From patchwork Sun Mar 24 17:49:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Sperl X-Patchwork-Id: 10867625 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 412601575 for ; Sun, 24 Mar 2019 17:50:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2BB3B28870 for ; Sun, 24 Mar 2019 17:50:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1F962292C0; Sun, 24 Mar 2019 17:50:27 +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,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 BCFA1290DB for ; Sun, 24 Mar 2019 17:50:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728882AbfCXRuZ (ORCPT ); Sun, 24 Mar 2019 13:50:25 -0400 Received: from 212-186-180-163.static.upcbusiness.at ([212.186.180.163]:53112 "EHLO cgate.sperl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728878AbfCXRuY (ORCPT ); Sun, 24 Mar 2019 13:50:24 -0400 Received: from hc1.intern.sperl.org (account martin@sperl.org [10.10.10.59] verified) by sperl.org (CommuniGate Pro SMTP 6.2.1 _community_) with ESMTPSA id 7759428; Sun, 24 Mar 2019 17:50:11 +0000 From: kernel@martin.sperl.org To: Mark Brown , Eric Anholt , Stefan Wahren , Hubert Denkmair , linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Cc: Martin Sperl Subject: [PATCH V2 6/9] spi: bcm2835aux: warn in dmesg that native cs is not really supported Date: Sun, 24 Mar 2019 17:49:59 +0000 Message-Id: <20190324175002.28969-7-kernel@martin.sperl.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190324175002.28969-1-kernel@martin.sperl.org> References: <20190324175002.28969-1-kernel@martin.sperl.org> Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Martin Sperl From personal bad experience (even as the author of the original driver) it shows that native-cs is "somewhat" supported by the spi bus driver when using a buggy device tree. So make sure that the driver is warning in dmesg about this fact that we are running in a not supported mode that may have surprizing limitations. Signed-off-by: Martin Sperl Fixes: 1ea29b39f4c812ece2f936065a0a3d6fe44a263e --- drivers/spi/spi-bcm2835aux.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) -- 2.11.0 diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c index c8acde017b6a..6af07dec5fdc 100644 --- a/drivers/spi/spi-bcm2835aux.c +++ b/drivers/spi/spi-bcm2835aux.c @@ -396,6 +396,38 @@ static void bcm2835aux_spi_handle_err(struct spi_master *master, bcm2835aux_spi_reset_hw(bs); } +static int bcm2835aux_spi_setup(struct spi_device *spi) +{ + int ret; + + if (spi->mode & SPI_NO_CS) + return 0; + /* sanity check for native cs */ + if (!gpio_is_valid(spi->cs_gpio)) { + /* for dt-backwards compatibility: only support native on CS0 + * known things not supported with broken native CS: + * * multiple chip-selects: cs0-cs2 are all + * simultaniously asserted whenever there is a transfer + * this even includes SPI_NO_CS + * * SPI_CS_HIGH: cs are always asserted low + * * cs_change: cs is deasserted after each spi_transfer + * * cs_delay_usec: cs is always deasserted one SCK cycle + * after the last transfer + * probably more... + */ + if (spi->chip_select == 0) { + dev_err(&spi->dev, + "native CS is not supported but may work for some use-cases for cs = 0 - please define a valid value cs-gpios in DT for complete feature set\n"); + return 0; + } + dev_err(&spi->dev, + "native CS is not supported for cs > 0 - please define a valid value cs-gpios in DT to enable multiple cs\n"); + return -EINVAL; + } + + return 0; +} + static int bcm2835aux_spi_probe(struct platform_device *pdev) { struct spi_master *master; @@ -425,6 +457,7 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev) * a spi_transfer */ master->num_chipselect = 1; + master->setup = bcm2835aux_spi_setup; master->transfer_one = bcm2835aux_spi_transfer_one; master->handle_err = bcm2835aux_spi_handle_err; master->prepare_message = bcm2835aux_spi_prepare_message;