pwm: Make the PWM_POLARITY flag in DTB optional

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 polarity flag as part of the specifier.

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@KARO-electronics.de>
Signed-off-by: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>
Suggested-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 012e27c7f27e4fcd0d95f25f6dff0cd01efbc3fd..e3d6c5437070efcc656c9088c138ccb9971b0ab7 100644 (file)
--- 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);
 
@@ -148,11 +153,10 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
                return pwm;
 
        pwm->args.period = args->args[1];
+       pwm->args.polarity = PWM_POLARITY_NORMAL;
 
-       if (args->args[2] & PWM_POLARITY_INVERTED)
+       if (args->args_count > 2 && args->args[2] & PWM_POLARITY_INVERTED)
                pwm->args.polarity = PWM_POLARITY_INVERSED;
-       else
-               pwm->args.polarity = PWM_POLARITY_NORMAL;
 
        return pwm;
 }
@@ -163,9 +167,14 @@ 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);
 
@@ -674,13 +683,6 @@ 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;