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 devm_pwmchip_alloc().
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
---
.../driver-api/driver-model/devres.rst | 1 +
Documentation/driver-api/pwm.rst | 10 ++++----
drivers/pwm/core.c | 25 +++++++++++++++++++
include/linux/pwm.h | 3 +++
4 files changed, 34 insertions(+), 5 deletions(-)
diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst
index c5f99d834ec5..e4df72c408d2 100644
--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -420,6 +420,7 @@ POWER
devm_reboot_mode_unregister()
PWM
+ devm_pwmchip_alloc()
devm_pwmchip_add()
devm_pwm_get()
devm_fwnode_pwm_get()
diff --git a/Documentation/driver-api/pwm.rst b/Documentation/driver-api/pwm.rst
index bb264490a87a..994ea5368805 100644
--- a/Documentation/driver-api/pwm.rst
+++ b/Documentation/driver-api/pwm.rst
@@ -134,11 +134,11 @@ to implement the pwm_*() functions itself. This means that it's impossible
to have multiple PWM drivers in the system. For this reason it's mandatory
for new drivers to use the generic PWM framework.
-A new PWM controller/chip can be added using pwmchip_add() and removed
-again with pwmchip_remove(). pwmchip_add() takes a filled in struct
-pwm_chip as argument which provides a description of the PWM chip, the
-number of PWM devices provided by the chip and the chip-specific
-implementation of the supported PWM operations to the framework.
+A new PWM controller/chip can be allocated using devm_pwmchip_alloc, then added
+using pwmchip_add() and removed again with pwmchip_remove(). pwmchip_add()
+takes a filled in struct pwm_chip as argument which provides a description of
+the PWM chip, the number of PWM devices provided by the chip and the
+chip-specific implementation of the supported PWM operations to the framework.
When implementing polarity support in a PWM driver, make sure to respect the
signal conventions in the PWM framework. By definition, normal polarity
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index eea93ed8a49b..fda72963016b 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -198,6 +198,31 @@ static bool pwm_ops_check(const struct pwm_chip *chip)
return true;
}
+static void *pwmchip_priv(struct pwm_chip *chip)
+{
+ return (void *)chip + sizeof(*chip);
+}
+
+struct pwm_chip *devm_pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv)
+{
+ struct pwm_chip *chip;
+ size_t alloc_size;
+
+ alloc_size = size_add(sizeof(*chip), sizeof_priv);
+
+ chip = devm_kzalloc(parent, alloc_size, GFP_KERNEL);
+ if (!chip)
+ return ERR_PTR(-ENOMEM);
+
+ chip->dev = parent;
+ chip->npwm = npwm;
+
+ pwmchip_set_drvdata(chip, pwmchip_priv(chip));
+
+ return chip;
+}
+EXPORT_SYMBOL_GPL(devm_pwmchip_alloc);
+
/**
* __pwmchip_add() - register a new PWM chip
* @chip: the PWM chip to add
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index e07b7a0c8471..b410ff38beb5 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -5,6 +5,7 @@
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/of.h>
+#include <linux/compiler_attributes.h>
struct pwm_chip;
@@ -403,6 +404,8 @@ static inline void pwm_disable(struct pwm_device *pwm)
int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
unsigned long timeout);
+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);
--
2.42.0
