Re: [PATCH] mt76: mt7921: add .set_sar_specs support

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> From: YN Chen <YN.Chen@mediatek.com>
> 
> add .set_sar_specs to allow configuring SAR power limitations on the
> frequency ranges from the userland.
> 
> Co-developed-by: Sean Wang <sean.wang@mediatek.com>
> Signed-off-by: Sean Wang <sean.wang@mediatek.com>
> Signed-off-by: YN Chen <YN.Chen@mediatek.com>
> ---
>  drivers/net/wireless/mediatek/mt76/mt76.h     |  3 ++
>  .../net/wireless/mediatek/mt76/mt76_connac.h  |  5 +++
>  .../wireless/mediatek/mt76/mt76_connac_mcu.c  | 24 +++++++++-
>  .../net/wireless/mediatek/mt76/mt7921/init.c  | 21 +++++++++
>  .../net/wireless/mediatek/mt76/mt7921/main.c  | 45 +++++++++++++++++++
>  5 files changed, 97 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
> index 25c5ceef5257..63ce5242c4d5 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76.h
> +++ b/drivers/net/wireless/mediatek/mt76/mt76.h
> @@ -636,6 +636,9 @@ struct mt76_phy {
>  		struct sk_buff **tail;
>  		u16 seqno;
>  	} rx_amsdu[__MT_RXQ_MAX];
> +
> +	void *frp_data;
> +	u8 num_frps;
>  };
>  
>  struct mt76_dev {
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76_connac.h b/drivers/net/wireless/mediatek/mt76/mt76_connac.h
> index f49d97d0a1c5..95c7d1cac7c4 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76_connac.h
> +++ b/drivers/net/wireless/mediatek/mt76/mt76_connac.h
> @@ -83,6 +83,11 @@ struct mt76_connac_coredump {
>  	unsigned long last_activity;
>  };
>  
> +struct mt76_connac_freq_range_power {
> +	const struct cfg80211_sar_freq_ranges *range;
> +	s8 power;
> +};
> +
>  extern const struct wiphy_wowlan_support mt76_connac_wowlan_support;
>  
>  static inline bool is_mt7921(struct mt76_dev *dev)
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c b/drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c
> index 5c3a81e5f559..07f45cb4f500 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c
> @@ -1749,6 +1749,24 @@ mt76_connac_mcu_build_sku(struct mt76_dev *dev, s8 *sku,
>  	}
>  }
>  
> +static s8 mt76_connac_get_sar_power(struct mt76_phy *phy,
> +				    struct ieee80211_channel *chan,
> +				    s8 target_power)
> +{
> +	struct mt76_connac_freq_range_power *frp = phy->frp_data;
> +	int freq, i;
> +
> +	freq = ieee80211_channel_to_frequency(chan->hw_value, chan->band);
> +	for (i = 0 ; i < phy->num_frps; i++) {
> +		if (frp[i].range &&
> +		    freq >= frp[i].range->start_freq &&
> +		    freq < frp[i].range->end_freq)
> +			target_power = min_t(s8, frp[i].power, target_power);

can we have overlapping freq range? if not I guess you can add a break here.

