static const struct attribute_group *typec_groups[] = {
+       &typec_group,
+       NULL
+};
 
 static int typec_uevent(struct device *dev, struct kobj_uevent_env *env)
 {