From patchwork Wed Jan 17 16:15:28 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxime Chevallier X-Patchwork-Id: 10169863 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 1EA33603ED for ; Wed, 17 Jan 2018 16:23:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F183A28590 for ; Wed, 17 Jan 2018 16:23:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E62A8285D2; Wed, 17 Jan 2018 16:23:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7C69328590 for ; Wed, 17 Jan 2018 16:23:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932106AbeAQQVn (ORCPT ); Wed, 17 Jan 2018 11:21:43 -0500 Received: from idris.smile.fr ([91.216.209.19]:60453 "EHLO idris.smile.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753915AbeAQQVk (ORCPT ); Wed, 17 Jan 2018 11:21:40 -0500 Received: from localhost (localhost [127.0.0.1]) by idris.smile.fr (Postfix) with ESMTP id BD66D1EE2BB1; Wed, 17 Jan 2018 17:14:10 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at smile.fr Received: from idris.smile.fr ([127.0.0.1]) by localhost (bluemind-mta.prod.vitry.intranet [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id PpwqY-qjFnFI; Wed, 17 Jan 2018 17:14:10 +0100 (CET) Received: from smile-e5570.sigfox.io (unknown [217.114.201.133]) by idris.smile.fr (Postfix) with ESMTPSA id 79C1B1EE2BAA; Wed, 17 Jan 2018 17:14:10 +0100 (CET) From: Maxime Chevallier To: broonie@kernel.org Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, gregory.clement@free-electrons.com, Maxime Chevallier Subject: [PATCH 4/4] spi: a3700: Add full-duplex support Date: Wed, 17 Jan 2018 17:15:28 +0100 Message-Id: <1516205728-3256-5-git-send-email-maxime.chevallier@smile.fr> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1516205728-3256-1-git-send-email-maxime.chevallier@smile.fr> References: <1516205728-3256-1-git-send-email-maxime.chevallier@smile.fr> Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The armada 3700 SPI controller has support for full-duplex transfers, but it can only be done without using the hardware FIFOs. A full duplex transfer is done by shifting 4 bytes at a time, or even one byte at a time for transfers less than 4 bytes long. While this method is perfectly suitable for small transfers, it is still slower than using the FIFOs. This commit implement full-duplex support, making sure that half-duplex transfers are still done using the FIFOs with the existing method. Some setup functions were moved around to make sure the controller is properly configured before beginning each transfer. This was tested on EspressoBin with a logical analyser, and a simple setup where MISO is connected on MOSI. Transfers were made from userspace using spidev and spi-pipe from the spi-tools project Signed-off-by: Maxime Chevallier --- drivers/spi/spi-armada-3700.c | 85 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 73 insertions(+), 12 deletions(-) diff --git a/drivers/spi/spi-armada-3700.c b/drivers/spi/spi-armada-3700.c index b387309..a8576c8 100644 --- a/drivers/spi/spi-armada-3700.c +++ b/drivers/spi/spi-armada-3700.c @@ -421,15 +421,20 @@ static void a3700_spi_transfer_setup(struct spi_device *spi, struct spi_transfer *xfer) { struct a3700_spi *a3700_spi; - unsigned int byte_len; a3700_spi = spi_master_get_devdata(spi->master); a3700_spi_clock_set(a3700_spi, xfer->speed_hz); - byte_len = xfer->bits_per_word >> 3; + /* Use 4 bytes long transfers. Each