[PATCH v5 0/2] Add IIO support for counter devices

[PATCH v5 0/2] Add IIO support for counter devices

[William Breathitt Gray]

Changes in v5:
  - Refactored scale to handle values of 1, 0.5, and 0.25, in order to
    be consistent with the multiplication usage of the other interfaces
  - Reimplemented preset as an ext_info since the preset functionality
    is rather device specific
  - Reimplemented ab_enable ext_info as IIO_CHAN_INFO_ENABLE; this
    should make the counter enable/disable interface more intuitive
  - Renamed "preset_enable" attribute to "set_to_preset_on_index" (and
    refactored as a boolean) to make the functionality clearer
  - Updated documentation to account for the changes in this patchset

This patchset adds new IIO channel type constants to facilitate support
for counter devices. In addition, a new "counter" subdirectory is
created to house drivers for these counter devices.

Quadrature encoders, such as rotary encoders and linear encoders, are
devices which are capable of encoding the relative position and
direction of motion of a shaft. This patchset introduces several IIO
constants for supporting quadrature encoder counter devices.

  IIO_COUNT: Current count (main data provided by the counter device)
  IIO_INDEX: Counter device index value

Specifically, this patchset introduces a driver to support the ACCES
104-QUAD-8 device, a general purpose quadrature encoder
counter/interface board capable of monitoring the outputs of eight
encoders.

William Breathitt Gray (2):
  iio: Implement counter channel type and info constants
  iio: 104-quad-8: Add IIO support for the ACCES 104-QUAD-8

 Documentation/ABI/testing/sysfs-bus-iio            |  18 +
 .../ABI/testing/sysfs-bus-iio-counter-104-quad-8   | 125 +++++
 MAINTAINERS                                        |   6 +
 drivers/iio/Kconfig                                |   1 +
 drivers/iio/Makefile                               |   1 +
 drivers/iio/counter/104-quad-8.c                   | 593 +++++++++++++++++++++
 drivers/iio/counter/Kconfig                        |  24 +
 drivers/iio/counter/Makefile                       |   7 +
 drivers/iio/industrialio-core.c                    |   2 +
 include/uapi/linux/iio/types.h                     |   2 +
 10 files changed, 779 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8
 create mode 100644 drivers/iio/counter/104-quad-8.c
 create mode 100644 drivers/iio/counter/Kconfig
 create mode 100644 drivers/iio/counter/Makefile

-- 
2.7.3

[PATCH v5 1/2] iio: Implement counter channel type and info constants

[William Breathitt Gray]

Quadrature encoders, such as rotary encoders and linear encoders, are
devices which are capable of encoding the relative position and
direction of motion of a shaft. This patch introduces several IIO
constants for supporting quadrature encoder counter devices.

  IIO_COUNT: Current count (main data provided by the counter device)
  IIO_INDEX: Counter device index value

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 Documentation/ABI/testing/sysfs-bus-iio | 18 ++++++++++++++++++
 drivers/iio/industrialio-core.c         |  2 ++
 include/uapi/linux/iio/types.h          |  2 ++
 3 files changed, 22 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index fee35c0..b8f220f 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -329,6 +329,7 @@ What:		/sys/bus/iio/devices/iio:deviceX/in_pressure_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_humidityrelative_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_velocity_sqrt(x^2+y^2+z^2)_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_illuminance_scale
+What:		/sys/bus/iio/devices/iio:deviceX/in_countY_scale
 KernelVersion:	2.6.35
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -1579,3 +1580,20 @@ Contact:	linux-iio@vger.kernel.org
 Description:
 		Raw (unscaled no offset etc.) electric conductivity reading that
 		can be processed to siemens per meter.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_countY_raw
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Raw counter device counts from channel Y. For quadrature
+		counters, multiplication by an available [Y]_scale results in
+		the counts of a single quadrature signal phase from channel Y.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_indexY_raw
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Raw counter device index value from channel Y. This attribute
+		provides an absolute positional reference (e.g. a pulse once per
+		revolution) which may be used to home positional systems as
+		required.
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index fc340ed..649725b 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -81,6 +81,8 @@ static const char * const iio_chan_type_name_spec[] = {
 	[IIO_PH] = "ph",
 	[IIO_UVINDEX] = "uvindex",
 	[IIO_ELECTRICALCONDUCTIVITY] = "electricalconductivity",
+	[IIO_COUNT] = "count",
+	[IIO_INDEX] = "index",
 };
 
 static const char * const iio_modifier_names[] = {
diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h
index 22e5e58..e54d14a 100644
--- a/include/uapi/linux/iio/types.h
+++ b/include/uapi/linux/iio/types.h
@@ -40,6 +40,8 @@ enum iio_chan_type {
 	IIO_PH,
 	IIO_UVINDEX,
 	IIO_ELECTRICALCONDUCTIVITY,
+	IIO_COUNT,
+	IIO_INDEX,
 };
 
 enum iio_modifier {
-- 
2.7.3

[PATCH v5 2/2] iio: 104-quad-8: Add IIO support for the ACCES 104-QUAD-8

[William Breathitt Gray]

The ACCES 104-QUAD-8 is a general purpose quadrature encoder
counter/interface board. The 104-QUAD-8 is capable of monitoring the
outputs of eight encoders via four on-board LSI/CSI LS7266R1 24-bit
dual-axis quadrature counter chips. Core functions handled by the
LS7266R1, such as direction and total count, are available.

Performing a write to a counter's IIO_CHAN_INFO_RAW sets the counter and
also clears the counter's respective error flag. Although the counters
have a 25-bit range, only the lower 24 bits may be set, either directly
or via a counter's preset attribute. Interrupts are not supported by
this driver.

This driver adds IIO support for the ACCES 104-QUAD-8 and ACCES
104-QUAD-4. The base port addresses for the devices may be configured
via the base array module parameter.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 .../ABI/testing/sysfs-bus-iio-counter-104-quad-8   | 125 +++++
 MAINTAINERS                                        |   6 +
 drivers/iio/Kconfig                                |   1 +
 drivers/iio/Makefile                               |   1 +
 drivers/iio/counter/104-quad-8.c                   | 593 +++++++++++++++++++++
 drivers/iio/counter/Kconfig                        |  24 +
 drivers/iio/counter/Makefile                       |   7 +
 7 files changed, 757 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8
 create mode 100644 drivers/iio/counter/104-quad-8.c
 create mode 100644 drivers/iio/counter/Kconfig
 create mode 100644 drivers/iio/counter/Makefile

