[PATCH 00/11] pwm: Add support for PWM Capture

[PATCH 00/11] pwm: Add support for PWM Capture

[Lee Jones]

The first part of this set extends the current PWM API to allow external
code to request a PWM Capture.  Subsequent patches then make use of the
new API by providing a userspace offering via /sysfs.  The final part of
the set supplies PWM Capture functionality into the already existing STi
PWM driver.

This patch-set has been tested end to end via /sysfs.

Lee Jones (11):
  pwm: Add PWM Capture support
  pwm: sysfs: Add PWM Capture support
  pwm: sti: Reorganise register names in preparation for new
    functionality
  pwm: sti: Only request clock rate when you need to
  pwm: sti: Supply PWM Capture register addresses and bit locations
  pwm: sti: Supply PWM Capture clock handling
  pwm: sti: Initialise PWM Capture channel data
  pwm: sti: Add support for PWM Capture IRQs
  pwm: sti: Add PWM Capture call-back
  pwm: sti: Enable PWM Capture
  pwm: sti: Take the opportunity to conduct a little house keeping

 drivers/pwm/core.c    |  26 ++++
 drivers/pwm/pwm-sti.c | 383 ++++++++++++++++++++++++++++++++++++++++++--------
 drivers/pwm/sysfs.c   |  28 ++++
 include/linux/pwm.h   |  13 ++
 4 files changed, 391 insertions(+), 59 deletions(-)

-- 
1.9.1

[PATCH 01/11] pwm: Add PWM Capture support

[Lee Jones]

Supply a PWM Capture call-back Op in order to pass back
information obtained by running analysis on PWM a signal.
This would normally (at least during testing) be called from
the Sysfs routines with a view to printing out PWM Capture
data which has been encoded into a string.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/core.c  | 26 ++++++++++++++++++++++++++
 include/linux/pwm.h | 13 +++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index d24ca5f..8f4a8a9 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -494,6 +494,32 @@ unlock:
 EXPORT_SYMBOL_GPL(pwm_set_polarity);
 
 /**
+ * pwm_capture() - capture and report a PWM signal
+ * @pwm: PWM device
+ * @channel: PWM capture channel to use
+ * @buf: buffer to place output message into
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+int pwm_capture(struct pwm_device *pwm, int channel, char *buf)
+{
+	int err;
+
+	if (!pwm || !pwm->chip->ops)
+		return -EINVAL;
+
+	if (!pwm->chip->ops->capture)
+		return -ENOSYS;
+
+	mutex_lock(&pwm->lock);
+	err = pwm->chip->ops->capture(pwm->chip, pwm, channel, buf);
+	mutex_unlock(&pwm->lock);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(pwm_capture);
+
+/**
  * pwm_enable() - start a PWM output toggling
  * @pwm: PWM device
  *
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index cfc3ed4..7bcff6b 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -33,6 +33,11 @@ int pwm_enable(struct pwm_device *pwm);
  * pwm_disable - stop a PWM output toggling
  */
 void pwm_disable(struct pwm_device *pwm);
+
+/*
+ * pwm_capture - capture and report a PWM signal
+ */
+int pwm_capture(struct pwm_device *pwm, int channel, char *buf);
 #else
 static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
 {
@@ -56,6 +61,11 @@ static inline int pwm_enable(struct pwm_device *pwm)
 static inline void pwm_disable(struct pwm_device *pwm)
 {
 }
+
+static inline int pwm_capture(struct pwm_device *pwm, int channel, char *buf)
+{
+	return -EINVAL;
+}
 #endif
 
 struct pwm_chip;
@@ -150,6 +160,7 @@ static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
  * @free: optional hook for freeing a PWM
  * @config: configure duty cycles and period length for this PWM
  * @set_polarity: configure the polarity of this PWM
+ * @capture: capture and report PWM signal
  * @enable: enable PWM output toggling
  * @disable: disable PWM output toggling
  * @dbg_show: optional routine to show contents in debugfs
@@ -162,6 +173,8 @@ struct pwm_ops {
 		      int duty_ns, int period_ns);
 	int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
 			    enum pwm_polarity polarity);
+	int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,
+		       int channel, char *buf);
 	int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
 	void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
 #ifdef CONFIG_DEBUG_FS
-- 
1.9.1

[PATCH 02/11] pwm: sysfs: Add PWM Capture support

[Lee Jones]

Allow a user to read PWM Capture results from /sysfs. First,
the user must tell PWM Capture which channel they wish to
read from:

  $ echo 2 > $PWMCHIP/capture

To start a capture and read the result, simply read the file:

  $ cat $PWMCHIP/capture

The output format is left to the device.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/sysfs.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index 9c90886..3572ef4 100644
--- a/drivers/pwm/sysfs.c
+++ b/drivers/pwm/sysfs.c
@@ -23,6 +23,8 @@
 #include <linux/kdev_t.h>
 #include <linux/pwm.h>
 
