mac80211: extend current rate control tx status API

This patch adds the new struct ieee80211_rate_status and replaces
'struct rate_info *rate' in ieee80211_tx_status with pointer and length
annotation.

The struct ieee80211_rate_status allows to:
(1)	receive tx power status feedback for transmit power control (TPC)
	per packet or packet retry
(2)	dynamic mapping of wifi chip specific multi-rate retry (mrr)
	chains with different lengths
(3)	increase the limit of annotatable rate indices to support
	IEEE802.11ac rate sets and beyond

ieee80211_tx_info, control and status buffer, and ieee80211_tx_rate
cannot be used to achieve these goals due to fixed size limitations.

Our new struct contains a struct rate_info to annotate the rate that was
used, retry count of the rate and tx power. It is intended for all
information related to RC and TPC that needs to be passed from driver to
mac80211 and its RC/TPC algorithms like Minstrel_HT. It corresponds to
one stage in an mrr. Multiple subsequent instances of this struct can be
included in struct ieee80211_tx_status via a pointer and a length variable.
Those instances can be allocated on-stack. The former reference to a single
instance of struct rate_info is replaced with our new annotation.

An extension is introduced to struct ieee80211_hw. There are two new
members called 'tx_power_levels' and 'max_txpwr_levels_idx' acting as a
tx power level table. When a wifi device is registered, the driver shall
supply all supported power levels in this list. This allows to support
several quirks like differing power steps in power level ranges or
alike. TPC can use this for algorithm and thus be designed more abstract
instead of handling all possible step widths individually.

Further mandatory changes in status.c, mt76 and ath11k drivers due to the
removal of 'struct rate_info *rate' are also included.
status.c already uses the information in ieee80211_tx_status->rate in
radiotap, this is now changed to use ieee80211_rate_status->rate_idx.
mt76 driver already uses struct rate_info to pass the tx rate to status
path. The new members of the ieee80211_tx_status are set to NULL and 0
because the previously passed rate is not relevant to rate control and
accurate information is passed via tx_info->status.rates.
For ath11k, the txrate can be passed via this struct because ath11k uses
firmware RC and thus the information does not interfere with software RC.

Compile-Tested: current wireless-next tree with all flags on
Tested-on: Xiaomi 4A Gigabit (MediaTek MT7603E, MT7612E) with OpenWrt
		Linux 5.10.113

Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://lore.kernel.org/r/20220509173958.1398201-2-jelonek.jonas@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 31 insertions, 2 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 944b31f0eb0d..ebadb2103968 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1143,20 +1143,41 @@ ieee80211_info_get_tx_time_est(struct ieee80211_tx_info *info)
 	return info->tx_time_est << 2;
 }
 
+/***
+ * struct ieee80211_rate_status - mrr stage for status path
+ *
+ * This struct is used in struct ieee80211_tx_status to provide drivers a
+ * dynamic way to report about used rates and power levels per packet.
+ *
+ * @rate_idx The actual used rate.
+ * @try_count How often the rate was tried.
+ * @tx_power_idx An idx into the ieee80211_hw->tx_power_levels list of the
+ * 	corresponding wifi hardware. The idx shall point to the power level
+ * 	that was used when sending the packet.
+ */
+struct ieee80211_rate_status {
+	struct rate_info rate_idx;
+	u8 try_count;
+	u8 tx_power_idx;
+};
+
 /**
  * struct ieee80211_tx_status - extended tx status info for rate control
  *
  * @sta: Station that the packet was transmitted for
  * @info: Basic tx status information
  * @skb: Packet skb (can be NULL if not provided by the driver)
- * @rate: The TX rate that was used when sending the packet
+ * @rates: Mrr stages that were used when sending the packet
+ * @n_rates: Number of mrr stages (count of instances for @rates)
  * @free_list: list where processed skbs are stored to be free'd by the driver
  */
 struct ieee80211_tx_status {
 	struct ieee80211_sta *sta;
 	struct ieee80211_tx_info *info;
 	struct sk_buff *skb;
-	struct rate_info *rate;
+	struct ieee80211_rate_status *rates;
+	u8 n_rates;
+
 	struct list_head *free_list;
 };
 
@@ -2657,6 +2678,12 @@ enum ieee80211_hw_flags {
  *	refilling deficit of each TXQ.
  *
  * @max_mtu: the max mtu could be set.
+ *
+ * @tx_power_levels: a list of power levels supported by the wifi hardware.
+ * 	The power levels can be specified either as integer or fractions.
+ * 	The power level at idx 0 shall be the maximum positive power level.
+ *
+ * @max_txpwr_levels_idx: the maximum valid idx of 'tx_power_levels' list.
  */
 struct ieee80211_hw {
 	struct ieee80211_conf conf;
@@ -2695,6 +2722,8 @@ struct ieee80211_hw {
 	u8 tx_sk_pacing_shift;
 	u8 weight_multiplier;
 	u32 max_mtu;
+	const s8 *tx_power_levels;
+	u8 max_txpwr_levels_idx;
 };
 
 static inline bool _ieee80211_hw_check(struct ieee80211_hw *hw,