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8 b/Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8
new file mode 100644
index 0000000..ba67652
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8
@@ -0,0 +1,125 @@
+What:		/sys/bus/iio/devices/iio:deviceX/in_count_count_direction_available
+What:		/sys/bus/iio/devices/iio:deviceX/in_count_count_mode_available
+What:		/sys/bus/iio/devices/iio:deviceX/in_count_noise_error_available
+What:		/sys/bus/iio/devices/iio:deviceX/in_count_quadrature_mode_available
+What:		/sys/bus/iio/devices/iio:deviceX/in_index_index_polarity_available
+What:		/sys/bus/iio/devices/iio:deviceX/in_index_synchronous_mode_available
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Discrete set of available values for the respective counter
+		configuration are listed in this file.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_countY_count_direction
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Read-only attribute that indicates whether the counter for
+		channel Y is counting up or down.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_countY_count_mode
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Count mode for channel Y. Four count modes are available:
+		normal, range limit, non-recycle, and modulo-n. The preset value
+		for channel Y is used by the count mode where required.
+
+		Normal:
+			Counting is continuous in either direction.
+
+		Range Limit:
+			An upper or lower limit is set, mimicking limit switches
+			in the mechanical counterpart. The upper limit is set to
+			the preset value, while the lower limit is set to 0. The
+			counter freezes at count = preset when counting up, and
+			at count = 0 when counting down. At either of these
+			limits, the counting is resumed only when the count
+			direction is reversed.
+
+		Non-recycle:
+			Counter is disabled whenever a 24-bit count overflow or
+			underflow takes place. The counter is re-enabled when a
+			new count value is loaded to the counter via a preset
+			operation or write to raw.
+
+		Modulo-N:
+			A count boundary is set between 0 and the preset value.
+			The counter is reset to 0 at count = preset when
+			counting up, while the counter is set to the preset
+			value at count = 0 when counting down; the counter does
+			not freeze at the bundary points, but counts
+			continuously throughout.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_countY_noise_error
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Read-only attribute that indicates whether excessive noise is
+		present at the channel Y count inputs in quadrature clock mode;
+		irrelevant in non-quadrature clock mode.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_countY_preset
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		If the counter device supports preset registers, the preset
+		count for channel Y is provided by this attribute.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_countY_quadrature_mode
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Configure channel Y counter for non-quadrature or quadrature
+		clock mode. Selecting non-quadrature clock mode will disable
+		synchronous load mode. In quadrature clock mode, the channel Y
+		scale attribute selects the encoder phase division (scale of 1
+		selects full-cycle, scale of 0.5 selects half-cycle, scale of
+		0.25 selects quarter-cycle) processed by the channel Y counter.
+
+		Non-quadrature:
+			The filter and decoder circuit are bypassed. Encoder A
+			input serves as the count input and B as the UP/DOWN
+			direction control input, with B = 1 selecting UP Count
+			mode and B = 0 selecting Down Count mode.
+
+		Quadrature:
+			Encoder A and B inputs are digitally filtered and
+			decoded for UP/DN clock.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_countY_set_to_preset_on_index
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Whether to set channel Y counter with channel Y preset value
+		when channel Y index input is active, or continuously count.
+		Valid attribute values are boolean.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_indexY_index_polarity
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Active level of channel Y index input; irrelevant in
+		non-synchronous load mode.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_indexY_synchronous_mode
+KernelVersion:	4.9
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Configure channel Y counter for non-synchronous or synchronous
+		load mode. Synchronous load mode cannot be selected in
+		non-quadrature clock mode.
+
+		Non-synchronous:
+			A logic low level is the active level at this index
+			input. The index function (as enabled via
+			set_to_preset_on_index) is performed directly on the
+			active level of the index input.
+
+		Synchronous:
+			Intended for interfacing with encoder Index output in
+			quadrature clock mode. The active level is configured
+			via index_polarity. The index function (as enabled via
+			set_to_preset_on_index) is performed synchronously with
+			the quadrature clock on the active level of the index
+			input.
diff --git a/MAINTAINERS b/MAINTAINERS
index e013c2b..982dff3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -255,6 +255,12 @@ L:	linux-gpio@vger.kernel.org
 S:	Maintained
 F:	drivers/gpio/gpio-104-idio-16.c
 
