pwm: Expose PWM_WFHWSIZE in public header

The WFHWSIZE constant defines the maximum size for the hardware-specific
waveform representation buffer. It is currently local to
drivers/pwm/core.c, which makes it inaccessible to external tools like
bindgen.

Move the constant to include/linux/pwm.h to make it part of the public
API. As part of this change, rename it to PWM_WFHWSIZE to follow
standard kernel conventions for namespacing macros in public headers.

This allows bindgen to automatically generate a corresponding constant
for the Rust PWM abstractions, ensuring the value remains synchronized
between the C core and Rust code and preventing future maintenance
issues.

Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
Link: https://lore.kernel.org/r/20250702-rust-next-pwm-working-fan-for-sending-v7-1-67ef39ff1d29@samsung.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>

Author: Michal Wilczynski

drivers/pwm/core.c

@@ -210,8 +210,6 @@ static int __pwm_write_waveform(struct pwm_chip *chip, struct pwm_device *pwm, c
 	return ret;
 }
 
-#define WFHWSIZE 20
-
 /**
  * pwm_round_waveform_might_sleep - Query hardware capabilities
  * Cannot be used in atomic context.
@@ -248,10 +246,10 @@ int pwm_round_waveform_might_sleep(struct pwm_device *pwm, struct pwm_waveform *
 	struct pwm_chip *chip = pwm->chip;
 	const struct pwm_ops *ops = chip->ops;
 	struct pwm_waveform wf_req = *wf;
-	char wfhw[WFHWSIZE];
+	char wfhw[PWM_WFHWSIZE];
 	int ret_tohw, ret_fromhw;
 
-	BUG_ON(WFHWSIZE < ops->sizeof_wfhw);
+	BUG_ON(PWM_WFHWSIZE < ops->sizeof_wfhw);
 
 	if (!pwmchip_supports_waveform(chip))
 		return -EOPNOTSUPP;
@@ -306,10 +304,10 @@ int pwm_get_waveform_might_sleep(struct pwm_device *pwm, struct pwm_waveform *wf
 {
 	struct pwm_chip *chip = pwm->chip;
 	const struct pwm_ops *ops = chip->ops;
-	char wfhw[WFHWSIZE];
+	char wfhw[PWM_WFHWSIZE];
 	int err;
 
-	BUG_ON(WFHWSIZE < ops->sizeof_wfhw);
+	BUG_ON(PWM_WFHWSIZE < ops->sizeof_wfhw);
 
 	if (!pwmchip_supports_waveform(chip) || !ops->read_waveform)
 		return -EOPNOTSUPP;
@@ -334,11 +332,11 @@ static int __pwm_set_waveform(struct pwm_device *pwm,
 {
 	struct pwm_chip *chip = pwm->chip;
 	const struct pwm_ops *ops = chip->ops;
-	char wfhw[WFHWSIZE];
+	char wfhw[PWM_WFHWSIZE];
 	struct pwm_waveform wf_rounded;
 	int err, ret_tohw;
 
-	BUG_ON(WFHWSIZE < ops->sizeof_wfhw);
+	BUG_ON(PWM_WFHWSIZE < ops->sizeof_wfhw);
 
 	if (!pwmchip_supports_waveform(chip))
 		return -EOPNOTSUPP;
@@ -650,9 +648,9 @@ static int __pwm_apply(struct pwm_device *pwm, const struct pwm_state *state)
 
 	if (pwmchip_supports_waveform(chip)) {
 		struct pwm_waveform wf;
-		char wfhw[WFHWSIZE];
+		char wfhw[PWM_WFHWSIZE];
 
-		BUG_ON(WFHWSIZE < ops->sizeof_wfhw);
+		BUG_ON(PWM_WFHWSIZE < ops->sizeof_wfhw);
 
 		pwm_state2wf(state, &wf);
 
@@ -809,10 +807,10 @@ int pwm_get_state_hw(struct pwm_device *pwm, struct pwm_state *state)
 		return -ENODEV;
 
 	if (pwmchip_supports_waveform(chip) && ops->read_waveform) {
-		char wfhw[WFHWSIZE];
+		char wfhw[PWM_WFHWSIZE];
 		struct pwm_waveform wf;
 
-		BUG_ON(WFHWSIZE < ops->sizeof_wfhw);
+		BUG_ON(PWM_WFHWSIZE < ops->sizeof_wfhw);
 
 		ret = __pwm_read_waveform(chip, pwm, &wfhw);
 		if (ret)
@@ -1696,8 +1694,8 @@ static bool pwm_ops_check(const struct pwm_chip *chip)
 		    !ops->write_waveform)
 			return false;
 
-		if (WFHWSIZE < ops->sizeof_wfhw) {
-			dev_warn(pwmchip_parent(chip), "WFHWSIZE < %zu\n", ops->sizeof_wfhw);
+		if (PWM_WFHWSIZE < ops->sizeof_wfhw) {
+			dev_warn(pwmchip_parent(chip), "PWM_WFHWSIZE < %zu\n", ops->sizeof_wfhw);
 			return false;
 		}
 	} else {

include/linux/pwm.h

@@ -274,6 +274,8 @@ struct pwm_capture {
 	unsigned int duty_cycle;
 };
 
+#define PWM_WFHWSIZE 20
+
 /**
  * struct pwm_ops - PWM controller operations
  * @request: optional hook for requesting a PWM