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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 09CF5C4338F for ; Sun, 8 Aug 2021 01:35:07 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0C69D60F50 for ; Sun, 8 Aug 2021 01:35:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0C69D60F50 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=roeck-us.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:33164 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mCXiS-00074t-Uo for qemu-devel@archiver.kernel.org; Sat, 07 Aug 2021 21:35:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60364) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mCXhe-0006Bc-KX; Sat, 07 Aug 2021 21:34:14 -0400 Received: from mail-ot1-x329.google.com ([2607:f8b0:4864:20::329]:38790) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mCXhc-0001No-RO; Sat, 07 Aug 2021 21:34:14 -0400 Received: by mail-ot1-x329.google.com with SMTP id g5-20020a9d6b050000b02904f21e977c3eso13747490otp.5; Sat, 07 Aug 2021 18:34:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=+9BsIZGgvgPMUOuiQBq2UHEDPz71+8oHL0hrWz+5YBE=; b=rwOVcpdqr5LJYOGQ5VABqXPMN/V/rXxXuMF4f7M3qrq9GmRsPz08Uo7Cya9w7vnflk ZT3/I2W/UUyfY2NZCfEUI/3/qexGcmBIg0zIm/xog02UBjqPAYvpVm+rrEnQSnORLVrk hWQQ15mIlSuEZQyBthcfwh+7TwZZPblyt8X6kDDJ8upgdd/M13RQqkcc4rBSVJQZdYpT rqWZ7OUkB0NENt5qGkeKB1ev2VdY7OwQ/IKdjGMsLM8zEa7oRMSzdubvNlP12cRi9KJW J73/Eq8brkgjO8RyPK0TqSj7N0j303Iiv2VnjxIhGL7Asc2xcr2z6Rs8iluo+A+eB8GL Lnmw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :mime-version:content-transfer-encoding; bh=+9BsIZGgvgPMUOuiQBq2UHEDPz71+8oHL0hrWz+5YBE=; b=SnsmxoE4i3Ti9TaVb7/TVk7xTBTzQPEcmyKgP4rdqzqS2jVNY9s2kTpOOu7mxoBhrE BUdpM7XSGnFCc+j/WtHGz3gLBNMekAWWY4iuf0o+EcKhRzoJ7ZUaX3Y2dZGbN6F8Hk0z VXIt8ySTGnkxTNocgiBnSMBrs0MCaxRsGZdfU/9oq02OSgG/l1MXO3CGnKcV/ZbBZZyw ziwxVsfEPaRRxesijhafuonnCbAvAD1AHF4912B/WD1LHR4Vs1b2/MvNUS/h8NhrQASI wiFz0XQyw6RQKIp2PUKn7O0XbYwcozuWlXPKZ4B1qPGI52Xk6vX5hoG8+Os2uUVQpDS8 KAcA== X-Gm-Message-State: AOAM533u7LmoGd5Z0fO4rqlPRN0O71pDKFu6Qg80+FEroMxirjHTGsUu yHirgaO9Vn38HbriPqwndfw= X-Google-Smtp-Source: ABdhPJzK2IzIJsE9/wrNrCn6bUedjzDsPb0WmgTM2wgifTWb+rj+T58/6zMdxY+bJKyRSgfhZCSGTA== X-Received: by 2002:a05:6830:25c6:: with SMTP id d6mr11570530otu.226.1628386450144; Sat, 07 Aug 2021 18:34:10 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id c26sm2396340otu.38.2021.08.07.18.34.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Aug 2021 18:34:09 -0700 (PDT) From: Guenter Roeck To: Peter Maydell Subject: [PATCH] hw/ssi: imx_spi: Improve chip select handling Date: Sat, 7 Aug 2021 18:34:06 -0700 Message-Id: <20210808013406.223506-1-linux@roeck-us.net> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::329; envelope-from=groeck7@gmail.com; helo=mail-ot1-x329.google.com X-Spam_score_int: -12 X-Spam_score: -1.3 X-Spam_bar: - X-Spam_report: (-1.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FORGED_FROMDOMAIN=0.248, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alistair Francis , Guenter Roeck , qemu-devel@nongnu.org, qemu-arm@nongnu.org, Jean-Christophe Dubois Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The control register does not really have a means to deselect all chip selects directly. As result, CS is effectively never deselected, and connected flash chips fail to perform read operations since they don't get the expected chip select signals to reset their state machine. Normally and per controller documentation one would assume that chip select should be set whenever a transfer starts (XCH is set or the tx fifo is written into), and that it should be disabled whenever a transfer is complete. However, that does not work in practice: attempts to implement this approach resulted in failures, presumably because a single transaction can be split into multiple transfers. At the same time, there is no explicit signal from the host indicating if chip select should be active or not. In the absence of such a direct signal, use the burst length written into the control register to determine if an access is ongoing or not. Disable all chip selects if the burst length field in the configuration register is set to 0, and (re-)enable chip select if a transfer is started. This is possible because the Linux driver clears the burst length field whenever it prepares the controller for the next transfer. This solution is less than perfect since it effectively only disables chip select when initiating the next transfer, but it does work with Linux and should otherwise do no harm. Stop complaining if the burst length field is set to a value of 0, since that is done by Linux for every transfer. With this patch, a command line parameter such as "-drive file=flash.sabre,format=raw,if=mtd" can be used to instantiate the flash chip in the sabrelite emulation. Without this patch, the flash instantiates, but it only reads zeroes. Signed-off-by: Guenter Roeck --- I am not entirely happy with this solution, but it is the best I was able to come up with. If anyone has a better idea, I'll be happy to give it a try. hw/ssi/imx_spi.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/hw/ssi/imx_spi.c b/hw/ssi/imx_spi.c index 189423bb3a..7a093156bd 100644 --- a/hw/ssi/imx_spi.c +++ b/hw/ssi/imx_spi.c @@ -167,6 +167,8 @@ static void imx_spi_flush_txfifo(IMXSPIState *s) DPRINTF("Begin: TX Fifo Size = %d, RX Fifo Size = %d\n", fifo32_num_used(&s->tx_fifo), fifo32_num_used(&s->rx_fifo)); + qemu_set_irq(s->cs_lines[imx_spi_selected_channel(s)], 0); + while (!fifo32_is_empty(&s->tx_fifo)) { int tx_burst = 0; @@ -385,13 +387,6 @@ static void imx_spi_write(void *opaque, hwaddr offset, uint64_t value, case ECSPI_CONREG: s->regs[ECSPI_CONREG] = value; - burst = EXTRACT(s->regs[ECSPI_CONREG], ECSPI_CONREG_BURST_LENGTH) + 1; - if (burst % 8) { - qemu_log_mask(LOG_UNIMP, - "[%s]%s: burst length %d not supported: rounding up to next multiple of 8\n", - TYPE_IMX_SPI, __func__, burst); - } - if (!imx_spi_is_enabled(s)) { /* device is disabled, so this is a soft reset */ imx_spi_soft_reset(s); @@ -404,9 +399,11 @@ static void imx_spi_write(void *opaque, hwaddr offset, uint64_t value, /* We are in master mode */ - for (i = 0; i < ECSPI_NUM_CS; i++) { - qemu_set_irq(s->cs_lines[i], - i == imx_spi_selected_channel(s) ? 0 : 1); + burst = EXTRACT(s->regs[ECSPI_CONREG], ECSPI_CONREG_BURST_LENGTH); + if (burst == 0) { + for (i = 0; i < ECSPI_NUM_CS; i++) { + qemu_set_irq(s->cs_lines[i], 1); + } } if ((value & change_mask & ECSPI_CONREG_SMC) && -- 2.25.1