+ACCES 104-QUAD-8 IIO DRIVER
+M:	William Breathitt Gray <vilhelm.gray@gmail.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	drivers/iio/counter/104-quad-8.c
+
 ACENIC DRIVER
 M:	Jes Sorensen <jes@trained-monkey.org>
 L:	linux-acenic@sunsite.dk
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index a31a8cf..a918270 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -73,6 +73,7 @@ source "drivers/iio/adc/Kconfig"
 source "drivers/iio/amplifiers/Kconfig"
 source "drivers/iio/chemical/Kconfig"
 source "drivers/iio/common/Kconfig"
+source "drivers/iio/counter/Kconfig"
 source "drivers/iio/dac/Kconfig"
 source "drivers/iio/dummy/Kconfig"
 source "drivers/iio/frequency/Kconfig"
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 2b6e276..33fa402 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -18,6 +18,7 @@ obj-y += amplifiers/
 obj-y += buffer/
 obj-y += chemical/
 obj-y += common/
+obj-y += counter/
 obj-y += dac/
 obj-y += dummy/
 obj-y += gyro/
diff --git a/drivers/iio/counter/104-quad-8.c b/drivers/iio/counter/104-quad-8.c
new file mode 100644
index 0000000..2d2ee35
--- /dev/null
+++ b/drivers/iio/counter/104-quad-8.c
@@ -0,0 +1,593 @@
+/*
+ * IIO driver for the ACCES 104-QUAD-8
+ * Copyright (C) 2016 William Breathitt Gray
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * This driver supports the ACCES 104-QUAD-8 and ACCES 104-QUAD-4.
+ */
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/isa.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+
+#define QUAD8_EXTENT 32
+
+static unsigned int base[max_num_isa_dev(QUAD8_EXTENT)];
+static unsigned int num_quad8;
+module_param_array(base, uint, &num_quad8, 0);
+MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
+
+#define QUAD8_NUM_COUNTERS 8
+
+/**
+ * struct quad8_iio - IIO device private data structure
+ * @preset:		array of preset values
+ * @count_mode:		array of count mode configurations
+ * @quadrature_mode:	array of quadrature mode configurations
+ * @quadrature_scale:	array of quadrature mode scale configurations
+ * @ab_enable:		array of A and B inputs enable configurations
+ * @preset_enable:	array of set_to_preset_on_index attribute configurations
+ * @synchronous_mode:	array of index function synchronous mode configurations
+ * @index_polarity:	array of index function polarity configurations
+ * @base:		base port address of the IIO device
+ */
+struct quad8_iio {
+	unsigned int preset[QUAD8_NUM_COUNTERS];
+	unsigned int count_mode[QUAD8_NUM_COUNTERS];
+	unsigned int quadrature_mode[QUAD8_NUM_COUNTERS];
+	unsigned int quadrature_scale[QUAD8_NUM_COUNTERS];
+	unsigned int ab_enable[QUAD8_NUM_COUNTERS];
+	unsigned int preset_enable[QUAD8_NUM_COUNTERS];
+	unsigned int synchronous_mode[QUAD8_NUM_COUNTERS];
+	unsigned int index_polarity[QUAD8_NUM_COUNTERS];
+	unsigned int base;
+};
+
+static int quad8_read_raw(struct iio_dev *indio_dev,
+	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
+{
+	struct quad8_iio *const priv = iio_priv(indio_dev);
+	const int base_offset = priv->base + 2 * chan->channel;
+	unsigned int flags;
+	unsigned int borrow;
+	unsigned int carry;
+	int i;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type == IIO_INDEX) {
+			*val = !!(inb(priv->base + 0x16) & BIT(chan->channel));
+			return IIO_VAL_INT;
+		}
+
+		flags = inb(base_offset);
+		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;
+	case IIO_CHAN_INFO_ENABLE:
+		*val = priv->ab_enable[chan->channel];
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 1;
+		*val2 = priv->quadrature_scale[chan->channel];
+		return IIO_VAL_FRACTIONAL_LOG2;
+	}
+
+	return -EINVAL;
+}
+
+static int quad8_write_raw(struct iio_dev *indio_dev,
+	struct iio_chan_spec const *chan, int val, int val2, long mask)
+{
+	struct quad8_iio *const priv = iio_priv(indio_dev);
+	const int base_offset = priv->base + 2 * chan->channel;
+	int i;
+	unsigned int ior_cfg;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type == IIO_INDEX)
+			return -EINVAL;
+
+		/* 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[chan->channel];
+		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;
+	case IIO_CHAN_INFO_ENABLE:
+		/* only boolean values accepted */
+		if (val < 0 || val > 1)
+			return -EINVAL;
+
+		priv->ab_enable[chan->channel] = val;
+
+		ior_cfg = val | priv->preset_enable[chan->channel] << 1;
+
+		/* Load I/O control configuration */
+		outb(0x40 | ior_cfg, base_offset);
+
+		return 0;
+	case IIO_CHAN_INFO_SCALE:
+		/* Quadrature scaling only available in quadrature mode */
+		if (!priv->quadrature_mode[chan->channel] && (val2 || val != 1))
+			return -EINVAL;
+
+		/* Only three gain states (1, 0.5, 0.25) */
+		if (val == 1 && !val2)
+			priv->quadrature_scale[chan->channel] = 0;
+		else if (!val)
+			switch (val2) {
+			case 500000:
+				priv->quadrature_scale[chan->channel] = 1;
+				break;
+			case 250000:
+				priv->quadrature_scale[chan->channel] = 2;
+				break;
+			default:
+				return -EINVAL;
+			}
+		else
+			return -EINVAL;
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info quad8_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = quad8_read_raw,
+	.write_raw = quad8_write_raw
+};
+
+static ssize_t quad8_read_preset(struct iio_dev *indio_dev, uintptr_t private,
+	const struct iio_chan_spec *chan, char *buf)
+{
+	const struct quad8_iio *const priv = iio_priv(indio_dev);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", priv->preset[chan->channel]);
+}
+
+static ssize_t quad8_write_preset(struct iio_dev *indio_dev, uintptr_t private,
+	const struct iio_chan_spec *chan, const char *buf, size_t len)
+{
+	struct quad8_iio *const priv = iio_priv(indio_dev);
+	const int base_offset = priv->base + 2 * chan->channel;
+	unsigned int preset;
+	int ret;
+	int i;
+
+	ret = kstrtouint(buf, 0, &preset);
+	if (ret)
+		return ret;
+
+	/* Only 24-bit values are supported */
+	if (preset > 0xFFFFFF)
+		return -EINVAL;
+
+	priv->preset[chan->channel] = preset;
+
+	/* Reset Byte Pointer */
+	outb(0x01, base_offset + 1);
+
+	/* Set Preset Register */
+	for (i = 0; i < 3; i++)
+		outb(preset >> (8 * i), base_offset);
+
+	return len;
+}
+
+static ssize_t quad8_read_set_to_preset_on_index(struct iio_dev *indio_dev,
+	uintptr_t private, const struct iio_chan_spec *chan, char *buf)
+{
+	const struct quad8_iio *const priv = iio_priv(indio_dev);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n",
+		priv->preset_enable[chan->channel]);
+}
+
+static ssize_t quad8_write_set_to_preset_on_index(struct iio_dev *indio_dev,
+	uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
+	size_t len)
+{
+	struct quad8_iio *const priv = iio_priv(indio_dev);
+	const int base_offset = priv->base + 2 * chan->channel;
+	bool preset_enable;
+	int ret;
+	unsigned int ior_cfg;
+
+	ret = kstrtobool(buf, &preset_enable);
+	if (ret)
+		return ret;
+
+	priv->preset_enable[chan->channel] = preset_enable;
+
+	ior_cfg = priv->ab_enable[chan->channel] |
+		(unsigned int)preset_enable << 1;
+
+	/* Load I/O control configuration to Input / Output Control Register */
+	outb(0x40 | ior_cfg, base_offset);
+
+	return len;
+}
+
+static const char *const quad8_noise_error_states[] = {
+	"No excessive noise is present at the count inputs",
+	"Excessive noise is present at the count inputs"
+};
+
+static int quad8_get_noise_error(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan)
+{
+	struct quad8_iio *const priv = iio_priv(indio_dev);
+	const int base_offset = priv->base + 2 * chan->channel + 1;
+
+	return !!(inb(base_offset) & BIT(4));
+}
+
+static const struct iio_enum quad8_noise_error_enum = {
+	.items = quad8_noise_error_states,
+	.num_items = ARRAY_SIZE(quad8_noise_error_states),
+	.get = quad8_get_noise_error
+};
+
+static const char *const quad8_count_direction_states[] = {
+	"down",
+	"up"
+};
+
+static int quad8_get_count_direction(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan)
+{
+	struct quad8_iio *const priv = iio_priv(indio_dev);
+	const int base_offset = priv->base + 2 * chan->channel + 1;
+
+	return !!(inb(base_offset) & BIT(5));
+}
+
+static const struct iio_enum quad8_count_direction_enum = {
+	.items = quad8_count_direction_states,
+	.num_items = ARRAY_SIZE(quad8_count_direction_states),
+	.get = quad8_get_count_direction
+};
+
+static const char *const quad8_count_modes[] = {
+	"normal",
+	"range limit",
+	"non-recycle",
+	"modulo-n"
+};
+
+static int quad8_set_count_mode(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan, unsigned int count_mode)
+{
+	struct quad8_iio *const priv = iio_priv(indio_dev);
+	unsigned int mode_cfg = count_mode << 1;
+	const int base_offset = priv->base + 2 * chan->channel + 1;
+
+	priv->count_mode[chan->channel] = count_mode;
+
+	/* Add quadrature mode configuration */
+	if (priv->quadrature_mode[chan->channel])
+		mode_cfg |= (priv->quadrature_scale[chan->channel] + 1) << 3;
+
+	/* Load mode configuration to Counter Mode Register */
+	outb(0x20 | mode_cfg, base_offset);
+
+	return 0;
+}
+
+static int quad8_get_count_mode(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan)
