[PATCH v4] pwm: Fix compilation error when CONFIG_PWM is not defined

[PATCH v4] pwm: Fix compilation error when CONFIG_PWM is not defined

[Tushar Behera]

Add dummy implemention of public symbols for compilation-safe inclusion
of include/linux/pwm.h file when CONFIG_PWM is not defined.

Reported-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
---
Changes since v3:
* Nitpicks

Changes since v2:
* #if condition for legacy functions modified
* Reverted layout changes, can be taken up when HAVE_PWM is no longer
required.

Changes since v1:
* Incorporated Thierry's suggestions regarding adding dummy function
implemention for all global functions
* Reorganized header file to have structure definitions first and then the
function definitions.

 include/linux/pwm.h |   71 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 21d076c..946651d 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -6,6 +6,7 @@
 struct pwm_device;
 struct seq_file;
 
+#if IS_ENABLED(CONFIG_PWM) || IS_ENABLED(CONFIG_HAVE_PWM)
 /*
  * pwm_request - request a PWM device
  */
@@ -30,8 +31,31 @@ int pwm_enable(struct pwm_device *pwm);
  * pwm_disable - stop a PWM output toggling
  */
 void pwm_disable(struct pwm_device *pwm);
+#else
+static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
+{
+	return NULL;
+}
+
+static inline void pwm_free(struct pwm_device *pwm)
+{
+}
+
+static inline int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+	return -EINVAL;
+}
+
+static inline int pwm_enable(struct pwm_device *pwm)
+{
+	return -EINVAL;
+}
+
+static inline void pwm_disable(struct pwm_device *pwm)
+{
+}
+#endif
 
-#ifdef CONFIG_PWM
 struct pwm_chip;
 
 enum {
@@ -113,6 +137,7 @@ struct pwm_chip {
 	unsigned int		of_pwm_n_cells;
 };
 
+#if IS_ENABLED(CONFIG_PWM)
 int pwm_set_chip_data(struct pwm_device *pwm, void *data);
 void *pwm_get_chip_data(struct pwm_device *pwm);
 
@@ -124,6 +149,44 @@ struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 
 struct pwm_device *pwm_get(struct device *dev, const char *consumer);
 void pwm_put(struct pwm_device *pwm);
+#else
+static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
+{
+	return -EINVAL;
+}
+
+static inline void *pwm_get_chip_data(struct pwm_device *pwm)
+{
+	return NULL;
+}
+
+static inline int pwmchip_add(struct pwm_chip *chip)
+{
+	return -EINVAL;
+}
+
+static inline int pwmchip_remove(struct pwm_chip *chip)
+{
+	return -EINVAL;
+}
+
+static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
+						       unsigned int index,
+						       const char *label)
+{
+	return NULL;
+}
+
+static inline struct pwm_device *pwm_get(struct device *dev,
+					 const char *consumer)
+{
+	return NULL;
+}
+
+static inline void pwm_put(struct pwm_device *pwm)
+{
+}
+#endif
 
 struct pwm_lookup {
 	struct list_head list;
@@ -141,8 +204,12 @@ struct pwm_lookup {
 		.con_id = _con_id,			\
 	}
 
+#if IS_ENABLED(CONFIG_PWM)
 void pwm_add_table(struct pwm_lookup *table, size_t num);
-
+#else
+static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
+{
+}
 #endif
 
 #endif /* __LINUX_PWM_H */
-- 
1.7.4.1

Re: [PATCH v4] pwm: Fix compilation error when CONFIG_PWM is not defined

[Thierry Reding]

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On Wed, Sep 12, 2012 at 03:31:46PM +0530, Tushar Behera wrote:
> Add dummy implemention of public symbols for compilation-safe inclusion
> of include/linux/pwm.h file when CONFIG_PWM is not defined.
> 
> Reported-by: Sachin Kamat <sachin.kamat@linaro.org>
> Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
> ---
> Changes since v3:
> * Nitpicks
> 
> Changes since v2:
> * #if condition for legacy functions modified
> * Reverted layout changes, can be taken up when HAVE_PWM is no longer
> required.
> 
> Changes since v1:
> * Incorporated Thierry's suggestions regarding adding dummy function
> implemention for all global functions
> * Reorganized header file to have structure definitions first and then the
> function definitions.
> 
>  include/linux/pwm.h |   71 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 69 insertions(+), 2 deletions(-)

Okay, I've applied this to my for-next branch, with some minor changes.
For one I had to merge it with Alex's managed functions patch. Second I
changed all dummy functions that return a struct pwm_device * to return
ERR_PTR(-ENODEV) instead of NULL because PWM users typically check for
IS_ERR(pwm) and not for NULL.

Thierry

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