[PATCH 6/7] media: rc: if protocols can't be changed, don't be writable

[Sean Young]

If the protocols of an rc device cannot be changed, ensure the sysfs
file is not writable.

This makes it possible to detect this from userspace, so ir-keytable
can deal with case without giving an error.

Signed-off-by: Sean Young <s...@mess.org>
---
 drivers/media/rc/rc-main.c | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
index 8781055ee058..cf0c407d8f5b 100644
--- a/drivers/media/rc/rc-main.c
+++ b/drivers/media/rc/rc-main.c
@@ -1487,7 +1487,10 @@ static int rc_dev_uevent(struct device *device, struct 
kobj_uevent_env *env)
 /*
  * Static device attribute struct with the sysfs attributes for IR's
  */
-static DEVICE_ATTR(protocols, 0644, show_protocols, store_protocols);
+static struct device_attribute dev_attr_ro_protocols =
+__ATTR(protocols, 0444, show_protocols, store_protocols);
+static struct device_attribute dev_attr_rw_protocols =
+__ATTR(protocols, 0644, show_protocols, NULL);
 static DEVICE_ATTR(wakeup_protocols, 0644, show_wakeup_protocols,
                   store_wakeup_protocols);
 static RC_FILTER_ATTR(filter, S_IRUGO|S_IWUSR,
@@ -1499,13 +1502,22 @@ static RC_FILTER_ATTR(wakeup_filter, S_IRUGO|S_IWUSR,
 static RC_FILTER_ATTR(wakeup_filter_mask, S_IRUGO|S_IWUSR,
                      show_filter, store_filter, RC_FILTER_WAKEUP, true);
 
-static struct attribute *rc_dev_protocol_attrs[] = {
-       &dev_attr_protocols.attr,
+static struct attribute *rc_dev_rw_protocol_attrs[] = {
+       &dev_attr_rw_protocols.attr,
        NULL,
 };
 
-static const struct attribute_group rc_dev_protocol_attr_grp = {
-       .attrs  = rc_dev_protocol_attrs,
+static const struct attribute_group rc_dev_rw_protocol_attr_grp = {
+       .attrs  = rc_dev_rw_protocol_attrs,
+};
+
+static struct attribute *rc_dev_ro_protocol_attrs[] = {
+       &dev_attr_ro_protocols.attr,
+       NULL,
+};
+
+static const struct attribute_group rc_dev_ro_protocol_attr_grp = {
+       .attrs  = rc_dev_ro_protocol_attrs,
 };
 
 static struct attribute *rc_dev_filter_attrs[] = {
@@ -1732,8 +1744,10 @@ int rc_register_device(struct rc_dev *dev)
        dev_set_drvdata(&dev->dev, dev);
 
        dev->dev.groups = dev->sysfs_groups;
-       if (dev->driver_type != RC_DRIVER_IR_RAW_TX)
-               dev->sysfs_groups[attr++] = &rc_dev_protocol_attr_grp;
+       if (dev->driver_type == RC_DRIVER_SCANCODE && !dev->change_protocol)
+               dev->sysfs_groups[attr++] = &rc_dev_ro_protocol_attr_grp;
+       else if (dev->driver_type != RC_DRIVER_IR_RAW_TX)
+               dev->sysfs_groups[attr++] = &rc_dev_rw_protocol_attr_grp;
        if (dev->s_filter)
                dev->sysfs_groups[attr++] = &rc_dev_filter_attr_grp;
        if (dev->s_wakeup_filter)
-- 
2.13.5