From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f53.google.com (mail-wm1-f53.google.com [209.85.128.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 23B5D365A1A for ; Wed, 22 Apr 2026 21:09:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776892196; cv=none; b=mHTsXulcUSMr0FRUZ008lXkc20YutCTGI324A39sp6kF8vWrHmXLfefh2dm2e+w9FmyHzVsQoXAUcFF6yImieNXw9nEQm7B+PRyID+edm91xKBhIsCsRJWr1AnhbT8vOb6HyLgxreLBGMPXSq/1EobAStXBXnFZyVoIn9jW499w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776892196; c=relaxed/simple; bh=fPUaGhBV9y5Y+5CqPe9ESQSxmwi2xQpZVeZbeoJlQuE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=EpIgr+vyZ/WCttvh0sCzP/rM3c32p6BRIp5U2iGDCh1Sj8C+WVX6XUyKMF+6W7RNtRi1pn5lgHOrewaBhJTZHnD3gAo2km2hnE/WwBr+LydBdXGusO+bROMeijKwywoq2m8CYVQd97AFzzMKiB/1MJ2z71Do4DgN2PYmYPzCPaU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=cL8BQ+LP; arc=none smtp.client-ip=209.85.128.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cL8BQ+LP" Received: by mail-wm1-f53.google.com with SMTP id 5b1f17b1804b1-488a8f97f6bso10996715e9.2 for ; Wed, 22 Apr 2026 14:09:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1776892192; x=1777496992; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=qHDnqtZPzLje7acSFaV39CbG4kFW6b0D4B/rafiqA78=; b=cL8BQ+LPcLC0EFK5+p5xvzMD4/8l6dPWKJ3kgmiMDMOAy6YJUWADOM+5GKA76z7hgl juaydtZmqKp+X47qbH7pLEYia62nTL/kHmdL4ANnUnQRIMH8iwL/pJlSIGUf3Fjo+QRP hsWlyprypIRmHagA3k5PYlFZIXRfqD9jsXDqPItmjrGGmBKm0sulG+fdmyAqKC8tG3o9 YWx83GZPmpXsLyCNzPBQC1DUCTM3a+wgZtTeX0FgspNHHEfW9wQWxkgYghNe48ZGUKzI 6bvDbYBAcnWlKhC04UJmXbwm3PtgHqI5cv7LG+f5gSAryWA9mSb2Gothu6fzhfMA4Ji6 c07A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776892192; x=1777496992; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=qHDnqtZPzLje7acSFaV39CbG4kFW6b0D4B/rafiqA78=; b=IvQhew09bfL3IcL7M9i1EHFPA9N6CjPsBmXkHm2nRLabhAf0nMaTEIUvLBIB7h/rdX Y5SRYCld2G2ta9/4+U3gDjGEKgux6DpQox5Zx27yNDeYFfhR89KpwotvHgbeeVmJZui8 ZpP2I0Fm55lXZe0j+wZKw1vbnzwA3jnV6an9daHKPDLG1RmE69f5qrxSX7VtAUNdKgVF S3E7t+rsNhF1qoT+8gkTlEfRG9P2DvRoWm/RB43+0RK3LzN81G/LGowIb+9qlTgbuepR NA898jUlCxRR+2tP9+qltn+3k1bdhw6dGjzpZj2n1JFcY6h9VA/L6QXOKY30WbXsw1PX v1xQ== X-Gm-Message-State: AOJu0YwxCJrFHZ7tLf83TCwT1Ty/lEcRiXdINYq841RfXkHjQz/Vulhj x/I+nVeBNwafLOB1uBFzrJKERIO+DG4zmCPH+CI+H+tHUzDJPNpdnNt2 X-Gm-Gg: AeBDievkyBrP6TwYGTyv4460CDh/jVgopS22j+YQ5BzqyfeJsEml6F+jhX+OyUOKo7+ dRYN1KyhAT3OaCE85DaR80tOhWPZDGnQu1Z0+MiSOkTg/dQTta+xxA4D64/6ygGBWqBmBA+6h3s +e5B7Yox6wGRi+nIv7wqyJm05g+RNrQsv0j7HFom4UE7EssbPuvFc4TJN7TohyGN22Uls3oHgWl FsDODgSXS7igEHbzhOTpbipoWTsaEPh2wDYLOyMM8lXcE0DPUTWOlCtTh5RYSbf1/MuYjxBJRzV Nz7+47P6Wn3LiGiRDrgkR3ATRt3mzcrgnbODctKV26FJjr/bzr7AR2JmdEyzkq/5sA3TDIy1uCt hKyG3/Nerr37IZNTH/hAgbAbg7R1wyIuSd+0vm8x2rTdsH0JKl4o3MvK5579NEizl+ErbIVpg4H NVeeclNiejskY3Y25swB+WDDwrHpFC2kzjKIZd2jG8VNCVFDD1YmBMXXSXEfgZ0bsw9tvUoACng W/lWKbmW5Gz X-Received: by 2002:a05:600c:4ecb:b0:485:358b:e7ee with SMTP id 5b1f17b1804b1-488fb6e1addmr189465975e9.0.1776892191490; Wed, 22 Apr 2026 14:09:51 -0700 (PDT) Received: from menon.v.cablecom.net (84-74-0-139.dclient.hispeed.ch. [84.74.0.139]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48a4b329542sm352469085e9.3.2026.04.22.14.09.