[PATCH v2 2/6] pwm: core: make the PWM_POLARITY flag in DTB optional

[Bhuvanchandra DV]

From: Lothar Wassmann <l...@karo-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 <l...@karo-electronics.de>
Signed-off-by: Bhuvanchandra DV <bhuvanchandra...@toradex.com>
Suggested-by: Thierry Reding <thierry.red...@gmail.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