Add support for encoding PWM properties in bit encoded form with
of_pwm_xlate_with_flags() function support. Platforms require platform
specific PWM properties has to populate in 3rd cell of the pwm-specifier
and PWM driver should also set .of_xlate support with this function.
Currently PWM property polarity encoded in bit position 0 of the third
cell in pwm-specifier.
Signed-off-by: Philip, Avinash <[email protected]>
---
Changes since v1:
- of_pwm_xlate_with_flags function support added.
- Documentation update
:100644 100644 73ec962... 04b0dc4... M Documentation/devicetree/bindings/pwm/pwm.txt
:100644 100644 f5acdaa... 9b49e78... M drivers/pwm/core.c
:100644 100644 112b314... 70756f2... M include/linux/pwm.h
Documentation/devicetree/bindings/pwm/pwm.txt | 18 +++++++++++++++---
drivers/pwm/core.c | 25 +++++++++++++++++++++++++
include/linux/pwm.h | 12 ++++++++++++
3 files changed, 52 insertions(+), 3 deletions(-)
diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt b/Documentation/devicetree/bindings/pwm/pwm.txt
index 73ec962..04b0dc4 100644
--- a/Documentation/devicetree/bindings/pwm/pwm.txt
+++ b/Documentation/devicetree/bindings/pwm/pwm.txt
@@ -37,10 +37,22 @@ device:
pwm-names = "backlight";
};
+Note that in the example above, specifying the "pwm-names" is redundant
+because the name "backlight" would be used as fallback anyway.
+
pwm-specifier typically encodes the chip-relative PWM number and the PWM
-period in nanoseconds. Note that in the example above, specifying the
-"pwm-names" is redundant because the name "backlight" would be used as
-fallback anyway.
+period in nanoseconds.
+
+Optionally, the pwm-specifier can encode a number of flags in a third cell:
+- bit 0: PWM signal polarity (0: normal polarity, 1: inverse polarity)
+
+Example with optional PWM specifier for inverse polarity
+
+ bl: backlight {
+ pwms = <&pwm 0 5000000 1>;
+ pwm-names = "backlight";
+ };
+
2) PWM controller nodes
-----------------------
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index f5acdaa..9b49e78 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -129,6 +129,31 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
return 0;
}
+struct pwm_device *
+of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
+{
+ struct pwm_device *pwm;
+
+ if (pc->of_pwm_n_cells < 3)
+ return ERR_PTR(-EINVAL);
+
+ if (args->args[0] >= pc->npwm)
+ return ERR_PTR(-EINVAL);
+
+ pwm = pwm_request_from_chip(pc, args->args[0], NULL);
+ if (IS_ERR(pwm))
+ return pwm;
+
+ pwm_set_period(pwm, args->args[1]);
+
+ if (args->args[2] & PWM_SPEC_POLARITY)
+ pwm_set_polarity(pwm, PWM_POLARITY_INVERSED);
+ else
+ pwm_set_polarity(pwm, PWM_POLARITY_NORMAL);
+
+ return pwm;
+}
+
static struct pwm_device *
of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
{
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 112b314..70756f2 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -78,6 +78,10 @@ enum {
PWMF_ENABLED = 1 << 1,
};
+/* flags in the third cell of the DT PWM specifier */
+#define PWM_SPEC_POLARITY (1 << 0)
+
+
struct pwm_device {
const char *label;
unsigned long flags;
@@ -176,6 +180,8 @@ void pwm_put(struct pwm_device *pwm);
struct pwm_device *devm_pwm_get(struct device *dev, const char *consumer);
void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
+struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
+ const struct of_phandle_args *args);
#else
static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
{
@@ -223,6 +229,12 @@ static inline struct pwm_device *devm_pwm_get(struct device *dev,
static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
{
}
+
+static inline struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
+ const struct of_phandle_args *args)
+{
+ return ERR_PTR(-ENODEV);
+}
#endif
struct pwm_lookup {
--
1.7.0.4
On Mon, Nov 19, 2012 at 11:21:12PM +0530, Philip, Avinash wrote:
[...]
> diff --git a/include/linux/pwm.h b/include/linux/pwm.h
> index 112b314..70756f2 100644
> --- a/include/linux/pwm.h
> +++ b/include/linux/pwm.h
> @@ -78,6 +78,10 @@ enum {
> PWMF_ENABLED = 1 << 1,
> };
>
> +/* flags in the third cell of the DT PWM specifier */
> +#define PWM_SPEC_POLARITY (1 << 0)
> +
> +
This doesn't belong in this header. It should go into core.c in
drivers/pwm.
> struct pwm_device {
> const char *label;
> unsigned long flags;
> @@ -176,6 +180,8 @@ void pwm_put(struct pwm_device *pwm);
>
> struct pwm_device *devm_pwm_get(struct device *dev, const char *consumer);
> void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
> +struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
> + const struct of_phandle_args *args);
The placement of this prototype is odd. I think a better place would be
between pwm_request_from_chip() and pwm_get(), separated by blank lines
to make it stand out as an OF specific function.
> #else
> static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
> {
> @@ -223,6 +229,12 @@ static inline struct pwm_device *devm_pwm_get(struct device *dev,
> static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
> {
> }
> +
> +static inline struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
> + const struct of_phandle_args *args)
> +{
> + return ERR_PTR(-ENODEV);
> +}
This function should only be used by PWM drivers and therefore doesn't
need to have a dummy implementation such as this.
Thierry
On Tue, Nov 20, 2012 at 20:37:55, Thierry Reding wrote:
> On Mon, Nov 19, 2012 at 11:21:12PM +0530, Philip, Avinash wrote:
> [...]
> > diff --git a/include/linux/pwm.h b/include/linux/pwm.h
> > index 112b314..70756f2 100644
> > --- a/include/linux/pwm.h
> > +++ b/include/linux/pwm.h
> > @@ -78,6 +78,10 @@ enum {
> > PWMF_ENABLED = 1 << 1,
> > };
> >
> > +/* flags in the third cell of the DT PWM specifier */
> > +#define PWM_SPEC_POLARITY (1 << 0)
> > +
> > +
>
> This doesn't belong in this header. It should go into core.c in
> drivers/pwm.
I will move.
>
> > struct pwm_device {
> > const char *label;
> > unsigned long flags;
> > @@ -176,6 +180,8 @@ void pwm_put(struct pwm_device *pwm);
> >
> > struct pwm_device *devm_pwm_get(struct device *dev, const char *consumer);
> > void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
> > +struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
> > + const struct of_phandle_args *args);
>
> The placement of this prototype is odd. I think a better place would be
> between pwm_request_from_chip() and pwm_get(), separated by blank lines
> to make it stand out as an OF specific function.
Ok I will move to between pwm_request_from_chip() and pwm_get().
>
> > #else
> > static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
> > {
> > @@ -223,6 +229,12 @@ static inline struct pwm_device *devm_pwm_get(struct device *dev,
> > static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
> > {
> > }
> > +
> > +static inline struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
> > + const struct of_phandle_args *args)
> > +{
> > + return ERR_PTR(-ENODEV);
> > +}
>
> This function should only be used by PWM drivers and therefore doesn't
> need to have a dummy implementation such as this.
Ok I will remove.
Thanks
Avinash
>
> Thierry
>