From 459a25afe97cb3d7f978b90c881f4d7aac8fb755 Mon Sep 17 00:00:00 2001
From: Boris BREZILLON <boris.brezillon@free-electrons.com>
Date: Wed, 30 Mar 2016 22:03:27 +0200
Subject: pwm: Get rid of pwm->lock

PWM devices are not protected against concurrent accesses. The lock in
struct pwm_device might let PWM users think it is, but it's actually
only protecting the enabled state.

Removing this lock should be fine as long as all PWM users are aware
that accesses to the PWM device have to be serialized, which seems to be
the case for all of them except the sysfs interface. Patch the sysfs
code by adding a lock to the pwm_export struct and making sure it's
taken for all relevant accesses to the exported PWM device.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
---
 drivers/pwm/core.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

(limited to 'drivers/pwm/core.c')

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 22cf3959041c..cb762cf51332 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -269,7 +269,6 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip,
 		pwm->pwm = chip->base + i;
 		pwm->hwpwm = i;
 		pwm->polarity = polarity;
-		mutex_init(&pwm->lock);
 
 		radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
 	}
@@ -474,22 +473,16 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
 	if (!pwm->chip->ops->set_polarity)
 		return -ENOSYS;
 
-	mutex_lock(&pwm->lock);
-
-	if (pwm_is_enabled(pwm)) {
-		err = -EBUSY;
-		goto unlock;
-	}
+	if (pwm_is_enabled(pwm))
+		return -EBUSY;
 
 	err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity);
 	if (err)
-		goto unlock;
+		return err;
 
 	pwm->polarity = polarity;
 
-unlock:
-	mutex_unlock(&pwm->lock);
-	return err;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(pwm_set_polarity);
 
@@ -506,16 +499,12 @@ int pwm_enable(struct pwm_device *pwm)
 	if (!pwm)
 		return -EINVAL;
 
-	mutex_lock(&pwm->lock);
-
 	if (!test_and_set_bit(PWMF_ENABLED, &pwm->flags)) {
 		err = pwm->chip->ops->enable(pwm->chip, pwm);
 		if (err)
 			clear_bit(PWMF_ENABLED, &pwm->flags);
 	}
 
-	mutex_unlock(&pwm->lock);
-
 	return err;
 }
 EXPORT_SYMBOL_GPL(pwm_enable);
-- 
cgit v1.2.3


From a8c3862551e063344f80c3e05d595f9d8836f355 Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@free-electrons.com>
Date: Thu, 14 Apr 2016 21:17:37 +0200
Subject: pwm: Keep PWM state in sync with hardware state

Before the introduction of pwm_args, the core was resetting the PWM
period and polarity states to the reference values (those provided
through the DT, a PWM lookup table or hardcoded in the driver).

Now that all PWM users are correctly using pwm_args to configure their
PWM device, we can safely remove the pwm_apply_args() call in pwm_get()
and of_pwm_get().

We can also get rid of the pwm_set_period() call in pwm_apply_args(),
because PWM users are now directly using pargs->period instead of
pwm_get_period(). By doing that we avoid messing with the current PWM
period.

The only remaining bit in pwm_apply_args() is the initial polarity
setting, and it should go away when all PWM users have been patched to
use the atomic API (with this API the polarity will be set along with
other PWM arguments when configuring the PWM).

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
---
 drivers/pwm/core.c  | 14 --------------
 include/linux/pwm.h |  1 -
 2 files changed, 15 deletions(-)

(limited to 'drivers/pwm/core.c')

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index cb762cf51332..64330595e17b 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -609,13 +609,6 @@ struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id)
 
 	pwm->label = con_id;
 
-	/*
-	 * FIXME: This should be removed once all PWM users properly make use
-	 * of struct pwm_args to initialize the PWM device. As long as this is
-	 * here, the PWM state and hardware state can get out of sync.
-	 */
-	pwm_apply_args(pwm);
-
 put:
 	of_node_put(args.np);
 
@@ -750,13 +743,6 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
 	pwm->args.period = chosen->period;
 	pwm->args.polarity = chosen->polarity;
 
-	/*
-	 * FIXME: This should be removed once all PWM users properly make use
-	 * of struct pwm_args to initialize the PWM device. As long as this is
-	 * here, the PWM state and hardware state can get out of sync.
-	 */
-	pwm_apply_args(pwm);
-
 out:
 	mutex_unlock(&pwm_lookup_lock);
 	return pwm;
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index d2e7430ccedb..7caf549f720e 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -171,7 +171,6 @@ static inline void pwm_get_args(const struct pwm_device *pwm,
 
 static inline void pwm_apply_args(struct pwm_device *pwm)
 {
-	pwm_set_period(pwm, pwm->args.period);
 	pwm_set_polarity(pwm, pwm->args.polarity);
 }
 
