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nl80211/cfg80211: add VHT MCS support
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Add support for reporting and calculating VHT MCSes.

Note that I'm not completely sure that the bitrate
calculations are correct, nor that they can't be
simplified.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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Johannes Berg committed Nov 26, 2012
1 parent 4bf8853 commit db9c64c
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Showing 4 changed files with 144 additions and 24 deletions.
24 changes: 17 additions & 7 deletions include/net/cfg80211.h
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Original file line number Diff line number Diff line change
Expand Up @@ -662,16 +662,24 @@ enum station_info_flags {
* Used by the driver to indicate the specific rate transmission
* type for 802.11n transmissions.
*
* @RATE_INFO_FLAGS_MCS: @tx_bitrate_mcs filled
* @RATE_INFO_FLAGS_40_MHZ_WIDTH: 40 Mhz width transmission
* @RATE_INFO_FLAGS_MCS: mcs field filled with HT MCS
* @RATE_INFO_FLAGS_VHT_MCS: mcs field filled with VHT MCS
* @RATE_INFO_FLAGS_40_MHZ_WIDTH: 40 MHz width transmission
* @RATE_INFO_FLAGS_80_MHZ_WIDTH: 80 MHz width transmission
* @RATE_INFO_FLAGS_80P80_MHZ_WIDTH: 80+80 MHz width transmission
* @RATE_INFO_FLAGS_160_MHZ_WIDTH: 160 MHz width transmission
* @RATE_INFO_FLAGS_SHORT_GI: 400ns guard interval
* @RATE_INFO_FLAGS_60G: 60gHz MCS
* @RATE_INFO_FLAGS_60G: 60GHz MCS
*/
enum rate_info_flags {
RATE_INFO_FLAGS_MCS = 1<<0,
RATE_INFO_FLAGS_40_MHZ_WIDTH = 1<<1,
RATE_INFO_FLAGS_SHORT_GI = 1<<2,
RATE_INFO_FLAGS_60G = 1<<3,
RATE_INFO_FLAGS_MCS = BIT(0),
RATE_INFO_FLAGS_VHT_MCS = BIT(1),
RATE_INFO_FLAGS_40_MHZ_WIDTH = BIT(2),
RATE_INFO_FLAGS_80_MHZ_WIDTH = BIT(3),
RATE_INFO_FLAGS_80P80_MHZ_WIDTH = BIT(4),
RATE_INFO_FLAGS_160_MHZ_WIDTH = BIT(5),
RATE_INFO_FLAGS_SHORT_GI = BIT(6),
RATE_INFO_FLAGS_60G = BIT(7),
};

/**
Expand All @@ -682,11 +690,13 @@ enum rate_info_flags {
* @flags: bitflag of flags from &enum rate_info_flags
* @mcs: mcs index if struct describes a 802.11n bitrate
* @legacy: bitrate in 100kbit/s for 802.11abg
* @nss: number of streams (VHT only)
*/
struct rate_info {
u8 flags;
u8 mcs;
u16 legacy;
u8 nss;
};