> +	}
> +
> +	return target_power;
> +}
> +
>  static int
>  mt76_connac_mcu_rate_txpower_band(struct mt76_phy *phy,
>  				  enum nl80211_band band)
> @@ -1816,9 +1834,13 @@ mt76_connac_mcu_rate_txpower_band(struct mt76_phy *phy,
>  				.hw_value = ch_list[idx],
>  				.band = band,
>  			};
> +			s8 sar_power;
> +
> +			sar_power = mt76_connac_get_sar_power(phy, &chan,
> +							      tx_power);
>  
>  			mt76_get_rate_power_limits(phy, &chan, &limits,
> -						   tx_power);
> +						   sar_power);
>  
>  			tx_power_tlv.last_msg = ch_list[idx] == last_ch;
>  			sku_tlbv.channel = ch_list[idx];
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/init.c b/drivers/net/wireless/mediatek/mt76/mt7921/init.c
> index a9ce10b98827..e7f66d988a49 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7921/init.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/init.c
> @@ -24,6 +24,20 @@ static const struct ieee80211_iface_combination if_comb[] = {
>  	}
>  };
>  
> +const struct cfg80211_sar_freq_ranges mt7921_sar_freq_ranges[] = {
> +	{ .start_freq = 2402, .end_freq = 2494, },
> +	{ .start_freq = 5150, .end_freq = 5350, },
> +	{ .start_freq = 5350, .end_freq = 5470, },
> +	{ .start_freq = 5470, .end_freq = 5725, },
> +	{ .start_freq = 5725, .end_freq = 5950, },
> +};
> +
> +static const struct cfg80211_sar_capa mt7921_sar_capa = {
> +	.type = NL80211_SAR_TYPE_POWER,
> +	.num_freq_ranges = ARRAY_SIZE(mt7921_sar_freq_ranges),
> +	.freq_ranges = &mt7921_sar_freq_ranges[0],
> +};
> +
>  static void
>  mt7921_regd_notifier(struct wiphy *wiphy,
>  		     struct regulatory_request *request)
> @@ -75,6 +89,13 @@ mt7921_init_wiphy(struct ieee80211_hw *hw)
>  	wiphy->max_sched_scan_reqs = 1;
>  	wiphy->flags |= WIPHY_FLAG_HAS_CHANNEL_SWITCH;
>  	wiphy->reg_notifier = mt7921_regd_notifier;
> +	wiphy->sar_capa = &mt7921_sar_capa;
> +
> +	phy->mt76->frp_data = devm_kcalloc(dev->mt76.dev,
> +					   wiphy->sar_capa->num_freq_ranges,
> +					   sizeof(struct mt76_connac_freq_range_power),
> +					   GFP_KERNEL);

Here I guess we need to check if devm_kcalloc fails returning an int from
mt7921_init_wiphy()

> +	phy->mt76->num_frps = wiphy->sar_capa->num_freq_ranges;
>  
>  	wiphy->features |= NL80211_FEATURE_SCHED_SCAN_RANDOM_MAC_ADDR |
>  			   NL80211_FEATURE_SCAN_RANDOM_MAC_ADDR;
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/main.c b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
> index 7fd21049ff5a..e9b5d79e139f 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7921/main.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
> @@ -1171,6 +1171,50 @@ static void mt7921_sta_set_decap_offload(struct ieee80211_hw *hw,
>  					     MCU_UNI_CMD_STA_REC_UPDATE);
>  }
>  
> +static int mt7921_set_sar_specs(struct ieee80211_hw *hw,
> +				const struct cfg80211_sar_specs *sar)
> +{
> +	const struct cfg80211_sar_capa *capa = hw->wiphy->sar_capa;
> +	struct mt76_connac_freq_range_power *frp_data, *frp;
> +	struct mt7921_dev *dev = mt7921_hw_dev(hw);
> +	struct mt76_phy *mphy = hw->priv;
> +	int err;
> +	u32 i;
> +
> +	mt7921_mutex_acquire(dev);
> +
> +	if (!sar || sar->type != NL80211_SAR_TYPE_POWER ||
> +	    sar->num_sub_specs == 0) {
> +		err = -EINVAL;
> +		goto out;
> +	}

I guess you can move this out of the lock

> +
> +	frp_data = mphy->frp_data;
> +
> +	for (i = 0; i < sar->num_sub_specs; i++) {
> +		u32 index = sar->sub_specs[i].freq_range_index;
> +		/* SAR specifies power limitaton in 0.25dbm */
> +		s32 power = sar->sub_specs[i].power >> 1;
> +
> +		if (power > 127 || power < -127)
> +			power = 127;
> +
> +		if (index >= mphy->num_frps)
> +			continue;
> +
> +		frp = &frp_data[index];
> +		frp->range = &capa->freq_ranges[index];

I guess there is an use-after-free here since sar is freed at the end of
nl80211_set_sar_specs, right?

Regards,
Lorenzo

> +		frp->power = power;
> +	}
> +
> +	err = mt76_connac_mcu_set_rate_txpower(mphy);
> +
> +out:
> +	mt7921_mutex_release(dev);
> +
> +	return err;
> +}
> +
>  const struct ieee80211_ops mt7921_ops = {
>  	.tx = mt7921_tx,
>  	.start = mt7921_start,
> @@ -1209,4 +1253,5 @@ const struct ieee80211_ops mt7921_ops = {
>  	.set_rekey_data = mt7921_set_rekey_data,
>  #endif /* CONFIG_PM */
>  	.flush = mt7921_flush,
> +	.set_sar_specs = mt7921_set_sar_specs,
>  };
> -- 
> 2.25.1
> 

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