-- 
cgit v1.2.3


From 43a276b003ed2e03de9d94b02a1ba49c1849b931 Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@free-electrons.com>
Date: Thu, 14 Apr 2016 21:17:38 +0200
Subject: pwm: Introduce the pwm_state concept

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>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
---
 drivers/pwm/core.c  |  8 ++++----
 include/linux/pwm.h | 54 +++++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 46 insertions(+), 16 deletions(-)

(limited to 'drivers/pwm/core.c')

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 64330595e17b..f3f91e716a42 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 7caf549f720e..51d4005418f9 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -98,6 +98,18 @@ 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
@@ -106,10 +118,8 @@ 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;
@@ -119,13 +129,21 @@ 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);
@@ -134,23 +152,31 @@ 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 state;
+
+	pwm_get_state(pwm, &state);
+
+	return state.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 state;
+
+	pwm_get_state(pwm, &state);
+
+	return state.duty_cycle;
 }
 
 /*
@@ -160,7 +186,11 @@ 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 state;
+
+	pwm_get_state(pwm, &state);
+
+	return state.polarity;
 }
 
 static inline void pwm_get_args(const struct pwm_device *pwm,
-- 
cgit v1.2.3


From 09a7e4a3d9fcb95ade2cb02167e85fbeb8315ce0 Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@free-electrons.com>
Date: Thu, 14 Apr 2016 21:17:39 +0200
Subject: pwm: Move the enabled/disabled info into pwm_state

Prepare the transition to PWM atomic update by moving the enabled and
disabled state into the pwm_state struct. This way we can easily update
the whole PWM state by copying the new state in the ->state field.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
---
 drivers/pwm/core.c  | 13 +++++++++----
 include/linux/pwm.h | 11 ++++++++---
 2 files changed, 17 insertions(+), 7 deletions(-)

(limited to 'drivers/pwm/core.c')

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index f3f91e716a42..c240b5437145 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -499,10 +499,10 @@ int pwm_enable(struct pwm_device *pwm)
 	if (!pwm)
 		return -EINVAL;
 
-	if (!test_and_set_bit(PWMF_ENABLED, &pwm->flags)) {
+	if (!pwm_is_enabled(pwm)) {
 		err = pwm->chip->ops->enable(pwm->chip, pwm);
-		if (err)
-			clear_bit(PWMF_ENABLED, &pwm->flags);
+		if (!err)
+			pwm->state.enabled = true;
 	}
 
 	return err;
@@ -515,8 +515,13 @@ EXPORT_SYMBOL_GPL(pwm_enable);
  */
 void pwm_disable(struct pwm_device *pwm)
 {
-	if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags))
+	if (!pwm)
+		return;
+
+	if (pwm_is_enabled(pwm)) {
 		pwm->chip->ops->disable(pwm->chip, pwm);
+		pwm->state.enabled = false;
+	}
 }
 EXPORT_SYMBOL_GPL(pwm_disable);
 
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 51d4005418f9..150563a806d6 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -94,8 +94,7 @@ struct pwm_args {
 
 enum {
 	PWMF_REQUESTED = 1 << 0,
-	PWMF_ENABLED = 1 << 1,
-	PWMF_EXPORTED = 1 << 2,
+	PWMF_EXPORTED = 1 << 1,
 };
 
 /*
@@ -103,11 +102,13 @@ enum {
  * @period: PWM period (in nanoseconds)
  * @duty_cycle: PWM duty cycle (in nanoseconds)
  * @polarity: PWM polarity
+ * @enabled: PWM enabled status
  */
 struct pwm_state {
 	unsigned int period;
 	unsigned int duty_cycle;
 	enum pwm_polarity polarity;
+	bool enabled;
 };
 
 /**
@@ -146,7 +147,11 @@ static inline void pwm_get_state(const struct pwm_device *pwm,
 
 static inline bool pwm_is_enabled(const struct pwm_device *pwm)
 {
-	return test_bit(PWMF_ENABLED, &pwm->flags);
+	struct pwm_state state;
+
+	pwm_get_state(pwm, &state);
+
+	return state.enabled;
 }
 
 static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
-- 
cgit v1.2.3


From 15fa8a43c147213a9563903c87b29671035eb6e8 Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@free-electrons.com>
Date: Thu, 14 Apr 2016 21:17:40 +0200
Subject: pwm: Add hardware readout infrastructure

Add a ->get_state() function to the pwm_ops struct to let PWM drivers
initialize the PWM state attached to a PWM device.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
---
 drivers/pwm/core.c  |  3 +++
 include/linux/pwm.h | 28 ++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

(limited to 'drivers/pwm/core.c')

