From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4EC6C43441 for ; Fri, 9 Nov 2018 22:01:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB8F7208A3 for ; Fri, 9 Nov 2018 22:01:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=usp-br.20150623.gappssmtp.com header.i=@usp-br.20150623.gappssmtp.com header.b="HGwpQeCL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AB8F7208A3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=usp.br Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728562AbeKJHn5 (ORCPT ); Sat, 10 Nov 2018 02:43:57 -0500 Received: from mail-qk1-f194.google.com ([209.85.222.194]:42701 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728532AbeKJHn4 (ORCPT ); Sat, 10 Nov 2018 02:43:56 -0500 Received: by mail-qk1-f194.google.com with SMTP id m5so4350066qka.9 for ; Fri, 09 Nov 2018 14:01:25 -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=gyA4qzOls2dsDUjH6ST4e0OKCIbB05c/8v+y7nhk1V4=; b=HGwpQeCLEUulEQrOBOVKkjGIqghtUITOC0ckE/3SfPwmVOobwnI32YUbh85q0awaBQ J+KI1prFWJ98s0gcXVtKOxj/de+HEo+maYiAwDD8g17xuRZQNdZkxqzs55kpE97rWo+R bty1WvAgGS70IJlhXRI4rBWBoIhIGbgFn+shZQMIHMIMIcX3w3c+PYtPLUzR0ywXRp9O 8A2I5r4l0TaCUn1vQn9SufQKeZ3qfBZ5B5tAqvHHwXz10V0O2W+9rvE9tTxKHFDvFZZm bOSyjHRrqGomfR7bIZyjpuAqi+9z7iTFc/xqJoknzS50lmtDwjCBynp/Jobvv8swNAWU n8+Q== 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=gyA4qzOls2dsDUjH6ST4e0OKCIbB05c/8v+y7nhk1V4=; b=fpkEd6iXPXWWIv6o5ZMA8mA8fh17VFRDm6vB2Zu1QhmCxTzAj/tce6EXP1wgO44U/B 6scHYYwacVk1YfpP9WnHrmXw2JO22KPz23fRrtuNkKGzRXPSpMLfpFZSyMCH1akZoRNA KaMaBRLc7aRkNrtFMEcZjtHHNr9OBwWy3IkOwMK+VPwG7zglIJCa2gFtjlxUL0/mu5SM Mj0CiXypRAQ12keGHFcoplazAoaro0PXpFq6KgGB5Xd4G5ncZTBnRw/dESssg9ELFzx/ tmgVev0QjwjIDxW3xFcJeuKD1Y35T/Ci0y/5kJ3m8R0tGke/w7dyH+2lG/wXtEI85X0v oB6w== X-Gm-Message-State: AGRZ1gIDze/I1HxrYmL/NZC4TZS/D1GJhNkVgcRKRoCkghtIJwfD1niO h3rlJAvaEWAYM/cvhUlhofQfng== X-Google-Smtp-Source: AJdET5f/KLCnyHZgNED3vTKjaHsL92kTxzZbo0naegSsvxqoT1sye/7PBziFZKD7fn84V6S3TfMUWQ== X-Received: by 2002:ac8:2b99:: with SMTP id m25mr7214545qtm.36.1541800885112; Fri, 09 Nov 2018 14:01:25 -0800 (PST) Received: from mango.spo.virtua.com.br ([2804:14c:81:942d::1]) by smtp.gmail.com with ESMTPSA id k6sm6082723qtk.41.2018.11.09.14.01.21 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Nov 2018 14:01:24 -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 3/6] staging:iio:ad2s90: Add max frequency check at probe Date: Fri, 9 Nov 2018 20:00:41 -0200 Message-Id: <20181109220044.24843-4-matheus.bernardino@usp.br> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20181109220044.24843-1-matheus.bernardino@usp.br> References: <20181109220044.24843-1-matheus.bernardino@usp.br> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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: Matheus Tavares Signed-off-by: Alexandru Ardelean --- Alex's S-o-B was added because he gave the code suggestion for this patch. 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 95c118c48400..949ff55ac6b0 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; -- 2.18.0