Re: [RFC 1/2] cfg80211: add support for advertising multiple radios belonging to a wiphy

[Ben Greear <greearb@candelatech.com>]

On 5/22/24 05:30, Felix Fietkau wrote:
> The prerequisite for MLO support in cfg80211/mac80211 is that all the links
> participating in MLO must be from the same wiphy/ieee80211_hw. To meet this
> expectation, some drivers may need to group multiple discrete hardware each
> acting as a link in MLO under single wiphy.
> With this change, the bands and supported frequencies of each individual
> radio are reported to user space. This allows user space to figure out the
> limitations of what combination of channels can be used concurrently.
> 
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>   include/net/cfg80211.h       | 34 ++++++++++++++++
>   include/uapi/linux/nl80211.h | 48 +++++++++++++++++++++++
>   net/wireless/nl80211.c       | 75 ++++++++++++++++++++++++++++++++++++
>   3 files changed, 157 insertions(+)
> 
> diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
> index f2ca495ac9f8..58d8375ffa11 100644
> --- a/include/net/cfg80211.h
> +++ b/include/net/cfg80211.h
> @@ -5407,6 +5407,34 @@ struct wiphy_iftype_akm_suites {
>   	int n_akm_suites;
>   };
>   
> +/**
> + * struct wiphy_radio_freq_range - wiphy frequency range
> + * @start_freq:  start range edge frequency (kHz)
> + * @end_freq:    end range edge frequency (kHz)
> + */
> +struct wiphy_radio_freq_range {
> +	u32 start_freq;
> +	u32 end_freq;
> +};
> +
> +
> +/**
> + * struct wiphy_radio - This structure describes a physical radio belonging
> + * to a wiphy. It is used to describe concurrent-channel capabilities of the
> + * phy. Only one channel can be active on the radio described by struct
> + * wiphy_radio.
> + *
> + * @band_mask: Mask of enum nl80211_band describing the bands that the radio
> + *	can operate on.
> + * @num_freq_range: number of elements in @freq_range
> + * @freq_range: frequency range that the radio can operate on (optional)
> + */
> +struct wiphy_radio {
> +	u16 band_mask;
> +	u16 n_freq_range;
> +	const struct wiphy_radio_freq_range *freq_range;
> +};

Do you think we might should add the radio_idx in here so that we don't
depend on position in the array in case we need to add/remove radios
for some reason?

Or radio MAC addr or some other more persistent way to detect exactly
what this is in user-space?


> +
>   #define CFG80211_HW_TIMESTAMP_ALL_PEERS	0xffff
>   
>   /**
> @@ -5625,6 +5653,9 @@ struct wiphy_iftype_akm_suites {
>    *	A value of %CFG80211_HW_TIMESTAMP_ALL_PEERS indicates the driver
>    *	supports enabling HW timestamping for all peers (i.e. no need to
>    *	specify a mac address).
> + *
> + * @radio: radios belonging to this wiphy
> + * @n_radio: number of radios
>    */
>   struct wiphy {
>   	struct mutex mtx;
> @@ -5775,6 +5806,9 @@ struct wiphy {
>   
>   	u16 hw_timestamp_max_peers;
>   
> +	const struct wiphy_radio *radio;
> +	int n_radio;
> +
>   	char priv[] __aligned(NETDEV_ALIGN);
>   };
>   
> diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
> index f917bc6c9b6f..dfb01d673094 100644
> --- a/include/uapi/linux/nl80211.h
> +++ b/include/uapi/linux/nl80211.h
> @@ -3401,6 +3401,8 @@ enum nl80211_attrs {
>   
>   	NL80211_ATTR_ASSOC_SPP_AMSDU,
>   
> +	NL80211_ATTR_RADIOS,
> +
>   	/* add attributes here, update the policy in nl80211.c */
>   
>   	__NL80211_ATTR_AFTER_LAST,
> @@ -7999,4 +8001,50 @@ enum nl80211_ap_settings_flags {
>   	NL80211_AP_SETTINGS_SA_QUERY_OFFLOAD_SUPPORT	= 1 << 1,
>   };
>   
> +/**
> + * enum nl80211_wiphy_radio_attrs - wiphy radio attributes
> + *
> + * @__NL80211_WIPHY_RADIO_ATTR_INVALID: Invalid
> + *
> + * @NL80211_WIPHY_RADIO_ATTR_BAND_MASK: Bitmask of bands supported by this
> + *	radio.
> + *
> + * @NL80211_WIPHY_RADIO_ATTR_FREQ_RANGES: Nested array of frequency ranges
> + *	supported by this radio.
> + *
> + * @__NL80211_WIPHY_RADIO_ATTR_LAST: Internal
> + * @NL80211_WIPHY_RADIO_ATTR_MAX: Highest attribute
> + */
> +enum nl80211_wiphy_radio_attrs {
> +	__NL80211_WIPHY_RADIO_ATTR_INVALID,
> +
> +	NL80211_WIPHY_RADIO_ATTR_BAND_MASK,
> +	NL80211_WIPHY_RADIO_ATTR_FREQ_RANGES,
> +
> +	/* keep last */
> +	__NL80211_WIPHY_RADIO_ATTR_LAST,
> +	NL80211_WIPHY_RADIO_ATTR_MAX = __NL80211_WIPHY_RADIO_ATTR_LAST - 1,
> +};
> +
> +/**
> + * enum nl80211_wiphy_radio_freq_range - wiphy radio frequency range
> + *
> + * @__NL80211_WIPHY_RADIO_FREQ_ATTR_INVALID: Invalid
> + *
> + * @NL80211_WIPHY_RADIO_FREQ_ATTR_START: Frequency range start
> + * @NL80211_WIPHY_RADIO_FREQ_ATTR_END: Frequency range end
> + *
> + * @__NL80211_WIPHY_RADIO_FREQ_ATTR_LAST: Internal
> + * @NL80211_WIPHY_RADIO_FREQ_ATTR_MAX: Highest attribute
> + */
> +enum nl80211_wiphy_radio_freq_range {
> +	__NL80211_WIPHY_RADIO_FREQ_ATTR_INVALID,
> +
> +	NL80211_WIPHY_RADIO_FREQ_ATTR_START,
> +	NL80211_WIPHY_RADIO_FREQ_ATTR_END,
> +
> +	__NL80211_WIPHY_RADIO_FREQ_ATTR_LAST,
> +	NL80211_WIPHY_RADIO_FREQ_ATTR_MAX = __NL80211_WIPHY_RADIO_FREQ_ATTR_LAST - 1,
> +};
> +
>   #endif /* __LINUX_NL80211_H */
> diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
> index 3c0bca4238d3..c07abdf104ec 100644
> --- a/net/wireless/nl80211.c
> +++ b/net/wireless/nl80211.c
> @@ -2392,6 +2392,78 @@ static int nl80211_put_mbssid_support(struct wiphy *wiphy, struct sk_buff *msg)
>   	return -ENOBUFS;
>   }
>   
> +static int nl80211_put_radio(struct wiphy *wiphy, struct sk_buff *msg, int idx)
> +{
> +	const struct wiphy_radio *r = &wiphy->radio[idx];

Maybe allow radio[] array to be sparse (ie, idx 0 is there, idx 2 is there, idx 1 is NULL
because user wants to remove that radio from MLO consideration for whatever reason?

For what it's worth, I like the general approach.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com