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index c240b5437145..a909c64ee863 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -270,6 +270,9 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip,
 		pwm->hwpwm = i;
 		pwm->state.polarity = polarity;
 
+		if (chip->ops->get_state)
+			chip->ops->get_state(chip, pwm, &pwm->state);
+
 		radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
 	}
 
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 150563a806d6..33f8decd9f38 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -206,6 +206,29 @@ static inline void pwm_get_args(const struct pwm_device *pwm,
 
 static inline void pwm_apply_args(struct pwm_device *pwm)
 {
+	/*
+	 * PWM users calling pwm_apply_args() expect to have a fresh config
+	 * where the polarity and period are set according to pwm_args info.
+	 * The problem is, polarity can only be changed when the PWM is
+	 * disabled.
+	 *
+	 * PWM drivers supporting hardware readout may declare the PWM device
+	 * as enabled, and prevent polarity setting, which changes from the
+	 * existing behavior, where all PWM devices are declared as disabled
+	 * at startup (even if they are actually enabled), thus authorizing
+	 * polarity setting.
+	 *
+	 * Instead of setting ->enabled to false, we call pwm_disable()
+	 * before pwm_set_polarity() to ensure that everything is configured
+	 * as expected, and the PWM is really disabled when the user request
+	 * it.
+	 *
+	 * Note that PWM users requiring a smooth handover between the
+	 * bootloader and the kernel (like critical regulators controlled by
+	 * PWM devices) will have to switch to the atomic API and avoid calling
+	 * pwm_apply_args().
+	 */
+	pwm_disable(pwm);
 	pwm_set_polarity(pwm, pwm->args.polarity);
 }
 
@@ -217,6 +240,9 @@ static inline void pwm_apply_args(struct pwm_device *pwm)
  * @set_polarity: configure the polarity of this PWM
  * @enable: enable PWM output toggling
  * @disable: disable PWM output toggling
+ * @get_state: get the current PWM state. This function is only
+ *	       called once per PWM device when the PWM chip is
+ *	       registered.
  * @dbg_show: optional routine to show contents in debugfs
  * @owner: helps prevent removal of modules exporting active PWMs
  */
@@ -229,6 +255,8 @@ struct pwm_ops {
 			    enum pwm_polarity polarity);
 	int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
 	void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
+	void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
+			  struct pwm_state *state);
 #ifdef CONFIG_DEBUG_FS
 	void (*dbg_show)(struct pwm_chip *chip, struct seq_file *s);
 #endif
-- 
cgit v1.2.3


From 5ec803edcb703fe379836f13560b79dfac79b01d Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@free-electrons.com>
Date: Thu, 14 Apr 2016 21:17:41 +0200
Subject: pwm: Add core infrastructure to allow atomic updates

Add an ->apply() method to the pwm_ops struct to allow PWM drivers to
implement atomic updates. This method is preferred over the ->enable(),
->disable() and ->config() methods if available.

Add the pwm_apply_state() function to the PWM user API.

Note that the pwm_apply_state() does not guarantee the atomicity of the
update operation, it all depends on the availability and implementation
of the ->apply() method.

pwm_enable/disable/set_polarity/config() are now implemented as wrappers
around the pwm_apply_state() function.

pwm_adjust_config() is allowing smooth handover between the bootloader
and the kernel. This function tries to adapt the current PWM state to
the PWM arguments coming from a PWM lookup table or a DT definition
without changing the duty_cycle/period proportion.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[thierry.reding@gmail.com: fix a couple of typos]
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
---
 drivers/pwm/core.c  | 187 +++++++++++++++++++++++-------------
 include/linux/pwm.h | 269 +++++++++++++++++++++++++++++++++++-----------------
 2 files changed, 303 insertions(+), 153 deletions(-)

(limited to 'drivers/pwm/core.c')

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index a909c64ee863..729d457861fd 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -226,6 +226,19 @@ void *pwm_get_chip_data(struct pwm_device *pwm)
 }
 EXPORT_SYMBOL_GPL(pwm_get_chip_data);
 
+static bool pwm_ops_check(const struct pwm_ops *ops)
+{
+	/* driver supports legacy, non-atomic operation */
+	if (ops->config && ops->enable && ops->disable)
+		return true;
+
+	/* driver supports atomic operation */
+	if (ops->apply)
+		return true;
+
+	return false;
+}
+
 /**
  * pwmchip_add_with_polarity() - register a new PWM chip
  * @chip: the PWM chip to add
@@ -244,8 +257,10 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip,
 	unsigned int i;
 	int ret;
 