+static int capture_channel;
+
 struct pwm_export {
 	struct device child;
 	struct pwm_device *pwm;
@@ -167,16 +169,42 @@ static ssize_t polarity_store(struct device *child,
 	return ret ? : size;
 }
 
+static ssize_t capture_show(struct device *child,
+			    struct device_attribute *attr,
+			    char *buf)
+{
+	struct pwm_device *pwm = child_to_pwm_device(child);
+
+	return pwm_capture(pwm, capture_channel, buf);
+}
+
+static ssize_t capture_store(struct device *child,
+			     struct device_attribute *attr,
+			     const char *buf, size_t size)
+{
+	int val, ret;
+
+	ret = kstrtoint(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	capture_channel = val;
+
+	return size;
+}
+
 static DEVICE_ATTR_RW(period);
 static DEVICE_ATTR_RW(duty_cycle);
 static DEVICE_ATTR_RW(enable);
 static DEVICE_ATTR_RW(polarity);
+static DEVICE_ATTR_RW(capture);
 
 static struct attribute *pwm_attrs[] = {
 	&dev_attr_period.attr,
 	&dev_attr_duty_cycle.attr,
 	&dev_attr_enable.attr,
 	&dev_attr_polarity.attr,
+	&dev_attr_capture.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(pwm);
-- 
1.9.1

[PATCH 03/11] pwm: sti: Reorganise register names in preparation for new functionality

[Lee Jones]

Exciting functionality is on the way to this device.  But
before we can add it, we need to do some basic housekeeping
so the additions can be added cleanly.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/pwm-sti.c | 76 +++++++++++++++++++++++++++------------------------
 1 file changed, 41 insertions(+), 35 deletions(-)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 92abbd5..4e06c4d 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -21,18 +21,22 @@
 #include <linux/slab.h>
 #include <linux/time.h>
 
-#define STI_DS_REG(ch)	(4 * (ch))	/* Channel's Duty Cycle register */
-#define STI_PWMCR	0x50		/* Control/Config register */
-#define STI_INTEN	0x54		/* Interrupt Enable/Disable register */
+#define PWM_OUT_VAL(x)	(0x00 + (4 * (x))) /* Channel's Duty Cycle register */
+
+#define STI_PWM_CTRL	0x50		/* Control/Config register */
+#define STI_INT_EN	0x54		/* Interrupt Enable/Disable register */
 #define PWM_PRESCALE_LOW_MASK		0x0f
 #define PWM_PRESCALE_HIGH_MASK		0xf0
 
 /* Regfield IDs */
 enum {
+	/* Bits in PWM_CTRL*/
 	PWMCLK_PRESCALE_LOW,
 	PWMCLK_PRESCALE_HIGH,
-	PWM_EN,
-	PWM_INT_EN,
+
+	PWM_OUT_EN,
+
+	PWM_CPT_INT_EN,
 
 	/* Keep last */
 	MAX_REGFIELDS
@@ -47,14 +51,14 @@ struct sti_pwm_compat_data {
 
 struct sti_pwm_chip {
 	struct device *dev;
-	struct clk *clk;
 	unsigned long clk_rate;
+	struct clk *pwm_clk;
 	struct regmap *regmap;
 	struct sti_pwm_compat_data *cdata;
 	struct regmap_field *prescale_low;
 	struct regmap_field *prescale_high;
-	struct regmap_field *pwm_en;
-	struct regmap_field *pwm_int_en;
+	struct regmap_field *pwm_out_en;
+	struct regmap_field *pwm_cpt_int_en;
 	struct pwm_chip chip;
 	struct pwm_device *cur;
 	unsigned long configured;
@@ -64,10 +68,10 @@ struct sti_pwm_chip {
 };
 
 static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
-	[PWMCLK_PRESCALE_LOW]	= REG_FIELD(STI_PWMCR, 0, 3),
-	[PWMCLK_PRESCALE_HIGH]	= REG_FIELD(STI_PWMCR, 11, 14),
-	[PWM_EN]		= REG_FIELD(STI_PWMCR, 9, 9),
-	[PWM_INT_EN]		= REG_FIELD(STI_INTEN, 0, 0),
+	[PWMCLK_PRESCALE_LOW]	= REG_FIELD(STI_PWM_CTRL, 0, 3),
+	[PWMCLK_PRESCALE_HIGH]	= REG_FIELD(STI_PWM_CTRL, 11, 14),
+	[PWM_OUT_EN]		= REG_FIELD(STI_PWM_CTRL, 9, 9),
+	[PWM_CPT_INT_EN]	= REG_FIELD(STI_INT_EN, 1, 4),
 };
 
 static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
@@ -144,7 +148,7 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	    ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
 	    ((ncfg > 1) && period_same)) {
 		/* Enable clock before writing to PWM registers. */
-		ret = clk_enable(pc->clk);
+		ret = clk_enable(pc->pwm_clk);
 		if (ret)
 			return ret;
 
@@ -174,11 +178,12 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 		 */
 		pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;
 
