From patchwork Thu May 28 15:27:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tim Harvey X-Patchwork-Id: 218315 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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 D284CC433E0 for ; Thu, 28 May 2020 15:28:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC51120888 for ; Thu, 28 May 2020 15:28:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404387AbgE1P2R (ORCPT ); Thu, 28 May 2020 11:28:17 -0400 Received: from lists.gateworks.com ([108.161.130.12]:57323 "EHLO lists.gateworks.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404080AbgE1P2P (ORCPT ); Thu, 28 May 2020 11:28:15 -0400 Received: from 068-189-091-139.biz.spectrum.com ([68.189.91.139] helo=tharvey.pdc.gateworks.com) by lists.gateworks.com with esmtp (Exim 4.82) (envelope-from ) id 1jeKUi-0000Yg-Hz; Thu, 28 May 2020 15:30:56 +0000 From: Tim Harvey To: Wolfgang Grandegger , Marc Kleine-Budde , linux-can@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "David S . Miller" , Sean Nyekjaer , Andy Shevchenko , =?utf-8?b?VGltbyBTY2hsw7zDn2xl?= =?utf-8?q?r?= , "Gustavo A . R . Silva" , Tim Harvey Subject: [PATCH] can: mcp251x: add support for half duplex controllers Date: Thu, 28 May 2020 08:27:57 -0700 Message-Id: <1590679677-2678-1-git-send-email-tharvey@gateworks.com> X-Mailer: git-send-email 2.7.4 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Some SPI host controllers do not support full-duplex SPI and are marked as such via the SPI_CONTROLLER_HALF_DUPLEX controller flag. For such controllers use half duplex transactions but retain full duplex transactions for the controllers that can handle those. Signed-off-by: Tim Harvey --- drivers/net/can/spi/mcp251x.c | 34 +++++++++++++++++++++++++++------- 1 file changed, 27 insertions(+), 7 deletions(-) diff --git a/drivers/net/can/spi/mcp251x.c b/drivers/net/can/spi/mcp251x.c index 5009ff2..203ef20 100644 --- a/drivers/net/can/spi/mcp251x.c +++ b/drivers/net/can/spi/mcp251x.c @@ -290,8 +290,12 @@ static u8 mcp251x_read_reg(struct spi_device *spi, u8 reg) priv->spi_tx_buf[0] = INSTRUCTION_READ; priv->spi_tx_buf[1] = reg; - mcp251x_spi_trans(spi, 3); - val = priv->spi_rx_buf[2]; + if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) { + spi_write_then_read(spi, priv->spi_tx_buf, 2, &val, 1); + } else { + mcp251x_spi_trans(spi, 3); + val = priv->spi_rx_buf[2]; + } return val; } @@ -303,10 +307,18 @@ static void mcp251x_read_2regs(struct spi_device *spi, u8 reg, u8 *v1, u8 *v2) priv->spi_tx_buf[0] = INSTRUCTION_READ; priv->spi_tx_buf[1] = reg; - mcp251x_spi_trans(spi, 4); + if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) { + u8 val[2] = { 0 }; - *v1 = priv->spi_rx_buf[2]; - *v2 = priv->spi_rx_buf[3]; + spi_write_then_read(spi, priv->spi_tx_buf, 2, val, 2); + *v1 = val[0]; + *v2 = val[1]; + } else { + mcp251x_spi_trans(spi, 4); + + *v1 = priv->spi_rx_buf[2]; + *v2 = priv->spi_rx_buf[3]; + } } static void mcp251x_write_reg(struct spi_device *spi, u8 reg, u8 val) @@ -409,8 +421,16 @@ static void mcp251x_hw_rx_frame(struct spi_device *spi, u8 *buf, buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i); } else { priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx); - mcp251x_spi_trans(spi, SPI_TRANSFER_BUF_LEN); - memcpy(buf, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN); + if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) { + spi_write_then_read(spi, priv->spi_tx_buf, 1, + priv->spi_rx_buf, + SPI_TRANSFER_BUF_LEN); + memcpy(buf + 1, priv->spi_rx_buf, + SPI_TRANSFER_BUF_LEN - 1); + } else { + mcp251x_spi_trans(spi, SPI_TRANSFER_BUF_LEN); + memcpy(buf, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN); + } } }