-	if (!chip || !chip->dev || !chip->ops || !chip->ops->config ||
-	    !chip->ops->enable || !chip->ops->disable || !chip->npwm)
+	if (!chip || !chip->dev || !chip->ops || !chip->npwm)
+		return -EINVAL;
+
+	if (!pwm_ops_check(chip->ops))
 		return -EINVAL;
 
 	mutex_lock(&pwm_lock);
@@ -431,102 +446,138 @@ void pwm_free(struct pwm_device *pwm)
 EXPORT_SYMBOL_GPL(pwm_free);
 
 /**
- * pwm_config() - change a PWM device configuration
+ * pwm_apply_state() - atomically apply a new state to a PWM device
  * @pwm: PWM device
- * @duty_ns: "on" time (in nanoseconds)
- * @period_ns: duration (in nanoseconds) of one cycle
- *
- * Returns: 0 on success or a negative error code on failure.
+ * @state: new state to apply. This can be adjusted by the PWM driver
+ *	   if the requested config is not achievable, for example,
+ *	   ->duty_cycle and ->period might be approximated.
  */
-int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state)
 {
 	int err;
 
-	if (!pwm || duty_ns < 0 || period_ns <= 0 || duty_ns > period_ns)
+	if (!pwm)
 		return -EINVAL;
 
-	err = pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns);
-	if (err)
-		return err;
-
-	pwm->state.duty_cycle = duty_ns;
-	pwm->state.period = period_ns;
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(pwm_config);
+	if (!memcmp(state, &pwm->state, sizeof(*state)))
+		return 0;
 
-/**
- * pwm_set_polarity() - configure the polarity of a PWM signal
- * @pwm: PWM device
- * @polarity: new polarity of the PWM signal
- *
- * Note that the polarity cannot be configured while the PWM device is
- * enabled.
- *
- * Returns: 0 on success or a negative error code on failure.
- */
-int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
-{
-	int err;
+	if (pwm->chip->ops->apply) {
+		err = pwm->chip->ops->apply(pwm->chip, pwm, state);
+		if (err)
+			return err;
 
-	if (!pwm || !pwm->chip->ops)
-		return -EINVAL;
+		pwm->state = *state;
+	} else {
+		/*
+		 * FIXME: restore the initial state in case of error.
+		 */
+		if (state->polarity != pwm->state.polarity) {
+			if (!pwm->chip->ops->set_polarity)
+				return -ENOTSUPP;
+
+			/*
+			 * Changing the polarity of a running PWM is
+			 * only allowed when the PWM driver implements
+			 * ->apply().
+			 */
+			if (pwm->state.enabled) {
+				pwm->chip->ops->disable(pwm->chip, pwm);
+				pwm->state.enabled = false;
+			}
+
+			err = pwm->chip->ops->set_polarity(pwm->chip, pwm,
+							   state->polarity);
+			if (err)
+				return err;
+
+			pwm->state.polarity = state->polarity;
+		}
 
-	if (!pwm->chip->ops->set_polarity)
-		return -ENOSYS;
+		if (state->period != pwm->state.period ||
+		    state->duty_cycle != pwm->state.duty_cycle) {
+			err = pwm->chip->ops->config(pwm->chip, pwm,
+						     state->duty_cycle,
+						     state->period);
+			if (err)
+				return err;
 
-	if (pwm_is_enabled(pwm))
-		return -EBUSY;
+			pwm->state.duty_cycle = state->duty_cycle;
+			pwm->state.period = state->period;
+		}
 
-	err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity);
-	if (err)
-		return err;
+		if (state->enabled != pwm->state.enabled) {
+			if (state->enabled) {
+				err = pwm->chip->ops->enable(pwm->chip, pwm);
+				if (err)
+					return err;
+			} else {
+				pwm->chip->ops->disable(pwm->chip, pwm);
+			}
 
-	pwm->state.polarity = polarity;
+			pwm->state.enabled = state->enabled;
+		}
+	}
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(pwm_set_polarity);
+EXPORT_SYMBOL_GPL(pwm_apply_state);
 
 /**
- * pwm_enable() - start a PWM output toggling
+ * pwm_adjust_config() - adjust the current PWM config to the PWM arguments
  * @pwm: PWM device
  *
- * Returns: 0 on success or a negative error code on failure.
+ * This function will adjust the PWM config to the PWM arguments provided
+ * by the DT or PWM lookup table. This is particularly useful to adapt
+ * the bootloader config to the Linux one.
  */
-int pwm_enable(struct pwm_device *pwm)
+int pwm_adjust_config(struct pwm_device *pwm)
 {
-	int err = 0;
+	struct pwm_state state;
+	struct pwm_args pargs;
 
