pwm: Introduce single-PWM of_xlate function

The existing pxa driver and the upcoming addition of PWM support in the
TI sn565dsi86 DSI/eDP bridge driver both has a single PWM channel and
thereby a need for a of_xlate function with the period as its single
argument.

Introduce a common helper function in the core that can be used as
of_xlate by such drivers and migrate the pxa driver to use this.
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: Steev Klimaszewski <steev@kali.org>
Tested-By: Steev Klimaszewski <steev@kali.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211025170925.3096444-1-bjorn.andersson@linaro.org

drivers/pwm/core.c

@@ -152,6 +152,32 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
 }
 EXPORT_SYMBOL_GPL(of_pwm_xlate_with_flags);
 
+struct pwm_device *
+of_pwm_single_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
+{
+	struct pwm_device *pwm;
+
+	if (pc->of_pwm_n_cells < 1)
+		return ERR_PTR(-EINVAL);
+
+	/* validate that one cell is specified, optionally with flags */
+	if (args->args_count != 1 && args->args_count != 2)
+		return ERR_PTR(-EINVAL);
+
+	pwm = pwm_request_from_chip(pc, 0, NULL);
+	if (IS_ERR(pwm))
+		return pwm;
+
+	pwm->args.period = args->args[0];
+	pwm->args.polarity = PWM_POLARITY_NORMAL;
+
+	if (args->args_count == 2 && args->args[2] & PWM_POLARITY_INVERTED)
+		pwm->args.polarity = PWM_POLARITY_INVERSED;
+
+	return pwm;
+}
+EXPORT_SYMBOL_GPL(of_pwm_single_xlate);
+
 static void of_pwmchip_add(struct pwm_chip *chip)
 {
 	if (!chip->dev || !chip->dev->of_node)

drivers/pwm/pwm-pxa.c

@@ -148,20 +148,6 @@ static const struct platform_device_id *pxa_pwm_get_id_dt(struct device *dev)
 	return id ? id->data : NULL;
 }
 
-static struct pwm_device *
-pxa_pwm_of_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
-{
-	struct pwm_device *pwm;
-
-	pwm = pwm_request_from_chip(pc, 0, NULL);
-	if (IS_ERR(pwm))
-		return pwm;
-
-	pwm->args.period = args->args[0];
-
-	return pwm;
-}
-
 static int pwm_probe(struct platform_device *pdev)
 {
 	const struct platform_device_id *id = platform_get_device_id(pdev);
@@ -187,7 +173,7 @@ static int pwm_probe(struct platform_device *pdev)
 	pc->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
 
 	if (IS_ENABLED(CONFIG_OF)) {
-		pc->chip.of_xlate = pxa_pwm_of_xlate;
+		pc->chip.of_xlate = of_pwm_single_xlate;
 		pc->chip.of_pwm_n_cells = 1;
 	}
 

include/linux/pwm.h

@@ -414,6 +414,8 @@ struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 
 struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
 		const struct of_phandle_args *args);
+struct pwm_device *of_pwm_single_xlate(struct pwm_chip *pc,
+				       const struct of_phandle_args *args);
 
 struct pwm_device *pwm_get(struct device *dev, const char *con_id);
 struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np,