Date:   Fri, 24 Feb 2017 15:48:15 +0100
From:   Benjamin Gaignard <benjamin.gaignard@...aro.org>
To:     linux-kernel@...r.kernel.org, jic23@...nel.org,
        linux-iio@...r.kernel.org, knaack.h@....de, lars@...afoo.de,
        pmeerw@...erw.net
Cc:     fabrice.gasnier@...com, linaro-kernel@...ts.linaro.org,
        benjamin.gaignard@...aro.org,
        Benjamin Gaignard <benjamin.gaignard@...com>
Subject: [PATCH v3 2/2] iio: stm32 trigger: Implement parent trigger feature

Add validate_trigger function in iio_trigger_ops and
dev_attr_parent_trigger into trigger attribute group to be able
to accept triggers as parents.

Introduce an IIO device with one IIO_COUNT channel to get access
to counter value. Counter directions can be set/get when writing/reading
/sys/bus/iio/devices/iio:deviceX/in_count0_count_direction.

The hardware have multiple way to use inputs edges and levels to
performing counting, those different modes are exposed in:
/sys/bus/iio/devices/iio:deviceX/in_count_count_mode_available.

"trigger_rising_edges" mode is automatically set when a valid
parent trigger is set.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>

version 2:
- use dev_attr_parent_trigger
- improve slave modes documentation

version 3:
- add one channel to get counter raw value
---
 .../ABI/testing/sysfs-bus-iio-timer-stm32          |  63 +++++
 drivers/iio/trigger/stm32-timer-trigger.c          | 256 ++++++++++++++++++++-
 include/linux/mfd/stm32-timers.h                   |   2 +
 3 files changed, 315 insertions(+), 6 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
index 6534a60..63852a9 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
+++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
@@ -27,3 +27,66 @@ Description:
 		Reading returns the current sampling frequency.
 		Writing an value different of 0 set and start sampling.
 		Writing 0 stop sampling.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_count0_raw
+KernelVersion:	4.12
+Contact:	benjamin.gaignard@...com
+Description:
+		Reading returns counter current value.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_count_count_direction_available
+KernelVersion:	4.12
+Contact:	benjamin.gaignard@...com
+Description:
+		Reading returns the list of possible counting directions which
+		are:
+		- "up"	: counter is increasing.
+		- "down": counter is decreasing.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_count0_count_direction
+KernelVersion:	4.12
+Contact:	benjamin.gaignard@...com
+Description:
+		Reading returns the counting directions:
+		- "up"	: counter is increasing.
+		- "down": counter is decreasing.
+		Writing set the counting direction.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_count_count_mode_available
+KernelVersion:	4.12
+Contact:	benjamin.gaignard@...com
+Description:
+		Reading returns the list of possible counting modes which are:
+		- "internal_clock": Counter is clocked by the internal clock rising edges.
+		- "encoder_1" : Counter counts up/down on channel 2 edge depending on channel 1 level.
+		- "encoder_2" : Counter counts up/down on channel 1 edge depending on channel 2 level.
+		- "encoder_3" : Counter counts up/down on channels 1 & 2 edge depending on channel 1 & 2 level.
+		- "reset"     : Rising edges on parent trigger reinitializes the counter value to preset value.
+		- "gated"     : Counter counts when the parent trigger input is high.
+				Counter stops (but is not reset) as soon as the parent trigger becomes low.
+		- "trigger"   : Counter starts at a rising edge of the parent trigger (but it is not reset).
+		- "trigger_rising_edges": Rising edges of the parent trigger are used as clock by the counter.
+
+		Encoder modes are used to automatically handle the counting direction of the internal counter.
+		Those modes are typically used for high-accuracy rotor position sensing in electrical motors
+		or for digital potentiometers. From the two outputs of a quadrature encoder sensor the timer
+		extracts a clock on each and every active edge and adjusts the counting direction depending on
+		the relative phase-shift between the two incomings signals. The timer counter thus directly
+		holds the angular position of the motor.
+
+		"trigger_rising_edges" mode is automatically set when a valid parent trigger is set.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_count0_count_mode
+KernelVersion:	4.12
+Contact:	benjamin.gaignard@...com
+Description:
+		Reading returns the current counting mode.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_count0_preset
+KernelVersion:	4.12
+Contact:	benjamin.gaignard@...com
+Description:
+		Reading returns the current preset value.
+		Writing set the preset value.
+		When counting up the counter start from 0 and fire an event when reach preset value.
+		When counting down the counter start from preset value and fire event when reach 0.
diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
index 994b96d..04f5f05 100644
--- a/drivers/iio/trigger/stm32-timer-trigger.c
+++ b/drivers/iio/trigger/stm32-timer-trigger.c
@@ -15,6 +15,7 @@
 #include <linux/platform_device.h>
 