-	if (!pwm)
-		return -EINVAL;
+	pwm_get_args(pwm, &pargs);
+	pwm_get_state(pwm, &state);
+
+	/*
+	 * If the current period is zero it means that either the PWM driver
+	 * does not support initial state retrieval or the PWM has not yet
+	 * been configured.
+	 *
+	 * In either case, we setup the new period and polarity, and assign a
+	 * duty cycle of 0.
+	 */
+	if (!state.period) {
+		state.duty_cycle = 0;
+		state.period = pargs.period;
+		state.polarity = pargs.polarity;
 
-	if (!pwm_is_enabled(pwm)) {
-		err = pwm->chip->ops->enable(pwm->chip, pwm);
-		if (!err)
-			pwm->state.enabled = true;
+		return pwm_apply_state(pwm, &state);
 	}
 
-	return err;
-}
-EXPORT_SYMBOL_GPL(pwm_enable);
+	/*
+	 * Adjust the PWM duty cycle/period based on the period value provided
+	 * in PWM args.
+	 */
+	if (pargs.period != state.period) {
+		u64 dutycycle = (u64)state.duty_cycle * pargs.period;
 
-/**
- * pwm_disable() - stop a PWM output toggling
- * @pwm: PWM device
- */
-void pwm_disable(struct pwm_device *pwm)
-{
-	if (!pwm)
-		return;
+		do_div(dutycycle, state.period);
+		state.duty_cycle = dutycycle;
+		state.period = pargs.period;
+	}
 
-	if (pwm_is_enabled(pwm)) {
-		pwm->chip->ops->disable(pwm->chip, pwm);
-		pwm->state.enabled = false;
+	/*
+	 * If the polarity changed, we should also change the duty cycle.
+	 */
+	if (pargs.polarity != state.polarity) {
+		state.polarity = pargs.polarity;
+		state.duty_cycle = state.period - state.duty_cycle;
 	}
+
+	return pwm_apply_state(pwm, &state);
 }
-EXPORT_SYMBOL_GPL(pwm_disable);
+EXPORT_SYMBOL_GPL(pwm_adjust_config);
 
 static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
 {
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 33f8decd9f38..17018f3c066e 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -5,59 +5,7 @@
 #include <linux/mutex.h>
 #include <linux/of.h>
 
-struct pwm_device;
 struct seq_file;
-
-#if IS_ENABLED(CONFIG_PWM)
-/*
- * pwm_request - request a PWM device
- */
-struct pwm_device *pwm_request(int pwm_id, const char *label);
-
-/*
- * pwm_free - free a PWM device
- */
-void pwm_free(struct pwm_device *pwm);
-
-/*
- * pwm_config - change a PWM device configuration
- */
-int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns);
-
-/*
- * pwm_enable - start a PWM output toggling
- */
-int pwm_enable(struct pwm_device *pwm);
-
-/*
- * pwm_disable - stop a PWM output toggling
- */
-void pwm_disable(struct pwm_device *pwm);
-#else
-static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
-{
-	return ERR_PTR(-ENODEV);
-}
-
-static inline void pwm_free(struct pwm_device *pwm)
-{
-}
-
-static inline int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
-{
-	return -EINVAL;
-}
-
-static inline int pwm_enable(struct pwm_device *pwm)
-{
-	return -EINVAL;
-}
-
-static inline void pwm_disable(struct pwm_device *pwm)
-{
-}
-#endif
-
 struct pwm_chip;
 
 /**
@@ -184,11 +132,6 @@ static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
 	return state.duty_cycle;
 }
 
-/*
- * pwm_set_polarity - configure the polarity of a PWM signal
- */
-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)
 {
 	struct pwm_state state;
@@ -204,34 +147,6 @@ static inline void pwm_get_args(const struct pwm_device *pwm,
 	*args = pwm->args;
 }
 
-static inline void pwm_apply_args(struct pwm_device *pwm)
-{
-	/*
-	 * PWM users calling pwm_apply_args() expect to have a fresh config
-	 * where the polarity and period are set according to pwm_args info.
-	 * The problem is, polarity can only be changed when the PWM is
-	 * disabled.
-	 *
-	 * PWM drivers supporting hardware readout may declare the PWM device
-	 * as enabled, and prevent polarity setting, which changes from the
-	 * existing behavior, where all PWM devices are declared as disabled
-	 * at startup (even if they are actually enabled), thus authorizing
-	 * polarity setting.
-	 *
-	 * Instead of setting ->enabled to false, we call pwm_disable()
-	 * before pwm_set_polarity() to ensure that everything is configured
-	 * as expected, and the PWM is really disabled when the user request
-	 * it.
-	 *
-	 * Note that PWM users requiring a smooth handover between the
-	 * bootloader and the kernel (like critical regulators controlled by
-	 * PWM devices) will have to switch to the atomic API and avoid calling
-	 * pwm_apply_args().
-	 */
-	pwm_disable(pwm);
-	pwm_set_polarity(pwm, pwm->args.polarity);
-}
-
 /**
  * struct pwm_ops - PWM controller operations
  * @request: optional hook for requesting a PWM
@@ -240,6 +155,10 @@ static inline void pwm_apply_args(struct pwm_device *pwm)
  * @set_polarity: configure the polarity of this PWM
  * @enable: enable PWM output toggling
  * @disable: disable PWM output toggling
+ * @apply: atomically apply a new PWM config. The state argument
+ *	   should be adjusted with the real hardware config (if the
+ *	   approximate the period or duty_cycle value, state should
+ *	   reflect it)
  * @get_state: get the current PWM state. This function is only
  *	       called once per PWM device when the PWM chip is
  *	       registered.
@@ -255,6 +174,8 @@ struct pwm_ops {
 			    enum pwm_polarity polarity);
 	int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
 	void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
+	int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
+		     struct pwm_state *state);
 	void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
 			  struct pwm_state *state);
 #ifdef CONFIG_DEBUG_FS
@@ -292,6 +213,115 @@ struct pwm_chip {
 };
 