/**
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12 changes: 11 additions & 1 deletion include/uapi/linux/nl80211.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1734,10 +1734,15 @@ struct nl80211_sta_flag_update {
* @__NL80211_RATE_INFO_INVALID: attribute number 0 is reserved
* @NL80211_RATE_INFO_BITRATE: total bitrate (u16, 100kbit/s)
* @NL80211_RATE_INFO_MCS: mcs index for 802.11n (u8)
* @NL80211_RATE_INFO_40_MHZ_WIDTH: 40 Mhz dualchannel bitrate
* @NL80211_RATE_INFO_40_MHZ_WIDTH: 40 MHz dualchannel bitrate
* @NL80211_RATE_INFO_SHORT_GI: 400ns guard interval
* @NL80211_RATE_INFO_BITRATE32: total bitrate (u32, 100kbit/s)
* @NL80211_RATE_INFO_MAX: highest rate_info number currently defined
* @NL80211_RATE_INFO_VHT_MCS: MCS index for VHT (u8)
* @NL80211_RATE_INFO_VHT_NSS: number of streams in VHT (u8)
* @NL80211_RATE_INFO_80_MHZ_WIDTH: 80 MHz VHT rate
* @NL80211_RATE_INFO_80P80_MHZ_WIDTH: 80+80 MHz VHT rate
* @NL80211_RATE_INFO_160_MHZ_WIDTH: 160 MHz VHT rate
* @__NL80211_RATE_INFO_AFTER_LAST: internal use
*/
enum nl80211_rate_info {
Expand All @@ -1747,6 +1752,11 @@ enum nl80211_rate_info {
NL80211_RATE_INFO_40_MHZ_WIDTH,
NL80211_RATE_INFO_SHORT_GI,
NL80211_RATE_INFO_BITRATE32,
NL80211_RATE_INFO_VHT_MCS,
NL80211_RATE_INFO_VHT_NSS,
NL80211_RATE_INFO_80_MHZ_WIDTH,
NL80211_RATE_INFO_80P80_MHZ_WIDTH,
NL80211_RATE_INFO_160_MHZ_WIDTH,

/* keep last */
__NL80211_RATE_INFO_AFTER_LAST,
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58 changes: 43 additions & 15 deletions net/wireless/nl80211.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2890,29 +2890,52 @@ static bool nl80211_put_sta_rate(struct sk_buff *msg, struct rate_info *info,

rate = nla_nest_start(msg, attr);
if (!rate)
goto nla_put_failure;
return false;

/* cfg80211_calculate_bitrate will return 0 for mcs >= 32 */
bitrate = cfg80211_calculate_bitrate(info);
/* report 16-bit bitrate only if we can */
bitrate_compat = bitrate < (1UL << 16) ? bitrate : 0;
if ((bitrate > 0 &&
nla_put_u32(msg, NL80211_RATE_INFO_BITRATE32, bitrate)) ||
(bitrate_compat > 0 &&
nla_put_u16(msg, NL80211_RATE_INFO_BITRATE, bitrate_compat)) ||
((info->flags & RATE_INFO_FLAGS_MCS) &&
nla_put_u8(msg, NL80211_RATE_INFO_MCS, info->mcs)) ||
((info->flags & RATE_INFO_FLAGS_40_MHZ_WIDTH) &&
nla_put_flag(msg, NL80211_RATE_INFO_40_MHZ_WIDTH)) ||
((info->flags & RATE_INFO_FLAGS_SHORT_GI) &&
nla_put_flag(msg, NL80211_RATE_INFO_SHORT_GI)))
goto nla_put_failure;
if (bitrate > 0 &&
nla_put_u32(msg, NL80211_RATE_INFO_BITRATE32, bitrate))
return false;
if (bitrate_compat > 0 &&
nla_put_u16(msg, NL80211_RATE_INFO_BITRATE, bitrate_compat))
return false;

if (info->flags & RATE_INFO_FLAGS_MCS) {
if (nla_put_u8(msg, NL80211_RATE_INFO_MCS, info->mcs))
return false;
if (info->flags & RATE_INFO_FLAGS_40_MHZ_WIDTH &&
nla_put_flag(msg, NL80211_RATE_INFO_40_MHZ_WIDTH))
return false;
if (info->flags & RATE_INFO_FLAGS_SHORT_GI &&
nla_put_flag(msg, NL80211_RATE_INFO_SHORT_GI))
return false;
} else if (info->flags & RATE_INFO_FLAGS_VHT_MCS) {
if (nla_put_u8(msg, NL80211_RATE_INFO_VHT_MCS, info->mcs))
return false;
if (nla_put_u8(msg, NL80211_RATE_INFO_VHT_NSS, info->nss))
return false;
if (info->flags & RATE_INFO_FLAGS_40_MHZ_WIDTH &&
nla_put_flag(msg, NL80211_RATE_INFO_40_MHZ_WIDTH))
return false;
if (info->flags & RATE_INFO_FLAGS_80_MHZ_WIDTH &&
nla_put_flag(msg, NL80211_RATE_INFO_80_MHZ_WIDTH))
return false;
if (info->flags & RATE_INFO_FLAGS_80P80_MHZ_WIDTH &&
nla_put_flag(msg, NL80211_RATE_INFO_80P80_MHZ_WIDTH))
return false;
if (info->flags & RATE_INFO_FLAGS_160_MHZ_WIDTH &&
nla_put_flag(msg, NL80211_RATE_INFO_160_MHZ_WIDTH))
return false;
if (info->flags & RATE_INFO_FLAGS_SHORT_GI &&
nla_put_flag(msg, NL80211_RATE_INFO_SHORT_GI))
return false;
}