 #define MAX_TRIGGERS 6
+#define MAX_VALIDS 5
 
 /* List the triggers created by each timer */
 static const void *triggers_table[][MAX_TRIGGERS] = {
@@ -32,12 +33,29 @@
 	{ TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
 };
 
+/* List the triggers accepted by each timer */
+static const void *valids_table[][MAX_VALIDS] = {
+	{ TIM5_TRGO, TIM2_TRGO, TIM3_TRGO, TIM4_TRGO,},
+	{ TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
+	{ TIM1_TRGO, TIM2_TRGO, TIM5_TRGO, TIM4_TRGO,},
+	{ TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
+	{ TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
+	{ }, /* timer 6 */
+	{ }, /* timer 7 */
+	{ TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
+	{ TIM2_TRGO, TIM3_TRGO,},
+	{ }, /* timer 10 */
+	{ }, /* timer 11 */
+	{ TIM4_TRGO, TIM5_TRGO,},
+};
+
 struct stm32_timer_trigger {
 	struct device *dev;
 	struct regmap *regmap;
 	struct clk *clk;
 	u32 max_arr;
 	const void *triggers;
+	const void *valids;
 };
 
 static int stm32_timer_start(struct stm32_timer_trigger *priv,
@@ -180,8 +198,7 @@ static ssize_t stm32_tt_show_master_mode(struct device *dev,
 					 struct device_attribute *attr,
 					 char *buf)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
-	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	struct stm32_timer_trigger *priv = dev_get_drvdata(dev);
 	u32 cr2;
 
 	regmap_read(priv->regmap, TIM_CR2, &cr2);
@@ -194,10 +211,10 @@ static ssize_t stm32_tt_store_master_mode(struct device *dev,
 					  struct device_attribute *attr,
 					  const char *buf, size_t len)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
-	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	struct stm32_timer_trigger *priv = dev_get_drvdata(dev);
 	int i;
 
+
 	for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
 		if (!strncmp(master_mode_table[i], buf,
 			     strlen(master_mode_table[i]))) {
@@ -225,6 +242,7 @@ static IIO_DEVICE_ATTR(master_mode, 0660,
 	&iio_dev_attr_sampling_frequency.dev_attr.attr,
 	&iio_dev_attr_master_mode.dev_attr.attr,
 	&iio_const_attr_master_mode_available.dev_attr.attr,
+	&dev_attr_parent_trigger.attr,
 	NULL,
 };
 
@@ -237,8 +255,49 @@ static IIO_DEVICE_ATTR(master_mode, 0660,
 	NULL,
 };
 
+static int stm32_validate_trigger(struct iio_trigger *trig,
+				  struct iio_trigger *parent)
+{
+	struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
+	const char * const *cur = priv->valids;
+	unsigned int i = 0;
+
+	if (!parent) {
+		regmap_update_bits(priv->regmap, TIM_SMCR, TIM_SMCR_TS, 0);
+		return 0;
+	}
+
+	if (!is_stm32_timer_trigger(parent))
+		return -EINVAL;
+
+	while (cur && *cur) {
+		if (!strncmp(parent->name, *cur, strlen(parent->name))) {
+			regmap_update_bits(priv->regmap,
+					   TIM_SMCR, TIM_SMCR_TS,
+					   i << TIM_SMCR_TS_SHIFT);
+
+			/*
+			 * By default make parent trigger rising edges
+			 * use as clock for the counter
+			 */
+			regmap_update_bits(priv->regmap, TIM_SMCR,
+					   TIM_SMCR_SMS, TIM_SMCR_SMS);
+
+			/* Enable controller */
+			regmap_update_bits(priv->regmap, TIM_CR1,
+					   TIM_CR1_CEN, TIM_CR1_CEN);
+			return 0;
+		}
+		cur++;
+		i++;
+	}
+
+	return -EINVAL;
+}
+
 static const struct iio_trigger_ops timer_trigger_ops = {
 	.owner = THIS_MODULE,
+	.validate_trigger = stm32_validate_trigger,
 };
 
