linux-kernel - [PATCH RESEND 2/4] pwm: mediatek: fix clk issue

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Message-ID: <1498032672-7172-3-git-send-email-zhi.mao@mediatek.com>
Date:   Wed, 21 Jun 2017 16:11:10 +0800
From:   Zhi Mao <zhi.mao@...iatek.com>
To:     <john@...ozen.org>, Thierry Reding <thierry.reding@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <linux-pwm@...r.kernel.org>
CC:     <srv_heupstream@...iatek.com>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>, <zhi.mao@...iatek.com>,
        <yingjoe.chen@...iatek.com>, <yt.shen@...iatek.com>,
        <sean.wang@...iatek.com>, <zhenbao.liu@...iatek.com>
Subject: [PATCH RESEND 2/4] pwm: mediatek: fix clk issue

1.fix clock control
 - prepare top/main clk in mtk_pwm_probe() function,
   it will increase power consumption
   and in original code these clocks is only prepeare but never enabled
 - pwm clock should be enabled before setting pwm registers
   in function: mtk_pwm_config()

2.fix pwm source clock selection
 - in original code, the pwm output frequency is not correct
   when set bit<3>=1 to PWMCON register.

Signed-off-by: Zhi Mao <zhi.mao@...iatek.com>
---
 drivers/pwm/pwm-mediatek.c |   69 +++++++++++++++++++++++++++-----------------
 1 file changed, 43 insertions(+), 26 deletions(-)

diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
index 5c11bc7..c803ff6 100644
--- a/drivers/pwm/pwm-mediatek.c
+++ b/drivers/pwm/pwm-mediatek.c
@@ -2,6 +2,7 @@
  * Mediatek Pulse Width Modulator driver
  *
  * Copyright (C) 2015 John Crispin <blogic@...nwrt.org>
+ * Copyright (C) 2017 Zhi Mao <zhi.mao@...iatek.com>
  *
  * This file is licensed under the terms of the GNU General Public
  * License version 2. This program is licensed "as is" without any
@@ -61,6 +62,40 @@ static inline struct mtk_pwm_chip *to_mtk_pwm_chip(struct pwm_chip *chip)
 	return container_of(chip, struct mtk_pwm_chip, chip);
 }
 
+static int mtk_pwm_clk_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct mtk_pwm_chip *pc = to_mtk_pwm_chip(chip);
+	int ret = 0;
+
+	ret = clk_prepare_enable(pc->clks[MTK_CLK_TOP]);
+	if (ret < 0)
+		return ret;
+
+	ret = clk_prepare_enable(pc->clks[MTK_CLK_MAIN]);
+	if (ret < 0) {
+		clk_disable_unprepare(pc->clks[MTK_CLK_TOP]);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(pc->clks[MTK_CLK_PWM1 + pwm->hwpwm]);
+	if (ret < 0) {
+		clk_disable_unprepare(pc->clks[MTK_CLK_MAIN]);
+		clk_disable_unprepare(pc->clks[MTK_CLK_TOP]);
+		return ret;
+	}
+
+	return ret;
+}
+
+static void mtk_pwm_clk_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct mtk_pwm_chip *pc = to_mtk_pwm_chip(chip);
+
+	clk_disable_unprepare(pc->clks[MTK_CLK_PWM1 + pwm->hwpwm]);
+	clk_disable_unprepare(pc->clks[MTK_CLK_MAIN]);
+	clk_disable_unprepare(pc->clks[MTK_CLK_TOP]);
+}
+
 static inline u32 mtk_pwm_readl(struct mtk_pwm_chip *chip, unsigned int num,
 				unsigned int offset)
 {
@@ -81,6 +116,8 @@ static int mtk_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	struct clk *clk = pc->clks[MTK_CLK_PWM1 + pwm->hwpwm];
 	u32 resolution, clkdiv = 0;
 
+	mtk_pwm_clk_enable(chip, pwm);
+
 	resolution = NSEC_PER_SEC / clk_get_rate(clk);
 
 	while (period_ns / resolution > 8191) {
@@ -91,10 +128,12 @@ static int mtk_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	if (clkdiv > 7)
 		return -EINVAL;
 
-	mtk_pwm_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | BIT(3) | clkdiv);
+	mtk_pwm_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | clkdiv);
 	mtk_pwm_writel(pc, pwm->hwpwm, PWMDWIDTH, period_ns / resolution);
 	mtk_pwm_writel(pc, pwm->hwpwm, PWMTHRES, duty_ns / resolution);
 
+	mtk_pwm_clk_disable(chip, pwm);
+
 	return 0;
 }
 
@@ -102,11 +141,8 @@ static int mtk_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct mtk_pwm_chip *pc = to_mtk_pwm_chip(chip);
 	u32 value;
-	int ret;
 
-	ret = clk_prepare(pc->clks[MTK_CLK_PWM1 + pwm->hwpwm]);
-	if (ret < 0)
-		return ret;
+	mtk_pwm_clk_enable(chip, pwm);
 
 	value = readl(pc->regs);
 	value |= BIT(pwm->hwpwm);
@@ -124,7 +160,7 @@ static void mtk_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 	value &= ~BIT(pwm->hwpwm);
 	writel(value, pc->regs);
 
-	clk_unprepare(pc->clks[MTK_CLK_PWM1 + pwm->hwpwm]);
+	mtk_pwm_clk_disable(chip, pwm);
 }
 
 static const struct pwm_ops mtk_pwm_ops = {
@@ -156,14 +192,6 @@ static int mtk_pwm_probe(struct platform_device *pdev)
 			return PTR_ERR(pc->clks[i]);
 	}
 
-	ret = clk_prepare(pc->clks[MTK_CLK_TOP]);
-	if (ret < 0)
-		return ret;
-
-	ret = clk_prepare(pc->clks[MTK_CLK_MAIN]);
-	if (ret < 0)
-		goto disable_clk_top;
-
 	platform_set_drvdata(pdev, pc);
 
 	pc->chip.dev = &pdev->dev;
@@ -174,26 +202,15 @@ static int mtk_pwm_probe(struct platform_device *pdev)
 	ret = pwmchip_add(&pc->chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
-		goto disable_clk_main;
+		return ret;
 	}
 
 	return 0;
-
-disable_clk_main:
-	clk_unprepare(pc->clks[MTK_CLK_MAIN]);
-disable_clk_top:
-	clk_unprepare(pc->clks[MTK_CLK_TOP]);
-
-	return ret;
 }
 
 static int mtk_pwm_remove(struct platform_device *pdev)
 {
 	struct mtk_pwm_chip *pc = platform_get_drvdata(pdev);
-	unsigned int i;
-
-	for (i = 0; i < pc->chip.npwm; i++)
-		pwm_disable(&pc->chip.pwms[i]);
 
 	return pwmchip_remove(&pc->chip);
 }
-- 
1.7.9.5