 #if IS_ENABLED(CONFIG_PWM)
+/* PWM user APIs */
+struct pwm_device *pwm_request(int pwm_id, const char *label);
+void pwm_free(struct pwm_device *pwm);
+int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state);
+int pwm_adjust_config(struct pwm_device *pwm);
+
+/**
+ * pwm_config() - change a PWM device configuration
+ * @pwm: PWM device
+ * @duty_ns: "on" time (in nanoseconds)
+ * @period_ns: duration (in nanoseconds) of one cycle
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
+			     int period_ns)
+{
+	struct pwm_state state;
+
+	if (!pwm)
+		return -EINVAL;
+
+	pwm_get_state(pwm, &state);
+	if (state.duty_cycle == duty_ns && state.period == period_ns)
+		return 0;
+
+	state.duty_cycle = duty_ns;
+	state.period = period_ns;
+	return pwm_apply_state(pwm, &state);
+}
+
+/**
+ * pwm_set_polarity() - configure the polarity of a PWM signal
+ * @pwm: PWM device
+ * @polarity: new polarity of the PWM signal
+ *
+ * Note that the polarity cannot be configured while the PWM device is
+ * enabled.
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+static inline int pwm_set_polarity(struct pwm_device *pwm,
+				   enum pwm_polarity polarity)
+{
+	struct pwm_state state;
+
+	if (!pwm)
+		return -EINVAL;
+
+	pwm_get_state(pwm, &state);
+	if (state.polarity == polarity)
+		return 0;
+
+	/*
+	 * Changing the polarity of a running PWM without adjusting the
+	 * dutycycle/period value is a bit risky (can introduce glitches).
+	 * Return -EBUSY in this case.
+	 * Note that this is allowed when using pwm_apply_state() because
+	 * the user specifies all the parameters.
+	 */
+	if (state.enabled)
+		return -EBUSY;
+
+	state.polarity = polarity;
+	return pwm_apply_state(pwm, &state);
+}
+
+/**
+ * pwm_enable() - start a PWM output toggling
+ * @pwm: PWM device
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+static inline int pwm_enable(struct pwm_device *pwm)
+{
+	struct pwm_state state;
+
+	if (!pwm)
+		return -EINVAL;
+
+	pwm_get_state(pwm, &state);
+	if (state.enabled)
+		return 0;
+
+	state.enabled = true;
+	return pwm_apply_state(pwm, &state);
+}
+
+/**
+ * pwm_disable() - stop a PWM output toggling
+ * @pwm: PWM device
+ */
+static inline void pwm_disable(struct pwm_device *pwm)
+{
+	struct pwm_state state;
+
+	if (!pwm)
+		return;
+
+	pwm_get_state(pwm, &state);
+	if (!state.enabled)
+		return;
+
+	state.enabled = false;
+	pwm_apply_state(pwm, &state);
+}
+
+
+/* PWM provider APIs */
 int pwm_set_chip_data(struct pwm_device *pwm, void *data);
 void *pwm_get_chip_data(struct pwm_device *pwm);
 
@@ -317,6 +347,47 @@ void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
 
 bool pwm_can_sleep(struct pwm_device *pwm);
 #else
+static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
+{
+	return ERR_PTR(-ENODEV);
+}
+
+static inline void pwm_free(struct pwm_device *pwm)
+{
+}
+
+static inline int pwm_apply_state(struct pwm_device *pwm,
+				  const struct pwm_state *state)
+{
+	return -ENOTSUPP;
+}
+
+static inline int pwm_adjust_config(struct pwm_device *pwm)
+{
+	return -ENOTSUPP;
+}
+
+static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
+			     int period_ns)
+{
+	return -EINVAL;
+}
+
+static inline int pwm_set_polarity(struct pwm_device *pwm,
+				   enum pwm_polarity polarity)
+{
+	return -ENOTSUPP;
+}
+
+static inline int pwm_enable(struct pwm_device *pwm)
+{
+	return -EINVAL;
+}
+
+static inline void pwm_disable(struct pwm_device *pwm)
+{
+}
+
 static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
 {
 	return -EINVAL;
@@ -388,6 +459,34 @@ static inline bool pwm_can_sleep(struct pwm_device *pwm)
 }
 #endif
 
