From patchwork Fri Apr 13 12:44:17 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vladimir Zapolskiy X-Patchwork-Id: 10340027 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 6C8426039A for ; Fri, 13 Apr 2018 12:44:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 75CE628468 for ; Fri, 13 Apr 2018 12:44:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6632627853; Fri, 13 Apr 2018 12:44:40 +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=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham 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 DFDC127853 for ; Fri, 13 Apr 2018 12:44:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754157AbeDMMoh (ORCPT ); Fri, 13 Apr 2018 08:44:37 -0400 Received: from relay1.mentorg.com ([192.94.38.131]:65092 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751536AbeDMMof (ORCPT ); Fri, 13 Apr 2018 08:44:35 -0400 Received: from nat-ies.mentorg.com ([192.94.31.2] helo=SVR-IES-MBX-04.mgc.mentorg.com) by relay1.mentorg.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-SHA384:256) id 1f6y4A-0001bj-MX from Vladimir_Zapolskiy@mentor.com ; Fri, 13 Apr 2018 05:44:34 -0700 Received: from eyas.local (137.202.0.87) by SVR-IES-MBX-04.mgc.mentorg.com (139.181.222.4) with Microsoft SMTP Server (TLS) id 15.0.1320.4; Fri, 13 Apr 2018 13:44:31 +0100 From: Vladimir Zapolskiy To: Mark Brown , Geert Uytterhoeven CC: , Subject: [PATCH 2/2] spi: sh-msiof: Simplify calculation of divisors for transfer rate Date: Fri, 13 Apr 2018 15:44:17 +0300 Message-ID: <1523623457-9682-3-git-send-email-vladimir_zapolskiy@mentor.com> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1523623457-9682-1-git-send-email-vladimir_zapolskiy@mentor.com> References: <1523623457-9682-1-git-send-email-vladimir_zapolskiy@mentor.com> MIME-Version: 1.0 X-Originating-IP: [137.202.0.87] X-ClientProxiedBy: svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) To SVR-IES-MBX-04.mgc.mentorg.com (139.181.222.4) 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 change updates sh_msiof_spi_set_clk_regs() function by iterating over BRDV power values. Note that the change is a functional one, namely prescaler output x 1/1 set in BRDV bit field (0b111) for MSO division rate set to 2 is substituted by BRDV = 0b000 and BRPS = 0b0, in terms of written values to TSCR setting of 0x0107 is substituted by 0x0000, and for all input parameter cases this is the only functional change, which touches the controller. As a result of the rework the function is supposed to be slightly more efficient and more readable and maintainable in case of any further extensions. Signed-off-by: Vladimir Zapolskiy --- drivers/spi/spi-sh-msiof.c | 67 ++++++++++++++++++++++++---------------------- 1 file changed, 35 insertions(+), 32 deletions(-) diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c index 8171eedbfc90..5c1ff0097e41 100644 --- a/drivers/spi/spi-sh-msiof.c +++ b/drivers/spi/spi-sh-msiof.c @@ -39,7 +39,7 @@ struct sh_msiof_chipdata { u16 tx_fifo_size; u16 rx_fifo_size; u16 master_flags; - u16 min_div; + u16 min_div_pow; }; struct sh_msiof_spi_priv { @@ -51,7 +51,7 @@ struct sh_msiof_spi_priv { struct completion done; unsigned int tx_fifo_size; unsigned int rx_fifo_size; - unsigned int min_div; + unsigned int min_div_pow; void *tx_dma_page; void *rx_dma_page; dma_addr_t tx_dma_addr; @@ -249,43 +249,46 @@ static irqreturn_t sh_msiof_spi_irq(int irq, void *data) return IRQ_HANDLED; } -static struct { - unsigned short div; - unsigned short brdv; -} const sh_msiof_spi_div_table[] = { - { 1, SCR_BRDV_DIV_1 }, - { 2, SCR_BRDV_DIV_2 }, - { 4, SCR_BRDV_DIV_4 }, - { 8, SCR_BRDV_DIV_8 }, - { 16, SCR_BRDV_DIV_16 }, - { 32, SCR_BRDV_DIV_32 }, +static const u32 sh_msiof_spi_div_array[] = { + SCR_BRDV_DIV_1, SCR_BRDV_DIV_2, SCR_BRDV_DIV_4, + SCR_BRDV_DIV_8, SCR_BRDV_DIV_16, SCR_BRDV_DIV_32, }; static void sh_msiof_spi_set_clk_regs(struct sh_msiof_spi_priv *p, unsigned long parent_rate, u32 spi_hz) { - unsigned long div = 1024; + unsigned long div; u32 brps, scr; - size_t k; + unsigned int div_pow = p->min_div_pow; - if (!WARN_ON(!spi_hz || !parent_rate)) - div = DIV_ROUND_UP(parent_rate, spi_hz); - - div = max_t(unsigned long, div, p->min_div); + if (!spi_hz || !parent_rate) { + WARN(1, "Invalid clock rate parameters %lu and %u\n", + parent_rate, spi_hz); + return; + } - for (k = 0; k < ARRAY_SIZE(sh_msiof_spi_div_table); k++) { - brps = DIV_ROUND_UP(div, sh_msiof_spi_div_table[k].div); + div = DIV_ROUND_UP(parent_rate, spi_hz); + if (div <= 1024) { /* SCR_BRDV_DIV_1 is valid only if BRPS is x 1/1 or x 1/2 */ - if (sh_msiof_spi_div_table[k].div == 1 && brps > 2) - continue; - if (brps <= 32) /* max of brdv is 32 */ - break; - } + if (!div_pow && div <= 32 && div > 2) + div_pow = 1; + + if (div_pow) + brps = (div + 1) >> div_pow; + else + brps = div; - k = min_t(int, k, ARRAY_SIZE(sh_msiof_spi_div_table) - 1); - brps = min_t(int, brps, 32); + for (; brps > 32; div_pow++) + brps = (brps + 1) >> 1; + } else { + /* Set transfer rate composite divisor to 2^5 * 32 = 1024 */ + dev_err(&p->pdev->dev, + "Requested SPI transfer rate %d is too low\n", spi_hz); + div_pow = 5; + brps = 32; + } - scr = sh_msiof_spi_div_table[k].brdv | SCR_BRPS(brps); + scr = sh_msiof_spi_div_array[div_pow] | SCR_BRPS(brps); sh_msiof_write(p, TSCR, scr); if (!(p->master->flags & SPI_MASTER_MUST_TX)) sh_msiof_write(p, RSCR, scr); @@ -1041,21 +1044,21 @@ static const struct sh_msiof_chipdata sh_data = { .tx_fifo_size = 64, .rx_fifo_size = 64, .master_flags = 0, - .min_div = 1, + .min_div_pow = 0, }; static const struct sh_msiof_chipdata rcar_gen2_data = { .tx_fifo_size = 64, .rx_fifo_size = 64, .master_flags = SPI_MASTER_MUST_TX, - .min_div = 1, + .min_div_pow = 0, }; static const struct sh_msiof_chipdata rcar_gen3_data = { .tx_fifo_size = 64, .rx_fifo_size = 64, .master_flags = SPI_MASTER_MUST_TX, - .min_div = 2, + .min_div_pow = 1, }; static const struct of_device_id sh_msiof_match[] = { @@ -1319,7 +1322,7 @@ static int sh_msiof_spi_probe(struct platform_device *pdev) platform_set_drvdata(pdev, p); p->master = master; p->info = info; - p->min_div = chipdata->min_div; + p->min_div_pow = chipdata->min_div_pow; init_completion(&p->done);