+{
+	const struct quad8_iio *const priv = iio_priv(indio_dev);
+
+	return priv->count_mode[chan->channel];
+}
+
+static const struct iio_enum quad8_count_mode_enum = {
+	.items = quad8_count_modes,
+	.num_items = ARRAY_SIZE(quad8_count_modes),
+	.set = quad8_set_count_mode,
+	.get = quad8_get_count_mode
+};
+
+static const char *const quad8_synchronous_modes[] = {
+	"non-synchronous",
+	"synchronous"
+};
+
+static int quad8_set_synchronous_mode(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan, unsigned int synchronous_mode)
+{
+	struct quad8_iio *const priv = iio_priv(indio_dev);
+	const unsigned int idr_cfg = synchronous_mode |
+		priv->index_polarity[chan->channel] << 1;
+	const int base_offset = priv->base + 2 * chan->channel + 1;
+
+	/* Index function must be non-synchronous in non-quadrature mode */
+	if (synchronous_mode && !priv->quadrature_mode[chan->channel])
+		return -EINVAL;
+
+	priv->synchronous_mode[chan->channel] = synchronous_mode;
+
+	/* Load Index Control configuration to Index Control Register */
+	outb(0x40 | idr_cfg, base_offset);
+
+	return 0;
+}
+
+static int quad8_get_synchronous_mode(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan)
+{
+	const struct quad8_iio *const priv = iio_priv(indio_dev);
+
+	return priv->synchronous_mode[chan->channel];
+}
+
+static const struct iio_enum quad8_synchronous_mode_enum = {
+	.items = quad8_synchronous_modes,
+	.num_items = ARRAY_SIZE(quad8_synchronous_modes),
+	.set = quad8_set_synchronous_mode,
+	.get = quad8_get_synchronous_mode
+};
+
+static const char *const quad8_quadrature_modes[] = {
+	"non-quadrature",
+	"quadrature"
+};
+
+static int quad8_set_quadrature_mode(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan, unsigned int quadrature_mode)
+{
+	struct quad8_iio *const priv = iio_priv(indio_dev);
+	unsigned int mode_cfg = priv->count_mode[chan->channel] << 1;
+	const int base_offset = priv->base + 2 * chan->channel + 1;
+
+	if (quadrature_mode)
+		mode_cfg |= (priv->quadrature_scale[chan->channel] + 1) << 3;
+	else {
+		/* Quadrature scaling only available in quadrature mode */
+		priv->quadrature_scale[chan->channel] = 0;
+
+		/* Synchronous function not supported in non-quadrature mode */
+		if (priv->synchronous_mode[chan->channel])
+			quad8_set_synchronous_mode(indio_dev, chan, 0);
+	}
+
+	priv->quadrature_mode[chan->channel] = quadrature_mode;
+
+	/* Load mode configuration to Counter Mode Register */
+	outb(0x20 | mode_cfg, base_offset);
+
+	return 0;
+}
+
+static int quad8_get_quadrature_mode(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan)
+{
+	const struct quad8_iio *const priv = iio_priv(indio_dev);
+
+	return priv->quadrature_mode[chan->channel];
+}
+
+static const struct iio_enum quad8_quadrature_mode_enum = {
+	.items = quad8_quadrature_modes,
+	.num_items = ARRAY_SIZE(quad8_quadrature_modes),
+	.set = quad8_set_quadrature_mode,
+	.get = quad8_get_quadrature_mode
+};
+
+static const char *const quad8_index_polarity_modes[] = {
+	"negative",
+	"positive"
+};
+
+static int quad8_set_index_polarity(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan, unsigned int index_polarity)
+{
+	struct quad8_iio *const priv = iio_priv(indio_dev);
+	const unsigned int idr_cfg = priv->synchronous_mode[chan->channel] |
+		index_polarity << 1;
+	const int base_offset = priv->base + 2 * chan->channel + 1;
+
+	priv->index_polarity[chan->channel] = index_polarity;
+
+	/* Load Index Control configuration to Index Control Register */
+	outb(0x40 | idr_cfg, base_offset);
+
+	return 0;
+}
+
+static int quad8_get_index_polarity(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan)
+{
+	const struct quad8_iio *const priv = iio_priv(indio_dev);
+
+	return priv->index_polarity[chan->channel];
+}
+
+static const struct iio_enum quad8_index_polarity_enum = {
+	.items = quad8_index_polarity_modes,
+	.num_items = ARRAY_SIZE(quad8_index_polarity_modes),
+	.set = quad8_set_index_polarity,
+	.get = quad8_get_index_polarity
+};
+
+static const struct iio_chan_spec_ext_info quad8_count_ext_info[] = {
+	{
+		.name = "preset",
+		.shared = IIO_SEPARATE,
+		.read = quad8_read_preset,
+		.write = quad8_write_preset
+	},
+	{
+		.name = "set_to_preset_on_index",
+		.shared = IIO_SEPARATE,
+		.read = quad8_read_set_to_preset_on_index,
+		.write = quad8_write_set_to_preset_on_index
+	},
+	IIO_ENUM("noise_error", IIO_SEPARATE, &quad8_noise_error_enum),
+	IIO_ENUM_AVAILABLE("noise_error", &quad8_noise_error_enum),
+	IIO_ENUM("count_direction", IIO_SEPARATE, &quad8_count_direction_enum),
+	IIO_ENUM_AVAILABLE("count_direction", &quad8_count_direction_enum),
+	IIO_ENUM("count_mode", IIO_SEPARATE, &quad8_count_mode_enum),
+	IIO_ENUM_AVAILABLE("count_mode", &quad8_count_mode_enum),
+	IIO_ENUM("quadrature_mode", IIO_SEPARATE, &quad8_quadrature_mode_enum),
+	IIO_ENUM_AVAILABLE("quadrature_mode", &quad8_quadrature_mode_enum),
+	{}
+};
+
+static const struct iio_chan_spec_ext_info quad8_index_ext_info[] = {
+	IIO_ENUM("synchronous_mode", IIO_SEPARATE,
+		&quad8_synchronous_mode_enum),
+	IIO_ENUM_AVAILABLE("synchronous_mode", &quad8_synchronous_mode_enum),
+	IIO_ENUM("index_polarity", IIO_SEPARATE, &quad8_index_polarity_enum),
+	IIO_ENUM_AVAILABLE("index_polarity", &quad8_index_polarity_enum),
+	{}
+};
+
+#define QUAD8_COUNT_CHAN(_chan) {					\
+	.type = IIO_COUNT,						\
+	.channel = (_chan),						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
+		BIT(IIO_CHAN_INFO_ENABLE) | BIT(IIO_CHAN_INFO_SCALE),	\
+	.ext_info = quad8_count_ext_info,				\
+	.indexed = 1							\
+}
+
+#define QUAD8_INDEX_CHAN(_chan) {			\
+	.type = IIO_INDEX,				\
+	.channel = (_chan),				\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
+	.ext_info = quad8_index_ext_info,		\
+	.indexed = 1					\
+}
+
+static const struct iio_chan_spec quad8_channels[] = {
+	QUAD8_COUNT_CHAN(0), QUAD8_INDEX_CHAN(0),
+	QUAD8_COUNT_CHAN(1), QUAD8_INDEX_CHAN(1),
+	QUAD8_COUNT_CHAN(2), QUAD8_INDEX_CHAN(2),
+	QUAD8_COUNT_CHAN(3), QUAD8_INDEX_CHAN(3),
+	QUAD8_COUNT_CHAN(4), QUAD8_INDEX_CHAN(4),
+	QUAD8_COUNT_CHAN(5), QUAD8_INDEX_CHAN(5),
+	QUAD8_COUNT_CHAN(6), QUAD8_INDEX_CHAN(6),
+	QUAD8_COUNT_CHAN(7), QUAD8_INDEX_CHAN(7)
+};
+
+static int quad8_probe(struct device *dev, unsigned int id)
+{
+	struct iio_dev *indio_dev;
+	struct quad8_iio *priv;
+	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))) {
+		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);
+
+	priv = iio_priv(indio_dev);
+	priv->base = base[id];
+
+	/* Reset all counters and disable interrupt function */
+	outb(0x01, base[id] + 0x11);
+	/* Set initial configuration for all counters */
+	for (i = 0; i < QUAD8_NUM_COUNTERS; i++) {
+		base_offset = base[id] + 2 * i;
+		/* Reset Byte Pointer */
+		outb(0x01, base_offset + 1);
+		/* Reset Preset Register */
+		for (j = 0; j < 3; j++)
+			outb(0x00, base_offset);
+		/* Reset Borrow, Carry, Compare, and Sign flags */
+		outb(0x04, base_offset + 1);
+		/* Reset Error flag */
+		outb(0x06, base_offset + 1);
+		/* Binary encoding; Normal count; non-quadrature mode */
+		outb(0x20, base_offset + 1);
+		/* Disable A and B inputs; preset on index; FLG1 as Carry */
+		outb(0x40, base_offset + 1);
+		/* Disable index function; negative index polarity */
+		outb(0x60, base_offset + 1);
+	}
+	/* Enable all counters */
+	outb(0x00, base[id] + 0x11);
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static struct isa_driver quad8_driver = {
+	.probe = quad8_probe,
+	.driver = {
+		.name = "104-quad-8"
+	}
+};
+
+module_isa_driver(quad8_driver, num_quad8);
+
+MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
+MODULE_DESCRIPTION("ACCES 104-QUAD-8 IIO driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/counter/Kconfig b/drivers/iio/counter/Kconfig
new file mode 100644
index 0000000..44627f6
--- /dev/null
+++ b/drivers/iio/counter/Kconfig
@@ -0,0 +1,24 @@
+#
+# Counter devices
+#
+# When adding new entries keep the list in alphabetical order
+
+menu "Counters"
+
+config 104_QUAD_8
+	tristate "ACCES 104-QUAD-8 driver"
+	depends on X86 && ISA_BUS_API
+	help
+	  Say yes here to build support for the ACCES 104-QUAD-8 quadrature
+	  encoder counter/interface device family (104-QUAD-8, 104-QUAD-4).
+
+	  Performing a write to a counter's IIO_CHAN_INFO_RAW sets the counter and
+	  also clears the counter's respective error flag. Although the counters
+	  have a 25-bit range, only the lower 24 bits may be set, either directly
+	  or via a counter's preset attribute. Interrupts are not supported by
+	  this driver.
+
+	  The base port addresses for the devices may be configured via the base
+	  array module parameter.
+
+endmenu
diff --git a/drivers/iio/counter/Makefile b/drivers/iio/counter/Makefile
new file mode 100644
index 0000000..007e884
--- /dev/null
+++ b/drivers/iio/counter/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for IIO counter devices
+#
+
+# When adding new entries keep the list in alphabetical order
+
+obj-$(CONFIG_104_QUAD_8)	+= 104-quad-8.o
-- 
2.7.3