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Apr 2026 14:09:51 -0700 (PDT) From: Lothar Rubusch To: herbert@gondor.apana.org.au, thorsten.blum@linux.dev, davem@davemloft.net, nicolas.ferre@microchip.com, alexandre.belloni@bootlin.com, claudiu.beznea@tuxon.dev, ardb@kernel.org, linusw@kernel.org Cc: linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, l.rubusch@gmail.com Subject: [PATCH v3 3/3] crypto: atmel-sha204a - fix non-blocking read logic Date: Wed, 22 Apr 2026 21:09:36 +0000 Message-Id: <20260422210936.20095-4-l.rubusch@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260422210936.20095-1-l.rubusch@gmail.com> References: <20260422210936.20095-1-l.rubusch@gmail.com> Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The non-blocking path was (also) failing to provide valid entropy due to improper buffer management and a lack of hardware execution time. Ensure cmd.msecs (30ms) and cmd.rxsize (35ms) are initialized before enqueuing the background work. Fix the data offset to skip the 1-byte hardware count header when copying bits to the caller. Correctly return 0 (busy) to the hwrng core while hardware execution is in progress, preventing zero-filled buffers, which was the situation before. With this fix applied, tests will look similar to this: $ socat -u OPEN:/dev/hwrng,nonblock - | head -c 32 | hexdump -C 00000000 23 cc 42 3c 90 b1 38 fc 54 37 35 4b 09 c5 e1 0d |#.B<..8.T75K....| 2026/03/23 14:30:18 socat[858] E read(5, 0x55be363000, 8192): Resource temporarily unavailable 00000010 73 3b af d9 02 70 76 bd 2d 59 4b 12 01 ac ae 2b |s;...pv.-YK....+| 00000020 Fixes: da001fb651b0 ("crypto: atmel-i2c - add support for SHA204A random number generator") Signed-off-by: Lothar Rubusch --- drivers/crypto/atmel-sha204a.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c index f7dc00d0f4cd..04cbf80c1411 100644 --- a/drivers/crypto/atmel-sha204a.c +++ b/drivers/crypto/atmel-sha204a.c @@ -33,7 +33,6 @@ static void atmel_sha204a_rng_done(struct atmel_i2c_work_data *work_data, "i2c transaction failed (%d)\n", status); kfree(work_data); - rng->priv = 0; atomic_dec(&i2c_priv->tfm_count); return; } @@ -49,20 +48,19 @@ static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *data, i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng); - /* Verify if data available from last run */ if (rng->priv) { work_data = (struct atmel_i2c_work_data *)rng->priv; - max = min(sizeof(work_data->cmd.data), max); - memcpy(data, &work_data->cmd.data, max); + max = min_t(size_t, ATMEL_RNG_BLOCK_SIZE, max); + memcpy(data, &work_data->cmd.data[1], max); - /* Now, free memory */ + /* Free memory and clear the in-flight flag */ kfree(work_data); rng->priv = 0; atomic_dec(&i2c_priv->tfm_count); return max; } - /* When a request is still in-flight but not processed */ + /* If a request is still in-flight, return 0 (busy) */ if (atomic_read(&i2c_priv->tfm_count) > 0) return 0; @@ -76,8 +74,14 @@ static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *data, work_data->client = i2c_priv->client; atmel_i2c_init_random_cmd(&work_data->cmd); + + /* Set the execution time for the RNG command (from datasheet) */ + work_data->cmd.msecs = ATMEL_RNG_EXEC_TIME; + work_data->cmd.rxsize = RANDOM_RSP_SIZE; + atmel_i2c_enqueue(work_data, atmel_sha204a_rng_done, rng); + /* Return 0 to indicate 'busy', data will be ready on next call */ return 0; } -- 2.53.0