From patchwork Mon May 10 13:11:20 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Shevchenko X-Patchwork-Id: 433420 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 B93B5C433ED for ; Mon, 10 May 2021 13:32:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F7AD613EE for ; Mon, 10 May 2021 13:32:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237448AbhEJNdo (ORCPT ); Mon, 10 May 2021 09:33:44 -0400 Received: from mga07.intel.com ([134.134.136.100]:33803 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352056AbhEJNNy (ORCPT ); Mon, 10 May 2021 09:13:54 -0400 IronPort-SDR: rlniRiIoyfB4uaifsHZFo0vM/58h3+8f3PowU0MYlks/rVjcf+YFFpX5JQtt0cilC7LzVC6r9T Q4wJONLNs5hA== X-IronPort-AV: E=McAfee;i="6200,9189,9980"; a="263122578" X-IronPort-AV: E=Sophos;i="5.82,286,1613462400"; d="scan'208";a="263122578" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 May 2021 06:11:14 -0700 IronPort-SDR: TYUGSpAYirdA6DAbx+o4/wISui+roA3VIJWoWqK6Jenkjck9dXiyzNFFHIbWVyH54q/qKaDfis XQl5dObFAJFg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.82,287,1613462400"; d="scan'208";a="468122274" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga002.fm.intel.com with ESMTP; 10 May 2021 06:11:11 -0700 Received: by black.fi.intel.com (Postfix, from userid 1003) id 7FA86D7; Mon, 10 May 2021 16:11:31 +0300 (EEST) From: Andy Shevchenko To: Mark Brown , linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Andy Shevchenko Subject: [PATCH v1 1/1] spi: Convert to use predefined time multipliers Date: Mon, 10 May 2021 16:11:20 +0300 Message-Id: <20210510131120.49253-1-andriy.shevchenko@linux.intel.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org We have a lot of hard coded values in nanoseconds or other units. Use predefined constants to make it more clear. While at it, add or amend comments in the corresponding functions. Signed-off-by: Andy Shevchenko --- drivers/spi/spi.c | 41 ++++++++++++++++++++++++++++------------- 1 file changed, 28 insertions(+), 13 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index f9885c096563..407420977a73 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1118,10 +1118,20 @@ static int spi_transfer_wait(struct spi_controller *ctlr, if (!speed_hz) speed_hz = 100000; - ms = 8LL * 1000LL * xfer->len; + /* + * For each byte we wait for 8 cycles of the SPI clock. + * Since speed is defined in Hz and we want milliseconds, + * use respective multiplier, but before the division, + * otherwise we may get 0 for short transfers. + */ + ms = 8LL * MSEC_PER_SEC * xfer->len; do_div(ms, speed_hz); - ms += ms + 200; /* some tolerance */ + /* + * Increase it twice and add 200 ms tolerance, use + * predefined maximum in case of overflow. + */ + ms += ms + 200; if (ms > UINT_MAX) ms = UINT_MAX; @@ -1144,10 +1154,10 @@ static void _spi_transfer_delay_ns(u32 ns) { if (!ns) return; - if (ns <= 1000) { + if (ns <= NSEC_PER_USEC) { ndelay(ns); } else { - u32 us = DIV_ROUND_UP(ns, 1000); + u32 us = DIV_ROUND_UP(ns, NSEC_PER_USEC); if (us <= 10) udelay(us); @@ -1167,21 +1177,25 @@ int spi_delay_to_ns(struct spi_delay *_delay, struct spi_transfer *xfer) switch (unit) { case SPI_DELAY_UNIT_USECS: - delay *= 1000; + delay *= NSEC_PER_USEC; break; - case SPI_DELAY_UNIT_NSECS: /* nothing to do here */ + case SPI_DELAY_UNIT_NSECS: + /* Nothing to do here */ break; case SPI_DELAY_UNIT_SCK: /* clock cycles need to be obtained from spi_transfer */ if (!xfer) return -EINVAL; - /* if there is no effective speed know, then approximate - * by underestimating with half the requested hz + /* + * If there is unknown effective speed, approximate it + * by underestimating with half of the requested hz. */ hz = xfer->effective_speed_hz ?: xfer->speed_hz / 2; if (!hz) return -EINVAL; - delay *= DIV_ROUND_UP(1000000000, hz); + + /* Convert delay to nanoseconds */ + delay *= DIV_ROUND_UP(NSEC_PER_SEC, hz); break; default: return -EINVAL; @@ -1213,6 +1227,7 @@ EXPORT_SYMBOL_GPL(spi_delay_exec); static void _spi_transfer_cs_change_delay(struct spi_message *msg, struct spi_transfer *xfer) { + u32 default_delay_ns = 10 * NSEC_PER_USEC; u32 delay = xfer->cs_change_delay.value; u32 unit = xfer->cs_change_delay.unit; int ret; @@ -1220,16 +1235,16 @@ static void _spi_transfer_cs_change_delay(struct spi_message *msg, /* return early on "fast" mode - for everything but USECS */ if (!delay) { if (unit == SPI_DELAY_UNIT_USECS) - _spi_transfer_delay_ns(10000); + _spi_transfer_delay_ns(default_delay_ns); return; } ret = spi_delay_exec(&xfer->cs_change_delay, xfer); if (ret) { dev_err_once(&msg->spi->dev, - "Use of unsupported delay unit %i, using default of 10us\n", - unit); - _spi_transfer_delay_ns(10000); + "Use of unsupported delay unit %i, using default of %luus\n", + unit, default_delay_ns / NSEC_PER_USEC); + _spi_transfer_delay_ns(default_delay_ns); } }