wifi: cfg80211: correctly implement and validate S1G chandef

Currently, the S1G channelisation implementation differs from that of
VHT, which is the PHY that S1G is based on. The major difference between
the clock rate is 1/10th of VHT. However how their channelisation is
represented within cfg80211 and mac80211 vastly differ.

To rectify this, remove the use of IEEE80211_CHAN_1/2/4.. flags that were
previously used to indicate the control channel width, however it should be
implied that the control channels are 1MHz in the case of S1G. Additionally,
introduce the invert - being IEEE80211_CHAN_NO_4/8/16MHz - that imply
the control channel may not be used for a certain bandwidth. With these
new flags, we can perform regulatory and chandef validation just as we would
for VHT.

To deal with the notion that S1G PHYs may contain a 2MHz primary channel,
introduce a new variable, s1g_primary_2mhz, which indicates whether we are
operating on a 2MHz primary channel. In this case, the chandef::chan points to
the 1MHz primary channel pointed to by the primary channel location. Alongside
this, introduce some new helper routines that can extract the sibling 1MHz
channel. The sibling being the alternate 1MHz primary subchannel within the
2MHz primary channel that is not pointed to by chandef::chan.

Furthermore, due to unique restrictions imposed on S1G PHYs, introduce
a new flag, IEEE80211_CHAN_S1G_NO_PRIMARY, which states that the 1MHz channel
cannot be used as a primary channel. This is assumed to be set by vendors
as it is hardware and regdom specific, When we validate a 2MHz primary channel,
we need to ensure both 1MHz subchannels do not contain this flag. If one or
both of the 1MHz subchannels contain this flag then the 2MHz primary is not
permitted for use as a primary channel.

Properly integrate S1G channel validation such that it is implemented
according with other PHY types such as VHT. Additionally, implement a new
S1G-specific regulatory flag to allow cfg80211 to understand specific
vendor requirements for S1G PHYs.

Signed-off-by: Arien Judge <arien.judge@morsemicro.com>
Signed-off-by: Andrew Pope <andrew.pope@morsemicro.com>
Signed-off-by: Lachlan Hodges <lachlan.hodges@morsemicro.com>
Link: https://patch.msgid.link/20250918051913.500781-2-lachlan.hodges@morsemicro.com
[remove redundant NL80211_ATTR_S1G_PRIMARY_2MHZ check]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 423e258cdbd2..8134f10e4e6c 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -2969,6 +2969,10 @@ enum nl80211_commands {
  *	capabilities supported by the driver. See &enum nl80211_nan_capabilities
  *	for details.
  *
+ * @NL80211_ATTR_S1G_PRIMARY_2MHZ: flag attribute indicating that the S1G
+ *	primary channel is 2 MHz wide, and the control channel designates
+ *	the 1 MHz primary subchannel within that 2 MHz primary.
+ *
  * @NUM_NL80211_ATTR: total number of nl80211_attrs available
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
@@ -3535,6 +3539,8 @@ enum nl80211_attrs {
 	NL80211_ATTR_NAN_NEW_CLUSTER,
 	NL80211_ATTR_NAN_CAPABILITIES,
 
+	NL80211_ATTR_S1G_PRIMARY_2MHZ,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
@@ -4432,6 +4438,12 @@ enum nl80211_wmm_rule {
  *	very low power (VLP) AP, despite being NO_IR.
  * @NL80211_FREQUENCY_ATTR_ALLOW_20MHZ_ACTIVITY: This channel can be active in
  *	20 MHz bandwidth, despite being NO_IR.
+ * @NL80211_FREQUENCY_ATTR_NO_4MHZ: 4 MHz operation is not allowed on this
+ *	channel in current regulatory domain.
+ * @NL80211_FREQUENCY_ATTR_NO_8MHZ: 8 MHz operation is not allowed on this
+ *	channel in current regulatory domain.
+ * @NL80211_FREQUENCY_ATTR_NO_16MHZ: 16 MHz operation is not allowed on this
+ *	channel in current regulatory domain.
  * @NL80211_FREQUENCY_ATTR_MAX: highest frequency attribute number
  *	currently defined
  * @__NL80211_FREQUENCY_ATTR_AFTER_LAST: internal use
@@ -4477,6 +4489,9 @@ enum nl80211_frequency_attr {
 	NL80211_FREQUENCY_ATTR_CAN_MONITOR,
 	NL80211_FREQUENCY_ATTR_ALLOW_6GHZ_VLP_AP,
 	NL80211_FREQUENCY_ATTR_ALLOW_20MHZ_ACTIVITY,
+	NL80211_FREQUENCY_ATTR_NO_4MHZ,
+	NL80211_FREQUENCY_ATTR_NO_8MHZ,
+	NL80211_FREQUENCY_ATTR_NO_16MHZ,
 
 	/* keep last */
 	__NL80211_FREQUENCY_ATTR_AFTER_LAST,