iio: stm32 trigger: Add support for TRGO2 triggers

Add support for TRGO2 trigger that can be found on STM32F7.
Add additional master modes supported by TRGO2.
Register additional "tim[1/8]_trgo2" triggers for timer1 & timer8.
Detect TRGO2 timer capability (master mode selection 2).

Signed-off-by: Fabrice Gasnier <[e-mail]>
Acked-by: Benjamin Gaignard <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

Documentation/ABI/testing/sysfs-bus-iio-timer-stm32

···
 		- "OC2REF"    : OC2REF signal is used as trigger output.
 		- "OC3REF"    : OC3REF signal is used as trigger output.
 		- "OC4REF"    : OC4REF signal is used as trigger output.
+		Additional modes (on TRGO2 only):
+		- "OC5REF"    : OC5REF signal is used as trigger output.
+		- "OC6REF"    : OC6REF signal is used as trigger output.
+		- "compare_pulse_OC4REF":
+		  OC4REF rising or falling edges generate pulses.
+		- "compare_pulse_OC6REF":
+		  OC6REF rising or falling edges generate pulses.
+		- "compare_pulse_OC4REF_r_or_OC6REF_r":
+		  OC4REF or OC6REF rising edges generate pulses.
+		- "compare_pulse_OC4REF_r_or_OC6REF_f":
+		  OC4REF rising or OC6REF falling edges generate pulses.
+		- "compare_pulse_OC5REF_r_or_OC6REF_r":
+		  OC5REF or OC6REF rising edges generate pulses.
+		- "compare_pulse_OC5REF_r_or_OC6REF_f":
+		  OC5REF rising or OC6REF falling edges generate pulses.
+
+		+-----------+   +-------------+            +---------+
+		| Prescaler +-> | Counter     |        +-> | Master  | TRGO(2)
+		+-----------+   +--+--------+-+        |-> | Control +-->
+		                   |        |          ||  +---------+
+		                +--v--------+-+ OCxREF ||  +---------+
+		                | Chx compare +----------> | Output  | ChX
+		                +-----------+-+         |  | Control +-->
+		                      .     |           |  +---------+
+		                      .     |           |    .
+		                +-----------v-+ OC6REF  |    .
+		                | Ch6 compare +---------+>
+		                +-------------+
+
+		Example with: "compare_pulse_OC4REF_r_or_OC6REF_r":
+
+		                X
+		              X   X
+		            X .   . X
+		          X   .   .   X
+		        X     .   .     X
+		count X .     .   .     . X
+		        .     .   .     .
+		        .     .   .     .
+		        +---------------+
+		OC4REF  |     .   .     |
+		      +-+     .   .     +-+
+		        .     +---+     .
+		OC6REF  .     |   |     .
+		      +-------+   +-------+
+		        +-+   +-+
+		TRGO2   | |   | |
+		      +-+ +---+ +---------+
 
 What:		/sys/bus/iio/devices/triggerX/master_mode
 KernelVersion:	4.11

drivers/iio/trigger/stm32-timer-trigger.c

···
 #include <linux/module.h>
 #include <linux/platform_device.h>
 
-#define MAX_TRIGGERS 6
+#define MAX_TRIGGERS 7
 #define MAX_VALIDS 5
 
 /* List the triggers created by each timer */
 static const void *triggers_table[][MAX_TRIGGERS] = {
-	{ TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
+	{ TIM1_TRGO, TIM1_TRGO2, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
 	{ TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4,},
 	{ TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4,},
 	{ TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4,},
 	{ TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4,},
 	{ TIM6_TRGO,},
 	{ TIM7_TRGO,},
-	{ TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
+	{ TIM8_TRGO, TIM8_TRGO2, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
 	{ TIM9_TRGO, TIM9_CH1, TIM9_CH2,},
 	{ }, /* timer 10 */
 	{ }, /* timer 11 */
···
 	u32 max_arr;
 	const void *triggers;
 	const void *valids;
+	bool has_trgo2;
 };
 
