pwm: Provide pwmchip_alloc() function and a devm variant of it

This function allocates a struct pwm_chip and driver data. Compared to
the status quo the split into pwm_chip and driver data is new, otherwise
it doesn't change anything relevant (yet).

The intention is that after all drivers are switched to use this
allocation function, its possible to add a struct device to struct
pwm_chip to properly track the latter's lifetime without touching all
drivers again. Proper lifetime tracking is a necessary precondition to
introduce character device support for PWMs (that implements atomic
setting and doesn't suffer from the sysfs overhead of the /sys/class/pwm
userspace support).

The new function pwmchip_priv() (obviously?) only works for chips
allocated with pwmchip_alloc().

Link: https://lore.kernel.org/r/9577d6053a5a52536057dc8654ff567181c2da82.1707900770.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

1 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 29a7d9140f77..4a6568dfdf3f 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -403,6 +403,10 @@ static inline bool pwm_might_sleep(struct pwm_device *pwm)
 int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
 		unsigned long timeout);
 
+void pwmchip_put(struct pwm_chip *chip);
+struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv);
+struct pwm_chip *devm_pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv);
+
 int __pwmchip_add(struct pwm_chip *chip, struct module *owner);
 #define pwmchip_add(chip) __pwmchip_add(chip, THIS_MODULE)
 void pwmchip_remove(struct pwm_chip *chip);
@@ -475,6 +479,24 @@ static inline int pwm_capture(struct pwm_device *pwm,
 	return -EINVAL;
 }
 
+static inline void pwmchip_put(struct pwm_chip *chip)
+{
+}
+
+static inline struct pwm_chip *pwmchip_alloc(struct device *parent,
+					     unsigned int npwm,
+					     size_t sizeof_priv)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline struct pwm_chip *devm_pwmchip_alloc(struct device *parent,
+						  unsigned int npwm,
+						  size_t sizeof_priv)
+{
+	return pwmchip_alloc(parent, npwm, sizeof_priv);
+}
+
 static inline int pwmchip_add(struct pwm_chip *chip)
 {
 	return -EINVAL;