[PATCH v2] pwm: Introduce single-PWM of_xlate function

[Bjorn Andersson <bjorn.andersson@linaro.org>]

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>
---

Changes since v1:
- Included the pwm.h change in the commit...

 drivers/pwm/core.c    | 24 ++++++++++++++++++++++++
 drivers/pwm/pwm-pxa.c | 16 +---------------
 include/linux/pwm.h   |  2 ++
 3 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index c4d5c0667137..25ed23cdf0d3 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -176,6 +176,30 @@ of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
 	return pwm;
 }
 
+struct pwm_device *
+of_pwm_single_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
+{
+	struct pwm_device *pwm;
+
+	/* sanity check driver is single PWM */
+	if (pc->of_pwm_n_cells != 1)
+		return ERR_PTR(-EINVAL);
+
+	/* validate that one cell is specified */
+	if (args->args_count != 1)
+		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;
+
+	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)
diff --git a/drivers/pwm/pwm-pxa.c b/drivers/pwm/pwm-pxa.c
index cfb683827d32..8cd82fb54483 100644
--- a/drivers/pwm/pwm-pxa.c
+++ b/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)
 	pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
 
 	if (IS_ENABLED(CONFIG_OF)) {
-		pwm->chip.of_xlate = pxa_pwm_of_xlate;
+		pwm->chip.of_xlate = of_pwm_single_xlate;
 		pwm->chip.of_pwm_n_cells = 1;
 	}
 
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 5bb90af4997e..0ac242a5b5e4 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -405,6 +405,8 @@ 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,
-- 
2.31.0