Re: [PATCH v5 2/2] iio: 104-quad-8: Add IIO support for the ACCES 104-QUAD-8

[Jonathan Cameron]

On 28/09/16 19:00, William Breathitt Gray wrote:
> The ACCES 104-QUAD-8 is a general purpose quadrature encoder
> counter/interface board. The 104-QUAD-8 is capable of monitoring the
> outputs of eight encoders via four on-board LSI/CSI LS7266R1 24-bit
> dual-axis quadrature counter chips. Core functions handled by the
> LS7266R1, such as direction and total count, are available.
> 
> Performing a write to a counter's IIO_CHAN_INFO_RAW sets the counter and
> also clears the counter's respective error flag. Although the counters
> have a 25-bit range, only the lower 24 bits may be set, either directly
> or via a counter's preset attribute. Interrupts are not supported by
> this driver.
> 
> This driver adds IIO support for the ACCES 104-QUAD-8 and ACCES
> 104-QUAD-4. The base port addresses for the devices may be configured
> via the base array module parameter.
> 
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Very nice. In particularly very good documentation.

I'm not 100 sure we've gotten the ABI right but as no else
has chipped in lets take the view that it might 'expand'
as we get more similar devices.

There was one suprise in there for me in that these support a direction
input in non quadrature mode.  Kit I've used tends to just ignore one
line.  Anyhow, not sure we'll ever really need to describe that as it's
more about wiring than the software side.

So applied to the togreg branch of iio.git - initially pushed out as testing
for the autobuilders to play with it.

You might not agree, but I am pleasantly suprised that it only took as to
v5 to get something we agree on ;)

