Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752132AbcJJVGx (ORCPT ); Mon, 10 Oct 2016 17:06:53 -0400 Received: from mail.kmu-office.ch ([178.209.48.109]:47607 "EHLO mail.kmu-office.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751882AbcJJVGw (ORCPT ); Mon, 10 Oct 2016 17:06:52 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Date: Mon, 10 Oct 2016 14:01:03 -0700 From: Stefan Agner To: Bhuvanchandra DV Cc: shawnguo@kernel.org, thierry.reding@gmail.com, l.majewski@samsung.com, robh+dt@kernel.org, mark.rutland@arm.com, kernel@pengutronix.de, fabio.estevam@nxp.com, linux-pwm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Lothar Wassmann , boris.brezillon@free-electrons.com Subject: Re: [PATCH v3 3/6] pwm: imx: support output polarity inversion In-Reply-To: <20161007151129.6043-4-bhuvanchandra.dv@toradex.com> References: <20161007151129.6043-1-bhuvanchandra.dv@toradex.com> <20161007151129.6043-4-bhuvanchandra.dv@toradex.com> Message-ID: <5325a332099473a2d8382530f79c5a8e@agner.ch> User-Agent: Roundcube Webmail/1.1.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6315 Lines: 186 On 2016-10-07 08:11, Bhuvanchandra DV wrote: > From: Lothar Wassmann > > The i.MX pwm unit on i.MX27 and newer SoCs provides a configurable output > polarity. This patch adds support to utilize this feature where available. > > Signed-off-by: Lothar Waßmann > Signed-off-by: Lukasz Majewski > Signed-off-by: Bhuvanchandra DV > Acked-by: Shawn Guo > Reviewed-by: Sascha Hauer > --- > Documentation/devicetree/bindings/pwm/imx-pwm.txt | 6 +-- > drivers/pwm/pwm-imx.c | 51 +++++++++++++++++++++-- > 2 files changed, 51 insertions(+), 6 deletions(-) > > diff --git a/Documentation/devicetree/bindings/pwm/imx-pwm.txt > b/Documentation/devicetree/bindings/pwm/imx-pwm.txt > index e00c2e9..c61bdf8 100644 > --- a/Documentation/devicetree/bindings/pwm/imx-pwm.txt > +++ b/Documentation/devicetree/bindings/pwm/imx-pwm.txt > @@ -6,8 +6,8 @@ Required properties: > - "fsl,imx1-pwm" for PWM compatible with the one integrated on i.MX1 > - "fsl,imx27-pwm" for PWM compatible with the one integrated on i.MX27 > - reg: physical base address and length of the controller's registers > -- #pwm-cells: should be 2. See pwm.txt in this directory for a description of > - the cells format. > +- #pwm-cells: 2 for i.MX1 and 3 for i.MX27 and newer SoCs. See pwm.txt > + in this directory for a description of the cells format. > - clocks : Clock specifiers for both ipg and per clocks. > - clock-names : Clock names should include both "ipg" and "per" > See the clock consumer binding, > @@ -17,7 +17,7 @@ See the clock consumer binding, > Example: > > pwm1: pwm@53fb4000 { > - #pwm-cells = <2>; > + #pwm-cells = <3>; > compatible = "fsl,imx53-pwm", "fsl,imx27-pwm"; > reg = <0x53fb4000 0x4000>; > clocks = <&clks IMX5_CLK_PWM1_IPG_GATE>, > diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c > index d600fd5..c37d223 100644 > --- a/drivers/pwm/pwm-imx.c > +++ b/drivers/pwm/pwm-imx.c > @@ -38,6 +38,7 @@ > #define MX3_PWMCR_DOZEEN (1 << 24) > #define MX3_PWMCR_WAITEN (1 << 23) > #define MX3_PWMCR_DBGEN (1 << 22) > +#define MX3_PWMCR_POUTC (1 << 18) > #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16) > #define MX3_PWMCR_CLKSRC_IPG (1 << 16) > #define MX3_PWMCR_SWR (1 << 3) > @@ -180,6 +181,9 @@ static int imx_pwm_config_v2(struct pwm_chip *chip, > if (enable) > cr |= MX3_PWMCR_EN; > > + if (pwm->args.polarity == PWM_POLARITY_INVERSED) > + cr |= MX3_PWMCR_POUTC; > + This seems wrong to me, the config callback is meant for