 static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
@@ -275,6 +334,185 @@ static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
 	return 0;
 }
 
+static int stm32_trigger_read_raw(struct iio_dev *indio_dev,
+				  struct iio_chan_spec const *chan,
+				  int *val, int *val2, long mask)
+{
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+	{
+		u32 cnt;
+
+		regmap_read(priv->regmap, TIM_CNT, &cnt);
+		*val = cnt;
+
+		return IIO_VAL_INT;
+	}
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info stm32_trigger_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = stm32_trigger_read_raw,
+};
+
+static const char *const stm32_count_modes[] = {
+	"internal_clock",
+	"encoder_1",
+	"encoder_2",
+	"encoder_3",
+	"reset",
+	"gated",
+	"trigger",
+	"trigger_rising_edges"
+};
+
+static int stm32_set_count_mode(struct iio_dev *indio_dev,
+				const struct iio_chan_spec *chan,
+				unsigned int mode)
+{
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+
+	regmap_update_bits(priv->regmap, TIM_SMCR, TIM_SMCR_SMS, mode);
+
+	return 0;
+}
+
+static int stm32_get_count_mode(struct iio_dev *indio_dev,
+				const struct iio_chan_spec *chan)
+{
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	u32 smcr;
+
+	regmap_read(priv->regmap, TIM_SMCR, &smcr);
+	smcr &= TIM_SMCR_SMS;
+
+	return smcr;
+}
+
+static const struct iio_enum stm32_count_mode_enum = {
+	.items = stm32_count_modes,
+	.num_items = ARRAY_SIZE(stm32_count_modes),
+	.set = stm32_set_count_mode,
+	.get = stm32_get_count_mode
+};
+
+static const char *const stm32_count_direction_states[] = {
+	"up",
+	"down"
+};
+
+static int stm32_set_count_direction(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     unsigned int mode)
+{
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+
+	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_DIR, mode);
+
+	return 0;
+}
+
+static int stm32_get_count_direction(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan)
+{
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	u32 cr1;
+
+	regmap_read(priv->regmap, TIM_CR1, &cr1);
+
+	return (cr1 & TIM_CR1_DIR);
+}
+
+static const struct iio_enum stm32_count_direction_enum = {
+	.items = stm32_count_direction_states,
+	.num_items = ARRAY_SIZE(stm32_count_direction_states),
+	.set = stm32_set_count_direction,
+	.get = stm32_get_count_direction
+};
+
+static ssize_t stm32_count_get_preset(struct iio_dev *indio_dev,
+				      uintptr_t private,
+				      const struct iio_chan_spec *chan,
+				      char *buf)
+{
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	u32 arr;
+
+	regmap_read(priv->regmap, TIM_ARR, &arr);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", arr);
+}
+
+static ssize_t stm32_count_set_preset(struct iio_dev *indio_dev,
+				      uintptr_t private,
+				      const struct iio_chan_spec *chan,
+				      const char *buf, size_t len)
+{
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	unsigned int preset;
+	int ret;
+
+	ret = kstrtouint(buf, 0, &preset);
+	if (ret)
+		return ret;
+
+	regmap_write(priv->regmap, TIM_ARR, preset);
+	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
+
+	return len;
+}
+
+static const struct iio_chan_spec_ext_info stm32_trigger_count_info[] = {
+	{
+		.name = "preset",
+		.shared = IIO_SEPARATE,
+		.read = stm32_count_get_preset,
+		.write = stm32_count_set_preset
+	},
+	IIO_ENUM("count_direction", IIO_SEPARATE, &stm32_count_direction_enum),
+	IIO_ENUM_AVAILABLE("count_direction", &stm32_count_direction_enum),
+	IIO_ENUM("count_mode", IIO_SEPARATE, &stm32_count_mode_enum),
+	IIO_ENUM_AVAILABLE("count_mode", &stm32_count_mode_enum),
+	{}
+};
+
+static const struct iio_chan_spec stm32_trigger_channel = {
+	.type = IIO_COUNT,
+	.channel = 0,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	.ext_info = stm32_trigger_count_info,
+	.indexed = 1
+};
+
+static struct stm32_timer_trigger *stm32_setup_iio_device(struct device *dev)
+{
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev,
+					  sizeof(struct stm32_timer_trigger));
+	if (!indio_dev)
+		return NULL;
+
+	indio_dev->name = dev_name(dev);
+	indio_dev->dev.parent = dev;
+	indio_dev->info = &stm32_trigger_info;
+	indio_dev->num_channels = 1;
+	indio_dev->channels = &stm32_trigger_channel;
+	indio_dev->dev.of_node = dev->of_node;
+
+	ret = devm_iio_device_register(dev, indio_dev);
+	if (ret)
+		return NULL;
+
+	return iio_priv(indio_dev);
+}
+
 /**
  * is_stm32_timer_trigger
  * @trig: trigger to be checked
@@ -299,10 +537,15 @@ static int stm32_timer_trigger_probe(struct platform_device *pdev)
 	if (of_property_read_u32(dev->of_node, "reg", &index))
 		return -EINVAL;
 