Jonathan
> ---
>  .../ABI/testing/sysfs-bus-iio-counter-104-quad-8   | 125 +++++
>  MAINTAINERS                                        |   6 +
>  drivers/iio/Kconfig                                |   1 +
>  drivers/iio/Makefile                               |   1 +
>  drivers/iio/counter/104-quad-8.c                   | 593 +++++++++++++++++++++
>  drivers/iio/counter/Kconfig                        |  24 +
>  drivers/iio/counter/Makefile                       |   7 +
>  7 files changed, 757 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8
>  create mode 100644 drivers/iio/counter/104-quad-8.c
>  create mode 100644 drivers/iio/counter/Kconfig
>  create mode 100644 drivers/iio/counter/Makefile
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8 b/Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8
> new file mode 100644
> index 0000000..ba67652
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8
> @@ -0,0 +1,125 @@
> +What:		/sys/bus/iio/devices/iio:deviceX/in_count_count_direction_available
> +What:		/sys/bus/iio/devices/iio:deviceX/in_count_count_mode_available
> +What:		/sys/bus/iio/devices/iio:deviceX/in_count_noise_error_available
> +What:		/sys/bus/iio/devices/iio:deviceX/in_count_quadrature_mode_available
> +What:		/sys/bus/iio/devices/iio:deviceX/in_index_index_polarity_available
> +What:		/sys/bus/iio/devices/iio:deviceX/in_index_synchronous_mode_available
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Discrete set of available values for the respective counter
> +		configuration are listed in this file.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_count_direction
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Read-only attribute that indicates whether the counter for
> +		channel Y is counting up or down.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_count_mode
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Count mode for channel Y. Four count modes are available:
> +		normal, range limit, non-recycle, and modulo-n. The preset value
> +		for channel Y is used by the count mode where required.
> +
> +		Normal:
> +			Counting is continuous in either direction.
> +
> +		Range Limit:
> +			An upper or lower limit is set, mimicking limit switches
> +			in the mechanical counterpart. The upper limit is set to
> +			the preset value, while the lower limit is set to 0. The
> +			counter freezes at count = preset when counting up, and
> +			at count = 0 when counting down. At either of these
> +			limits, the counting is resumed only when the count
> +			direction is reversed.
> +
> +		Non-recycle:
> +			Counter is disabled whenever a 24-bit count overflow or
> +			underflow takes place. The counter is re-enabled when a
> +			new count value is loaded to the counter via a preset
> +			operation or write to raw.
> +
> +		Modulo-N:
> +			A count boundary is set between 0 and the preset value.
> +			The counter is reset to 0 at count = preset when
> +			counting up, while the counter is set to the preset
> +			value at count = 0 when counting down; the counter does
> +			not freeze at the bundary points, but counts
> +			continuously throughout.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_noise_error
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Read-only attribute that indicates whether excessive noise is
> +		present at the channel Y count inputs in quadrature clock mode;
> +		irrelevant in non-quadrature clock mode.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_preset
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		If the counter device supports preset registers, the preset
> +		count for channel Y is provided by this attribute.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_quadrature_mode
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Configure channel Y counter for non-quadrature or quadrature
> +		clock mode. Selecting non-quadrature clock mode will disable
> +		synchronous load mode. In quadrature clock mode, the channel Y
> +		scale attribute selects the encoder phase division (scale of 1
> +		selects full-cycle, scale of 0.5 selects half-cycle, scale of
> +		0.25 selects quarter-cycle) processed by the channel Y counter.
> +
> +		Non-quadrature:
> +			The filter and decoder circuit are bypassed. Encoder A
> +			input serves as the count input and B as the UP/DOWN
> +			direction control input, with B = 1 selecting UP Count
> +			mode and B = 0 selecting Down Count mode.
Glad you documented this bit clearly. I'd normaly have expected B to just
be ignored.  Interesting.  
> +
> +		Quadrature:
> +			Encoder A and B inputs are digitally filtered and
> +			decoded for UP/DN clock.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_set_to_preset_on_index
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Whether to set channel Y counter with channel Y preset value
> +		when channel Y index input is active, or continuously count.
> +		Valid attribute values are boolean.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_indexY_index_polarity
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Active level of channel Y index input; irrelevant in
> +		non-synchronous load mode.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_indexY_synchronous_mode
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Configure channel Y counter for non-synchronous or synchronous
> +		load mode. Synchronous load mode cannot be selected in
> +		non-quadrature clock mode.
> +
> +		Non-synchronous:
> +			A logic low level is the active level at this index
> +			input. The index function (as enabled via
> +			set_to_preset_on_index) is performed directly on the
> +			active level of the index input.
> +
> +		Synchronous:
> +			Intended for interfacing with encoder Index output in
> +			quadrature clock mode. The active level is configured
> +			via index_polarity. The index function (as enabled via
> +			set_to_preset_on_index) is performed synchronously with
> +			the quadrature clock on the active level of the index
> +			input.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e013c2b..982dff3 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -255,6 +255,12 @@ L:	linux-gpio@vger.kernel.org
>  S:	Maintained
>  F:	drivers/gpio/gpio-104-idio-16.c
>  
> +ACCES 104-QUAD-8 IIO DRIVER
> +M:	William Breathitt Gray <vilhelm.gray@gmail.com>
> +L:	linux-iio@vger.kernel.org
> +S:	Maintained
> +F:	drivers/iio/counter/104-quad-8.c
> +
>  ACENIC DRIVER
>  M:	Jes Sorensen <jes@trained-monkey.org>
>  L:	linux-acenic@sunsite.dk
> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index a31a8cf..a918270 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -73,6 +73,7 @@ source "drivers/iio/adc/Kconfig"
>  source "drivers/iio/amplifiers/Kconfig"
>  source "drivers/iio/chemical/Kconfig"
>  source "drivers/iio/common/Kconfig"
> +source "drivers/iio/counter/Kconfig"
>  source "drivers/iio/dac/Kconfig"
>  source "drivers/iio/dummy/Kconfig"
>  source "drivers/iio/frequency/Kconfig"
> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
> index 2b6e276..33fa402 100644
> --- a/drivers/iio/Makefile
> +++ b/drivers/iio/Makefile
> @@ -18,6 +18,7 @@ obj-y += amplifiers/
>  obj-y += buffer/
>  obj-y += chemical/
>  obj-y += common/
> +obj-y += counter/
>  obj-y += dac/
>  obj-y += dummy/
>  obj-y += gyro/
> diff --git a/drivers/iio/counter/104-quad-8.c b/drivers/iio/counter/104-quad-8.c
> new file mode 100644
> index 0000000..2d2ee35
> --- /dev/null
> +++ b/drivers/iio/counter/104-quad-8.c
> @@ -0,0 +1,593 @@
> +/*
> + * IIO driver for the ACCES 104-QUAD-8
> + * Copyright (C) 2016 William Breathitt Gray
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License, version 2, as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * General Public License for more details.
> + *
> + * This driver supports the ACCES 104-QUAD-8 and ACCES 104-QUAD-4.
> + */
> +#include <linux/bitops.h>
> +#include <linux/device.h>
> +#include <linux/errno.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/types.h>
> +#include <linux/io.h>
> +#include <linux/ioport.h>
> +#include <linux/isa.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/types.h>
> +
> +#define QUAD8_EXTENT 32
> +
> +static unsigned int base[max_num_isa_dev(QUAD8_EXTENT)];
> +static unsigned int num_quad8;
> +module_param_array(base, uint, &num_quad8, 0);
> +MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
> +
> +#define QUAD8_NUM_COUNTERS 8
> +
> +/**
> + * struct quad8_iio - IIO device private data structure
> + * @preset:		array of preset values
> + * @count_mode:		array of count mode configurations
> + * @quadrature_mode:	array of quadrature mode configurations
> + * @quadrature_scale:	array of quadrature mode scale configurations
> + * @ab_enable:		array of A and B inputs enable configurations
> + * @preset_enable:	array of set_to_preset_on_index attribute configurations
> + * @synchronous_mode:	array of index function synchronous mode configurations
> + * @index_polarity:	array of index function polarity configurations
> + * @base:		base port address of the IIO device
> + */
> +struct quad8_iio {
> +	unsigned int preset[QUAD8_NUM_COUNTERS];
> +	unsigned int count_mode[QUAD8_NUM_COUNTERS];
> +	unsigned int quadrature_mode[QUAD8_NUM_COUNTERS];
> +	unsigned int quadrature_scale[QUAD8_NUM_COUNTERS];
> +	unsigned int ab_enable[QUAD8_NUM_COUNTERS];
> +	unsigned int preset_enable[QUAD8_NUM_COUNTERS];
> +	unsigned int synchronous_mode[QUAD8_NUM_COUNTERS];
> +	unsigned int index_polarity[QUAD8_NUM_COUNTERS];
> +	unsigned int base;
> +};
> +
> +static int quad8_read_raw(struct iio_dev *indio_dev,
> +	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
> +{
> +	struct quad8_iio *const priv = iio_priv(indio_dev);
> +	const int base_offset = priv->base + 2 * chan->channel;
> +	unsigned int flags;
> +	unsigned int borrow;
> +	unsigned int carry;
> +	int i;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (chan->type == IIO_INDEX) {
> +			*val = !!(inb(priv->base + 0x16) & BIT(chan->channel));
> +			return IIO_VAL_INT;
> +		}
> +
> +		flags = inb(base_offset);
> +		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;
> +	case IIO_CHAN_INFO_ENABLE:
> +		*val = priv->ab_enable[chan->channel];
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = 1;
> +		*val2 = priv->quadrature_scale[chan->channel];
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int quad8_write_raw(struct iio_dev *indio_dev,
> +	struct iio_chan_spec const *chan, int val, int val2, long mask)
> +{
> +	struct quad8_iio *const priv = iio_priv(indio_dev);
> +	const int base_offset = priv->base + 2 * chan->channel;
> +	int i;
> +	unsigned int ior_cfg;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (chan->type == IIO_INDEX)
> +			return -EINVAL;
> +
> +		/* 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[chan->channel];
> +		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;
> +	case IIO_CHAN_INFO_ENABLE:
> +		/* only boolean values accepted */
> +		if (val < 0 || val > 1)
> +			return -EINVAL;
> +
> +		priv->ab_enable[chan->channel] = val;
> +
> +		ior_cfg = val | priv->preset_enable[chan->channel] << 1;
> +
> +		/* Load I/O control configuration */
> +		outb(0x40 | ior_cfg, base_offset);
> +
> +		return 0;
> +	case IIO_CHAN_INFO_SCALE:
> +		/* Quadrature scaling only available in quadrature mode */
> +		if (!priv->quadrature_mode[chan->channel] && (val2 || val != 1))
> +			return -EINVAL;
> +
> +		/* Only three gain states (1, 0.5, 0.25) */
> +		if (val == 1 && !val2)
> +			priv->quadrature_scale[chan->channel] = 0;
> +		else if (!val)
> +			switch (val2) {
> +			case 500000:
> +				priv->quadrature_scale[chan->channel] = 1;
> +				break;
> +			case 250000:
> +				priv->quadrature_scale[chan->channel] = 2;
> +				break;
> +			default:
> +				return -EINVAL;
> +			}
> +		else
> +			return -EINVAL;
> +
> +		return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info quad8_info = {
> +	.driver_module = THIS_MODULE,
> +	.read_raw = quad8_read_raw,
> +	.write_raw = quad8_write_raw
> +};
> +
> +static ssize_t quad8_read_preset(struct iio_dev *indio_dev, uintptr_t private,
> +	const struct iio_chan_spec *chan, char *buf)
> +{
> +	const struct quad8_iio *const priv = iio_priv(indio_dev);
> +
> +	return snprintf(buf, PAGE_SIZE, "%u\n", priv->preset[chan->channel]);
> +}
> +
> +static ssize_t quad8_write_preset(struct iio_dev *indio_dev, uintptr_t private,
> +	const struct iio_chan_spec *chan, const char *buf, size_t len)
> +{
> +	struct quad8_iio *const priv = iio_priv(indio_dev);
> +	const int base_offset = priv->base + 2 * chan->channel;
> +	unsigned int preset;
> +	int ret;
> +	int i;
> +
> +	ret = kstrtouint(buf, 0, &preset);
> +	if (ret)
> +		return ret;
> +
> +	/* Only 24-bit values are supported */
> +	if (preset > 0xFFFFFF)
> +		return -EINVAL;
> +
> +	priv->preset[chan->channel] = preset;