-		ret = regmap_write(pc->regmap, STI_DS_REG(pwm->hwpwm), pwmvalx);
+		ret = regmap_write(pc->regmap,
+				   PWM_OUT_VAL(pwm->hwpwm), pwmvalx);
 		if (ret)
 			goto clk_dis;
 
-		ret = regmap_field_write(pc->pwm_int_en, 0);
+		ret = regmap_field_write(pc->pwm_cpt_int_en, 0);
 
 		set_bit(pwm->hwpwm, &pc->configured);
 		pc->cur = pwm;
@@ -190,7 +195,7 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	}
 
 clk_dis:
-	clk_disable(pc->clk);
+	clk_disable(pc->pwm_clk);
 	return ret;
 }
 
@@ -206,11 +211,11 @@ static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 	 */
 	mutex_lock(&pc->sti_pwm_lock);
 	if (!pc->en_count) {
-		ret = clk_enable(pc->clk);
+		ret = clk_enable(pc->pwm_clk);
 		if (ret)
 			goto out;
 
-		ret = regmap_field_write(pc->pwm_en, 1);
+		ret = regmap_field_write(pc->pwm_out_en, 1);
 		if (ret) {
 			dev_err(dev, "failed to enable PWM device:%d\n",
 				pwm->hwpwm);
@@ -232,9 +237,9 @@ static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 		mutex_unlock(&pc->sti_pwm_lock);
 		return;
 	}
-	regmap_field_write(pc->pwm_en, 0);
+	regmap_field_write(pc->pwm_out_en, 0);
 
-	clk_disable(pc->clk);
+	clk_disable(pc->pwm_clk);
 	mutex_unlock(&pc->sti_pwm_lock);
 }
 
@@ -277,15 +282,16 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 	if (IS_ERR(pc->prescale_high))
 		return PTR_ERR(pc->prescale_high);
 
-	pc->pwm_en = devm_regmap_field_alloc(dev, pc->regmap,
-					     reg_fields[PWM_EN]);
-	if (IS_ERR(pc->pwm_en))
-		return PTR_ERR(pc->pwm_en);
 
-	pc->pwm_int_en = devm_regmap_field_alloc(dev, pc->regmap,
-						 reg_fields[PWM_INT_EN]);
-	if (IS_ERR(pc->pwm_int_en))
-		return PTR_ERR(pc->pwm_int_en);
+	pc->pwm_out_en = devm_regmap_field_alloc(dev, pc->regmap,
+						 reg_fields[PWM_OUT_EN]);
+	if (IS_ERR(pc->pwm_out_en))
+		return PTR_ERR(pc->pwm_out_en);
+
+	pc->pwm_cpt_int_en = devm_regmap_field_alloc(dev, pc->regmap,
+						 reg_fields[PWM_CPT_INT_EN]);
+	if (IS_ERR(pc->pwm_cpt_int_en))
+		return PTR_ERR(pc->pwm_cpt_int_en);
 
 	return 0;
 }
@@ -341,19 +347,19 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	pc->clk = of_clk_get_by_name(dev->of_node, "pwm");
-	if (IS_ERR(pc->clk)) {
+	pc->pwm_clk = of_clk_get_by_name(dev->of_node, "pwm");
+	if (IS_ERR(pc->pwm_clk)) {
 		dev_err(dev, "failed to get PWM clock\n");
-		return PTR_ERR(pc->clk);
+		return PTR_ERR(pc->pwm_clk);
 	}
 
-	pc->clk_rate = clk_get_rate(pc->clk);
+	pc->clk_rate = clk_get_rate(pc->pwm_clk);
 	if (!pc->clk_rate) {
 		dev_err(dev, "failed to get clock rate\n");
 		return -EINVAL;
 	}
 
-	ret = clk_prepare(pc->clk);
+	ret = clk_prepare(pc->pwm_clk);
 	if (ret) {
 		dev_err(dev, "failed to prepare clock\n");
 		return ret;
@@ -367,7 +373,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
 
 	ret = pwmchip_add(&pc->chip);
 	if (ret < 0) {
-		clk_unprepare(pc->clk);
+		clk_unprepare(pc->pwm_clk);
 		return ret;
 	}
 
@@ -384,7 +390,7 @@ static int sti_pwm_remove(struct platform_device *pdev)
 	for (i = 0; i < pc->cdata->num_chan; i++)
 		pwm_disable(&pc->chip.pwms[i]);
 
-	clk_unprepare(pc->clk);
+	clk_unprepare(pc->pwm_clk);
 
 	return pwmchip_remove(&pc->chip);
 }
-- 
1.9.1

[PATCH 04/11] pwm: sti: Only request clock rate when you need to

[Lee Jones]