period/duty cycle only. The set_polarity callback should get called in case a different polarity is requested. > writel(cr, imx->mmio_base + MX3_PWMCR); > > return 0; > @@ -240,27 +244,62 @@ static void imx_pwm_disable(struct pwm_chip > *chip, struct pwm_device *pwm) > clk_disable_unprepare(imx->clk_per); > } > > -static struct pwm_ops imx_pwm_ops = { > +static int imx_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, > + enum pwm_polarity polarity) > +{ > + struct imx_chip *imx = to_imx_chip(chip); > + u32 val; > + > + if (polarity == pwm->args.polarity) > + return 0; I don't think that this is right. Today, pwm_apply_args (in include/linux/pwm.h) copies the polarity from args to state.polarity, which is then passed as polarity argument to this function. So this will always return 0 afaict. I would just drop that. There is probably one little problem in the current state of affairs: If the bootloader makes use of a PWM channel with inverted state, then the kernel would not know about that and currently assume a wrong initial state... I guess at one point in time we should implement the state retrieval callback and move to the new atomic PWM API, which would mean to implement apply callback. -- Stefan > + > + val = readl(imx->mmio_base + MX3_PWMCR); > + > + if (polarity == PWM_POLARITY_INVERSED) > + val |= MX3_PWMCR_POUTC; > + else > + val &= ~MX3_PWMCR_POUTC; > + > + writel(val, imx->mmio_base + MX3_PWMCR); > + > + dev_dbg(imx->chip.dev, "%s: polarity set to %s\n", __func__, > + polarity == PWM_POLARITY_INVERSED ? "inverted" : "normal"); > + > + return 0; > +} > + > +static struct pwm_ops imx_pwm_ops_v1 = { > .enable = imx_pwm_enable, > .disable = imx_pwm_disable, > .config = imx_pwm_config, > .owner = THIS_MODULE, > }; > > +static struct pwm_ops imx_pwm_ops_v2 = { > + .enable = imx_pwm_enable, > + .disable = imx_pwm_disable, > + .set_polarity = imx_pwm_set_polarity, > + .config = imx_pwm_config, > + .owner = THIS_MODULE, > +}; > + > struct imx_pwm_data { > int (*config)(struct pwm_chip *chip, > struct pwm_device *pwm, int duty_ns, int period_ns); > void (*set_enable)(struct pwm_chip *chip, bool enable); > + struct pwm_ops *pwm_ops; > }; > > static struct imx_pwm_data imx_pwm_data_v1 = { > .config = imx_pwm_config_v1, > .set_enable = imx_pwm_set_enable_v1, > + .pwm_ops = &imx_pwm_ops_v1, > }; > > static struct imx_pwm_data imx_pwm_data_v2 = { > .config = imx_pwm_config_v2, > .set_enable = imx_pwm_set_enable_v2, > + .pwm_ops = &imx_pwm_ops_v2, > }; > > static const struct of_device_id imx_pwm_dt_ids[] = { > @@ -282,6 +321,8 @@ static int imx_pwm_probe(struct platform_device *pdev) > if (!of_id) > return -ENODEV; > > + data = of_id->data; > + > imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL); > if (imx == NULL) > return -ENOMEM; > @@ -300,18 +341,22 @@ static int imx_pwm_probe(struct platform_device *pdev) > return PTR_ERR(imx->clk_ipg); > } > > - imx->chip.ops = &imx_pwm_ops; > + imx->chip.ops = data->pwm_ops; > imx->chip.dev = &pdev->dev; > imx->chip.base = -1; > imx->chip.npwm = 1; > imx->chip.can_sleep = true; > + if (data->pwm_ops->set_polarity) { > + dev_dbg(&pdev->dev, "PWM supports output inversion\n"); > + imx->chip.of_xlate = of_pwm_xlate_with_flags; > + imx->chip.of_pwm_n_cells = 3; > + } > > r = platform_get_resource(pdev, IORESOURCE_MEM, 0); > imx->mmio_base = devm_ioremap_resource(&pdev->dev, r); > if (IS_ERR(imx->mmio_base)) > return PTR_ERR(imx->mmio_base); > > - data = of_id->data; > imx->config = data->config; > imx->set_enable = data->set_enable;