[PATCH v2 5/5] iio: 104-quad-8: Add IIO generic counter interface support

[William Breathitt Gray]

This patch adds support for the IIO generic counter interface to the
104-QUAD-8 driver. The existing 104-QUAD-8 device interface should not
be affected by this patch; all changes are intended as supplemental
additions as perceived by the user.

IIO Counter Signals are defined for all quadrature input pairs
(A and B), as well as index input lines. However, IIO Counter Triggers
are not created for the index input Signals. IIO Counter Values are
created for the eight quadrature channel counts, and their respective
Signals are associated via IIO Counter Triggers.

The new generic counter interface sysfs attributes expose the same
functionality and data available via the existing 104-QUAD-8 device
interface. Four IIO Counter Value function modes are available,
correlating to the four possible quadrature mode configurations:
"non-quadrature," "quadrature x1," "quadrature x2," and "quadrature x4."

A quad8_remove function is defined to call iio_counter_unregister. This
function can be eliminated once a devm_iio_counter_register function is
defined.

Signed-off-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
---
 drivers/iio/counter/104-quad-8.c | 306 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 289 insertions(+), 17 deletions(-)

diff --git a/drivers/iio/counter/104-quad-8.c b/drivers/iio/counter/104-quad-8.c
index b56985078d8c..625b49fe91cf 100644
--- a/drivers/iio/counter/104-quad-8.c
+++ b/drivers/iio/counter/104-quad-8.c
@@ -16,6 +16,7 @@
 #include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/errno.h>
+#include <linux/iio/counter.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/types.h>
 #include <linux/io.h>
@@ -24,6 +25,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/string.h>
 #include <linux/types.h>
 
 #define QUAD8_EXTENT 32
@@ -37,6 +39,7 @@ MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
 
 /**
  * struct quad8_iio - IIO device private data structure
+ * @counter:		instance of the iio_counter
  * @preset:		array of preset values
  * @count_mode:		array of count mode configurations
  * @quadrature_mode:	array of quadrature mode configurations
@@ -48,6 +51,7 @@ MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
  * @base:		base port address of the IIO device
  */
 struct quad8_iio {
+	struct iio_counter counter;
 	unsigned int preset[QUAD8_NUM_COUNTERS];
 	unsigned int count_mode[QUAD8_NUM_COUNTERS];
 	unsigned int quadrature_mode[QUAD8_NUM_COUNTERS];
@@ -527,33 +531,289 @@ static const struct iio_chan_spec quad8_channels[] = {
 	QUAD8_COUNT_CHAN(7), QUAD8_INDEX_CHAN(7)
 };
 