> +
> +	/* Reset Byte Pointer */
> +	outb(0x01, base_offset + 1);
> +
> +	/* Set Preset Register */
> +	for (i = 0; i < 3; i++)
> +		outb(preset >> (8 * i), base_offset);
> +
> +	return len;
> +}
> +
> +static ssize_t quad8_read_set_to_preset_on_index(struct iio_dev *indio_dev,
> +	uintptr_t private, const struct iio_chan_spec *chan, char *buf)
> +{
> +	const struct quad8_iio *const priv = iio_priv(indio_dev);
> +
> +	return snprintf(buf, PAGE_SIZE, "%u\n",
> +		priv->preset_enable[chan->channel]);
> +}
> +
> +static ssize_t quad8_write_set_to_preset_on_index(struct iio_dev *indio_dev,
> +	uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
> +	size_t len)
> +{
> +	struct quad8_iio *const priv = iio_priv(indio_dev);
> +	const int base_offset = priv->base + 2 * chan->channel;
> +	bool preset_enable;
> +	int ret;
> +	unsigned int ior_cfg;
> +
> +	ret = kstrtobool(buf, &preset_enable);
> +	if (ret)
> +		return ret;
> +
> +	priv->preset_enable[chan->channel] = preset_enable;
> +
> +	ior_cfg = priv->ab_enable[chan->channel] |
> +		(unsigned int)preset_enable << 1;
> +
> +	/* Load I/O control configuration to Input / Output Control Register */
> +	outb(0x40 | ior_cfg, base_offset);
> +
> +	return len;
> +}
> +
> +static const char *const quad8_noise_error_states[] = {
> +	"No excessive noise is present at the count inputs",
> +	"Excessive noise is present at the count inputs"
> +};
> +
> +static int quad8_get_noise_error(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan)
> +{
> +	struct quad8_iio *const priv = iio_priv(indio_dev);
> +	const int base_offset = priv->base + 2 * chan->channel + 1;
> +
> +	return !!(inb(base_offset) & BIT(4));
> +}
> +
> +static const struct iio_enum quad8_noise_error_enum = {
> +	.items = quad8_noise_error_states,
> +	.num_items = ARRAY_SIZE(quad8_noise_error_states),
> +	.get = quad8_get_noise_error
> +};
> +
> +static const char *const quad8_count_direction_states[] = {
> +	"down",
> +	"up"
> +};
> +
> +static int quad8_get_count_direction(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan)
> +{
> +	struct quad8_iio *const priv = iio_priv(indio_dev);
> +	const int base_offset = priv->base + 2 * chan->channel + 1;
> +
> +	return !!(inb(base_offset) & BIT(5));
> +}
> +
> +static const struct iio_enum quad8_count_direction_enum = {
> +	.items = quad8_count_direction_states,
> +	.num_items = ARRAY_SIZE(quad8_count_direction_states),
> +	.get = quad8_get_count_direction
> +};
> +
> +static const char *const quad8_count_modes[] = {
> +	"normal",
> +	"range limit",
> +	"non-recycle",
> +	"modulo-n"
> +};
> +
> +static int quad8_set_count_mode(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan, unsigned int count_mode)
> +{
> +	struct quad8_iio *const priv = iio_priv(indio_dev);
> +	unsigned int mode_cfg = count_mode << 1;
> +	const int base_offset = priv->base + 2 * chan->channel + 1;
> +
> +	priv->count_mode[chan->channel] = count_mode;
> +
> +	/* Add quadrature mode configuration */
> +	if (priv->quadrature_mode[chan->channel])
> +		mode_cfg |= (priv->quadrature_scale[chan->channel] + 1) << 3;
> +
> +	/* Load mode configuration to Counter Mode Register */
> +	outb(0x20 | mode_cfg, base_offset);
> +
> +	return 0;
> +}
> +
> +static int quad8_get_count_mode(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan)
> +{
> +	const struct quad8_iio *const priv = iio_priv(indio_dev);
> +
> +	return priv->count_mode[chan->channel];
> +}
> +
> +static const struct iio_enum quad8_count_mode_enum = {
> +	.items = quad8_count_modes,
> +	.num_items = ARRAY_SIZE(quad8_count_modes),
> +	.set = quad8_set_count_mode,
> +	.get = quad8_get_count_mode
> +};
> +
> +static const char *const quad8_synchronous_modes[] = {
> +	"non-synchronous",
> +	"synchronous"
> +};
> +
> +static int quad8_set_synchronous_mode(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan, unsigned int synchronous_mode)
> +{
> +	struct quad8_iio *const priv = iio_priv(indio_dev);
> +	const unsigned int idr_cfg = synchronous_mode |
> +		priv->index_polarity[chan->channel] << 1;
> +	const int base_offset = priv->base + 2 * chan->channel + 1;
> +
> +	/* Index function must be non-synchronous in non-quadrature mode */
> +	if (synchronous_mode && !priv->quadrature_mode[chan->channel])
> +		return -EINVAL;
> +
> +	priv->synchronous_mode[chan->channel] = synchronous_mode;
> +
> +	/* Load Index Control configuration to Index Control Register */
> +	outb(0x40 | idr_cfg, base_offset);
> +
> +	return 0;
> +}
> +
> +static int quad8_get_synchronous_mode(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan)
> +{
> +	const struct quad8_iio *const priv = iio_priv(indio_dev);
> +
> +	return priv->synchronous_mode[chan->channel];
> +}
> +
> +static const struct iio_enum quad8_synchronous_mode_enum = {
> +	.items = quad8_synchronous_modes,
> +	.num_items = ARRAY_SIZE(quad8_synchronous_modes),
> +	.set = quad8_set_synchronous_mode,
> +	.get = quad8_get_synchronous_mode
> +};
> +
> +static const char *const quad8_quadrature_modes[] = {
> +	"non-quadrature",
> +	"quadrature"
> +};
> +
> +static int quad8_set_quadrature_mode(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan, unsigned int quadrature_mode)
> +{
> +	struct quad8_iio *const priv = iio_priv(indio_dev);
> +	unsigned int mode_cfg = priv->count_mode[chan->channel] << 1;
> +	const int base_offset = priv->base + 2 * chan->channel + 1;
> +
> +	if (quadrature_mode)
> +		mode_cfg |= (priv->quadrature_scale[chan->channel] + 1) << 3;
> +	else {
> +		/* Quadrature scaling only available in quadrature mode */
> +		priv->quadrature_scale[chan->channel] = 0;
> +
> +		/* Synchronous function not supported in non-quadrature mode */
> +		if (priv->synchronous_mode[chan->channel])
> +			quad8_set_synchronous_mode(indio_dev, chan, 0);
> +	}
> +
> +	priv->quadrature_mode[chan->channel] = quadrature_mode;
> +
> +	/* Load mode configuration to Counter Mode Register */
> +	outb(0x20 | mode_cfg, base_offset);
> +
> +	return 0;
> +}
> +
> +static int quad8_get_quadrature_mode(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan)
> +{
> +	const struct quad8_iio *const priv = iio_priv(indio_dev);
> +
> +	return priv->quadrature_mode[chan->channel];
> +}
> +
> +static const struct iio_enum quad8_quadrature_mode_enum = {
> +	.items = quad8_quadrature_modes,
> +	.num_items = ARRAY_SIZE(quad8_quadrature_modes),
> +	.set = quad8_set_quadrature_mode,
> +	.get = quad8_get_quadrature_mode
> +};
> +
> +static const char *const quad8_index_polarity_modes[] = {
> +	"negative",
> +	"positive"
> +};
> +
> +static int quad8_set_index_polarity(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan, unsigned int index_polarity)
> +{
> +	struct quad8_iio *const priv = iio_priv(indio_dev);
> +	const unsigned int idr_cfg = priv->synchronous_mode[chan->channel] |
> +		index_polarity << 1;
> +	const int base_offset = priv->base + 2 * chan->channel + 1;
> +
> +	priv->index_polarity[chan->channel] = index_polarity;
> +
> +	/* Load Index Control configuration to Index Control Register */
> +	outb(0x40 | idr_cfg, base_offset);
> +
> +	return 0;
> +}
> +
> +static int quad8_get_index_polarity(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan)
> +{
> +	const struct quad8_iio *const priv = iio_priv(indio_dev);
> +
> +	return priv->index_polarity[chan->channel];
> +}
> +
> +static const struct iio_enum quad8_index_polarity_enum = {
> +	.items = quad8_index_polarity_modes,
> +	.num_items = ARRAY_SIZE(quad8_index_polarity_modes),
> +	.set = quad8_set_index_polarity,
> +	.get = quad8_get_index_polarity
> +};
> +
> +static const struct iio_chan_spec_ext_info quad8_count_ext_info[] = {
> +	{
> +		.name = "preset",
> +		.shared = IIO_SEPARATE,
> +		.read = quad8_read_preset,
> +		.write = quad8_write_preset
> +	},
> +	{
> +		.name = "set_to_preset_on_index",
> +		.shared = IIO_SEPARATE,
> +		.read = quad8_read_set_to_preset_on_index,
> +		.write = quad8_write_set_to_preset_on_index
> +	},
> +	IIO_ENUM("noise_error", IIO_SEPARATE, &quad8_noise_error_enum),
> +	IIO_ENUM_AVAILABLE("noise_error", &quad8_noise_error_enum),
> +	IIO_ENUM("count_direction", IIO_SEPARATE, &quad8_count_direction_enum),
> +	IIO_ENUM_AVAILABLE("count_direction", &quad8_count_direction_enum),
> +	IIO_ENUM("count_mode", IIO_SEPARATE, &quad8_count_mode_enum),
> +	IIO_ENUM_AVAILABLE("count_mode", &quad8_count_mode_enum),
> +	IIO_ENUM("quadrature_mode", IIO_SEPARATE, &quad8_quadrature_mode_enum),
> +	IIO_ENUM_AVAILABLE("quadrature_mode", &quad8_quadrature_mode_enum),
> +	{}
> +};
> +
> +static const struct iio_chan_spec_ext_info quad8_index_ext_info[] = {
> +	IIO_ENUM("synchronous_mode", IIO_SEPARATE,
> +		&quad8_synchronous_mode_enum),
> +	IIO_ENUM_AVAILABLE("synchronous_mode", &quad8_synchronous_mode_enum),
> +	IIO_ENUM("index_polarity", IIO_SEPARATE, &quad8_index_polarity_enum),
> +	IIO_ENUM_AVAILABLE("index_polarity", &quad8_index_polarity_enum),
> +	{}
> +};
> +
> +#define QUAD8_COUNT_CHAN(_chan) {					\
> +	.type = IIO_COUNT,						\
> +	.channel = (_chan),						\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
> +		BIT(IIO_CHAN_INFO_ENABLE) | BIT(IIO_CHAN_INFO_SCALE),	\
> +	.ext_info = quad8_count_ext_info,				\
> +	.indexed = 1							\
> +}
> +
> +#define QUAD8_INDEX_CHAN(_chan) {			\
> +	.type = IIO_INDEX,				\
> +	.channel = (_chan),				\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
> +	.ext_info = quad8_index_ext_info,		\
> +	.indexed = 1					\
> +}
> +
> +static const struct iio_chan_spec quad8_channels[] = {
> +	QUAD8_COUNT_CHAN(0), QUAD8_INDEX_CHAN(0),
> +	QUAD8_COUNT_CHAN(1), QUAD8_INDEX_CHAN(1),
> +	QUAD8_COUNT_CHAN(2), QUAD8_INDEX_CHAN(2),
> +	QUAD8_COUNT_CHAN(3), QUAD8_INDEX_CHAN(3),
> +	QUAD8_COUNT_CHAN(4), QUAD8_INDEX_CHAN(4),
> +	QUAD8_COUNT_CHAN(5), QUAD8_INDEX_CHAN(5),
> +	QUAD8_COUNT_CHAN(6), QUAD8_INDEX_CHAN(6),
> +	QUAD8_COUNT_CHAN(7), QUAD8_INDEX_CHAN(7)
> +};
> +
> +static int quad8_probe(struct device *dev, unsigned int id)
> +{
> +	struct iio_dev *indio_dev;
> +	struct quad8_iio *priv;
> +	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))) {
> +		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);
> +
> +	priv = iio_priv(indio_dev);
> +	priv->base = base[id];
> +
> +	/* Reset all counters and disable interrupt function */
> +	outb(0x01, base[id] + 0x11);
> +	/* Set initial configuration for all counters */
> +	for (i = 0; i < QUAD8_NUM_COUNTERS; i++) {
> +		base_offset = base[id] + 2 * i;
> +		/* Reset Byte Pointer */
> +		outb(0x01, base_offset + 1);
> +		/* Reset Preset Register */
> +		for (j = 0; j < 3; j++)
> +			outb(0x00, base_offset);
> +		/* Reset Borrow, Carry, Compare, and Sign flags */
> +		outb(0x04, base_offset + 1);
> +		/* Reset Error flag */
> +		outb(0x06, base_offset + 1);
> +		/* Binary encoding; Normal count; non-quadrature mode */
> +		outb(0x20, base_offset + 1);
> +		/* Disable A and B inputs; preset on index; FLG1 as Carry */
> +		outb(0x40, base_offset + 1);
> +		/* Disable index function; negative index polarity */
> +		outb(0x60, base_offset + 1);
> +	}
> +	/* Enable all counters */
> +	outb(0x00, base[id] + 0x11);
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +static struct isa_driver quad8_driver = {
> +	.probe = quad8_probe,
> +	.driver = {
> +		.name = "104-quad-8"
> +	}
> +};
> +
> +module_isa_driver(quad8_driver, num_quad8);
> +
> +MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
> +MODULE_DESCRIPTION("ACCES 104-QUAD-8 IIO driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/counter/Kconfig b/drivers/iio/counter/Kconfig
> new file mode 100644
> index 0000000..44627f6
> --- /dev/null
> +++ b/drivers/iio/counter/Kconfig
> @@ -0,0 +1,24 @@
> +#
> +# Counter devices
> +#
> +# When adding new entries keep the list in alphabetical order
> +
> +menu "Counters"
> +
> +config 104_QUAD_8
> +	tristate "ACCES 104-QUAD-8 driver"
> +	depends on X86 && ISA_BUS_API
> +	help
> +	  Say yes here to build support for the ACCES 104-QUAD-8 quadrature
> +	  encoder counter/interface device family (104-QUAD-8, 104-QUAD-4).
> +
> +	  Performing a write to a counter's IIO_CHAN_INFO_RAW sets the counter and
> +	  also clears the counter's respective error flag. Although the counters
> +	  have a 25-bit range, only the lower 24 bits may be set, either directly
> +	  or via a counter's preset attribute. Interrupts are not supported by
> +	  this driver.
> +
> +	  The base port addresses for the devices may be configured via the base
> +	  array module parameter.
> +
> +endmenu
> diff --git a/drivers/iio/counter/Makefile b/drivers/iio/counter/Makefile
> new file mode 100644
> index 0000000..007e884
> --- /dev/null
> +++ b/drivers/iio/counter/Makefile
> @@ -0,0 +1,7 @@
> +#
> +# Makefile for IIO counter devices
> +#
> +
> +# When adding new entries keep the list in alphabetical order
> +
> +obj-$(CONFIG_104_QUAD_8)	+= 104-quad-8.o
> 