nla_nest_end(msg, rate);
return true;

nla_put_failure:
return false;
}

static int nl80211_send_station(struct sk_buff *msg, u32 portid, u32 seq,
Expand Down Expand Up @@ -5475,6 +5498,11 @@ static int nl80211_join_ibss(struct sk_buff *skb, struct genl_info *info)
if (!cfg80211_reg_can_beacon(&rdev->wiphy, &ibss.chandef))
return -EINVAL;

if (ibss.chandef.width > NL80211_CHAN_WIDTH_40)
return -EINVAL;
if (ibss.chandef.width != NL80211_CHAN_WIDTH_20_NOHT &&
!(rdev->wiphy.features & NL80211_FEATURE_HT_IBSS))

ibss.channel_fixed = !!info->attrs[NL80211_ATTR_FREQ_FIXED];
ibss.privacy = !!info->attrs[NL80211_ATTR_PRIVACY];

Expand Down
74 changes: 73 additions & 1 deletion net/wireless/util.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -944,14 +944,86 @@ static u32 cfg80211_calculate_bitrate_60g(struct rate_info *rate)
return __mcs2bitrate[rate->mcs];
}

static u32 cfg80211_calculate_bitrate_vht(struct rate_info *rate)
{
static const u32 base[4][10] = {
{ 6500000,
13000000,
19500000,
26000000,
39000000,
52000000,
58500000,
65000000,
78000000,
0,
},
{ 13500000,
27000000,
40500000,
54000000,
81000000,
108000000,
121500000,
135000000,
162000000,
180000000,
},
{ 29300000,
58500000,
87800000,
117000000,
175500000,
234000000,
263300000,
292500000,
351000000,
390000000,
},
{ 58500000,
117000000,
175500000,
234000000,
351000000,
468000000,
526500000,
585000000,
702000000,
780000000,
},
};
u32 bitrate;
int idx;

if (WARN_ON_ONCE(rate->mcs > 9))
return 0;

idx = rate->flags & (RATE_INFO_FLAGS_160_MHZ_WIDTH |
RATE_INFO_FLAGS_80P80_MHZ_WIDTH) ? 3 :
rate->flags & RATE_INFO_FLAGS_80_MHZ_WIDTH ? 2 :
rate->flags & RATE_INFO_FLAGS_40_MHZ_WIDTH ? 1 : 0;

bitrate = base[idx][rate->mcs];
bitrate *= rate->nss;

if (rate->flags & RATE_INFO_FLAGS_SHORT_GI)
bitrate = (bitrate / 9) * 10;

/* do NOT round down here */
return (bitrate + 50000) / 100000;
}

u32 cfg80211_calculate_bitrate(struct rate_info *rate)
{
int modulation, streams, bitrate;

if (!(rate->flags & RATE_INFO_FLAGS_MCS))
if (!(rate->flags & RATE_INFO_FLAGS_MCS) &&
!(rate->flags & RATE_INFO_FLAGS_VHT_MCS))
return rate->legacy;
if (rate->flags & RATE_INFO_FLAGS_60G)
return cfg80211_calculate_bitrate_60g(rate);
if (rate->flags & RATE_INFO_FLAGS_VHT_MCS)
return cfg80211_calculate_bitrate_vht(rate);

/* the formula below does only work for MCS values smaller than 32 */
if (WARN_ON_ONCE(rate->mcs >= 32))
Expand Down

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