+static int quad8_signal_read(struct iio_counter *counter,
+	struct iio_counter_signal *signal, int *val, int *val2)
+{
+	struct quad8_iio *const priv = counter->driver_data;
+
+	if (signal->id < 16)
+		return -EINVAL;
+
+	*val = !!(inb(priv->base + 0x16) & BIT(signal->id - 16));
+
+	return IIO_VAL_INT;
+}
+
+static int quad8_trigger_mode_get(struct iio_counter *counter,
+	struct iio_counter_value *value, struct iio_counter_trigger *trigger)
+{
+	struct quad8_iio *const priv = counter->driver_data;
+	const unsigned int mode = priv->quadrature_mode[value->id];
+	const unsigned int scale = priv->quadrature_scale[value->id];
+	unsigned int direction;
+	const unsigned int flag_addr = priv->base + 2 * value->id + 1;
+	const int signal_id = trigger->signal->id % 2;
+
+	if (mode)
+		switch (scale) {
+		case 0:
+			/* U/D flag: 1 = up, 0 = down */
+			/* direction: 0 = up, 1 = down */
+			direction = !(inb(flag_addr) & BIT(5));
+			if (!signal_id)
+				return direction + 1;
+			break;
+		case 1:
+			if (!signal_id)
+				return 3;
+			break;
+		case 2:
+			return 3;
+		}
+	else
+		if (!signal_id)
+			return 1;
+
+	return 0;
+}
+
+static int quad8_value_read(struct iio_counter *counter,
+	struct iio_counter_value *value, int *val, int *val2)
+{
+	struct quad8_iio *const priv = counter->driver_data;
+	const int base_offset = priv->base + 2 * value->id;
+	unsigned int flags;
+	unsigned int borrow;
+	unsigned int carry;
+	int i;
+
+	flags = inb(base_offset + 1);
+	borrow = flags & BIT(0);
+	carry = !!(flags & BIT(1));
+
+	/* Borrow XOR Carry effectively doubles count range */
+	*val = (borrow ^ carry) << 24;
+
+	/* Reset Byte Pointer; transfer Counter to Output Latch */
+	outb(0x11, base_offset + 1);
+
+	for (i = 0; i < 3; i++)
+		*val |= (unsigned int)inb(base_offset) << (8 * i);
+
+	return IIO_VAL_INT;
+}
+
+static int quad8_value_write(struct iio_counter *counter,
+	struct iio_counter_value *value, int val, int val2)
+{
+	struct quad8_iio *const priv = counter->driver_data;
+	const int base_offset = priv->base + 2 * value->id;
+	int i;
+
+	/* Only 24-bit values are supported */
+	if ((unsigned int)val > 0xFFFFFF)
+		return -EINVAL;
+
+	/* Reset Byte Pointer */
+	outb(0x01, base_offset + 1);
+
+	/* Counter can only be set via Preset Register */
+	for (i = 0; i < 3; i++)
+		outb(val >> (8 * i), base_offset);
+
+	/* Transfer Preset Register to Counter */
+	outb(0x08, base_offset + 1);
+
+	/* Reset Byte Pointer */
+	outb(0x01, base_offset + 1);
+
+	/* Set Preset Register back to original value */
+	val = priv->preset[value->id];
+	for (i = 0; i < 3; i++)
+		outb(val >> (8 * i), base_offset);
+
+	/* Reset Borrow, Carry, Compare, and Sign flags */
+	outb(0x02, base_offset + 1);
+	/* Reset Error flag */
+	outb(0x06, base_offset + 1);
+
+	return 0;
+}
+
+static int quad8_value_function_set(struct iio_counter *counter,
+	struct iio_counter_value *value, unsigned int mode)
+{
+	struct quad8_iio *const priv = counter->driver_data;
+	const unsigned int mode_cfg = mode << 3 |
+		priv->count_mode[value->id] << 1;
+	const unsigned int idr_cfg = priv->index_polarity[value->id] << 1;
+	const int base_offset = priv->base + 2 * value->id + 1;
+
+	if (mode)
+		priv->quadrature_scale[value->id] = mode - 1;
+	else {
+		/* Quadrature scaling only available in quadrature mode */
+		priv->quadrature_scale[value->id] = 0;
+
+		/* Synchronous function not supported in non-quadrature mode */
