From patchwork Thu Jun 4 08:05:54 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Javier Martinez Canillas X-Patchwork-Id: 6544651 Return-Path: X-Original-To: patchwork-linux-samsung-soc@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id F12259F326 for ; Thu, 4 Jun 2015 08:10:26 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id ED14C20788 for ; Thu, 4 Jun 2015 08:10:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B08942074E for ; Thu, 4 Jun 2015 08:10:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752831AbbFDIKX (ORCPT ); Thu, 4 Jun 2015 04:10:23 -0400 Received: from bhuna.collabora.co.uk ([93.93.135.160]:43418 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752802AbbFDIHC (ORCPT ); Thu, 4 Jun 2015 04:07:02 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: javier) with ESMTPSA id 02574601360 From: Javier Martinez Canillas To: Lee Jones Cc: Samuel Ortiz , Olof Johansson , Doug Anderson , Bill Richardson , Simon Glass , Gwendal Grignou , Stephen Barber , Filipe Brandenburger , Todd Broch , Alexandru M Stan , Heiko Stuebner , linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Chris Zhong , Javier Martinez Canillas Subject: [PATCH v6 8/8] mfd: cros_ec: spi: Add delay for asserting CS Date: Thu, 4 Jun 2015 10:05:54 +0200 Message-Id: <1433405154-16273-9-git-send-email-javier.martinez@collabora.co.uk> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1433405154-16273-1-git-send-email-javier.martinez@collabora.co.uk> References: <1433405154-16273-1-git-send-email-javier.martinez@collabora.co.uk> Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Alexandru M Stan Some ECs need a little time for waking up before they can accept SPI data at a high speed. This is configurable via a DT property "google,cros-ec-spi-pre-delay". This patch makes the cros_ec_spi driver to cause a delay before the beginning of a SPI transaction, to make sure that the EC has already woken up, if the property has been defined in the DTS. Signed-off-by: Alexandru M Stan Reviewed-by: Doug Anderson Signed-off-by: Chris Zhong Signed-off-by: Javier Martinez Canillas Tested-by: Heiko Stuebner Acked-by: Lee Jones --- Changes since v5: None. Changes since v4: None. Changes since v3: - New patch, split DT binding and driver implementation as suggested by Lee Jones. - Add tested-by tag from Heiko Stuebner. - Add acked-by tag from Lee Jones. --- drivers/mfd/cros_ec_spi.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c index faba03e2f1ef..16f228dc243f 100644 --- a/drivers/mfd/cros_ec_spi.c +++ b/drivers/mfd/cros_ec_spi.c @@ -71,12 +71,15 @@ * @spi: SPI device we are connected to * @last_transfer_ns: time that we last finished a transfer, or 0 if there * if no record + * @start_of_msg_delay: used to set the delay_usecs on the spi_transfer that + * is sent when we want to turn on CS at the start of a transaction. * @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that * is sent when we want to turn off CS at the end of a transaction. */ struct cros_ec_spi { struct spi_device *spi; s64 last_transfer_ns; + unsigned int start_of_msg_delay; unsigned int end_of_msg_delay; }; @@ -366,7 +369,7 @@ static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev, struct ec_host_request *request; struct ec_host_response *response; struct cros_ec_spi *ec_spi = ec_dev->priv; - struct spi_transfer trans; + struct spi_transfer trans, trans_delay; struct spi_message msg; int i, len; u8 *ptr; @@ -393,13 +396,23 @@ static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev, goto exit; } + /* + * Leave a gap between CS assertion and clocking of data to allow the + * EC time to wakeup. + */ + spi_message_init(&msg); + if (ec_spi->start_of_msg_delay) { + memset(&trans_delay, 0, sizeof(trans_delay)); + trans_delay.delay_usecs = ec_spi->start_of_msg_delay; + spi_message_add_tail(&trans_delay, &msg); + } + /* Transmit phase - send our message */ memset(&trans, 0, sizeof(trans)); trans.tx_buf = ec_dev->dout; trans.rx_buf = rx_buf; trans.len = len; trans.cs_change = 1; - spi_message_init(&msg); spi_message_add_tail(&trans, &msg); ret = spi_sync(ec_spi->spi, &msg); @@ -602,6 +615,10 @@ static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev) u32 val; int ret; + ret = of_property_read_u32(np, "google,cros-ec-spi-pre-delay", &val); + if (!ret) + ec_spi->start_of_msg_delay = val; + ret = of_property_read_u32(np, "google,cros-ec-spi-msg-delay", &val); if (!ret) ec_spi->end_of_msg_delay = val;