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=-7.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED 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 BCF63ECE560 for ; Sun, 16 Sep 2018 11:32:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5EF4721476 for ; Sun, 16 Sep 2018 11:32:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="VBY8WI9n" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5EF4721476 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 S1728232AbeIPQzG (ORCPT ); Sun, 16 Sep 2018 12:55:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:45800 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726859AbeIPQzG (ORCPT ); Sun, 16 Sep 2018 12:55:06 -0400 Received: from archlinux (cpc91196-cmbg18-2-0-cust659.5-4.cable.virginm.net [81.96.234.148]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 94E8520867; Sun, 16 Sep 2018 11:32:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1537097547; bh=Lpd7+9rXkM8lNUyIUkpXIOXsmP7Ig8wQCkbBZeCWxP4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VBY8WI9nHmDMQSG2ufc0pelNmkc+r8hE2/GlMzf1vUsU4uKhF0Jte2qT3OoJekY7p quxbzdcOVaMuRgooIg9EEVQfr8+zLv/trmP1UBFrSVUmMjz7uTCI9Ay6YyAYSfwMKb datP/14zNukYArOaJvv5GywAwcOyfqkn94SdIWgI= Date: Sun, 16 Sep 2018 12:32:22 +0100 From: Jonathan Cameron To: David Lechner Cc: linux-spi@vger.kernel.org, linux-iio@vger.kernel.org, Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , Mark Brown , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/4] spi: add software implementation for SPI_CS_WORD Message-ID: <20180916123222.67136773@archlinux> In-Reply-To: <20180913003920.30600-3-david@lechnology.com> References: <20180913003920.30600-1-david@lechnology.com> <20180913003920.30600-3-david@lechnology.com> X-Mailer: Claws Mail 3.17.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 12 Sep 2018 19:39:18 -0500 David Lechner wrote: > This adds a default software implementation for the SPI_CS_WORD flag for > controllers that don't have such a feature. > > The SPI_CS_WORD flag indicates that the CS line should be toggled > between each word sent, not just between each transfer. The > implementation works by using existing functions to split transfers into > one-word-sized transfers and sets the cs_change bit for each of the > new transfers. > > Signed-off-by: David Lechner Looks good to me but I'm not that familiar with this code.. Acked-by: Jonathan Cameron > --- > drivers/spi/spi.c | 31 +++++++++++++++++++++++++++++++- > 1 file changed, 30 insertions(+), 1 deletion(-) > > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > index 9da0bc5a036c..84518ed58872 100644 > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -2783,8 +2783,10 @@ int spi_setup(struct spi_device *spi) > return -EINVAL; > /* help drivers fail *cleanly* when they need options > * that aren't supported with their current controller > + * SPI_CS_WORD has a fallback software implementation, > + * so it is ignored here. > */ > - bad_bits = spi->mode & ~spi->controller->mode_bits; > + bad_bits = spi->mode & ~(spi->controller->mode_bits | SPI_CS_WORD); > ugly_bits = bad_bits & > (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD); > if (ugly_bits) { > @@ -2838,6 +2840,33 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message) > if (list_empty(&message->transfers)) > return -EINVAL; > > + /* If an SPI controller does not support toggling the CS line on each > + * transfer (indicated by the SPI_CS_WORD flag), we can emulate it by > + * splitting transfers into one-word transfers and ensuring that > + * cs_change is set for each transfer. > + */ > + if ((spi->mode & SPI_CS_WORD) && !(ctlr->mode_bits & SPI_CS_WORD)) { > + size_t maxsize; > + int ret; > + > + maxsize = (spi->bits_per_word + 7) / 8; > + > + /* spi_split_transfers_maxsize() requires message->spi */ > + message->spi = spi; > + > + ret = spi_split_transfers_maxsize(ctlr, message, maxsize, > + GFP_KERNEL); > + if (ret) > + return ret; > + > + list_for_each_entry(xfer, &message->transfers, transfer_list) { > + /* don't change cs_change on the last entry in the list */ > + if (list_is_last(&xfer->transfer_list, &message->transfers)) > + break; > + xfer->cs_change = 1; > + } > + } > + > /* Half-duplex links include original MicroWire, and ones with > * only one data pin like SPI_3WIRE (switches direction) or where > * either MOSI or MISO is missing. 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