From patchwork Thu Sep 15 00:41:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bryan O'Donoghue X-Patchwork-Id: 12976736 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2992C6FA8A for ; Thu, 15 Sep 2022 00:41:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230191AbiIOAl3 (ORCPT ); Wed, 14 Sep 2022 20:41:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230152AbiIOAl1 (ORCPT ); Wed, 14 Sep 2022 20:41:27 -0400 Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 906B28708A for ; Wed, 14 Sep 2022 17:41:26 -0700 (PDT) Received: by mail-wm1-x331.google.com with SMTP id az24-20020a05600c601800b003a842e4983cso12762765wmb.0 for ; Wed, 14 Sep 2022 17:41:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date; bh=FA6FZ814jhwKtiNB3fDGO6OHKlGHF/CZ20X5ABmDnJY=; b=e3EotmICuvn2jp0ftJmC1IKHs7ce/fHQ2Avstne5EoNlNQyyVnMfGkA+gN60FhDh0d MNje9y3OV4JEHlKk6apbNF6rfnJLYDjIPT0tSyespgTtA8nv5vQgHHgntAJbQN/A5NlX YOXqmwG3QlVFk2mv2BbBN5zq38V8ZGmrLFalY3onUu1H/1B31RN9zz9NVMCDeK+zNi42 vi1HjXEHXo+hQy650d8GAsQ2XxcC48ny1B/kRr4aJ3oJSzioR7T9yO1WY/5SeDGAONXH i6JnlheMJ/8QQKrKppgQ1oJnrqpea5hX1XRQSeh9dwO+cjh0HuId6MCFS3WptMUTMbJo E4nA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date; bh=FA6FZ814jhwKtiNB3fDGO6OHKlGHF/CZ20X5ABmDnJY=; b=5PfNLDYXrtOUynFglv0Wh14cUgxRVvqvw7luOB29mVsiBfng394LG4qS4xJTiMCVdn h5PyZh6AZ+ZIyoxvAykBHNO+X7sw3Jr+j1ueSkWexVnN+MLaxNZ/KmopL+is8NjYeSnw ELlSqpPG01lZmmBcyn7qBTJuBc8Yc46ZPyjxhfuMCis4YgOyE83ftEv/veiAoTLbqheD cxBEm0B9294oIpjBm7vq4jqFtI5kfd2+MXyG+y+7mLPMFv8aDPY9klEP3mnAsOlxH7CM IC2xUqSv2y0W94dNl67PyW73MTXgeScxlxPuwul9RdZmE3hayJaK7mRcQ8/bNX0lQOBe HgCw== X-Gm-Message-State: ACgBeo2HIVjOQpGYng5J2hyqqG9eKKwJbIuUYLBGLWUj8phErjIxlj1+ qi73/QT5o7v64stu1KRxJfXAUg== X-Google-Smtp-Source: AA6agR7q6zVRLTmce+4BE3c7kuhYUQ63KrypCmfOKBdCEaNKyZaaCnos7nHE34rDGTlkVtMOvKgqsA== X-Received: by 2002:a05:600c:3acd:b0:3b4:88ba:a75f with SMTP id d13-20020a05600c3acd00b003b488baa75fmr4783088wms.140.1663202485144; Wed, 14 Sep 2022 17:41:25 -0700 (PDT) Received: from sagittarius-a.chello.ie (188-141-3-169.dynamic.upc.ie. [188.141.3.169]) by smtp.gmail.com with ESMTPSA id d8-20020adfef88000000b002250c35826dsm645476wro.104.2022.09.14.17.41.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Sep 2022 17:41:24 -0700 (PDT) From: Bryan O'Donoghue To: loic.poulain@linaro.org, kvalo@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: wcn36xx@lists.infradead.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, bryan.odonoghue@linaro.org, "Jason A . Donenfeld" Subject: [PATCH v3 1/1] wcn36xx: Add RX frame SNR as a source of system entropy Date: Thu, 15 Sep 2022 01:41:17 +0100 Message-Id: <20220915004117.1562703-2-bryan.odonoghue@linaro.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220915004117.1562703-1-bryan.odonoghue@linaro.org> References: <20220915004117.1562703-1-bryan.odonoghue@linaro.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org The signal-to-noise-ratio SNR is returned by the wcn36xx firmware for each received frame. SNR represents all of the unwanted interference signal after filtering out the fundamental frequency and harmonics of the frequency. Noise can come from various electromagnetic sources, from temperature affecting the performance hardware components or quantization effects converting from analog to digital domains. The SNR value returned by the WiFi firmware then is a good source of entropy. Other WiFi drivers offer up the noise component of the FFT as an entropy source for the random pool e.g. commit 2aa56cca3571 ("ath9k: Mix the received FFT bins to the random pool") I attended Jason's talk on sources of randomness at Plumbers and it occurred to me that SNR is a reasonable candidate to add. Cc: Jason A. Donenfeld Signed-off-by: Bryan O'Donoghue --- drivers/net/wireless/ath/wcn36xx/txrx.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/wireless/ath/wcn36xx/txrx.c b/drivers/net/wireless/ath/wcn36xx/txrx.c index 8da3955995b6e..0802ed7288249 100644 --- a/drivers/net/wireless/ath/wcn36xx/txrx.c +++ b/drivers/net/wireless/ath/wcn36xx/txrx.c @@ -16,6 +16,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include #include "txrx.h" static inline int get_rssi0(struct wcn36xx_rx_bd *bd) @@ -278,6 +279,7 @@ static void wcn36xx_update_survey(struct wcn36xx *wcn, int rssi, int snr, struct ieee80211_supported_band *sband; int idx; int i; + u8 snr_sample = snr & 0xff; idx = 0; if (band == NL80211_BAND_5GHZ) @@ -297,6 +299,8 @@ static void wcn36xx_update_survey(struct wcn36xx *wcn, int rssi, int snr, wcn->chan_survey[idx].rssi = rssi; wcn->chan_survey[idx].snr = snr; spin_unlock(&wcn->survey_lock); + + add_device_randomness(&snr_sample, sizeof(snr_sample)); } int wcn36xx_rx_skb(struct wcn36xx *wcn, struct sk_buff *skb)