+static bool stm32_timer_is_trgo2_name(const char *name)
+{
+	return !!strstr(name, "trgo2");
+}
+
 static int stm32_timer_start(struct stm32_timer_trigger *priv,
+			     struct iio_trigger *trig,
 			     unsigned int frequency)
 {
 	unsigned long long prd, div;
···
 	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
 
 	/* Force master mode to update mode */
-	regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS, 0x20);
+	if (stm32_timer_is_trgo2_name(trig->name))
+		regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS2,
+				   0x2 << TIM_CR2_MMS2_SHIFT);
+	else
+		regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS,
+				   0x2 << TIM_CR2_MMS_SHIFT);
 
 	/* Make sure that registers are updated */
 	regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
···
 	if (freq == 0) {
 		stm32_timer_stop(priv);
 	} else {
-		ret = stm32_timer_start(priv, freq);
+		ret = stm32_timer_start(priv, trig, freq);
 		if (ret)
 			return ret;
 	}
···
 			      stm32_tt_read_frequency,
 			      stm32_tt_store_frequency);
 
+#define MASTER_MODE_MAX		7
+#define MASTER_MODE2_MAX	15
+
 static char *master_mode_table[] = {
 	"reset",
 	"enable",
···
 	"OC1REF",
 	"OC2REF",
 	"OC3REF",
-	"OC4REF"
+	"OC4REF",
+	/* Master mode selection 2 only */
+	"OC5REF",
+	"OC6REF",
+	"compare_pulse_OC4REF",
+	"compare_pulse_OC6REF",
+	"compare_pulse_OC4REF_r_or_OC6REF_r",
+	"compare_pulse_OC4REF_r_or_OC6REF_f",
+	"compare_pulse_OC5REF_r_or_OC6REF_r",
+	"compare_pulse_OC5REF_r_or_OC6REF_f",
 };
 
 static ssize_t stm32_tt_show_master_mode(struct device *dev,
···
 					 char *buf)
 {
 	struct stm32_timer_trigger *priv = dev_get_drvdata(dev);
+	struct iio_trigger *trig = to_iio_trigger(dev);
 	u32 cr2;
 
 	regmap_read(priv->regmap, TIM_CR2, &cr2);
-	cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
+
+	if (stm32_timer_is_trgo2_name(trig->name))
+		cr2 = (cr2 & TIM_CR2_MMS2) >> TIM_CR2_MMS2_SHIFT;
+	else
+		cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
 
 	return snprintf(buf, PAGE_SIZE, "%s\n", master_mode_table[cr2]);
 }
···
 					  const char *buf, size_t len)
 {
 	struct stm32_timer_trigger *priv = dev_get_drvdata(dev);
+	struct iio_trigger *trig = to_iio_trigger(dev);
+	u32 mask, shift, master_mode_max;
 	int i;
 
-	for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
+	if (stm32_timer_is_trgo2_name(trig->name)) {
+		mask = TIM_CR2_MMS2;
+		shift = TIM_CR2_MMS2_SHIFT;
+		master_mode_max = MASTER_MODE2_MAX;
+	} else {
+		mask = TIM_CR2_MMS;
+		shift = TIM_CR2_MMS_SHIFT;
+		master_mode_max = MASTER_MODE_MAX;
+	}
+
+	for (i = 0; i <= master_mode_max; i++) {
 		if (!strncmp(master_mode_table[i], buf,
 			     strlen(master_mode_table[i]))) {
-			regmap_update_bits(priv->regmap, TIM_CR2,
-					   TIM_CR2_MMS, i << TIM_CR2_MMS_SHIFT);
+			regmap_update_bits(priv->regmap, TIM_CR2, mask,
+					   i << shift);
 			/* Make sure that registers are updated */
 			regmap_update_bits(priv->regmap, TIM_EGR,
 					   TIM_EGR_UG, TIM_EGR_UG);
···
 	return -EINVAL;
 }
 