-	if (index >= ARRAY_SIZE(triggers_table))
+	if (index >= ARRAY_SIZE(triggers_table)
+	    || index >= ARRAY_SIZE(valids_table))
 		return -EINVAL;
 
-	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	/* Create an IIO device only if we have triggers to be validated */
+	if (*valids_table[index])
+		priv = stm32_setup_iio_device(dev);
+	else
+		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 
 	if (!priv)
 		return -ENOMEM;
@@ -312,6 +555,7 @@ static int stm32_timer_trigger_probe(struct platform_device *pdev)
 	priv->clk = ddata->clk;
 	priv->max_arr = ddata->max_arr;
 	priv->triggers = triggers_table[index];
+	priv->valids = valids_table[index];
 
 	ret = stm32_setup_iio_triggers(priv);
 	if (ret)
diff --git a/include/linux/mfd/stm32-timers.h b/include/linux/mfd/stm32-timers.h
index d030004..4a0abbc 100644
--- a/include/linux/mfd/stm32-timers.h
+++ b/include/linux/mfd/stm32-timers.h
@@ -21,6 +21,7 @@
 #define TIM_CCMR1	0x18	/* Capt/Comp 1 Mode Reg    */
 #define TIM_CCMR2	0x1C	/* Capt/Comp 2 Mode Reg    */
 #define TIM_CCER	0x20	/* Capt/Comp Enable Reg    */
+#define TIM_CNT		0x24	/* Counter		   */
 #define TIM_PSC		0x28	/* Prescaler               */
 #define TIM_ARR		0x2c	/* Auto-Reload Register    */
 #define TIM_CCR1	0x34	/* Capt/Comp Register 1    */
@@ -30,6 +31,7 @@
 #define TIM_BDTR	0x44	/* Break and Dead-Time Reg */
 
 #define TIM_CR1_CEN	BIT(0)	/* Counter Enable	   */
+#define TIM_CR1_DIR	BIT(4)  /* Counter Direction	   */
 #define TIM_CR1_ARPE	BIT(7)	/* Auto-reload Preload Ena */
 #define TIM_CR2_MMS	(BIT(4) | BIT(5) | BIT(6)) /* Master mode selection */
 #define TIM_SMCR_SMS	(BIT(0) | BIT(1) | BIT(2)) /* Slave mode selection */
-- 
1.9.1

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