The i.MX PWM controller supports inverting the polarity of the PWM
output. Make this feature available in the pxm-imx driver.
Signed-off-by: Lothar Waßmann <LW@xxxxxxxxxxxxxxxxxxx>
---
Documentation/devicetree/bindings/pwm/imx-pwm.txt | 5 +-
drivers/pwm/pwm-imx.c | 42 +++++++++++++++++++++
2 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/Documentation/devicetree/bindings/pwm/imx-pwm.txt b/Documentation/devicetree/bindings/pwm/imx-pwm.txt
index b50d7a6d..d0b04b5 100644
--- a/Documentation/devicetree/bindings/pwm/imx-pwm.txt
+++ b/Documentation/devicetree/bindings/pwm/imx-pwm.txt
@@ -3,8 +3,9 @@ Freescale i.MX PWM controller
Required properties:
- compatible: should be "fsl,<soc>-pwm"
- 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: may be 2 for backwards compatibility or 3 to support
+ switching the output polarity. See pwm.txt in this directory for a
+ description of the cells format.
- interrupts: The interrupt for the pwm controller
Example:
diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
index 3b00a82..05461bb 100644
--- a/drivers/pwm/pwm-imx.c
+++ b/drivers/pwm/pwm-imx.c
@@ -36,6 +36,7 @@
#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_EN (1 << 0)
@@ -138,6 +139,9 @@ 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);
return 0;
@@ -155,6 +159,11 @@ 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);
}
@@ -198,6 +207,17 @@ static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
clk_disable_unprepare(imx->clk_per);
}
+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 = {
.enable = imx_pwm_enable,
.disable = imx_pwm_disable,
@@ -209,6 +229,7 @@ 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);
+ unsigned output_polarity:1;
};
static struct imx_pwm_data imx_pwm_data_v1 = {
@@ -219,6 +240,7 @@ static struct imx_pwm_data imx_pwm_data_v1 = {
static struct imx_pwm_data imx_pwm_data_v2 = {
.config = imx_pwm_config_v2,
.set_enable = imx_pwm_set_enable_v2,
+ .output_polarity = 1,
};
static const struct of_device_id imx_pwm_dt_ids[] = {
@@ -271,6 +293,26 @@ static int imx_pwm_probe(struct platform_device *pdev)
return PTR_ERR(imx->mmio_base);
data = of_id->data;
+ if (data->output_polarity) {
+ const struct device_node *np = pdev->dev.of_node;
+ u32 num_cells;
+
+ dev_dbg(&pdev->dev, "PWM supports output inversion\n");
+ ret = of_property_read_u32(np, "#pwm-cells", &num_cells);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "missing property '#pwm-cells'\n");
+ return ret;
+ }
+ if (num_cells == 3) {
+ imx_pwm_ops.set_polarity = imx_pwm_set_polarity;
+ imx->chip.of_xlate = of_pwm_xlate_with_flags;
+ } else if (num_cells != 2) {
+ dev_err(&pdev->dev, "'#pwm-cells' must be <2> or <3>\n");
+ return -EINVAL;
+ }
+ imx->chip.of_pwm_n_cells = num_cells;
+ }
+
imx->config = data->config;
imx->set_enable = data->set_enable;
--
1.7.2.5
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