[PATCH v2 03/22] cfg80211: regulatory: handle S1G channels

Thomas Pedersen
2020-08-31T20:56:14Z

S1G channels have a minimum bandwidth of 1Mhz, and there
is a 1:1 mapping of allowed bandwidth to channel number.

Signed-off-by: Thomas Pedersen <thomas@adapt-ip.com>

---

v2:
- drop the freq_reg_info() interface changes and move the
check for S1G band inside. Fixes a driver compile
error.
- fix iterating past bws[] in __freq_reg_info() by
setting initial element to 0.
Reported-by: kernel test robot <lkp@intel.com>
---
net/wireless/reg.c | 70 ++++++++++++++++++++++++++++++++++++++--------
1 file changed, 58 insertions(+), 12 deletions(-)

diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index 0ab7808fcec8..be6f54b70ad3 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -1617,9 +1617,11 @@ __freq_reg_info(struct wiphy *wiphy, u32 center_freq, u32 min_bw)
{
const struct ieee80211_regdomain *regd = reg_get_regdomain(wiphy);
const struct ieee80211_reg_rule *reg_rule = NULL;
+ const u32 bws[] = {0, 1, 2, 4, 5, 8, 10, 16, 20};
+ int i = sizeof(bws) / sizeof(u32) - 1;
u32 bw;

- for (bw = MHZ_TO_KHZ(20); bw >= min_bw; bw = bw / 2) {
+ for (bw = MHZ_TO_KHZ(bws[i]); bw >= min_bw; bw = MHZ_TO_KHZ(bws[i--])) {
reg_rule = freq_reg_info_regd(center_freq, regd, bw);
if (!IS_ERR(reg_rule))
return reg_rule;
@@ -1631,7 +1633,9 @@ __freq_reg_info(struct wiphy *wiphy, u32 center_freq, u32 min_bw)
const struct ieee80211_reg_rule *freq_reg_info(struct wiphy *wiphy,
u32 center_freq)
{
- return __freq_reg_info(wiphy, center_freq, MHZ_TO_KHZ(20));
+ u32 min_bw = center_freq < MHZ_TO_KHZ(1000) ? 1 : 20;
+
+ return __freq_reg_info(wiphy, center_freq, MHZ_TO_KHZ(min_bw));
}
EXPORT_SYMBOL(freq_reg_info);

@@ -1659,6 +1663,7 @@ static uint32_t reg_rule_to_chan_bw_flags(const struct ieee80211_regdomain *regd
{
const struct ieee80211_freq_range *freq_range = NULL;
u32 max_bandwidth_khz, center_freq_khz, bw_flags = 0;
+ bool is_s1g = chan->band == NL80211_BAND_S1GHZ;

freq_range = &reg_rule->freq_range;

@@ -1678,16 +1683,57 @@ static uint32_t reg_rule_to_chan_bw_flags(const struct ieee80211_regdomain *regd
MHZ_TO_KHZ(20)))
bw_flags |= IEEE80211_CHAN_NO_20MHZ;

- if (max_bandwidth_khz < MHZ_TO_KHZ(10))
- bw_flags |= IEEE80211_CHAN_NO_10MHZ;
- if (max_bandwidth_khz < MHZ_TO_KHZ(20))
- bw_flags |= IEEE80211_CHAN_NO_20MHZ;
- if (max_bandwidth_khz < MHZ_TO_KHZ(40))
- bw_flags |= IEEE80211_CHAN_NO_HT40;
- if (max_bandwidth_khz < MHZ_TO_KHZ(80))
- bw_flags |= IEEE80211_CHAN_NO_80MHZ;
- if (max_bandwidth_khz < MHZ_TO_KHZ(160))
- bw_flags |= IEEE80211_CHAN_NO_160MHZ;
+ if (is_s1g) {
+ /* S1G is strict about non overlapping channels. We can
+ * calculate which bandwidth is allowed per channel by finding
+ * the largest bandwidth which cleanly divides the freq_range.
+ */
+ int edge_offset;
+ int ch_bw = max_bandwidth_khz;
+
+ while (ch_bw) {
+ edge_offset = (center_freq_khz - ch_bw / 2) -
+ freq_range->start_freq_khz;
+ if (edge_offset % ch_bw == 0) {
+ switch (KHZ_TO_MHZ(ch_bw)) {
+ case 1:
+ bw_flags |= IEEE80211_CHAN_1MHZ;
+ break;
+ case 2:
+ bw_flags |= IEEE80211_CHAN_2MHZ;
+ break;
+ case 4:
+ bw_flags |= IEEE80211_CHAN_4MHZ;
+ break;
+ case 8:
+ bw_flags |= IEEE80211_CHAN_8MHZ;
+ break;
+ case 16:
+ bw_flags |= IEEE80211_CHAN_16MHZ;
+ break;
+ default:
+ /* If we got here, no bandwidths fit on
+ * this frequency, ie. band edge.
+ */
+ bw_flags |= IEEE80211_CHAN_DISABLED;
+ break;
+ }
+ break;
+ }
+ ch_bw /= 2;
+ }
+ } else {
+ if (max_bandwidth_khz < MHZ_TO_KHZ(10))
+ bw_flags |= IEEE80211_CHAN_NO_10MHZ;
+ if (max_bandwidth_khz < MHZ_TO_KHZ(20))
+ bw_flags |= IEEE80211_CHAN_NO_20MHZ;
+ if (max_bandwidth_khz < MHZ_TO_KHZ(40))
+ bw_flags |= IEEE80211_CHAN_NO_HT40;
+ if (max_bandwidth_khz < MHZ_TO_KHZ(80))
+ bw_flags |= IEEE80211_CHAN_NO_80MHZ;
+ if (max_bandwidth_khz < MHZ_TO_KHZ(160))
+ bw_flags |= IEEE80211_CHAN_NO_160MHZ;
+ }
return bw_flags;
}

--
2.20.1