[PATCH 1/3] pwm: Add pwm_cansleep() as exported API to users

From: Florian Vaussard
Date: Fri Jan 25 2013 - 05:08:29 EST


Calls to some external PWM chips can sleep. To help users,
add pwm_cansleep() API.

Signed-off-by: Florian Vaussard <florian.vaussard@xxxxxxx>
---
drivers/pwm/core.c | 12 ++++++++++++
include/linux/pwm.h | 10 ++++++++++
2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 4a13da4..f49bfa6 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -763,6 +763,18 @@ void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
}
EXPORT_SYMBOL_GPL(devm_pwm_put);

+/**
+ * pwm_can_sleep() - report whether pwm access will sleep
+ * @pwm: PWM device
+ *
+ * It returns nonzero if accessing the PWM can sleep.
+ */
+int pwm_can_sleep(struct pwm_device *pwm)
+{
+ return pwm->chip->can_sleep;
+}
+EXPORT_SYMBOL_GPL(pwm_can_sleep);
+
#ifdef CONFIG_DEBUG_FS
static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
{
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 70655a2..2aee75d 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -146,6 +146,8 @@ struct pwm_ops {
* @base: number of first PWM controlled by this chip
* @npwm: number of PWMs controlled by this chip
* @pwms: array of PWM devices allocated by the framework
+ * @can_sleep: flag must be set iff config()/enable()/disable() methods sleep,
+ * as they must while accessing PWM chips over I2C or SPI
*/
struct pwm_chip {
struct device *dev;
@@ -159,6 +161,7 @@ struct pwm_chip {
struct pwm_device * (*of_xlate)(struct pwm_chip *pc,
const struct of_phandle_args *args);
unsigned int of_pwm_n_cells;
+ unsigned int can_sleep:1;
};

#if IS_ENABLED(CONFIG_PWM)
@@ -182,6 +185,8 @@ struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
const char *con_id);
void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
+
+int pwm_can_sleep(struct pwm_device *pwm);
#else
static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
{
@@ -242,6 +247,11 @@ static inline struct pwm_device *devm_of_pwm_get(struct device *dev,
static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
{
}
+
+static inline int pwm_can_sleep(struct pwm_device *pwm)
+{
+ return -EINVAL;
+}
#endif

struct pwm_lookup {
--
1.7.5.4

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