From patchwork Sat Nov 24 00:23:08 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matheus Tavares X-Patchwork-Id: 10696401 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 06497175A for ; Sat, 24 Nov 2018 00:24:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E9E6D2B437 for ; Sat, 24 Nov 2018 00:24:15 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DD7972B5D7; Sat, 24 Nov 2018 00:24:15 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 74D332B437 for ; Sat, 24 Nov 2018 00:24:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728269AbeKXLKB (ORCPT ); Sat, 24 Nov 2018 06:10:01 -0500 Received: from mail-qt1-f195.google.com ([209.85.160.195]:44015 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728266AbeKXLKA (ORCPT ); Sat, 24 Nov 2018 06:10:00 -0500 Received: by mail-qt1-f195.google.com with SMTP id i7so12055440qtj.10 for ; Fri, 23 Nov 2018 16:23:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=usp-br.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=5hn8QyLV53KfTj8TSZxKFEiF2d3t53n213nmb376iXM=; b=Sve25buHyKAXVnsqGlNQdjsWiFBcs4WBwtUm+K7XC/FuWEpfVXHJ9qmR9+mvw0EniD WCd05thH3TKNycbEkH9NHiLN+tUEx3QrbbkCKAM8zlXM00wK96XIhZqHFMmFxIrTJzQC GgJQC65D41JbgKvUCm7K12WEd2MZeYMdmvnlh2iIR89e9M9pVLkuuoVF7tYzdJ9U1Mhh 6zVeWQHn3+X/ynGQZyaZij62cTYD8Kk8CpFyBuZg2Eia6AHc+bWp/o+EFbLrf7KO1ID6 9NRtRbCV4m2eYZB0T1FL3U19Owod4gL1hy2mqC0G0pe8VJwH6so4IuL+rNrCnTK+MHuF tqKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=5hn8QyLV53KfTj8TSZxKFEiF2d3t53n213nmb376iXM=; b=aRG3R/Ll3j3B0lmhqoPr8QHsZKMEyqedn98pVjj6c+9a2vy/M1gBUYEe1GVdin70nD 1uFlwtBTGuwywA/pDmuVvNfvdmJ4iSlhzdNUKv9AVROsm1tTR6JQcP7A8tPTJDY0TNrH M97Ay251EG7LZ8kt/13sonEErS2QkIfqFRRI41zb5iy0JDdDLlqvNleZGp2yvSvG4r6F bdLzLwhOhvUEzysnIdnnB5bqNuBFTf7Tin5hraIREsuR8WUEX8VYciop0eSqcgv+jIeo hkQesFUUigteGOv/CfSTsR+uKBa02pjZFaMqn6x5SzkGx6M43+Zz6/ZmNdvG4PkLOPuA iuBg== X-Gm-Message-State: AGRZ1gIHYWGVqN7U1lwYl0OjYbeoTonjEGADh9NITSn/9Qc+km0+VTHY NRE8zU4kwkYZyBC9Y1B9dF97mQ== X-Google-Smtp-Source: AJdET5fX6exuYRx/hMZr/sAOy6Fhch0BZ38+A8farzbkOxWnDMsZNFhaS/ME7aJOhAPtYTzjJCx32A== X-Received: by 2002:ac8:4258:: with SMTP id r24mr16959175qtm.213.1543019018603; Fri, 23 Nov 2018 16:23:38 -0800 (PST) Received: from mango.spo.virtua.com.br ([2804:14c:81:942d::3]) by smtp.gmail.com with ESMTPSA id o34sm26707515qte.4.2018.11.23.16.23.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 Nov 2018 16:23:38 -0800 (PST) From: Matheus Tavares To: Lars-Peter Clausen , Michael Hennerich , Jonathan Cameron , Hartmut Knaack , Peter Meerwald-Stadler , Greg Kroah-Hartman , Rob Herring , Mark Rutland Cc: linux-iio@vger.kernel.org, devel@driverdev.osuosl.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Alexandru Ardelean , kernel-usp@googlegroups.com, victorcolombo@gmail.com Subject: [PATCH v3 3/7] staging:iio:ad2s90: Add max frequency check at probe Date: Fri, 23 Nov 2018 22:23:08 -0200 Message-Id: <20181124002312.6923-4-matheus.bernardino@usp.br> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20181124002312.6923-1-matheus.bernardino@usp.br> References: <20181124002312.6923-1-matheus.bernardino@usp.br> Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Alexandru Ardelean This patch adds a max frequency check at the beginning of ad2s90_probe function so that when it is set to a value above 0.83Mhz, dev_err is called with an appropriate message and -EINVAL is returned. The defined limit is 0.83Mhz instead of 2Mhz, which is the chip's max frequency as specified in the datasheet, because, as also specified in the datasheet, a 600ns delay is expected between the application of a logic LO to CS and the application of SCLK. Since the delay is not implemented in the spi code, to satisfy it, SCLK's period should be at most 2 * 600ns, so the max frequency should be 1 / (2 * 6e-7), which gives roughly 830000Hz. Signed-off-by: Alexandru Ardelean Signed-off-by: Matheus Tavares --- Changes in v3: - none Changes in v2: - Correctly credit Alexandru as the patch's author drivers/staging/iio/resolver/ad2s90.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/staging/iio/resolver/ad2s90.c b/drivers/staging/iio/resolver/ad2s90.c index abb9b9147ee6..4721e9bbb8b0 100644 --- a/drivers/staging/iio/resolver/ad2s90.c +++ b/drivers/staging/iio/resolver/ad2s90.c @@ -19,6 +19,12 @@ #include #include +/* + * Although chip's max frequency is 2Mhz, it needs 600ns between CS and the + * first falling edge of SCLK, so frequency should be at most 1 / (2 * 6e-7) + */ +#define AD2S90_MAX_SPI_FREQ_HZ 830000 + struct ad2s90_state { struct mutex lock; struct spi_device *sdev; @@ -78,6 +84,12 @@ static int ad2s90_probe(struct spi_device *spi) struct iio_dev *indio_dev; struct ad2s90_state *st; + if (spi->max_speed_hz > AD2S90_MAX_SPI_FREQ_HZ) { + dev_err(&spi->dev, "SPI CLK, %d Hz exceeds %d Hz\n", + spi->max_speed_hz, AD2S90_MAX_SPI_FREQ_HZ); + return -EINVAL; + } + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); if (!indio_dev) return -ENOMEM;