This API controls both the PWM period/duty_cycle config and the
enable/disable state.
+PWM devices can be used from atomic context, if the PWM does not sleep. You
+can check if this the case with::
+
+ bool pwm_might_sleep(struct pwm_device *pwm);
+
+If false, the PWM can also be configured from atomic context with::
+
+ int pwm_apply_atomic(struct pwm_device *pwm, struct pwm_state *state);
+
As a consumer, don't rely on the output's state for a disabled PWM. If it's
easily possible, drivers are supposed to emit the inactive state, but some
drivers cannot. If you rely on getting the inactive state, use .duty_cycle=0,
F: include/dt-bindings/pwm/
F: include/linux/pwm.h
F: include/linux/pwm_backlight.h
-K: pwm_(config|apply_might_sleep|ops)
+K: pwm_(config|apply_might_sleep|apply_atomic|ops)
PXA GPIO DRIVER
M: Robert Jarzmik <robert.jarzmik@free.fr>
}
/**
- * pwm_apply_might_sleep() - atomically apply a new state to a PWM device
+ * __pwm_apply() - atomically apply a new state to a PWM device
* @pwm: PWM device
* @state: new state to apply
*/
-int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
+static int __pwm_apply(struct pwm_device *pwm, const struct pwm_state *state)
{
struct pwm_chip *chip;
int err;
- /*
- * Some lowlevel driver's implementations of .apply() make use of
- * mutexes, also with some drivers only returning when the new
- * configuration is active calling pwm_apply_might_sleep() from atomic context
- * is a bad idea. So make it explicit that calling this function might
- * sleep.
- */
- might_sleep();
-
if (!pwm || !state || !state->period ||
state->duty_cycle > state->period)
return -EINVAL;
return 0;
}
+
+/**
+ * pwm_apply_might_sleep() - atomically apply a new state to a PWM device
+ * Cannot be used in atomic context.
+ * @pwm: PWM device
+ * @state: new state to apply
+ */
+int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
+{
+ int err;
+
+ /*
+ * Some lowlevel driver's implementations of .apply() make use of
+ * mutexes, also with some drivers only returning when the new
+ * configuration is active calling pwm_apply_might_sleep() from atomic context
+ * is a bad idea. So make it explicit that calling this function might
+ * sleep.
+ */
+ might_sleep();
+
+ if (IS_ENABLED(CONFIG_PWM_DEBUG) && pwm->chip->atomic) {
+ /*
+ * Catch any drivers that have been marked as atomic but
+ * that will sleep anyway.
+ */
+ non_block_start();
+ err = __pwm_apply(pwm, state);
+ non_block_end();
+ } else {
+ err = __pwm_apply(pwm, state);
+ }
+
+ return err;
+}
EXPORT_SYMBOL_GPL(pwm_apply_might_sleep);
+/**
+ * pwm_apply_atomic() - apply a new state to a PWM device from atomic context
+ * Not all PWM devices support this function, check with pwm_might_sleep().
+ * @pwm: PWM device
+ * @state: new state to apply
+ */
+int pwm_apply_atomic(struct pwm_device *pwm, const struct pwm_state *state)
+{
+ WARN_ONCE(!pwm->chip->atomic,
+ "sleeping PWM driver used in atomic context\n");
+
+ return __pwm_apply(pwm, state);
+}
+EXPORT_SYMBOL_GPL(pwm_apply_atomic);
+
/**
* pwm_capture() - capture and report a PWM signal
* @pwm: PWM device
* @npwm: number of PWMs controlled by this chip
* @of_xlate: request a PWM device given a device tree PWM specifier
* @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
+ * @atomic: can the driver's ->apply() be called in atomic context
* @pwms: array of PWM devices allocated by the framework
*/
struct pwm_chip {
struct pwm_device * (*of_xlate)(struct pwm_chip *chip,
const struct of_phandle_args *args);
unsigned int of_pwm_n_cells;
+ bool atomic;
/* only used internally by the PWM framework */
struct pwm_device *pwms;
#if IS_ENABLED(CONFIG_PWM)
/* PWM user APIs */
int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state);
+int pwm_apply_atomic(struct pwm_device *pwm, const struct pwm_state *state);
int pwm_adjust_config(struct pwm_device *pwm);
/**
pwm_apply_might_sleep(pwm, &state);
}
+/**
+ * pwm_might_sleep() - is pwm_apply_atomic() supported?
+ * @pwm: PWM device
+ *
+ * Returns: false if pwm_apply_atomic() can be called from atomic context.
+ */
+static inline bool pwm_might_sleep(struct pwm_device *pwm)
+{
+ return !pwm->chip->atomic;
+}
+
/* PWM provider APIs */
int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
unsigned long timeout);
struct fwnode_handle *fwnode,
const char *con_id);
#else
+static inline bool pwm_might_sleep(struct pwm_device *pwm)
+{
+ return true;
+}
+
static inline int pwm_apply_might_sleep(struct pwm_device *pwm,
const struct pwm_state *state)
{
return -EOPNOTSUPP;
}
+static inline int pwm_apply_atomic(struct pwm_device *pwm,
+ const struct pwm_state *state)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int pwm_adjust_config(struct pwm_device *pwm)
{
return -EOPNOTSUPP;