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/* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause */
/*
* Copyright (C) 2024-2025 Intel Corporation
*/
#include <net/gso.h>
#include <linux/ieee80211.h>
#include <net/ip.h>
#include "iwl-drv.h"
#include "iwl-utils.h"
#ifdef CONFIG_INET
int iwl_tx_tso_segment(struct sk_buff *skb, unsigned int num_subframes,
netdev_features_t netdev_flags,
struct sk_buff_head *mpdus_skbs)
{
struct sk_buff *tmp, *next;
struct ieee80211_hdr *hdr = (void *)skb->data;
char cb[sizeof(skb->cb)];
u16 i = 0;
unsigned int tcp_payload_len;
unsigned int mss = skb_shinfo(skb)->gso_size;
bool ipv4 = (skb->protocol == htons(ETH_P_IP));
bool qos = ieee80211_is_data_qos(hdr->frame_control);
u16 ip_base_id = ipv4 ? ntohs(ip_hdr(skb)->id) : 0;
skb_shinfo(skb)->gso_size = num_subframes * mss;
memcpy(cb, skb->cb, sizeof(cb));
next = skb_gso_segment(skb, netdev_flags);
skb_shinfo(skb)->gso_size = mss;
skb_shinfo(skb)->gso_type = ipv4 ? SKB_GSO_TCPV4 : SKB_GSO_TCPV6;
if (IS_ERR(next) && PTR_ERR(next) == -ENOMEM)
return -ENOMEM;
if (WARN_ONCE(IS_ERR(next),
"skb_gso_segment error: %d\n", (int)PTR_ERR(next)))
return PTR_ERR(next);
if (next)
consume_skb(skb);
skb_list_walk_safe(next, tmp, next) {
memcpy(tmp->cb, cb, sizeof(tmp->cb));
/*
* Compute the length of all the data added for the A-MSDU.
* This will be used to compute the length to write in the TX
* command. We have: SNAP + IP + TCP for n -1 subframes and
* ETH header for n subframes.
*/
tcp_payload_len = skb_tail_pointer(tmp) -
skb_transport_header(tmp) -
tcp_hdrlen(tmp) + tmp->data_len;
if (ipv4)
ip_hdr(tmp)->id = htons(ip_base_id + i * num_subframes);
if (tcp_payload_len > mss) {
skb_shinfo(tmp)->gso_size = mss;
skb_shinfo(tmp)->gso_type = ipv4 ? SKB_GSO_TCPV4 :
SKB_GSO_TCPV6;
} else {
if (qos) {
u8 *qc;
if (ipv4)
ip_send_check(ip_hdr(tmp));
qc = ieee80211_get_qos_ctl((void *)tmp->data);
*qc &= ~IEEE80211_QOS_CTL_A_MSDU_PRESENT;
}
skb_shinfo(tmp)->gso_size = 0;
}
skb_mark_not_on_list(tmp);
__skb_queue_tail(mpdus_skbs, tmp);
i++;
}
return 0;
}
IWL_EXPORT_SYMBOL(iwl_tx_tso_segment);
#endif /* CONFIG_INET */
static u32 iwl_div_by_db(u32 value, u8 db)
{
/*
* 2^32 * 10**(i / 10) for i = [1, 10], skipping 0 and simply stopping
* at 10 dB and looping instead of using a much larger table.
*
* Using 64 bit math is overkill, but means the helper does not require
* a limit on the input range.
*/
static const u32 db_to_val[] = {
0xcb59185e, 0xa1866ba8, 0x804dce7a, 0x65ea59fe, 0x50f44d89,
0x404de61f, 0x331426af, 0x2892c18b, 0x203a7e5b, 0x1999999a,
};
while (value && db > 0) {
u8 change = min_t(u8, db, ARRAY_SIZE(db_to_val));
value = (((u64)value) * db_to_val[change - 1]) >> 32;
db -= change;
}
return value;
}
s8 iwl_average_neg_dbm(const u8 *neg_dbm_values, u8 len)
{
int average_magnitude;
u32 average_factor;
int sum_magnitude = -128;
u32 sum_factor = 0;
int i, count = 0;
/*
* To properly average the decibel values (signal values given in dBm)
* we need to do the math in linear space. Doing a linear average of
* dB (dBm) values is a bit annoying though due to the large range of
* at least -10 to -110 dBm that will not fit into a 32 bit integer.
*
* A 64 bit integer should be sufficient, but then we still have the
* problem that there are no directly usable utility functions
* available.
*
* So, lets not deal with that and instead do much of the calculation
* with a 16.16 fixed point integer along with a base in dBm. 16.16 bit
* gives us plenty of head-room for adding up a few values and even
* doing some math on it. And the tail should be accurate enough too
* (1/2^16 is somewhere around -48 dB, so effectively zero).
*
* i.e. the real value of sum is:
* sum = sum_factor / 2^16 * 10^(sum_magnitude / 10) mW
*
* However, that does mean we need to be able to bring two values to
* a common base, so we need a helper for that.
*
* Note that this function takes an input with unsigned negative dBm
* values but returns a signed dBm (i.e. a negative value).
*/
for (i = 0; i < len; i++) {
int val_magnitude;
u32 val_factor;
/* Assume invalid */
if (neg_dbm_values[i] == 0xff)
continue;
val_factor = 0x10000;
val_magnitude = -neg_dbm_values[i];
if (val_magnitude <= sum_magnitude) {
u8 div_db = sum_magnitude - val_magnitude;
val_factor = iwl_div_by_db(val_factor, div_db);
val_magnitude = sum_magnitude;
} else {
u8 div_db = val_magnitude - sum_magnitude;
sum_factor = iwl_div_by_db(sum_factor, div_db);
sum_magnitude = val_magnitude;
}
sum_factor += val_factor;
count++;
}
/* No valid noise measurement, return a very high noise level */
if (count == 0)
return 0;
average_magnitude = sum_magnitude;
average_factor = sum_factor / count;
/*
* average_factor will be a number smaller than 1.0 (0x10000) at this
* point. What we need to do now is to adjust average_magnitude so that
* average_factor is between -0.5 dB and 0.5 dB.
*
* Just do -1 dB steps and find the point where
* -0.5 dB * -i dB = 0x10000 * 10^(-0.5/10) / i dB
* = div_by_db(0xe429, i)
* is smaller than average_factor.
*/
for (i = 0; average_factor < iwl_div_by_db(0xe429, i); i++) {
/* nothing */
}
return clamp(average_magnitude - i, -128, 0);
}
IWL_EXPORT_SYMBOL(iwl_average_neg_dbm);
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