In the original code the clock rate was only obtained during
initialisation; however, the rate may change between then and
its use.  This patch ensures the correct rate is acquired just
before use.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/pwm-sti.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 4e06c4d..aa217e2 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -51,7 +51,6 @@ struct sti_pwm_compat_data {
 
 struct sti_pwm_chip {
 	struct device *dev;
-	unsigned long clk_rate;
 	struct clk *pwm_clk;
 	struct regmap *regmap;
 	struct sti_pwm_compat_data *cdata;
@@ -86,13 +85,20 @@ static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
 				unsigned int *prescale)
 {
 	struct sti_pwm_compat_data *cdata = pc->cdata;
+	unsigned long clk_rate;
 	unsigned long val;
 	unsigned int ps;
 
+	clk_rate = clk_get_rate(pc->pwm_clk);
+	if (!clk_rate) {
+		dev_err(pc->dev, "failed to get clock rate\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_count + 1)) - 1
 	 */
-	val = NSEC_PER_SEC / pc->clk_rate;
+	val = NSEC_PER_SEC / clk_rate;
 	val *= cdata->max_pwm_cnt + 1;
 
 	if (period % val) {
@@ -353,12 +359,6 @@ static int sti_pwm_probe(struct platform_device *pdev)
 		return PTR_ERR(pc->pwm_clk);
 	}
 
-	pc->clk_rate = clk_get_rate(pc->pwm_clk);
-	if (!pc->clk_rate) {
-		dev_err(dev, "failed to get clock rate\n");
-		return -EINVAL;
-	}
-
 	ret = clk_prepare(pc->pwm_clk);
 	if (ret) {
 		dev_err(dev, "failed to prepare clock\n");
-- 
1.9.1

[PATCH 05/11] pwm: sti: Supply PWM Capture register addresses and bit locations

[Lee Jones]

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/pwm-sti.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index aa217e2..2336bac 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -22,26 +22,48 @@
 #include <linux/time.h>
 
 #define PWM_OUT_VAL(x)	(0x00 + (4 * (x))) /* Channel's Duty Cycle register */
+#define PWM_CPT_VAL(x)	(0x10 + (4 * (x))) /* Capture value */
+#define PWM_CPT_EDGE(x) (0x30 + (4 * (x))) /* Edge to capture on */
 
 #define STI_PWM_CTRL	0x50		/* Control/Config register */
 #define STI_INT_EN	0x54		/* Interrupt Enable/Disable register */
+#define STI_INT_STA	0x58		/* Interrupt Status register */
+#define PWM_INT_ACK			0x5c
 #define PWM_PRESCALE_LOW_MASK		0x0f
 #define PWM_PRESCALE_HIGH_MASK		0xf0
+#define PWM_CPT_EDGE_MASK		0x03
+#define PWM_INT_ACK_MASK		0x1ff
+
+#define STI_MAX_CPT_CHANS		4
+#define CPT_DC_MAX			0xff
 
 /* Regfield IDs */
 enum {
 	/* Bits in PWM_CTRL*/
 	PWMCLK_PRESCALE_LOW,
 	PWMCLK_PRESCALE_HIGH,
+	CPTCLK_PRESCALE,
 
 	PWM_OUT_EN,
+	PWM_CPT_EN,
 
 	PWM_CPT_INT_EN,
+	PWM_CPT_INT_STAT,
 
 	/* Keep last */
 	MAX_REGFIELDS
 };
 
+/* Each capture input can be programmed to detect rising-edge, falling-edge,
+ * either edge or neither egde
+ */
+enum sti_cpt_edge {
+	CPT_EDGE_DISABLED,
+	CPT_EDGE_RISING,
+	CPT_EDGE_FALLING,
+	CPT_EDGE_BOTH,
+};
+
 struct sti_pwm_compat_data {
 	const struct reg_field *reg_fields;
 	unsigned int num_chan;
@@ -69,8 +91,11 @@ struct sti_pwm_chip {
 static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
 	[PWMCLK_PRESCALE_LOW]	= REG_FIELD(STI_PWM_CTRL, 0, 3),
 	[PWMCLK_PRESCALE_HIGH]	= REG_FIELD(STI_PWM_CTRL, 11, 14),
+	[CPTCLK_PRESCALE]	= REG_FIELD(STI_PWM_CTRL, 4, 8),
 	[PWM_OUT_EN]		= REG_FIELD(STI_PWM_CTRL, 9, 9),
+	[PWM_CPT_EN]		= REG_FIELD(STI_PWM_CTRL, 10, 10),
 	[PWM_CPT_INT_EN]	= REG_FIELD(STI_INT_EN, 1, 4),
+	[PWM_CPT_INT_STAT]	= REG_FIELD(STI_INT_STA, 1, 4),
 };
 
 static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
-- 
1.9.1

[PATCH 06/11] pwm: sti: Supply PWM Capture clock handling

[Lee Jones]

ST's PWM IP is supplied by 2 different clocks.  One for PWM
Output and the other for Capture.  This patch provides clock
handling for the latter.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/pwm-sti.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 2336bac..9e6b1c8 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -74,6 +74,7 @@ struct sti_pwm_compat_data {
 struct sti_pwm_chip {
 	struct device *dev;
 	struct clk *pwm_clk;
+	struct clk *cpt_clk;
 	struct regmap *regmap;
 	struct sti_pwm_compat_data *cdata;
 	struct regmap_field *prescale_low;
@@ -183,6 +184,10 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 		if (ret)
 			return ret;
 
