cfg80211: support ieee80211-freq-limit DT property
This patch adds a helper for reading that new property and applying
limitations of supported channels specified this way.
It is used with devices that normally support a wide wireless band but
in a given config are limited to some part of it (usually due to board
design). For example a dual-band chipset may be able to support one band
only because of used antennas.
It's also common that tri-band routers have separated radios for lower
and higher part of 5 GHz band and it may be impossible to say which is
which without a DT info.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
[add new function to documentation, fix link]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/of.c b/net/wireless/of.c
new file mode 100644
index 0000000..de221f0
--- /dev/null
+++ b/net/wireless/of.c
@@ -0,0 +1,138 @@
+/*
+ * Copyright (C) 2017 Rafał Miłecki <rafal@milecki.pl>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <linux/of.h>
+#include <net/cfg80211.h>
+#include "core.h"
+
+static bool wiphy_freq_limits_valid_chan(struct wiphy *wiphy,
+ struct ieee80211_freq_range *freq_limits,
+ unsigned int n_freq_limits,
+ struct ieee80211_channel *chan)
+{
+ u32 bw = MHZ_TO_KHZ(20);
+ int i;
+
+ for (i = 0; i < n_freq_limits; i++) {
+ struct ieee80211_freq_range *limit = &freq_limits[i];
+
+ if (cfg80211_does_bw_fit_range(limit,
+ MHZ_TO_KHZ(chan->center_freq),
+ bw))
+ return true;
+ }
+
+ return false;
+}
+
+static void wiphy_freq_limits_apply(struct wiphy *wiphy,
+ struct ieee80211_freq_range *freq_limits,
+ unsigned int n_freq_limits)
+{
+ enum nl80211_band band;
+ int i;
+
+ if (WARN_ON(!n_freq_limits))
+ return;
+
+ for (band = 0; band < NUM_NL80211_BANDS; band++) {
+ struct ieee80211_supported_band *sband = wiphy->bands[band];
+
+ if (!sband)
+ continue;
+
+ for (i = 0; i < sband->n_channels; i++) {
+ struct ieee80211_channel *chan = &sband->channels[i];
+
+ if (chan->flags & IEEE80211_CHAN_DISABLED)
+ continue;
+
+ if (!wiphy_freq_limits_valid_chan(wiphy, freq_limits,
+ n_freq_limits,
+ chan)) {
+ pr_debug("Disabling freq %d MHz as it's out of OF limits\n",
+ chan->center_freq);
+ chan->flags |= IEEE80211_CHAN_DISABLED;
+ }
+ }
+ }
+}
+
+void wiphy_read_of_freq_limits(struct wiphy *wiphy)
+{
+ struct device *dev = wiphy_dev(wiphy);
+ struct device_node *np;
+ struct property *prop;
+ struct ieee80211_freq_range *freq_limits;
+ unsigned int n_freq_limits;
+ const __be32 *p;
+ int len, i;
+ int err = 0;
+
+ if (!dev)
+ return;
+ np = dev_of_node(dev);
+ if (!np)
+ return;
+
+ prop = of_find_property(np, "ieee80211-freq-limit", &len);
+ if (!prop)
+ return;
+
+ if (!len || len % sizeof(u32) || len / sizeof(u32) % 2) {
+ dev_err(dev, "ieee80211-freq-limit wrong format");
+ return;
+ }
+ n_freq_limits = len / sizeof(u32) / 2;
+
+ freq_limits = kcalloc(n_freq_limits, sizeof(*freq_limits), GFP_KERNEL);
+ if (!freq_limits) {
+ err = -ENOMEM;
+ goto out_kfree;
+ }
+
+ p = NULL;
+ for (i = 0; i < n_freq_limits; i++) {
+ struct ieee80211_freq_range *limit = &freq_limits[i];
+
+ p = of_prop_next_u32(prop, p, &limit->start_freq_khz);
+ if (!p) {
+ err = -EINVAL;
+ goto out_kfree;
+ }
+
+ p = of_prop_next_u32(prop, p, &limit->end_freq_khz);
+ if (!p) {
+ err = -EINVAL;
+ goto out_kfree;
+ }
+
+ if (!limit->start_freq_khz ||
+ !limit->end_freq_khz ||
+ limit->start_freq_khz >= limit->end_freq_khz) {
+ err = -EINVAL;
+ goto out_kfree;
+ }
+ }
+
+ wiphy_freq_limits_apply(wiphy, freq_limits, n_freq_limits);
+
+out_kfree:
+ kfree(freq_limits);
+ if (err)
+ dev_err(dev, "Failed to get limits: %d\n", err);
+}
+EXPORT_SYMBOL(wiphy_read_of_freq_limits);