transfer method has its way to deal + * with the remaining bytes for non 4-bytes aligned transfers. + */ + a3700_spi_bytelen_set(a3700_spi, 4); - a3700_spi_fifo_thres_set(a3700_spi, byte_len); + /* Initialize the working buffers */ + a3700_spi->tx_buf = xfer->tx_buf; + a3700_spi->rx_buf = xfer->rx_buf; + a3700_spi->buf_len = xfer->len; } static void a3700_spi_set_cs(struct spi_device *spi, bool enable) @@ -584,27 +589,26 @@ static int a3700_spi_prepare_message(struct spi_master *master, if (ret) return ret; - a3700_spi_bytelen_set(a3700_spi, 4); - a3700_spi_mode_set(a3700_spi, spi->mode); return 0; } -static int a3700_spi_transfer_one(struct spi_master *master, +static int a3700_spi_transfer_one_fifo(struct spi_master *master, struct spi_device *spi, struct spi_transfer *xfer) { struct a3700_spi *a3700_spi = spi_master_get_devdata(master); int ret = 0, timeout = A3700_SPI_TIMEOUT; - unsigned int nbits = 0; + unsigned int nbits = 0, byte_len; u32 val; - a3700_spi_transfer_setup(spi, xfer); + /* Make sure we use FIFO mode */ + a3700_spi_fifo_mode_set(a3700_spi, true); - a3700_spi->tx_buf = xfer->tx_buf; - a3700_spi->rx_buf = xfer->rx_buf; - a3700_spi->buf_len = xfer->len; + /* Configure FIFO thresholds */ + byte_len = xfer->bits_per_word >> 3; + a3700_spi_fifo_thres_set(a3700_spi, byte_len); if (xfer->tx_buf) nbits = xfer->tx_nbits; @@ -739,6 +743,64 @@ static int a3700_spi_transfer_one(struct spi_master *master, return ret; } +static int a3700_spi_transfer_one_full_duplex(struct spi_master *master, + struct spi_device *spi, + struct spi_transfer *xfer) +{ + struct a3700_spi *a3700_spi = spi_master_get_devdata(master); + u32 val_in, val_out; + + /* Disable FIFO mode */ + a3700_spi_fifo_mode_set(a3700_spi, false); + + while (a3700_spi->buf_len) { + + /* When we have less than 4 bytes to transfer, switch to 1 byte + * mode. This is reset after each transfer + */ + if (a3700_spi->buf_len < 4) + a3700_spi_bytelen_set(a3700_spi, 1); + + if (a3700_spi->byte_len == 1) + val_out = *a3700_spi->tx_buf; + else + val_out = cpu_to_le32(*(u32 *)a3700_spi->tx_buf); + + spireg_write(a3700_spi, A3700_SPI_DATA_OUT_REG, val_out); + + /* Wait for all the data to be shifted in / out */ + while (!(spireg_read(a3700_spi, A3700_SPI_IF_CTRL_REG) & + A3700_SPI_XFER_DONE)) + cpu_relax(); + + val_in = le32_to_cpu(spireg_read(a3700_spi, + A3700_SPI_DATA_IN_REG)); + + memcpy(a3700_spi->rx_buf, &val_in, a3700_spi->byte_len); + + a3700_spi->buf_len -= a3700_spi->byte_len; + a3700_spi->tx_buf += a3700_spi->byte_len; + a3700_spi->rx_buf += a3700_spi->byte_len; + + } + + spi_finalize_current_transfer(master); + + return 0; +} + +static int a3700_spi_transfer_one(struct spi_master *master, + struct spi_device *spi, + struct spi_transfer *xfer) +{ + a3700_spi_transfer_setup(spi, xfer); + + if (xfer->tx_buf && xfer->rx_buf) + return a3700_spi_transfer_one_full_duplex(master, spi, xfer); + + return a3700_spi_transfer_one_fifo(master, spi, xfer); +} + static int a3700_spi_unprepare_message(struct spi_master *master, struct spi_message *message) { @@ -788,7 +850,6 @@ static int a3700_spi_probe(struct platform_device *pdev) master->transfer_one = a3700_spi_transfer_one; master->unprepare_message = a3700_spi_unprepare_message; master->set_cs = a3700_spi_set_cs; - master->flags = SPI_MASTER_HALF_DUPLEX; master->mode_bits |= (SPI_RX_DUAL | SPI_TX_DUAL | SPI_RX_QUAD | SPI_TX_QUAD);