From patchwork Mon Jun 8 09:59:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Geert Uytterhoeven X-Patchwork-Id: 11592985 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 43D3792A for ; Mon, 8 Jun 2020 10:04:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3473F206A4 for ; Mon, 8 Jun 2020 10:04:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729282AbgFHKEr (ORCPT ); Mon, 8 Jun 2020 06:04:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729262AbgFHKEr (ORCPT ); Mon, 8 Jun 2020 06:04:47 -0400 Received: from albert.telenet-ops.be (albert.telenet-ops.be [IPv6:2a02:1800:110:4::f00:1a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 454BFC08C5C3 for ; Mon, 8 Jun 2020 03:04:47 -0700 (PDT) Received: from ramsan ([IPv6:2a02:1810:ac12:ed60:c85f:a5bf:b1bd:702b]) by albert.telenet-ops.be with bizsmtp id oZzi2200C0R8aca06ZziCh; Mon, 08 Jun 2020 11:59:43 +0200 Received: from rox.of.borg ([192.168.97.57]) by ramsan with esmtp (Exim 4.90_1) (envelope-from ) id 1jiEZC-0007P4-C4; Mon, 08 Jun 2020 11:59:42 +0200 Received: from geert by rox.of.borg with local (Exim 4.90_1) (envelope-from ) id 1jiEZC-0007x8-9y; Mon, 08 Jun 2020 11:59:42 +0200 From: Geert Uytterhoeven To: Mark Brown Cc: Chris Brandt , linux-spi@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-sh@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH 2/8] spi: rspi: Use requested instead of maximum bit rate Date: Mon, 8 Jun 2020 11:59:34 +0200 Message-Id: <20200608095940.30516-3-geert+renesas@glider.be> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200608095940.30516-1-geert+renesas@glider.be> References: <20200608095940.30516-1-geert+renesas@glider.be> Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org Currently, the RSPI driver always tries to use the maximum configured bit rate for communicating with a slave device, even if the transfer(s) in the current message specify a lower rate. Use the mininum rate specified in the message instead. Rename rspi_data.max_speed_hz accordingly. Signed-off-by: Geert Uytterhoeven --- drivers/spi/spi-rspi.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c index 0e786af546c9f513..1b635d6b7881f5b9 100644 --- a/drivers/spi/spi-rspi.c +++ b/drivers/spi/spi-rspi.c @@ -179,7 +179,7 @@ struct rspi_data { void __iomem *addr; - u32 max_speed_hz; + u32 speed_hz; struct spi_controller *ctlr; struct platform_device *pdev; wait_queue_head_t wait; @@ -258,8 +258,7 @@ static int rspi_set_config_register(struct rspi_data *rspi, int access_size) rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR); /* Sets transfer bit rate */ - spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), - 2 * rspi->max_speed_hz) - 1; + spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->speed_hz) - 1; rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR); /* Disable dummy transmission, set 16-bit word access, 1 frame */ @@ -299,14 +298,14 @@ static int rspi_rz_set_config_register(struct rspi_data *rspi, int access_size) clksrc = clk_get_rate(rspi->clk); while (div < 3) { - if (rspi->max_speed_hz >= clksrc/4) /* 4=(CLK/2)/2 */ + if (rspi->speed_hz >= clksrc/4) /* 4=(CLK/2)/2 */ break; div++; clksrc /= 2; } /* Sets transfer bit rate */ - spbr = DIV_ROUND_UP(clksrc, 2 * rspi->max_speed_hz) - 1; + spbr = DIV_ROUND_UP(clksrc, 2 * rspi->speed_hz) - 1; rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR); rspi->spcmd |= div << 2; @@ -341,7 +340,7 @@ static int qspi_set_config_register(struct rspi_data *rspi, int access_size) rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR); /* Sets transfer bit rate */ - spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->max_speed_hz); + spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->speed_hz); rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR); /* Disable dummy transmission, set byte access */ @@ -949,9 +948,24 @@ static int rspi_prepare_message(struct spi_controller *ctlr, { struct rspi_data *rspi = spi_controller_get_devdata(ctlr); struct spi_device *spi = msg->spi; + const struct spi_transfer *xfer; int ret; - rspi->max_speed_hz = spi->max_speed_hz; + /* + * As the Bit Rate Register must not be changed while the device is + * active, all transfers in a message must use the same bit rate. + * In theory, the sequencer could be enabled, and each Command Register + * could divide the base bit rate by a different value. + * However, most RSPI variants do not have Transfer Data Length + * Multiplier Setting Registers, so each sequence step would be limited + * to a single word, making this feature unsuitable for large + * transfers, which would gain most from it. + */ + rspi->speed_hz = spi->max_speed_hz; + list_for_each_entry(xfer, &msg->transfers, transfer_list) { + if (xfer->speed_hz < rspi->speed_hz) + rspi->speed_hz = xfer->speed_hz; + } rspi->spcmd = SPCMD_SSLKP; if (spi->mode & SPI_CPOL)