mac80211: debugfs: improve airtime_flags handler readability

Improve airtime_flags debugfs handler readability reporting configured
airtime flags in both numeric and human readable manner
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/9df7e40b45e95bb0b320317831455beaed1ee3ee.1574872357.git.lorenzo@kernel.org
[remove AQL since it's no longer there]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/debugfs.c

@@ -150,6 +150,59 @@ static const struct file_operations aqm_ops = {
 	.llseek = default_llseek,
 };
 
+static ssize_t airtime_flags_read(struct file *file,
+				  char __user *user_buf,
+				  size_t count, loff_t *ppos)
+{
+	struct ieee80211_local *local = file->private_data;
+	char buf[128] = {}, *pos, *end;
+
+	pos = buf;
+	end = pos + sizeof(buf) - 1;
+
+	if (local->airtime_flags & AIRTIME_USE_TX)
+		pos += scnprintf(pos, end - pos, "AIRTIME_TX\t(%lx)\n",
+				 AIRTIME_USE_TX);
+	if (local->airtime_flags & AIRTIME_USE_RX)
+		pos += scnprintf(pos, end - pos, "AIRTIME_RX\t(%lx)\n",
+				 AIRTIME_USE_RX);
+
+	return simple_read_from_buffer(user_buf, count, ppos, buf,
+				       strlen(buf));
+}
+
+static ssize_t airtime_flags_write(struct file *file,
+				   const char __user *user_buf,
+				   size_t count, loff_t *ppos)
+{
+	struct ieee80211_local *local = file->private_data;
+	char buf[16];
+	size_t len;
+
+	if (count > sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(buf, user_buf, count))
+		return -EFAULT;
+
+	buf[sizeof(buf) - 1] = 0;
+	len = strlen(buf);
+	if (len > 0 && buf[len - 1] == '\n')
+		buf[len - 1] = 0;
+
+	if (kstrtou16(buf, 0, &local->airtime_flags))
+		return -EINVAL;
+
+	return count;
+}
+
+static const struct file_operations airtime_flags_ops = {
+	.write = airtime_flags_write,
+	.read = airtime_flags_read,
+	.open = simple_open,
+	.llseek = default_llseek,
+};
+
 static ssize_t aql_txq_limit_read(struct file *file,
 				  char __user *user_buf,
 				  size_t count,
@@ -522,8 +575,7 @@ void debugfs_hw_add(struct ieee80211_local *local)
 	if (local->ops->wake_tx_queue)
 		DEBUGFS_ADD_MODE(aqm, 0600);
 
-	debugfs_create_u16("airtime_flags", 0600,
-			   phyd, &local->airtime_flags);
+	DEBUGFS_ADD_MODE(airtime_flags, 0600);
 
 	DEBUGFS_ADD(aql_txq_limit);
 	debugfs_create_u32("aql_threshold", 0600,