+		ret = clk_enable(pc->cpt_clk);
+		if (ret)
+			return ret;
+
 		if (!period_same) {
 			ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
 			if (ret)
@@ -227,6 +232,7 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 clk_dis:
 	clk_disable(pc->pwm_clk);
+	clk_disable(pc->cpt_clk);
 	return ret;
 }
 
@@ -246,6 +252,10 @@ static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 		if (ret)
 			goto out;
 
+		ret = clk_enable(pc->cpt_clk);
+		if (ret)
+			goto out;
+
 		ret = regmap_field_write(pc->pwm_out_en, 1);
 		if (ret) {
 			dev_err(dev, "failed to enable PWM device:%d\n",
@@ -271,6 +281,7 @@ static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 	regmap_field_write(pc->pwm_out_en, 0);
 
 	clk_disable(pc->pwm_clk);
+	clk_disable(pc->cpt_clk);
 	mutex_unlock(&pc->sti_pwm_lock);
 }
 
@@ -390,6 +401,18 @@ static int sti_pwm_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	pc->cpt_clk = of_clk_get_by_name(dev->of_node, "capture");
+	if (IS_ERR(pc->cpt_clk)) {
+		dev_err(dev, "failed to get PWM capture clock\n");
+		return PTR_ERR(pc->cpt_clk);
+	}
+
+	ret = clk_prepare(pc->cpt_clk);
+	if (ret) {
+		dev_err(dev, "failed to prepare clock\n");
+		return ret;
+	}
+
 	pc->chip.dev = dev;
 	pc->chip.ops = &sti_pwm_ops;
 	pc->chip.base = -1;
@@ -399,6 +422,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	ret = pwmchip_add(&pc->chip);
 	if (ret < 0) {
 		clk_unprepare(pc->pwm_clk);
+		clk_unprepare(pc->cpt_clk);
 		return ret;
 	}
 
@@ -416,6 +440,7 @@ static int sti_pwm_remove(struct platform_device *pdev)
 		pwm_disable(&pc->chip.pwms[i]);
 
 	clk_unprepare(pc->pwm_clk);
+	clk_unprepare(pc->cpt_clk);
 
 	return pwmchip_remove(&pc->chip);
 }
-- 
1.9.1

[PATCH 07/11] pwm: sti: Initialise PWM Capture channel data

[Lee Jones]

Each PWM Capture channel is allocated a structure to hold its own
state.  During a capture the channel may be partaking in one of 3
phases.  Initial (rising) phase change, a subsequent (falling)
phase change indicating end of the duty-cycle phase and finally
a final (rising) phase change indicating the end of the period.
The timer value snapshot each event is held in a variable of the
same name, and the phase number (0, 1, 2) is contained in the
index variable.  Other channel specific information, such as GPIO
pin, the IRQ wait queue and locking is also contained in the
structure.  This patch initialises this structure for each of
the available channels.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/pwm-sti.c | 49 ++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 42 insertions(+), 7 deletions(-)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 9e6b1c8..fca692a 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -11,15 +11,19 @@
  */
 
 #include <linux/clk.h>
+#include <linux/gpio.h>
 #include <linux/math64.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_gpio.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 #include <linux/regmap.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/time.h>
+#include <linux/wait.h>
 
 #define PWM_OUT_VAL(x)	(0x00 + (4 * (x))) /* Channel's Duty Cycle register */
 #define PWM_CPT_VAL(x)	(0x10 + (4 * (x))) /* Capture value */
@@ -64,9 +68,18 @@ enum sti_cpt_edge {
 	CPT_EDGE_BOTH,
 };
 
+struct sti_cpt_data {
+	u32 snapshot[3];
+	int index;
+	int gpio;
+	struct mutex lock;
+	wait_queue_head_t wait;
+};
+
 struct sti_pwm_compat_data {
 	const struct reg_field *reg_fields;
-	unsigned int num_chan;
+	unsigned int pwm_num_chan;
+	unsigned int cpt_num_chan;
 	unsigned int max_pwm_cnt;
 	unsigned int max_prescale;
 };
@@ -77,6 +90,7 @@ struct sti_pwm_chip {
 	struct clk *cpt_clk;
 	struct regmap *regmap;
 	struct sti_pwm_compat_data *cdata;
+	struct sti_cpt_data *cpt_data[STI_MAX_CPT_CHANS];
 	struct regmap_field *prescale_low;
 	struct regmap_field *prescale_high;
 	struct regmap_field *pwm_out_en;
@@ -307,10 +321,15 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 	struct device_node *np = dev->of_node;
 	struct sti_pwm_compat_data *cdata = pc->cdata;
 	u32 num_chan;
+	int ret;
 
