[PATCH v5 01/24] pwm: introduce the pwm_args concept

[Boris Brezillon]

Currently the PWM core mixes the current PWM state with the per-platform
reference config (specified through the PWM lookup table, DT definition or
directly hardcoded in PWM drivers).

Create a pwm_args struct to store this reference config, so that PWM users
can differentiate the current config from the reference one.

Patch all places where pwm->args should be initialized. We keep the
pwm_set_polarity/period() calls until all PWM users are patched to
use pwm_args instead of pwm_get_period/polarity().

Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>
---
 drivers/pwm/core.c         | 22 +++++++++++++++-------
 drivers/pwm/pwm-clps711x.c |  2 +-
 drivers/pwm/pwm-pxa.c      |  2 +-
 include/linux/pwm.h        | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 49 insertions(+), 9 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 7c330ff..ac89529 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -128,6 +128,14 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
 	set_bit(PWMF_REQUESTED, &pwm->flags);
 	pwm->label = label;
 
+	/*
+	 * FIXME: this should be removed as soon as all PWM users are
+	 * properly making use of pwm_args to initialize the PWM device.
+	 * If we don't get rid of it, then PWM state and hardware can be
+	 * desynchronized.
+	 */
+	pwm_apply_args(pwm);
+
 	return 0;
 }
 
@@ -146,12 +154,12 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
 	if (IS_ERR(pwm))
 		return pwm;
 
-	pwm_set_period(pwm, args->args[1]);
+	pwm->args.period = args->args[1];
 
 	if (args->args[2] & PWM_POLARITY_INVERTED)
-		pwm_set_polarity(pwm, PWM_POLARITY_INVERSED);
+		pwm->args.polarity = PWM_POLARITY_INVERSED;
 	else
-		pwm_set_polarity(pwm, PWM_POLARITY_NORMAL);
+		pwm->args.polarity = PWM_POLARITY_NORMAL;
 
 	return pwm;
 }
@@ -172,7 +180,7 @@ of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
 	if (IS_ERR(pwm))
 		return pwm;
 
-	pwm_set_period(pwm, args->args[1]);
+	pwm->args.period = args->args[1];
 
 	return pwm;
 }
@@ -736,13 +744,13 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
 	if (!chip)
 		goto out;
 
+	pwm->args.period = chosen->period;
+	pwm->args.polarity = chosen->polarity;
+
 	pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id);
 	if (IS_ERR(pwm))
 		goto out;
 
-	pwm_set_period(pwm, chosen->period);
-	pwm_set_polarity(pwm, chosen->polarity);
-
 out:
 	mutex_unlock(&pwm_lookup_lock);
 	return pwm;
diff --git a/drivers/pwm/pwm-clps711x.c b/drivers/pwm/pwm-clps711x.c
index a80c108..7d33542 100644
--- a/drivers/pwm/pwm-clps711x.c
+++ b/drivers/pwm/pwm-clps711x.c
@@ -60,7 +60,7 @@ static int clps711x_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 		return -EINVAL;
 
 	/* Store constant period value */
-	pwm_set_period(pwm, DIV_ROUND_CLOSEST(NSEC_PER_SEC, freq));
+	pwm->args.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, freq);
 
 	return 0;
 }
diff --git a/drivers/pwm/pwm-pxa.c b/drivers/pwm/pwm-pxa.c
index cb2f702..58b709f 100644
--- a/drivers/pwm/pwm-pxa.c
+++ b/drivers/pwm/pwm-pxa.c
@@ -160,7 +160,7 @@ pxa_pwm_of_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
 	if (IS_ERR(pwm))
 		return pwm;
 
-	pwm_set_period(pwm, args->args[0]);
+	pwm->args.period = args->args[0];
 
 	return pwm;
 }
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 6555f01..c8859b7 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -74,6 +74,23 @@ enum pwm_polarity {
 	PWM_POLARITY_INVERSED,
 };
 
+/**
+ * struct pwm_args - PWM arguments
+ * @period: reference period
+ * @polarity: reference polarity
+ *
+ * This structure describes board-dependent arguments attached to a PWM
+ * device. Those arguments are usually retrieved from the PWM lookup table or
+ * DT definition.
+ * This should not be confused with the PWM state: PWM args don't represent
+ * the current PWM state, but the configuration the PWM user plans to use
+ * on this PWM device.
+ */
+struct pwm_args {
+	unsigned int period;
+	enum pwm_polarity polarity;
+};
+
 enum {
 	PWMF_REQUESTED = 1 << 0,
 	PWMF_ENABLED = 1 << 1,
@@ -91,6 +108,7 @@ enum {
  * @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
  */
 struct pwm_device {
 	const char *label;
@@ -103,6 +121,8 @@ struct pwm_device {
 	unsigned int period;
 	unsigned int duty_cycle;
 	enum pwm_polarity polarity;
+
+	struct pwm_args args;
 };
 
 static inline bool pwm_is_enabled(const struct pwm_device *pwm)
@@ -142,6 +162,18 @@ static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
 	return pwm ? pwm->polarity : PWM_POLARITY_NORMAL;
 }
 
+static inline void pwm_get_args(const struct pwm_device *pwm,
+				struct pwm_args *args)
+{
+	*args = pwm->args;
+}
+
+static inline void pwm_apply_args(struct pwm_device *pwm)
+{
+	pwm_set_period(pwm, pwm->args.period);
+	pwm_set_polarity(pwm, pwm->args.polarity);
+}
+
 /**
  * struct pwm_ops - PWM controller operations
  * @request: optional hook for requesting a PWM
-- 
2.5.0