pwm: imx: support output polarity inversion

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.

diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
index 582ac3aa4e4d3cab6754ba3033a62fe3f65162b9..7357bbb8acc9ef630ccb29d2f9fa39da102a0060 100644 (file)
--- a/drivers/pwm/pwm-imx.c
+++ b/drivers/pwm/pwm-imx.c
@@ -138,6 +138,8 @@ static int imx_pwm_config_v2(struct pwm_chip *chip,
 
        if (test_bit(PWMF_ENABLED, &pwm->flags))
                cr |= MX3_PWMCR_EN;
+       if (pwm->polarity == PWM_POLARITY_INVERSED)
+               cr |= MX3_PWMCR_POUTC;
 
        writel(cr, imx->mmio_base + MX3_PWMCR);
 
@@ -156,6 +158,11 @@ static void imx_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
        else
                val &= ~MX3_PWMCR_EN;
 
+       if (chip->pwms[0].polarity == PWM_POLARITY_INVERSED)
+               val |= MX3_PWMCR_POUTC;
+       else
+               val &= ~MX3_PWMCR_POUTC;
+
        writel(val, imx->mmio_base + MX3_PWMCR);
 }
 
@@ -199,27 +206,49 @@ 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);
+
+       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[] = {
@@ -241,6 +270,10 @@ static int imx_pwm_probe(struct platform_device *pdev)
        if (!of_id)
                return -ENODEV;
 
+       data = of_id->data;
+       if (data->pwm_ops->set_polarity)
+               dev_dbg(&pdev->dev, "PWM supports output inversion\n");
+
        imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
        if (imx == NULL)
                return -ENOMEM;
@@ -259,7 +292,7 @@ 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;
@@ -269,7 +302,6 @@ static int imx_pwm_probe(struct platform_device *pdev)
        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;