-	of_property_read_u32(np, "st,pwm-num-chan", &num_chan);
-	if (num_chan)
-		cdata->num_chan = num_chan;
+	ret = of_property_read_u32(np, "st,pwm-num-chan", &num_chan);
+	if (!ret)
+		cdata->pwm_num_chan = num_chan;
+
+	ret = of_property_read_u32(np, "st,capture-num-chan", &num_chan);
+	if (!ret)
+		cdata->cpt_num_chan = num_chan;
 
 	reg_fields = cdata->reg_fields;
 
@@ -347,9 +366,11 @@ static const struct regmap_config sti_pwm_regmap_config = {
 static int sti_pwm_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
 	struct sti_pwm_compat_data *cdata;
 	struct sti_pwm_chip *pc;
 	struct resource *res;
+	unsigned int chan;
 	int ret;
 
 	pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
@@ -378,7 +399,8 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	cdata->reg_fields   = &sti_pwm_regfields[0];
 	cdata->max_prescale = 0xff;
 	cdata->max_pwm_cnt  = 255;
-	cdata->num_chan     = 1;
+	cdata->pwm_num_chan     = 1;
+	cdata->cpt_num_chan	= 0;
 
 	pc->cdata = cdata;
 	pc->dev = dev;
@@ -389,6 +411,19 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	for (chan = 0; chan < cdata->cpt_num_chan; chan++) {
+		struct sti_cpt_data *data;
+
+		data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+		if (!data)
+			return -ENOMEM;
+
+		init_waitqueue_head(&data->wait);
+		mutex_init(&data->lock);
+		data->gpio = of_get_named_gpio(np, "capture-gpios", chan);
+		pc->cpt_data[chan] = data;
+	}
+
 	pc->pwm_clk = of_clk_get_by_name(dev->of_node, "pwm");
 	if (IS_ERR(pc->pwm_clk)) {
 		dev_err(dev, "failed to get PWM clock\n");
@@ -416,7 +451,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	pc->chip.dev = dev;
 	pc->chip.ops = &sti_pwm_ops;
 	pc->chip.base = -1;
-	pc->chip.npwm = pc->cdata->num_chan;
+	pc->chip.npwm = pc->cdata->pwm_num_chan;
 	pc->chip.can_sleep = true;
 
 	ret = pwmchip_add(&pc->chip);
@@ -436,7 +471,7 @@ static int sti_pwm_remove(struct platform_device *pdev)
 	struct sti_pwm_chip *pc = platform_get_drvdata(pdev);
 	unsigned int i;
 
-	for (i = 0; i < pc->cdata->num_chan; i++)
+	for (i = 0; i < pc->cdata->pwm_num_chan; i++)
 		pwm_disable(&pc->chip.pwms[i]);
 
 	clk_unprepare(pc->pwm_clk);
-- 
1.9.1

[PATCH 08/11] pwm: sti: Add support for PWM Capture IRQs

[Lee Jones]

Here we're requesting the PWM Capture IRQ and supplying the
handler which will be called in the event of an IRQ fire to
handle it.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/pwm-sti.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 90 insertions(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index fca692a..82a69e4 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -12,6 +12,7 @@
 
 #include <linux/clk.h>
 #include <linux/gpio.h>
+#include <linux/interrupt.h>
 #include <linux/math64.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
@@ -94,7 +95,9 @@ struct sti_pwm_chip {
 	struct regmap_field *prescale_low;
 	struct regmap_field *prescale_high;
 	struct regmap_field *pwm_out_en;
+	struct regmap_field *pwm_cpt_en;
 	struct regmap_field *pwm_cpt_int_en;
+	struct regmap_field *pwm_cpt_int_stat;
 	struct pwm_chip chip;
 	struct pwm_device *cur;
 	unsigned long configured;
@@ -314,6 +317,74 @@ static const struct pwm_ops sti_pwm_ops = {
 	.owner = THIS_MODULE,
 };
 
