[PATCH v5 15/46] pwm: introduce the pwm_state concept

Boris Brezillon
2016-03-30T20:03:38Z

The PWM state, represented by its period, duty_cycle and polarity,
is currently directly stored in the PWM device.
Declare a pwm_state structure embedding those field so that we can later
use this struct to atomically update all the PWM parameters at once.

All pwm_get_xxx() helpers are now implemented as wrappers around
pwm_get_state().

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
drivers/pwm/core.c | 8 ++++----
include/linux/pwm.h | 54 +++++++++++++++++++++++++++++++++++++++++------------
2 files changed, 46 insertions(+), 16 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 6433059..f3f91e7 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -268,7 +268,7 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip,
pwm->chip = chip;
pwm->pwm = chip->base + i;
pwm->hwpwm = i;
- pwm->polarity = polarity;
+ pwm->state.polarity = polarity;

radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
}
@@ -446,8 +446,8 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
if (err)
return err;

- pwm->duty_cycle = duty_ns;
- pwm->period = period_ns;
+ pwm->state.duty_cycle = duty_ns;
+ pwm->state.period = period_ns;

return 0;
}
@@ -480,7 +480,7 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
if (err)
return err;

- pwm->polarity = polarity;
+ pwm->state.polarity = polarity;

return 0;
}
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index ed65354..f0f0f37 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -97,6 +97,18 @@ enum {
PWMF_EXPORTED = 1 << 2,
};

+/*
+ * struct pwm_state - state of a PWM channel
+ * @period: PWM period (in nanoseconds)
+ * @duty_cycle: PWM duty cycle (in nanoseconds)
+ * @polarity: PWM polarity
+ */
+struct pwm_state {
+ unsigned int period;
+ unsigned int duty_cycle;
+ enum pwm_polarity polarity;
+};
+
/**
* struct pwm_device - PWM channel object
* @label: name of the PWM device
@@ -105,10 +117,8 @@ enum {
* @pwm: global index of the PWM device
* @chip: PWM chip providing this PWM device
* @chip_data: chip-private data associated with the PWM device
- * @period: period of the PWM signal (in nanoseconds)
- * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
- * @polarity: polarity of the PWM signal
* @args: PWM arguments
+ * @state: curent PWM channel state
*/
struct pwm_device {
const char *label;
@@ -118,13 +128,21 @@ struct pwm_device {
struct pwm_chip *chip;
void *chip_data;

- unsigned int period;
- unsigned int duty_cycle;
- enum pwm_polarity polarity;
-
struct pwm_args args;
+ struct pwm_state state;
};

+/**
+ * pwm_get_state() - retrieve the current PWM state
+ * @pwm: PWM device
+ * @state: state to fill with the current PWM state
+ */
+static inline void pwm_get_state(const struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ *state = pwm->state;
+}
+
static inline bool pwm_is_enabled(const struct pwm_device *pwm)
{
return test_bit(PWMF_ENABLED, &pwm->flags);
@@ -133,23 +151,31 @@ static inline bool pwm_is_enabled(const struct pwm_device *pwm)
static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
{
if (pwm)
- pwm->period = period;
+ pwm->state.period = period;
}

static inline unsigned int pwm_get_period(const struct pwm_device *pwm)
{
- return pwm ? pwm->period : 0;
+ struct pwm_state pstate;
+
+ pwm_get_state(pwm, &pstate);
+
+ return pstate.period;
}

static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
{
if (pwm)
- pwm->duty_cycle = duty;
+ pwm->state.duty_cycle = duty;
}

static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
{
- return pwm ? pwm->duty_cycle : 0;
+ struct pwm_state pstate;
+
+ pwm_get_state(pwm, &pstate);
+
+ return pstate.duty_cycle;
}

/*
@@ -159,7 +185,11 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity);

static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
{
- return pwm ? pwm->polarity : PWM_POLARITY_NORMAL;
+ struct pwm_state pstate;
+
+ pwm_get_state(pwm, &pstate);
+
+ return pstate.polarity;
}

static inline void pwm_get_args(const struct pwm_device *pwm,
--
2.5.0