+		if (priv->synchronous_mode[value->id]) {
+			priv->synchronous_mode[value->id] = 0;
+			outb(0x60 | idr_cfg, base_offset);
+		}
+	}
+
+	priv->quadrature_mode[value->id] = !!mode;
+
+	/* Load mode configuration to Counter Mode Register */
+	outb(0x20 | mode_cfg, base_offset);
+
+	return 0;
+}
+
+static int quad8_value_function_get(struct iio_counter *counter,
+	struct iio_counter_value *value)
+{
+	struct quad8_iio *const priv = counter->driver_data;
+	unsigned int quadrature_mode = priv->quadrature_mode[value->id];
+
+	return (quadrature_mode) ? priv->quadrature_scale[value->id] + 1 : 0;
+}
+
+static const struct iio_counter_ops quad8_ops = {
+	.signal_read = quad8_signal_read,
+	.trigger_mode_get = quad8_trigger_mode_get,
+	.value_read = quad8_value_read,
+	.value_write = quad8_value_write,
+	.value_function_set = quad8_value_function_set,
+	.value_function_get = quad8_value_function_get
+};
+
+static const char *const quad8_function_modes[] = {
+	"non-quadrature",
+	"quadrature x1",
+	"quadrature x2",
+	"quadrature x4"
+};
+
+#define QUAD8_SIGNAL(_id, _name) {	\
+	.id = _id,			\
+	.name = _name			\
+}
+
+static const struct iio_counter_signal quad8_signals[] = {
+	QUAD8_SIGNAL(0, "Channel 1 Quadrature A"),
+	QUAD8_SIGNAL(1, "Channel 1 Quadrature B"),
+	QUAD8_SIGNAL(2, "Channel 2 Quadrature A"),
+	QUAD8_SIGNAL(3, "Channel 2 Quadrature B"),
+	QUAD8_SIGNAL(4, "Channel 3 Quadrature A"),
+	QUAD8_SIGNAL(5, "Channel 3 Quadrature B"),
+	QUAD8_SIGNAL(6, "Channel 4 Quadrature A"),
+	QUAD8_SIGNAL(7, "Channel 4 Quadrature B"),
+	QUAD8_SIGNAL(8, "Channel 5 Quadrature A"),
+	QUAD8_SIGNAL(9, "Channel 5 Quadrature B"),
+	QUAD8_SIGNAL(10, "Channel 6 Quadrature A"),
+	QUAD8_SIGNAL(11, "Channel 6 Quadrature B"),
+	QUAD8_SIGNAL(12, "Channel 7 Quadrature A"),
+	QUAD8_SIGNAL(13, "Channel 7 Quadrature B"),
+	QUAD8_SIGNAL(14, "Channel 8 Quadrature A"),
+	QUAD8_SIGNAL(15, "Channel 8 Quadrature B"),
+	QUAD8_SIGNAL(16, "Channel 1 Index"),
+	QUAD8_SIGNAL(17, "Channel 2 Index"),
+	QUAD8_SIGNAL(18, "Channel 3 Index"),
+	QUAD8_SIGNAL(19, "Channel 4 Index"),
+	QUAD8_SIGNAL(20, "Channel 5 Index"),
+	QUAD8_SIGNAL(21, "Channel 6 Index"),
+	QUAD8_SIGNAL(22, "Channel 7 Index"),
+	QUAD8_SIGNAL(23, "Channel 8 Index")
+};
+
+#define QUAD8_VALUE(_id, _name) {					\
+	.id = _id,							\
+	.name = _name,							\
+	.mode = 0,							\
+	.function_modes = quad8_function_modes,				\
+	.num_function_modes = ARRAY_SIZE(quad8_function_modes)		\
+}
+
+static const struct iio_counter_value quad8_values[] = {
+	QUAD8_VALUE(0, "Channel 1 Count"), QUAD8_VALUE(1, "Channel 2 Count"),
+	QUAD8_VALUE(2, "Channel 3 Count"), QUAD8_VALUE(3, "Channel 4 Count"),
+	QUAD8_VALUE(4, "Channel 5 Count"), QUAD8_VALUE(5, "Channel 6 Count"),
+	QUAD8_VALUE(6, "Channel 7 Count"), QUAD8_VALUE(7, "Channel 8 Count")
+};
+
+static const char *const quad8_trigger_modes[] = {
+	"none",
+	"rising edge",
+	"falling edge",
+	"both edges"
+};
+
 static int quad8_probe(struct device *dev, unsigned int id)
 {
-	struct iio_dev *indio_dev;
-	struct quad8_iio *priv;
+	struct iio_counter_signal *init_signals;
+	const size_t num_init_signals = ARRAY_SIZE(quad8_signals);
+	struct iio_counter_value *init_values;
+	const size_t num_init_values = ARRAY_SIZE(quad8_values);
+	struct iio_counter_trigger *triggers;
+	struct quad8_iio *quad8iio;
 	int i, j;
 	unsigned int base_offset;
 