+static irqreturn_t sti_pwm_interrupt(int irq, void *data)
+{
+	struct sti_pwm_chip *pc = data;
+	struct device *dev = pc->dev;
+	struct sti_cpt_data *d;
+	int channel;
+	int cpt_int_stat;
+	int reg;
+	int ret = IRQ_NONE;
+
+	ret = regmap_field_read(pc->pwm_cpt_int_stat, &cpt_int_stat);
+	if (ret)
+		return ret;
+
+	while (cpt_int_stat) {
+		channel = ffs(cpt_int_stat) - 1;
+
+		d = pc->cpt_data[channel];
+
+		/*
+		 * Capture input:
+		 *    _______                   _______
+		 *   |       |                 |       |
+		 * __|       |_________________|       |________
+		 *   ^0      ^1                ^2
+		 *
+		 * Capture start by the first available rising edge
+		 * When a capture event occurs, capture value (CPT_VALx)
+		 * is stored, index incremented, capture edge changed.
+		 *
+		 * After the capture, if the index > 1, we have collected
+		 * the necessary data so we signal the thread waiting for it
+		 * and disable the capture by setting capture edge to none
+		 *
+		 */
+
+		regmap_read(pc->regmap,
+			    PWM_CPT_VAL(channel), &d->snapshot[d->index]);
+
+		switch (d->index) {
+		case 0:
+		case 1:
+			regmap_read(pc->regmap, PWM_CPT_EDGE(channel), &reg);
+			reg ^= PWM_CPT_EDGE_MASK;
+			regmap_write(pc->regmap, PWM_CPT_EDGE(channel), reg);
+
+			d->index++;
+			break;
+		case 2:
+			regmap_write(pc->regmap,
+				     PWM_CPT_EDGE(channel), CPT_EDGE_DISABLED);
+			wake_up(&d->wait);
+			break;
+		default:
+			dev_err(dev, "Internal error\n");
+		}
+
+		clear_bit(channel, (unsigned long int *)&cpt_int_stat);
+
+		ret = IRQ_HANDLED;
+	}
+
+	/* Just ACK everything */
+	regmap_write(pc->regmap, PWM_INT_ACK, PWM_INT_ACK_MASK);
+
+	return ret;
+}
+
 static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 {
 	struct device *dev = pc->dev;
@@ -354,6 +425,11 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 	if (IS_ERR(pc->pwm_cpt_int_en))
 		return PTR_ERR(pc->pwm_cpt_int_en);
 
+	pc->pwm_cpt_int_stat = devm_regmap_field_alloc(dev, pc->regmap,
+						reg_fields[PWM_CPT_INT_STAT]);
+	if (IS_ERR(pc->pwm_cpt_int_stat))
+		return PTR_ERR(pc->pwm_cpt_int_stat);
+
 	return 0;
 }
 
@@ -371,7 +447,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	struct sti_pwm_chip *pc;
 	struct resource *res;
 	unsigned int chan;
-	int ret;
+	int ret, irq;
 
 	pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
 	if (!pc)
@@ -392,6 +468,19 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	if (IS_ERR(pc->regmap))
 		return PTR_ERR(pc->regmap);
 
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "Failed to obtain IRQ\n");
+		return -ENODEV;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irq, sti_pwm_interrupt,
+			       0, pdev->name, (void *) pc);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to request IRQ\n");
+		return ret;
+	}
+
 	/*
 	 * Setup PWM data with default values: some values could be replaced
 	 * with specific ones provided from Device Tree.
-- 
1.9.1

[PATCH 09/11] pwm: sti: Add PWM Capture call-back

[Lee Jones]

Once a PWM Capture has been initiated, the capture call
enables a rising edge detection IRQ, then waits.  Once each
of the 3 phase changes have been recorded the thread then
wakes.  The remaining part of the call carries out the
relevant calculations and passes back a formatted string to
the caller.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/pwm-sti.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 82a69e4..8de9b4a 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -309,7 +309,79 @@ static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 	clear_bit(pwm->hwpwm, &pc->configured);
 }
 
+static int sti_pwm_capture(struct pwm_chip *chip, struct pwm_device *pwm,
+			   int channel, char *buf)
+{
+	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+	struct sti_pwm_compat_data *cdata = pc->cdata;
+	struct sti_cpt_data *d = pc->cpt_data[channel];
+	struct device *dev = pc->dev;
+	unsigned int f, dc;
+	unsigned int high, low;
+	bool level;
+	int ret;
+
+	if (channel > cdata->cpt_num_chan - 1) {
+		dev_err(dev, "Channel %d is not valid\n", channel);
+		return -EINVAL;
+	}
+
+	mutex_lock(&d->lock);
+
+	/* Prepare capture measurement */
+	d->index = 0;
+	regmap_write(pc->regmap, PWM_CPT_EDGE(channel), CPT_EDGE_RISING);
+	regmap_field_write(pc->pwm_cpt_int_en, BIT(channel));
+	ret = wait_event_interruptible_timeout(d->wait, d->index > 1, HZ);
+
+	/*
+	 * In case we woke up for another reason than completion
+	 * make sure to disable the capture.
+	 */
+	regmap_write(pc->regmap, PWM_CPT_EDGE(channel), CPT_EDGE_DISABLED);
+
+	if (ret == -ERESTARTSYS)
+		goto out;
+
+	switch (d->index) {
+	case 0:
+	case 1:
+		/*
+		 * Getting here could mean :
+		 *  - input signal is constant of less than 1Hz
+		 *  - there is no input signal at all
+		 *
+		 * In such case the frequency is rounded down to 0
+		 * level of the supposed constant signal is reported
+		 * using duty cycle min and max values.
+		 */
+		level = gpio_get_value(d->gpio);
+
+		ret = sprintf(buf, "0:%u\n", level ? CPT_DC_MAX : 0);
+		break;
+	case 2:
+		/* We have evertying we need */
+		high = d->snapshot[1] - d->snapshot[0];
+		low  = d->snapshot[2] - d->snapshot[1];
+
+		/* Calculate frequency in Hz */
+		f = clk_get_rate(pc->cpt_clk) / (1 * (high + low));
+
+		/* Calculate the duty cycle */
+		dc = CPT_DC_MAX * high / (high + low);
+
+		ret = sprintf(buf, "%u:%u\n", f, dc);
+	default:
+		dev_err(dev, "Internal error\n");
+	}
+
+out:
+	mutex_unlock(&d->lock);
+	return ret;
+}
+
 static const struct pwm_ops sti_pwm_ops = {
+	.capture = sti_pwm_capture,
 	.config = sti_pwm_config,
 	.enable = sti_pwm_enable,
 	.disable = sti_pwm_disable,
-- 
1.9.1

