[PATCH v7 1/8] pwm: Expose PWM_WFHWSIZE in public header

Michal Wilczynski
2025-07-02T13:49:57Z

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>
---
drivers/pwm/core.c | 26 ++++++++++++--------------
include/linux/pwm.h | 2 ++
2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index b86f06ab2a324ac98115845f72d9386966a0a3b8..c1e8ab1a0945889d92dada003060b8b109f2a138 100644
--- a/drivers/pwm/core.c
+++ b/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 {
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 2492c91452f9641881e9923e5a97e0705047da59..8cafc483db53addf95591d1ac74287532c0fa0ee 100644
--- a/include/linux/pwm.h
+++ b/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

--
2.34.1