From patchwork Tue Jun 2 22:31:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guru Das Srinagesh X-Patchwork-Id: 11584625 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 6E159618 for ; Tue, 2 Jun 2020 22:33:13 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 37CBF2068D for ; Tue, 2 Jun 2020 22:33:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="PngfpMKB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 37CBF2068D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=SysnwYtyKXsj1sSEhF21E9bYQ7zKMdAQWhwG2b7B90U=; b=PngfpMKBFL+Mca/XePesFSNB+U 1Gz4NbENiSiqkY5NFZPQRuBDat1PSd72ouHri1iZObskwgO+6xi/n8PSuUU2yJoERkwl2vsf0HeZ2 X+YFlEW3GYDxOEnAXbKklt73FH4VJO5FrcWLwV5zQm4y9MjTLVLMo9VphcPHhpWXVrtfaNrVjjo99 IZ9GasydfKLTLtdFnlqUE0JfCwe9/VUa+Nnel+BPvPIqDi6IlqPtCKWLe+cWAi6ythbb6hD0bOCFm iznI8MF2R114KMNkV/WavCGTNAnqHhy0Xlc52hqBp2QmyHEa8RSBMxwDSjfrRr/wtFnexTW0A5brx blrTpG0Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jgFT3-0003Zz-BG; Tue, 02 Jun 2020 22:33:09 +0000 Received: from alexa-out-sd-02.qualcomm.com ([199.106.114.39]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jgFRP-0001qk-Rt for linux-arm-kernel@lists.infradead.org; Tue, 02 Jun 2020 22:31:29 +0000 Received: from unknown (HELO ironmsg03-sd.qualcomm.com) ([10.53.140.143]) by alexa-out-sd-02.qualcomm.com with ESMTP; 02 Jun 2020 15:31:23 -0700 Received: from gurus-linux.qualcomm.com ([10.46.162.81]) by ironmsg03-sd.qualcomm.com with ESMTP; 02 Jun 2020 15:31:22 -0700 Received: by gurus-linux.qualcomm.com (Postfix, from userid 383780) id 735944D82; Tue, 2 Jun 2020 15:31:22 -0700 (PDT) From: Guru Das Srinagesh To: linux-pwm@vger.kernel.org, Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= Subject: [PATCH v16 06/11] pwm: imx27: Use 64-bit division macro and function Date: Tue, 2 Jun 2020 15:31:10 -0700 Message-Id: X-Mailer: git-send-email 1.9.1 In-Reply-To: References: In-Reply-To: References: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200602_153127_953925_F547FEEC X-CRM114-Status: GOOD ( 14.69 ) X-Spam-Score: -2.1 (--) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-2.1 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [199.106.114.39 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.2 HEADER_FROM_DIFFERENT_DOMAINS From and EnvelopeFrom 2nd level mail domains are different X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arm-kernel@lists.infradead.org, Guru Das Srinagesh , Daniel Thompson , Fabio Estevam , Arnd Bergmann , David Collins , Stephen Boyd , Shawn Guo , Sascha Hauer , linux-kernel@vger.kernel.org, Geert Uytterhoeven , Dan Carpenter , Pengutronix Kernel Team , Joe Perches , Subbaraman Narayanamurthy , Lee Jones , Guenter Roeck , NXP Linux Team MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Since the PWM framework is switching struct pwm_state.period's datatype to u64, prepare for this transition by using DIV_ROUND_UP_ULL to handle a 64-bit dividend, and div64_u64 to handle a 64-bit divisor. Also handle a possible overflow in the calculation of period_cycles when both clk_rate and period are large numbers. This logic was unit-tested out by calculating period_cycles using both the existing logic and the proposed one, and the results are as below. ---------------------------------------------------------------------------- clk_rate period existing proposed ---------------------------------------------------------------------------- 1000000000 18446744073709551615 18446744072 18446744073000000000 (U64_MAX) ---------------------------------------------------------------------------- 1000000000 4294967291 4294967291 4294967291 ---------------------------------------------------------------------------- Overflow occurs in the first case with the existing logic, whereas the proposed logic handles it better, sacrificing some precision in a best-effort attempt to handle overflow. As for the second case where there are more typical values of period, the proposed logic handles that correctly too. Cc: Shawn Guo Cc: Sascha Hauer Cc: Pengutronix Kernel Team Cc: Fabio Estevam Cc: NXP Linux Team Signed-off-by: Guru Das Srinagesh --- drivers/pwm/pwm-imx27.c | 48 +++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 43 insertions(+), 5 deletions(-) diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c index 732a6f3..147729d 100644 --- a/drivers/pwm/pwm-imx27.c +++ b/drivers/pwm/pwm-imx27.c @@ -202,7 +202,7 @@ static void pwm_imx27_wait_fifo_slot(struct pwm_chip *chip, sr = readl(imx->mmio_base + MX3_PWMSR); fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr); if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) { - period_ms = DIV_ROUND_UP(pwm_get_period(pwm), + period_ms = DIV_ROUND_UP_ULL(pwm_get_period(pwm), NSEC_PER_MSEC); msleep(period_ms); @@ -212,6 +212,45 @@ static void pwm_imx27_wait_fifo_slot(struct pwm_chip *chip, } } +static int pwm_imx27_calc_period_cycles(const struct pwm_state *state, + unsigned long clk_rate, + unsigned long *period_cycles) +{ + u64 c = 0, c1, c2; + + c1 = clk_rate; + c2 = state->period; + if (c2 > c1) { + c2 = c1; + c1 = state->period; + } + + if (!c1 || !c2) { + pr_err("clk rate and period should be nonzero\n"); + return -EINVAL; + } + + if (c2 <= div64_u64(U64_MAX, c1)) { + c = c1 * c2; + do_div(c, 1000000000); + } else if (c2 <= div64_u64(U64_MAX, div64_u64(c1, 1000))) { + do_div(c1, 1000); + c = c1 * c2; + do_div(c, 1000000); + } else if (c2 <= div64_u64(U64_MAX, div64_u64(c1, 1000000))) { + do_div(c1, 1000000); + c = c1 * c2; + do_div(c, 1000); + } else if (c2 <= div64_u64(U64_MAX, div64_u64(c1, 1000000000))) { + do_div(c1, 1000000000); + c = c1 * c2; + } + + *period_cycles = c; + + return 0; +} + static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_state *state) { @@ -226,10 +265,9 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm, pwm_get_state(pwm, &cstate); clkrate = clk_get_rate(imx->clk_per); - c = clkrate * state->period; - - do_div(c, NSEC_PER_SEC); - period_cycles = c; + ret = pwm_imx27_calc_period_cycles(state, clkrate, &period_cycles); + if (ret) + return ret; prescale = period_cycles / 0x10000 + 1;