Re: [PATCH v5 1/2] iio: Implement counter channel type and info constants

[Jonathan Cameron]

On 28/09/16 18:59, William Breathitt Gray wrote:
> Quadrature encoders, such as rotary encoders and linear encoders, are
> devices which are capable of encoding the relative position and
> direction of motion of a shaft. This patch introduces several IIO
> constants for supporting quadrature encoder counter devices.
> 
>   IIO_COUNT: Current count (main data provided by the counter device)
>   IIO_INDEX: Counter device index value
> 
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Applied

Thanks,
> ---
>  Documentation/ABI/testing/sysfs-bus-iio | 18 ++++++++++++++++++
>  drivers/iio/industrialio-core.c         |  2 ++
>  include/uapi/linux/iio/types.h          |  2 ++
>  3 files changed, 22 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> index fee35c0..b8f220f 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio
> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> @@ -329,6 +329,7 @@ What:		/sys/bus/iio/devices/iio:deviceX/in_pressure_scale
>  What:		/sys/bus/iio/devices/iio:deviceX/in_humidityrelative_scale
>  What:		/sys/bus/iio/devices/iio:deviceX/in_velocity_sqrt(x^2+y^2+z^2)_scale
>  What:		/sys/bus/iio/devices/iio:deviceX/in_illuminance_scale
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_scale
>  KernelVersion:	2.6.35
>  Contact:	linux-iio@vger.kernel.org
>  Description:
> @@ -1579,3 +1580,20 @@ Contact:	linux-iio@vger.kernel.org
>  Description:
>  		Raw (unscaled no offset etc.) electric conductivity reading that
>  		can be processed to siemens per meter.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_raw
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Raw counter device counts from channel Y. For quadrature
> +		counters, multiplication by an available [Y]_scale results in
> +		the counts of a single quadrature signal phase from channel Y.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_indexY_raw
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Raw counter device index value from channel Y. This attribute
> +		provides an absolute positional reference (e.g. a pulse once per
> +		revolution) which may be used to home positional systems as
> +		required.
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index fc340ed..649725b 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -81,6 +81,8 @@ static const char * const iio_chan_type_name_spec[] = {
>  	[IIO_PH] = "ph",
>  	[IIO_UVINDEX] = "uvindex",
>  	[IIO_ELECTRICALCONDUCTIVITY] = "electricalconductivity",
> +	[IIO_COUNT] = "count",
> +	[IIO_INDEX] = "index",
>  };
>  
>  static const char * const iio_modifier_names[] = {
> diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h
> index 22e5e58..e54d14a 100644
> --- a/include/uapi/linux/iio/types.h
> +++ b/include/uapi/linux/iio/types.h
> @@ -40,6 +40,8 @@ enum iio_chan_type {
>  	IIO_PH,
>  	IIO_UVINDEX,
>  	IIO_ELECTRICALCONDUCTIVITY,
> +	IIO_COUNT,
> +	IIO_INDEX,
>  };
>  
>  enum iio_modifier {
>