[PATCH 10/11] pwm: sti: Enable PWM Capture

[Lee Jones]

Once all functionality is in place, we provide the means to
enable PWM Capture.  Here we are simply obtaining the
associated regmap and twiddling the relevant enable register
bits.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/pwm-sti.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 8de9b4a..93cf20e 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -279,6 +279,13 @@ static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 				pwm->hwpwm);
 			goto out;
 		}
+
+		ret = regmap_field_write(pc->pwm_cpt_en, 1);
+		if (ret) {
+			dev_err(dev, "failed to enable PWM capture:%d\n",
+				pwm->hwpwm);
+			goto out;
+		}
 	}
 	pc->en_count++;
 out:
@@ -296,6 +303,7 @@ static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 		return;
 	}
 	regmap_field_write(pc->pwm_out_en, 0);
+	regmap_field_write(pc->pwm_cpt_en, 0);
 
 	clk_disable(pc->pwm_clk);
 	clk_disable(pc->cpt_clk);
@@ -492,6 +500,11 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 	if (IS_ERR(pc->pwm_out_en))
 		return PTR_ERR(pc->pwm_out_en);
 
+	pc->pwm_cpt_en = devm_regmap_field_alloc(dev, pc->regmap,
+						 reg_fields[PWM_CPT_EN]);
+	if (IS_ERR(pc->pwm_cpt_en))
+		return PTR_ERR(pc->pwm_cpt_en);
+
 	pc->pwm_cpt_int_en = devm_regmap_field_alloc(dev, pc->regmap,
 						 reg_fields[PWM_CPT_INT_EN]);
 	if (IS_ERR(pc->pwm_cpt_int_en))
-- 
1.9.1

[PATCH 11/11] pwm: sti: Take the opportunity to conduct a little house keeping

[Lee Jones]

This includes fixing some Coding Style issues and re-ordering/
simplifying a little code.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/pwm-sti.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 93cf20e..93e3abf 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -144,13 +144,13 @@ static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
 	val = NSEC_PER_SEC / clk_rate;
 	val *= cdata->max_pwm_cnt + 1;
 
-	if (period % val) {
+	if (period % val)
 		return -EINVAL;
-	} else {
-		ps  = period / val - 1;
-		if (ps > cdata->max_prescale)
-			return -EINVAL;
-	}
+
+	ps  = period / val - 1;
+	if (ps > cdata->max_prescale)
+		return -EINVAL;
+
 	*prescale = ps;
 
 	return 0;
@@ -166,7 +166,7 @@ static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
  * 256 values.
  */
 static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
-			 int duty_ns, int period_ns)
+			int duty_ns, int period_ns)
 {
 	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 	struct sti_pwm_compat_data *cdata = pc->cdata;
@@ -212,7 +212,7 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 			ret =
 			regmap_field_write(pc->prescale_low,
-					   prescale & PWM_PRESCALE_LOW_MASK);
+				prescale & PWM_PRESCALE_LOW_MASK);
 			if (ret)
 				goto clk_dis;
 
@@ -506,7 +506,7 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 		return PTR_ERR(pc->pwm_cpt_en);
 
 	pc->pwm_cpt_int_en = devm_regmap_field_alloc(dev, pc->regmap,
-						 reg_fields[PWM_CPT_INT_EN]);
+						reg_fields[PWM_CPT_INT_EN]);
 	if (IS_ERR(pc->pwm_cpt_int_en))
 		return PTR_ERR(pc->pwm_cpt_int_en);
 
@@ -570,10 +570,11 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	 * Setup PWM data with default values: some values could be replaced
 	 * with specific ones provided from Device Tree.
 	 */
-	cdata->reg_fields   = &sti_pwm_regfields[0];
-	cdata->max_prescale = 0xff;
-	cdata->max_pwm_cnt  = 255;
-	cdata->pwm_num_chan     = 1;
+
+	cdata->reg_fields	= &sti_pwm_regfields[0];
+	cdata->max_prescale	= 0xff;
+	cdata->max_pwm_cnt	= 255;
+	cdata->pwm_num_chan	= 1;
 	cdata->cpt_num_chan	= 0;
 
 	pc->cdata = cdata;
-- 
1.9.1