From patchwork Wed Sep 7 14:11:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 603742 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 966A0C38145 for ; Wed, 7 Sep 2022 14:13:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229566AbiIGONx (ORCPT ); Wed, 7 Sep 2022 10:13:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39550 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230057AbiIGONv (ORCPT ); Wed, 7 Sep 2022 10:13:51 -0400 Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B19D5AC68; Wed, 7 Sep 2022 07:13:47 -0700 (PDT) Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4MN4495FRdz9sk7; Wed, 7 Sep 2022 16:13:45 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id NbQ0L84h4YdI; Wed, 7 Sep 2022 16:13:45 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4MN4494R6wz9sk5; Wed, 7 Sep 2022 16:13:45 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 839B28B78B; Wed, 7 Sep 2022 16:13:45 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id RvCiRwW5QFyp; Wed, 7 Sep 2022 16:13:45 +0200 (CEST) Received: from PO20335.IDSI0.si.c-s.fr (unknown [192.168.232.234]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 332CC8B763; Wed, 7 Sep 2022 16:13:45 +0200 (CEST) Received: from PO20335.IDSI0.si.c-s.fr (localhost [127.0.0.1]) by PO20335.IDSI0.si.c-s.fr (8.17.1/8.16.1) with ESMTPS id 287EDNDw3203669 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Wed, 7 Sep 2022 16:13:23 +0200 Received: (from chleroy@localhost) by PO20335.IDSI0.si.c-s.fr (8.17.1/8.17.1/Submit) id 287EBZlP3203513; Wed, 7 Sep 2022 16:11:35 +0200 X-Authentication-Warning: PO20335.IDSI0.si.c-s.fr: chleroy set sender to christophe.leroy@csgroup.eu using -f From: Christophe Leroy To: Mark Brown Cc: Christophe Leroy , linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Subject: [PATCH v3 REBASED] spi: Add capability to perform some transfer with chipselect off Date: Wed, 7 Sep 2022 16:11:25 +0200 Message-Id: <434165c46f06d802690208a11e7ea2500e8da4c7.1662558898.git.christophe.leroy@csgroup.eu> X-Mailer: git-send-email 2.37.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1662559883; l=3320; s=20211009; h=from:subject:message-id; bh=nhEy38PTRF9ranS0NmdK0DMBPj0AbmzHk2k5M/5fx/Y=; b=7JH9vrLSGNogatlUQo3OoL53sgXR5y6jdrk3XO5Qzq3rqH/1opFMfHaCL3yQCBkIO1vlXFyxiHEZ 1YCOVkFGAuJpOiyq5GWAYVJeuIGBIAr1GDkHPgql7j5SIwQ8+kGD X-Developer-Key: i=christophe.leroy@csgroup.eu; a=ed25519; pk=HIzTzUj91asvincQGOFx6+ZF5AoUuP9GdOtQChs7Mm0= Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org Some components require a few clock cycles with chipselect off before or/and after the data transfer done with CS on. Typically IDT 801034 QUAD PCM CODEC datasheet states "Note *: CCLK should have one cycle before CS goes low, and two cycles after CS goes high". The cycles "before" are implicitely provided by all previous activity on the SPI bus. But the cycles "after" must be provided in order to terminate the SPI transfer. In order to use that kind of component, add a cs_off flag to spi_transfer struct. When this flag is set, the transfer is performed with chipselect off. This allows consummer to add a dummy transfer at the end of the transfer list which is performed with chipselect OFF, providing the required additional clock cycles. Signed-off-by: Christophe Leroy --- Rebased on today's linus' master drivers/spi/spi.c | 12 +++++++++--- include/linux/spi/spi.h | 2 ++ 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 83da8862b8f2..cc5cb948978e 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1435,7 +1435,8 @@ static int spi_transfer_one_message(struct spi_controller *ctlr, struct spi_statistics __percpu *statm = ctlr->pcpu_statistics; struct spi_statistics __percpu *stats = msg->spi->pcpu_statistics; - spi_set_cs(msg->spi, true, false); + xfer = list_first_entry(&msg->transfers, struct spi_transfer, transfer_list); + spi_set_cs(msg->spi, !xfer->cs_off, false); SPI_STATISTICS_INCREMENT_FIELD(statm, messages); SPI_STATISTICS_INCREMENT_FIELD(stats, messages); @@ -1503,10 +1504,15 @@ static int spi_transfer_one_message(struct spi_controller *ctlr, &msg->transfers)) { keep_cs = true; } else { - spi_set_cs(msg->spi, false, false); + if (!xfer->cs_off) + spi_set_cs(msg->spi, false, false); _spi_transfer_cs_change_delay(msg, xfer); - spi_set_cs(msg->spi, true, false); + if (!list_next_entry(xfer, transfer_list)->cs_off) + spi_set_cs(msg->spi, true, false); } + } else if (!list_is_last(&xfer->transfer_list, &msg->transfers) && + xfer->cs_off != list_next_entry(xfer, transfer_list)->cs_off) { + spi_set_cs(msg->spi, xfer->cs_off, false); } msg->actual_length += xfer->len; diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index e6c73d5ff1a8..6e6c62c59957 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -847,6 +847,7 @@ struct spi_res { * for this transfer. If 0 the default (from @spi_device) is used. * @dummy_data: indicates transfer is dummy bytes transfer. * @cs_change: affects chipselect after this transfer completes + * @cs_off: performs the transfer with chipselect off. * @cs_change_delay: delay between cs deassert and assert when * @cs_change is set and @spi_transfer is not the last in @spi_message * @delay: delay to be introduced after this transfer before @@ -959,6 +960,7 @@ struct spi_transfer { unsigned cs_change:1; unsigned tx_nbits:3; unsigned rx_nbits:3; + unsigned cs_off:1; #define SPI_NBITS_SINGLE 0x01 /* 1bit transfer */ #define SPI_NBITS_DUAL 0x02 /* 2bits transfer */ #define SPI_NBITS_QUAD 0x04 /* 4bits transfer */