+static inline void pwm_apply_args(struct pwm_device *pwm)
+{
+	/*
+	 * PWM users calling pwm_apply_args() expect to have a fresh config
+	 * where the polarity and period are set according to pwm_args info.
+	 * The problem is, polarity can only be changed when the PWM is
+	 * disabled.
+	 *
+	 * PWM drivers supporting hardware readout may declare the PWM device
+	 * as enabled, and prevent polarity setting, which changes from the
+	 * existing behavior, where all PWM devices are declared as disabled
+	 * at startup (even if they are actually enabled), thus authorizing
+	 * polarity setting.
+	 *
+	 * Instead of setting ->enabled to false, we call pwm_disable()
+	 * before pwm_set_polarity() to ensure that everything is configured
+	 * as expected, and the PWM is really disabled when the user request
+	 * it.
+	 *
+	 * Note that PWM users requiring a smooth handover between the
+	 * bootloader and the kernel (like critical regulators controlled by
+	 * PWM devices) will have to switch to the atomic API and avoid calling
+	 * pwm_apply_args().
+	 */
+	pwm_disable(pwm);
+	pwm_set_polarity(pwm, pwm->args.polarity);
+}
+
 struct pwm_lookup {
 	struct list_head list;
 	const char *provider;
-- 
cgit v1.2.3


From 39100ceea79ff2efeb2fb094baf120c73d5ccf47 Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@free-electrons.com>
Date: Thu, 14 Apr 2016 21:17:43 +0200
Subject: pwm: Switch to the atomic API

Replace legacy pwm_get/set_xxx() and pwm_config/enable/disable() calls
by pwm_get/apply_state().

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
---
 drivers/pwm/core.c  |  5 ++++-
 drivers/pwm/sysfs.c | 48 +++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 41 insertions(+), 12 deletions(-)

(limited to 'drivers/pwm/core.c')

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 729d457861fd..b0b87b3b52a6 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -948,13 +948,16 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
 
 	for (i = 0; i < chip->npwm; i++) {
 		struct pwm_device *pwm = &chip->pwms[i];
+		struct pwm_state state;
+
+		pwm_get_state(pwm, &state);
 
 		seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);
 
 		if (test_bit(PWMF_REQUESTED, &pwm->flags))
 			seq_puts(s, " requested");
 
-		if (pwm_is_enabled(pwm))
+		if (state.enabled)
 			seq_puts(s, " enabled");
 
 		seq_puts(s, "\n");
diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index 187ca0875cf6..d98599249a05 100644
--- a/drivers/pwm/sysfs.c
+++ b/drivers/pwm/sysfs.c
@@ -46,8 +46,11 @@ static ssize_t period_show(struct device *child,
 			   char *buf)
 {
 	const struct pwm_device *pwm = child_to_pwm_device(child);
+	struct pwm_state state;
 
-	return sprintf(buf, "%u\n", pwm_get_period(pwm));
+	pwm_get_state(pwm, &state);
+
+	return sprintf(buf, "%u\n", state.period);
 }
 
 static ssize_t period_store(struct device *child,
@@ -56,6 +59,7 @@ static ssize_t period_store(struct device *child,
 {
 	struct pwm_export *export = child_to_pwm_export(child);
 	struct pwm_device *pwm = export->pwm;
+	struct pwm_state state;
 	unsigned int val;
 	int ret;
 
@@ -64,7 +68,9 @@ static ssize_t period_store(struct device *child,
 		return ret;
 
 	mutex_lock(&export->lock);
-	ret = pwm_config(pwm, pwm_get_duty_cycle(pwm), val);
+	pwm_get_state(pwm, &state);
+	state.period = val;
+	ret = pwm_apply_state(pwm, &state);
 	mutex_unlock(&export->lock);
 
 	return ret ? : size;
@@ -75,8 +81,11 @@ static ssize_t duty_cycle_show(struct device *child,
 			       char *buf)
 {
 	const struct pwm_device *pwm = child_to_pwm_device(child);
+	struct pwm_state state;
+
+	pwm_get_state(pwm, &state);
 
