From patchwork Thu Dec 17 20:28:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sowjanya Komatineni X-Patchwork-Id: 345299 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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 1D1E4C35270 for ; Thu, 17 Dec 2020 20:30:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 096E323A03 for ; Thu, 17 Dec 2020 20:30:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731639AbgLQUaS (ORCPT ); Thu, 17 Dec 2020 15:30:18 -0500 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:8611 "EHLO hqnvemgate24.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731389AbgLQUaR (ORCPT ); Thu, 17 Dec 2020 15:30:17 -0500 Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Thu, 17 Dec 2020 12:29:01 -0800 Received: from HQMAIL107.nvidia.com (172.20.187.13) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 17 Dec 2020 20:28:56 +0000 Received: from skomatineni-linux.nvidia.com (172.20.145.6) by mail.nvidia.com (172.20.187.13) with Microsoft SMTP Server id 15.0.1473.3 via Frontend Transport; Thu, 17 Dec 2020 20:28:55 +0000 From: Sowjanya Komatineni To: , , , , CC: , , , , , , , Subject: [PATCH v4 6/9] spi: tegra210-quad: Add support for hardware dummy cycles transfer Date: Thu, 17 Dec 2020 12:28:44 -0800 Message-ID: <1608236927-28701-7-git-send-email-skomatineni@nvidia.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1608236927-28701-1-git-send-email-skomatineni@nvidia.com> References: <1608236927-28701-1-git-send-email-skomatineni@nvidia.com> X-NVConfidentiality: public MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1608236941; bh=jmc7L6L+XTlt/mdhhipcIsZ+/q6GiritSmf7bmM215U=; h=From:To:CC:Subject:Date:Message-ID:X-Mailer:In-Reply-To: References:X-NVConfidentiality:MIME-Version:Content-Type; b=V7AFKY98NtHczjdjj2QTpZICckChqpZsbFZmqqZPUylPa67e5KY07kXijX9f+k1ZF UbJ+fYZXWjmT8uSwIjEVFgcBCcQmeZ6yN3y2I1sojZagNf/OWit11H7PFedpr0gNqH XtotAIF8aWeCDK2o7T02YaGH2vxBTOJG6FbTFty26M5ZcSX+7TP5b5QiabOOMin/M/ 2d72OxjH0QpS4gF4qHJVxixiSuKVtlBhMSUtsrEdhWF0dLNq0tDIqeiOdIC6vMagg3 LkEvtXparipybt/9ONNh8Z8irFhkMYX+sFAYCym0J/CxSkc73IVSyM8fojI92knkdo foPAly5lSd72Q== Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org Tegra Quad SPI controller hardware supports sending dummy bytes based on programmed dummy clock cycles after the actual transfer bytes. This patch adds this support of hardware dummy bytes transfer and skips transfer of dummy bytes from the software. For dummy cycles more than Tegra Quad SPI hardware maximum dummy cycles limit, driver transfers dummy bytes from the software. Signed-off-by: Sowjanya Komatineni --- drivers/spi/spi-tegra210-quad.c | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-tegra210-quad.c b/drivers/spi/spi-tegra210-quad.c index e7bee8d..695a296 100644 --- a/drivers/spi/spi-tegra210-quad.c +++ b/drivers/spi/spi-tegra210-quad.c @@ -117,6 +117,7 @@ #define QSPI_MISC_REG 0x194 #define QSPI_NUM_DUMMY_CYCLE(x) (((x) & 0xff) << 0) +#define QSPI_DUMMY_CYCLES_MAX 0xff #define DATA_DIR_TX BIT(0) #define DATA_DIR_RX BIT(1) @@ -170,6 +171,7 @@ struct tegra_qspi { u32 def_command2_reg; u32 spi_cs_timing1; u32 spi_cs_timing2; + u8 dummy_cycles; struct completion xfer_completion; struct spi_transfer *curr_xfer; @@ -856,6 +858,8 @@ static int tegra_qspi_start_transfer_one(struct spi_device *spi, tqspi->command1_reg = command1; + tegra_qspi_writel(tqspi, QSPI_NUM_DUMMY_CYCLE(tqspi->dummy_cycles), QSPI_MISC_REG); + ret = tegra_qspi_flush_fifos(tqspi, false); if (ret < 0) return ret; @@ -974,7 +978,8 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi { struct tegra_qspi *tqspi = spi_master_get_devdata(master); struct spi_device *spi = msg->spi; - struct spi_transfer *xfer; + struct spi_transfer *xfer, *next_xfer; + bool use_hw_dummy_cycles = false; bool is_first_msg = true; int ret; @@ -984,8 +989,42 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi tqspi->rx_status = 0; list_for_each_entry(xfer, &msg->transfers, transfer_list) { + u8 dummy_cycles = 0; u32 cmd1; + /* + * Skip dummy bytes transfer if they are transferred by the hardware along + * with previous transfer. + */ + if (xfer->dummy_data && use_hw_dummy_cycles) { + msg->actual_length += xfer->len; + continue; + } + + /* + * Tegra QSPI hardware supports dummy bytes transfer after actual transfer + * bytes based on programmed dummy clock cycles in the QSPI_MISC register. + * So, check if the next transfer is dummy data transfer and program dummy + * clock cycles along with the current transfer. + */ + if (!list_is_last(&xfer->transfer_list, &msg->transfers)) { + next_xfer = list_next_entry(xfer, transfer_list); + if (next_xfer && next_xfer->dummy_data) { + dummy_cycles = next_xfer->len * 8 / next_xfer->tx_nbits; + use_hw_dummy_cycles = true; + /* + * Use software dummy bytes transfer if dummy cycles exceeds + * Tegra QSPI hardware maximum dummy cycles limit. + */ + if (dummy_cycles > QSPI_DUMMY_CYCLES_MAX) { + use_hw_dummy_cycles = false; + dummy_cycles = 0; + } + } + } + + tqspi->dummy_cycles = dummy_cycles; + reinit_completion(&tqspi->xfer_completion); cmd1 = tegra_qspi_setup_transfer_one(spi, xfer, is_first_msg);