From patchwork Mon Dec 19 17:17:13 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hanna Hawa X-Patchwork-Id: 635327 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 64FF5C4332F for ; Mon, 19 Dec 2022 17:17:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231531AbiLSRRo (ORCPT ); Mon, 19 Dec 2022 12:17:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232215AbiLSRRi (ORCPT ); Mon, 19 Dec 2022 12:17:38 -0500 Received: from smtp-fw-6002.amazon.com (smtp-fw-6002.amazon.com [52.95.49.90]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6C5365C0; Mon, 19 Dec 2022 09:17:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1671470258; x=1703006258; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=pgUvBnVCbGJYeuahVflnK3XdhoiYPjLg+A5dzxEHAs4=; b=aRSkQ4S+HFg0jBUYwVIa7SjU3gaQ70eGHh0jj0L357rO9v+T4xlEMEp8 zGR/DDIqfpIiHauRxvp6rXgsX1wB6hj6k3TLJuAQOH5agPy9ZANE1mTYR WfkDo9J7LaevU+7dKrdYJBnhGmwDZy9OWxIyP76apNluqfXAAy4RW4u8N Q=; X-IronPort-AV: E=Sophos;i="5.96,257,1665446400"; d="scan'208";a="278734712" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-pdx-2c-m6i4x-f7c754c9.us-west-2.amazon.com) ([10.43.8.6]) by smtp-border-fw-6002.iad6.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Dec 2022 17:17:37 +0000 Received: from EX13D42EUA004.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan3.pdx.amazon.com [10.236.137.198]) by email-inbound-relay-pdx-2c-m6i4x-f7c754c9.us-west-2.amazon.com (Postfix) with ESMTPS id 1CD7341648; Mon, 19 Dec 2022 17:17:35 +0000 (UTC) Received: from EX19D019EUA002.ant.amazon.com (10.252.50.84) by EX13D42EUA004.ant.amazon.com (10.43.165.34) with Microsoft SMTP Server (TLS) id 15.0.1497.42; Mon, 19 Dec 2022 17:17:33 +0000 Received: from dev-dsk-hhhawa-1b-84e0d7ff.eu-west-1.amazon.com (10.43.161.114) by EX19D019EUA002.ant.amazon.com (10.252.50.84) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.1118.20; Mon, 19 Dec 2022 17:17:28 +0000 From: Hanna Hawa To: , , , , , , CC: , , , , , , , , , Subject: [PATCH v3 1/1] i2c: designware: use casting of u64 in clock multiplication to avoid overflow Date: Mon, 19 Dec 2022 17:17:13 +0000 Message-ID: <20221219171713.10108-1-hhhawa@amazon.com> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 X-Originating-IP: [10.43.161.114] X-ClientProxiedBy: EX13D19UWA003.ant.amazon.com (10.43.160.170) To EX19D019EUA002.ant.amazon.com (10.252.50.84) Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org From: Lareine Khawaly In functions i2c_dw_scl_lcnt() and i2c_dw_scl_hcnt() may have overflow by depending on the values of the given parameters including the ic_clk. For example in our use case where ic_clk is larger than one million, multiplication of ic_clk * 4700 will result in 32 bit overflow. Add cast of u64 to the calculation to avoid multiplication overflow, and use the corresponding define for divide. Fixes: 2373f6b9744d ("i2c-designware: split of i2c-designware.c into core and bus specific parts") Signed-off-by: Lareine Khawaly Signed-off-by: Hanna Hawa Change Log v2->v3: - Avoid changing the ic_clk parameter to u64, and do casting in the calculation itself instead. - use DIV_ROUND_CLOSEST_ULL instead of DIV_ROUND_CLOSEST Change Log v1->v2: - Update commit message and add fix tag. --- drivers/i2c/busses/i2c-designware-common.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c index e0a46dfd1c15..9cc02d0142df 100644 --- a/drivers/i2c/busses/i2c-designware-common.c +++ b/drivers/i2c/busses/i2c-designware-common.c @@ -351,7 +351,8 @@ u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset) * * If your hardware is free from tHD;STA issue, try this one. */ - return DIV_ROUND_CLOSEST(ic_clk * tSYMBOL, MICRO) - 8 + offset; + return DIV_ROUND_CLOSEST_ULL((u64)ic_clk * tSYMBOL, + MICRO) - 8 + offset; else /* * Conditional expression: @@ -367,7 +368,8 @@ u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset) * The reason why we need to take into account "tf" here, * is the same as described in i2c_dw_scl_lcnt(). */ - return DIV_ROUND_CLOSEST(ic_clk * (tSYMBOL + tf), MICRO) - 3 + offset; + return DIV_ROUND_CLOSEST_ULL((u64)ic_clk * (tSYMBOL + tf), + MICRO) - 3 + offset; } u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset) @@ -383,7 +385,8 @@ u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset) * account the fall time of SCL signal (tf). Default tf value * should be 0.3 us, for safety. */ - return DIV_ROUND_CLOSEST(ic_clk * (tLOW + tf), MICRO) - 1 + offset; + return DIV_ROUND_CLOSEST_ULL((u64)ic_clk * (tLOW + tf), + MICRO) - 1 + offset; } int i2c_dw_set_sda_hold(struct dw_i2c_dev *dev)