-	return sprintf(buf, "%u\n", pwm_get_duty_cycle(pwm));
+	return sprintf(buf, "%u\n", state.duty_cycle);
 }
 
 static ssize_t duty_cycle_store(struct device *child,
@@ -85,6 +94,7 @@ static ssize_t duty_cycle_store(struct device *child,
 {
 	struct pwm_export *export = child_to_pwm_export(child);
 	struct pwm_device *pwm = export->pwm;
+	struct pwm_state state;
 	unsigned int val;
 	int ret;
 
@@ -93,7 +103,9 @@ static ssize_t duty_cycle_store(struct device *child,
 		return ret;
 
 	mutex_lock(&export->lock);
-	ret = pwm_config(pwm, val, pwm_get_period(pwm));
+	pwm_get_state(pwm, &state);
+	state.duty_cycle = val;
+	ret = pwm_apply_state(pwm, &state);
 	mutex_unlock(&export->lock);
 
 	return ret ? : size;
@@ -104,8 +116,11 @@ static ssize_t enable_show(struct device *child,
 			   char *buf)
 {
 	const struct pwm_device *pwm = child_to_pwm_device(child);
+	struct pwm_state state;
 
-	return sprintf(buf, "%d\n", pwm_is_enabled(pwm));
+	pwm_get_state(pwm, &state);
+
+	return sprintf(buf, "%d\n", state.enabled);
 }
 
 static ssize_t enable_store(struct device *child,
@@ -114,6 +129,7 @@ static ssize_t enable_store(struct device *child,
 {
 	struct pwm_export *export = child_to_pwm_export(child);
 	struct pwm_device *pwm = export->pwm;
+	struct pwm_state state;
 	int val, ret;
 
 	ret = kstrtoint(buf, 0, &val);
@@ -122,20 +138,24 @@ static ssize_t enable_store(struct device *child,
 
 	mutex_lock(&export->lock);
 
+	pwm_get_state(pwm, &state);
+
 	switch (val) {
 	case 0:
-		pwm_disable(pwm);
+		state.enabled = false;
 		break;
 	case 1:
-		ret = pwm_enable(pwm);
+		state.enabled = true;
 		break;
 	default:
 		ret = -EINVAL;
-		break;
+		goto unlock;
 	}
 
-	mutex_unlock(&export->lock);
+	pwm_apply_state(pwm, &state);
 
+unlock:
+	mutex_unlock(&export->lock);
 	return ret ? : size;
 }
 
@@ -145,8 +165,11 @@ static ssize_t polarity_show(struct device *child,
 {
 	const struct pwm_device *pwm = child_to_pwm_device(child);
 	const char *polarity = "unknown";
+	struct pwm_state state;
+
+	pwm_get_state(pwm, &state);
 
-	switch (pwm_get_polarity(pwm)) {
+	switch (state.polarity) {
 	case PWM_POLARITY_NORMAL:
 		polarity = "normal";
 		break;
@@ -166,6 +189,7 @@ static ssize_t polarity_store(struct device *child,
 	struct pwm_export *export = child_to_pwm_export(child);
 	struct pwm_device *pwm = export->pwm;
 	enum pwm_polarity polarity;
+	struct pwm_state state;
 	int ret;
 
 	if (sysfs_streq(buf, "normal"))
@@ -176,7 +200,9 @@ static ssize_t polarity_store(struct device *child,
 		return -EINVAL;
 
 	mutex_lock(&export->lock);
-	ret = pwm_set_polarity(pwm, polarity);
+	pwm_get_state(pwm, &state);
+	state.polarity = polarity;
+	ret = pwm_apply_state(pwm, &state);
 	mutex_unlock(&export->lock);
 
 	return ret ? : size;
-- 
cgit v1.2.3


From 23e3523f5d3a980edf7f189743cf4bb9490400a9 Mon Sep 17 00:00:00 2001
From: Heiko Stübner <heiko@sntech.de>
Date: Thu, 14 Apr 2016 21:17:44 +0200
Subject: pwm: Add information about polarity, duty cycle and period to debugfs

The PWM states make it possible to also output the polarity, duty cycle
and period information in the debugfs summary output. This simplifies
gathering information about PWMs without needing to walk through the
sysfs attributes of every PWM.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[thierry.reding@gmail.com: use more spaces in debugfs output]
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
---
 drivers/pwm/core.c | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'drivers/pwm/core.c')

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index b0b87b3b52a6..c2e1a4bb23ac 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -960,6 +960,11 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
 		if (state.enabled)
 			seq_puts(s, " enabled");
 
+		seq_printf(s, " period: %u ns", state.period);
+		seq_printf(s, " duty: %u ns", state.duty_cycle);
+		seq_printf(s, " polarity: %s",
+			   state.polarity ? "inverse" : "normal");
+
 		seq_puts(s, "\n");
 	}
 }
-- 
cgit v1.2.3