linux-kernel - [PATCH v2 2/6] pwm: core: make the PWM

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Date:   Sat, 1 Oct 2016 15:42:31 +0530
From:   Bhuvanchandra DV <bhuvanchandra.dv@...adex.com>
To:     <shawnguo@...nel.org>, <thierry.reding@...il.com>
CC:     <stefan@...er.ch>, <l.majewski@...sung.com>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <kernel@...gutronix.de>,
        <fabio.estevam@....com>, <linux-pwm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Lothar Wassmann <LW@...O-electronics.de>,
        Bhuvanchandra DV <bhuvanchandra.dv@...adex.com>
Subject: [PATCH v2 2/6] pwm: core: make the PWM_POLARITY flag in DTB optional

From: Lothar Wassmann <LW@...O-electronics.de>

Change the pwm chip driver registration, so that a chip driver that supports
polarity inversion can still be used with DTBs that don't provide the
'PWM_POLARITY' flag.

This is done to provide polarity inversion support for the pwm-imx driver
without having to modify all existing DTS files.

Signed-off-by: Lothar Wassmann <LW@...O-electronics.de>
Signed-off-by: Bhuvanchandra DV <bhuvanchandra.dv@...adex.com>
Suggested-by: Thierry Reding <thierry.reding@...il.com>
---
 drivers/pwm/core.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 195373e..aae8db3 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -137,9 +137,14 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
 {
 	struct pwm_device *pwm;
 
+	/* check, whether the driver supports a third cell for flags */
 	if (pc->of_pwm_n_cells < 3)
 		return ERR_PTR(-EINVAL);
 
+	/* flags in the third cell are optional */
+	if (args->args_count < 2)
+		return ERR_PTR(-EINVAL);
+
 	if (args->args[0] >= pc->npwm)
 		return ERR_PTR(-EINVAL);
 
@@ -149,10 +154,12 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
 
 	pwm->args.period = args->args[1];
 
-	if (args->args[2] & PWM_POLARITY_INVERTED)
-		pwm->args.polarity = PWM_POLARITY_INVERSED;
-	else
-		pwm->args.polarity = PWM_POLARITY_NORMAL;
+	if (args->args_count > 2) {
+		if (args->args[2] & PWM_POLARITY_INVERTED)
+			pwm_set_polarity(pwm, PWM_POLARITY_INVERSED);
+		else
+			pwm_set_polarity(pwm, PWM_POLARITY_NORMAL);
+	}
 
 	return pwm;
 }
@@ -163,9 +170,14 @@ of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
 {
 	struct pwm_device *pwm;
 
+	/* sanity check driver support */
 	if (pc->of_pwm_n_cells < 2)
 		return ERR_PTR(-EINVAL);
 
+	/* all cells are required */
+	if (args->args_count != pc->of_pwm_n_cells)
+		return ERR_PTR(-EINVAL);
+
 	if (args->args[0] >= pc->npwm)
 		return ERR_PTR(-EINVAL);
 
@@ -672,13 +684,6 @@ struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id)
 		goto put;
 	}
 
-	if (args.args_count != pc->of_pwm_n_cells) {
-		pr_debug("%s: wrong #pwm-cells for %s\n", np->full_name,
-			 args.np->full_name);
-		pwm = ERR_PTR(-EINVAL);
-		goto put;
-	}
-
 	pwm = pc->of_xlate(pc, &args);
 	if (IS_ERR(pwm))
 		goto put;
-- 
2.9.2