From patchwork Fri Aug 9 12:30:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 1144620 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=crapouillou.net Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=crapouillou.net header.i=@crapouillou.net header.b="JPbfun6S"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 464l3B4lZ2z9sP7 for ; Fri, 9 Aug 2019 22:31:18 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406676AbfHIMbR (ORCPT ); Fri, 9 Aug 2019 08:31:17 -0400 Received: from outils.crapouillou.net ([89.234.176.41]:55616 "EHLO crapouillou.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726168AbfHIMbR (ORCPT ); Fri, 9 Aug 2019 08:31:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1565353850; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/v3/BAVtZKNue7NyDFb+jY+xt8Nkkuc47WZZP4QpfNk=; b=JPbfun6S2OJfE2xqfYQWl1jnD/Ozp5dKiDu/llBTvLQ05O3NBIMb8Sqj5lAoVom7AloJ17 X3p60uEuk+ek/JNHCeR43zIQ9nIAfVptGFmw4PWYNu5CTweg0Qm+hlYxBeYCh5wH4CRd1H Qpi3ru3npbC+YSbixgD5w07JFoEBQVo= From: Paul Cercueil To: Thierry Reding Cc: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , od@zcrc.me, linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Cercueil , Mathieu Malaterre , Artur Rojek Subject: [PATCH 4/7] pwm: jz4740: Improve algorithm of clock calculation Date: Fri, 9 Aug 2019 14:30:28 +0200 Message-Id: <20190809123031.24219-5-paul@crapouillou.net> In-Reply-To: <20190809123031.24219-1-paul@crapouillou.net> References: <20190809123031.24219-1-paul@crapouillou.net> MIME-Version: 1.0 Sender: linux-pwm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org The previous algorithm hardcoded details about how the TCU clocks work. The new algorithm will use clk_round_rate to find the perfect clock rate for the PWM channel. Signed-off-by: Paul Cercueil Tested-by: Mathieu Malaterre Tested-by: Artur Rojek --- drivers/pwm/pwm-jz4740.c | 60 +++++++++++++++++++++++++++++----------- 1 file changed, 44 insertions(+), 16 deletions(-) diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c index 6ec8794d3b99..f20dc2e19240 100644 --- a/drivers/pwm/pwm-jz4740.c +++ b/drivers/pwm/pwm-jz4740.c @@ -110,24 +110,56 @@ static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip); struct clk *clk = pwm_get_chip_data(pwm), *parent_clk = clk_get_parent(clk); - unsigned long rate, period, duty; + unsigned long rate, parent_rate, period, duty; unsigned long long tmp; - unsigned int prescaler = 0; + int ret; - rate = clk_get_rate(parent_clk); - tmp = (unsigned long long)rate * state->period; - do_div(tmp, 1000000000); - period = tmp; + parent_rate = clk_get_rate(parent_clk); + + jz4740_pwm_disable(chip, pwm); - while (period > 0xffff && prescaler < 6) { - period >>= 2; - rate >>= 2; - ++prescaler; + /* Reset the clock to the maximum rate, and we'll reduce it if needed */ + ret = clk_set_max_rate(clk, parent_rate); + if (ret) { + dev_err(chip->dev, "Unable to set max rate: %d\n", ret); + return ret; } - if (prescaler == 6) - return -EINVAL; + ret = clk_set_rate(clk, parent_rate); + if (ret) { + dev_err(chip->dev, "Unable to reset to parent rate (%lu Hz)", + parent_rate); + return ret; + } + + /* + * Limit the clock to a maximum rate that still gives us a period value + * which fits in 16 bits. + */ + tmp = 0xffffull * NSEC_PER_SEC; + do_div(tmp, state->period); + ret = clk_set_max_rate(clk, tmp); + if (ret) { + dev_err(chip->dev, "Unable to set max rate: %d\n", ret); + return ret; + } + + /* + * Read back the clock rate, as it may have been modified by + * clk_set_max_rate() + */ + rate = clk_get_rate(clk); + + if (rate != parent_rate) + dev_dbg(chip->dev, "PWM clock updated to %lu Hz\n", rate); + + /* Calculate period value */ + tmp = (unsigned long long)rate * state->period; + do_div(tmp, NSEC_PER_SEC); + period = (unsigned long)tmp; + + /* Calculate duty value */ tmp = (unsigned long long)period * state->duty_cycle; do_div(tmp, state->period); duty = period - tmp; @@ -135,14 +167,10 @@ static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, if (duty >= period) duty = period - 1; - jz4740_pwm_disable(chip, pwm); - /* Set abrupt shutdown */ regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm), TCU_TCSR_PWM_SD, TCU_TCSR_PWM_SD); - clk_set_rate(clk, rate); - /* Reset counter to 0 */ regmap_write(jz4740->map, TCU_REG_TCNTc(pwm->hwpwm), 0);