From patchwork Fri Feb 18 14:58:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tudor Ambarus X-Patchwork-Id: 12751529 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 E1DD8C433FE for ; Fri, 18 Feb 2022 15:01:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236365AbiBRPBt (ORCPT ); Fri, 18 Feb 2022 10:01:49 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:50524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236789AbiBRPAY (ORCPT ); Fri, 18 Feb 2022 10:00:24 -0500 Received: from esa.microchip.iphmx.com (esa.microchip.iphmx.com [68.232.153.233]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E5F3E61C0; Fri, 18 Feb 2022 06:59:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1645196349; x=1676732349; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=1kB/UXvtaiyeXTg8NuvWf/Arx24JYsUgr40cN0Fyi6s=; b=TdnaZrZsh2FuRviuIhCzd4htnrysYkQibMjtwxBWtx+e7t0qF7GZSZXV DRdcB9F9STv/GFK7yauuqbFxBHV0nsD5ssBJbaPTRgueq9QlS4nktj+SB H91ELhbbSikBpJIq1MzIxoAYMCe21UJ/MYN2QvBpeJteqBcRWpnsH8Q0h gD8+y+TwOeGZNxLy5gf2JDImmouOOKK8EGzkzDPj8+EM3XCKEvpoH5PWV j0/T8fjvqsEdaMoueku18Tx+h9SS2PJGx1/08+oe+apW4D9XvhoQUI5mW Y1sLllrfYouK46McTrWZuqq6bfjCNQPZOlYn9OyqOnUNQ9EnyUbQMiIY1 g==; X-IronPort-AV: E=Sophos;i="5.88,379,1635231600"; d="scan'208";a="154088331" Received: from smtpout.microchip.com (HELO email.microchip.com) ([198.175.253.82]) by esa3.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 18 Feb 2022 07:59:08 -0700 Received: from chn-vm-ex02.mchp-main.com (10.10.85.144) by chn-vm-ex01.mchp-main.com (10.10.85.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.17; Fri, 18 Feb 2022 07:59:08 -0700 Received: from ROB-ULT-M18064N.mchp-main.com (10.10.115.15) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server id 15.1.2375.17 via Frontend Transport; Fri, 18 Feb 2022 07:59:05 -0700 From: Tudor Ambarus To: , , CC: , , , , , , , , , Tudor Ambarus Subject: [PATCH 1/4] spi: spi-mem: Allow specifying the byte order in DTR mode Date: Fri, 18 Feb 2022 16:58:57 +0200 Message-ID: <20220218145900.1440045-2-tudor.ambarus@microchip.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220218145900.1440045-1-tudor.ambarus@microchip.com> References: <20220218145900.1440045-1-tudor.ambarus@microchip.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org There are NOR flashes (Macronix) that swap the bytes on a 16-bit boundary when configured in DTR mode. The byte order of 16-bit words is swapped when read or written in Double Transfer Rate (DTR) mode compared to Single Transfer Rate (STR) mode. If one writes D0 D1 D2 D3 bytes using 1-1-1 mode, and uses 8D-8D-8D SPI mode for reading, it will read back D1 D0 D3 D2. Swapping the bytes is a bad design decision because this may introduce some endianness problems. It can affect the boot sequence if the entire boot sequence is not handled in either 8D-8D-8D mode or 1-1-1 mode. Fortunately there are controllers that can swap back the bytes at runtime, fixing the endiannesses. Provide a way for the upper layers to specify the byte order in DTR mode. Signed-off-by: Tudor Ambarus --- include/linux/spi/spi-mem.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h index 85e2ff7b840d..e1878417420c 100644 --- a/include/linux/spi/spi-mem.h +++ b/include/linux/spi/spi-mem.h @@ -89,6 +89,8 @@ enum spi_mem_data_dir { * @dummy.dtr: whether the dummy bytes should be sent in DTR mode or not * @data.buswidth: number of IO lanes used to send/receive the data * @data.dtr: whether the data should be sent in DTR mode or not + * @data.dtr_bswap16: whether the byte order of 16-bit words is swapped when + * read or written in DTR mode compared to STR mode. * @data.dir: direction of the transfer * @data.nbytes: number of data bytes to send/receive. Can be zero if the * operation does not involve transferring data @@ -119,6 +121,7 @@ struct spi_mem_op { struct { u8 buswidth; u8 dtr : 1; + u8 dtr_bswap16 : 1; enum spi_mem_data_dir dir; unsigned int nbytes; union {