-	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
-	if (!indio_dev)
-		return -ENOMEM;
-
-	if (!devm_request_region(dev, base[id], QUAD8_EXTENT,
-		dev_name(dev))) {
+	if (!devm_request_region(dev, base[id], QUAD8_EXTENT, dev_name(dev))) {
 		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
 			base[id], base[id] + QUAD8_EXTENT);
 		return -EBUSY;
 	}
 
-	indio_dev->info = &quad8_info;
-	indio_dev->modes = INDIO_DIRECT_MODE;
-	indio_dev->num_channels = ARRAY_SIZE(quad8_channels);
-	indio_dev->channels = quad8_channels;
-	indio_dev->name = dev_name(dev);
-	indio_dev->dev.parent = dev;
+	init_signals = devm_kmalloc(dev, sizeof(quad8_signals), GFP_KERNEL);
+	if (!init_signals)
+		return -ENOMEM;
+
+	memcpy(init_signals, quad8_signals, sizeof(quad8_signals));
+
+	init_values = devm_kmalloc(dev, sizeof(quad8_values), GFP_KERNEL);
+	if (!init_values)
+		return -ENOMEM;
+
+	memcpy(init_values, quad8_values, sizeof(quad8_values));
+
+	/* Associate values with their respective signals */
+	for (i = 0; i < num_init_values; i++) {
+		triggers = devm_kmalloc(dev, 2 * sizeof(*triggers), GFP_KERNEL);
+		if (!triggers)
+			return -ENOMEM;
+
+		/* Starts up in non-quadrature mode */
+		triggers[0].mode = 1;
+		triggers[0].trigger_modes = quad8_trigger_modes;
+		triggers[0].num_trigger_modes = ARRAY_SIZE(quad8_trigger_modes);
+		triggers[0].signal = &init_signals[2 * i];
+		triggers[1].mode = 0;
+		triggers[1].trigger_modes = quad8_trigger_modes;
+		triggers[1].num_trigger_modes = ARRAY_SIZE(quad8_trigger_modes);
+		triggers[1].signal = &init_signals[2 * i + 1];
+
+		init_values[i].init_triggers = triggers;
+		init_values[i].num_init_triggers = 2;
+	}
+
+	quad8iio = devm_kzalloc(dev, sizeof(*quad8iio), GFP_KERNEL);
+	if (!quad8iio)
+		return -ENOMEM;
 
-	priv = iio_priv(indio_dev);
-	priv->base = base[id];
+	quad8iio->counter.name = dev_name(dev);
+	quad8iio->counter.dev = dev;
+	quad8iio->counter.ops = &quad8_ops;
+	quad8iio->counter.init_signals = init_signals;
+	quad8iio->counter.num_init_signals = num_init_signals;
+	quad8iio->counter.init_values = init_values;
+	quad8iio->counter.num_init_values = num_init_values;
+	quad8iio->counter.channels = quad8_channels;
+	quad8iio->counter.num_channels = ARRAY_SIZE(quad8_channels);
+	quad8iio->counter.info = &quad8_info;
+	quad8iio->counter.driver_data = quad8iio;
+	quad8iio->base = base[id];
 
 	/* Reset all counters and disable interrupt function */
 	outb(0x01, base[id] + 0x11);
@@ -579,11 +839,23 @@ static int quad8_probe(struct device *dev, unsigned int id)
 	/* Enable all counters */
 	outb(0x00, base[id] + 0x11);
 
-	return devm_iio_device_register(dev, indio_dev);
+	dev_set_drvdata(dev, &quad8iio->counter);
+
+	return iio_counter_register(&quad8iio->counter);
+}
+
+static int quad8_remove(struct device *dev, unsigned int id)
+{
+	struct iio_counter *counter = dev_get_drvdata(dev);
+
+	iio_counter_unregister(counter);
+
+	return 0;
 }
 
 static struct isa_driver quad8_driver = {
 	.probe = quad8_probe,
+	.remove = quad8_remove,
 	.driver = {
 		.name = "104-quad-8"
 	}
-- 
2.14.1