-static IIO_CONST_ATTR(master_mode_available,
-	"reset enable update compare_pulse OC1REF OC2REF OC3REF OC4REF");
+static ssize_t stm32_tt_show_master_mode_avail(struct device *dev,
+					       struct device_attribute *attr,
+					       char *buf)
+{
+	struct iio_trigger *trig = to_iio_trigger(dev);
+	unsigned int i, master_mode_max;
+	size_t len = 0;
+
+	if (stm32_timer_is_trgo2_name(trig->name))
+		master_mode_max = MASTER_MODE2_MAX;
+	else
+		master_mode_max = MASTER_MODE_MAX;
+
+	for (i = 0; i <= master_mode_max; i++)
+		len += scnprintf(buf + len, PAGE_SIZE - len,
+			"%s ", master_mode_table[i]);
+
+	/* replace trailing space by newline */
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static IIO_DEVICE_ATTR(master_mode_available, 0444,
+		       stm32_tt_show_master_mode_avail, NULL, 0);
 
 static IIO_DEVICE_ATTR(master_mode, 0660,
 		       stm32_tt_show_master_mode,
···
 static struct attribute *stm32_trigger_attrs[] = {
 	&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,
+	&iio_dev_attr_master_mode_available.dev_attr.attr,
 	NULL,
 };
 
···
 
 	while (cur && *cur) {
 		struct iio_trigger *trig;
+		bool cur_is_trgo2 = stm32_timer_is_trgo2_name(*cur);
+
+		if (cur_is_trgo2 && !priv->has_trgo2) {
+			cur++;
+			continue;
+		}
 
 		trig = devm_iio_trigger_alloc(priv->dev, "%s", *cur);
 		if  (!trig)
···
 		 * should only be available on trgo trigger which
 		 * is always the first in the list.
 		 */
-		if (cur == priv->triggers)
+		if (cur == priv->triggers || cur_is_trgo2)
 			trig->dev.groups = stm32_trigger_attr_groups;
 
 		iio_trigger_set_drvdata(trig, priv);
···
 }
 EXPORT_SYMBOL(is_stm32_timer_trigger);
 
+static void stm32_timer_detect_trgo2(struct stm32_timer_trigger *priv)
+{
+	u32 val;
+
+	/*
+	 * Master mode selection 2 bits can only be written and read back when
+	 * timer supports it.
+	 */
+	regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS2, TIM_CR2_MMS2);
+	regmap_read(priv->regmap, TIM_CR2, &val);
+	regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS2, 0);
+	priv->has_trgo2 = !!val;
+}
+
 static int stm32_timer_trigger_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
···
 	priv->max_arr = ddata->max_arr;
 	priv->triggers = triggers_table[index];
 	priv->valids = valids_table[index];
+	stm32_timer_detect_trgo2(priv);
 
 	ret = stm32_setup_iio_triggers(priv);
 	if (ret)

include/linux/iio/timer/stm32-timer-trigger.h

···
 #define _STM32_TIMER_TRIGGER_H_
 
 #define TIM1_TRGO	"tim1_trgo"
+#define TIM1_TRGO2	"tim1_trgo2"
 #define TIM1_CH1	"tim1_ch1"
 #define TIM1_CH2	"tim1_ch2"
 #define TIM1_CH3	"tim1_ch3"
···
 #define TIM7_TRGO	"tim7_trgo"
 
 #define TIM8_TRGO	"tim8_trgo"
+#define TIM8_TRGO2	"tim8_trgo2"
 #define TIM8_CH1	"tim8_ch1"
 #define TIM8_CH2	"tim8_ch2"
 #define TIM8_CH3	"tim8_ch3"

include/linux/mfd/stm32-timers.h

···
 #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_CR2_MMS2	GENMASK(23, 20) /* Master mode selection 2 */
 #define TIM_SMCR_SMS	(BIT(0) | BIT(1) | BIT(2)) /* Slave mode selection */
 #define TIM_SMCR_TS	(BIT(4) | BIT(5) | BIT(6)) /* Trigger selection */
 #define TIM_DIER_UIE	BIT(0)	/* Update interrupt	   */
···
 
 #define MAX_TIM_PSC		0xFFFF
 #define TIM_CR2_MMS_SHIFT	4
+#define TIM_CR2_MMS2_SHIFT	20
 #define TIM_SMCR_TS_SHIFT	4
 #define TIM_BDTR_BKF_MASK	0xF
 #define TIM_BDTR_BKF_SHIFT	16