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Subject[PATCHv4 4/4] pwm: imx: support output polarity inversion
Date
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 <LW@KARO-electronics.de>
---
drivers/pwm/pwm-imx.c | 38 +++++++++++++++++++++++++++++++++++---
1 file changed, 35 insertions(+), 3 deletions(-)

diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
index 582ac3a..7357bbb 100644
--- 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;

--
1.7.10.4
--
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