[PATCH v2 0/3] iio: stx104: Add IIO support for the ADC channels

[PATCH v2 0/3] iio: stx104: Add IIO support for the ADC channels

[William Breathitt Gray]

Changes in v2:
  - IIO_CHAN_INFO_RAW mask used for analog input channels
  - STX104_ prefix added to IN_CHAN_OFFSET define
  - STX104_MAX_NUM_CHAN define removed as unnecessary
  - Whitespace added to pad comment about ADC sample capture and completion wait
  - Switch statement in write_raw callback refactored to return 0
  - Comma added to last element initialization of stx104_info
  - Comment added to warn why stx104_channels is not const
  - Comment added to explain GPIO offset in gpio_get_direction callback
  - ARRAY_SIZE macro utilized to get number of channels in stx104_channels
  - Replace devm_iio_device_register with iio_device_register call and
    respective iio_device_unregister call
  - Perform GPIO chip registration before iio_device_register to prevent race
    condition

The first patch in this patchset ("iio: stx104: Unregister IIO device on remove
callback") fixes the improper registration of the IIO device by replacing the
devm_iio_device_register call with a iio_device_register call and a subsequent
iio_device_unregister call in the remove callback. This issue when GPIO support
was added in commit 765550e4d98d ("iio: stx104: Add GPIO support for the Apex
Embedded Systems STX104"); a remove callback was introduced, but
devm_iio_device_register related code was not reimplemented.

The second patch is the actual code to implement the ADC support, while the
third patch is simply to move the STX104 driver to the IIO ADC directory; I
separated the move to its own patch in order to make the addition of the ADC
support code clear in the commit log.

William Breathitt Gray (3):
  iio: stx104: Unregister IIO device on remove callback
  iio: stx104: Add IIO support for the ADC channels
  iio: stx104: Move the STX104 IIO driver to the ADC directory

 MAINTAINERS              |   2 +-
 drivers/iio/adc/Kconfig  |  15 ++
 drivers/iio/adc/Makefile |   1 +
 drivers/iio/adc/stx104.c | 390 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/iio/dac/Kconfig  |  10 --
 drivers/iio/dac/Makefile |   1 -
 drivers/iio/dac/stx104.c | 255 -------------------------------
 7 files changed, 407 insertions(+), 267 deletions(-)
 create mode 100644 drivers/iio/adc/stx104.c
 delete mode 100644 drivers/iio/dac/stx104.c

-- 
2.7.3

[PATCH v2 1/3] iio: stx104: Unregister IIO device on remove callback

[William Breathitt Gray]

The devm_iio_device_register function should not be used if custom
operations must be performed in the remove callback. This patch replaces
the dem_iio_device_register call with a iio_device_register call and
respective iio_device_unregister call in the remove callback.

Fixes: 765550e4d98d ("iio: stx104: Add GPIO support for the Apex Embedded Systems STX104")
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 drivers/iio/dac/stx104.c | 38 +++++++++++++++++++++++++++++---------
 1 file changed, 29 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/dac/stx104.c b/drivers/iio/dac/stx104.c
index 792a971..bebbd00 100644
--- a/drivers/iio/dac/stx104.c
+++ b/drivers/iio/dac/stx104.c
@@ -65,6 +65,16 @@ struct stx104_gpio {
 	unsigned int out_state;
 };
 
+/**
+ * struct stx104_dev - STX104 device private data structure
+ * @indio_dev:	IIO device
+ * @chip:	instance of the gpio_chip
+ */
+struct stx104_dev {
+	struct iio_dev *indio_dev;
+	struct gpio_chip *chip;
+};
+
 static int stx104_read_raw(struct iio_dev *indio_dev,
 	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
 {
@@ -107,6 +117,7 @@ static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
 static int stx104_gpio_get_direction(struct gpio_chip *chip,
 	unsigned int offset)
 {
+	/* GPIO 0-3 are input only, while the rest are output only */
 	if (offset < 4)
 		return 1;
 
@@ -169,6 +180,7 @@ static int stx104_probe(struct device *dev, unsigned int id)
 	struct iio_dev *indio_dev;
 	struct stx104_iio *priv;
 	struct stx104_gpio *stx104gpio;
+	struct stx104_dev *stx104dev;
 	int err;
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
@@ -179,6 +191,10 @@ static int stx104_probe(struct device *dev, unsigned int id)
 	if (!stx104gpio)
 		return -ENOMEM;
 
+	stx104dev = devm_kzalloc(dev, sizeof(*stx104dev), GFP_KERNEL);
+	if (!stx104dev)
+		return -ENOMEM;
+
 	if (!devm_request_region(dev, base[id], STX104_EXTENT,
 		dev_name(dev))) {
 		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
@@ -199,12 +215,6 @@ static int stx104_probe(struct device *dev, unsigned int id)
 	outw(0, base[id] + 4);
 	outw(0, base[id] + 6);
 
-	err = devm_iio_device_register(dev, indio_dev);
-	if (err) {
-		dev_err(dev, "IIO device registering failed (%d)\n", err);
-		return err;
-	}
-
 	stx104gpio->chip.label = dev_name(dev);
 	stx104gpio->chip.parent = dev;
 	stx104gpio->chip.owner = THIS_MODULE;
@@ -220,7 +230,9 @@ static int stx104_probe(struct device *dev, unsigned int id)
 
 	spin_lock_init(&stx104gpio->lock);
 
-	dev_set_drvdata(dev, stx104gpio);
+	stx104dev->indio_dev = indio_dev;
+	stx104dev->chip = &stx104gpio->chip;
+	dev_set_drvdata(dev, stx104dev);
 
 	err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
 	if (err) {
@@ -228,14 +240,22 @@ static int stx104_probe(struct device *dev, unsigned int id)
 		return err;
 	}
 
+	err = iio_device_register(indio_dev);
+	if (err) {
+		dev_err(dev, "IIO device registering failed (%d)\n", err);
+		gpiochip_remove(&stx104gpio->chip);
+		return err;
+	}
+
 	return 0;
 }
 
 static int stx104_remove(struct device *dev, unsigned int id)
 {
-	struct stx104_gpio *const stx104gpio = dev_get_drvdata(dev);
+	struct stx104_dev *const stx104dev = dev_get_drvdata(dev);
 
-	gpiochip_remove(&stx104gpio->chip);
+	iio_device_unregister(stx104dev->indio_dev);
+	gpiochip_remove(stx104dev->chip);
 
 	return 0;
 }
-- 
2.7.3

[PATCH v2 2/3] iio: stx104: Add IIO support for the ADC channels

[William Breathitt Gray]

The Apex Embedded Systems STX104 features 16 channels of single-ended (8
channels of true differential) 16-bit analog input. Differential input
configuration may be selected via a physical jumper on the device.
Similarly, input polarity (unipolar/bipolar) is configured via a
physical jumper on the device.

Input gain selection is available to the user via software, thus
allowing eight possible input ranges: +-10V, +-5V, +-2.5V, +-1.25V,
0 to 10V, 0 to 5V, 0 to 2.5V, and 0 to 1.25V. Four input gain
configurations are supported: x1, x2, x4, and x8.

This ADC resolution is 16-bits (1/65536 of full scale). Analog input
samples are taken on software trigger; neither FIFO sampling nor
interrupt triggering is supported by this driver.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 drivers/iio/dac/Kconfig  |  15 +++--
 drivers/iio/dac/stx104.c | 159 ++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 147 insertions(+), 27 deletions(-)

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index ca81447..60294ef 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -246,14 +246,19 @@ config MCP4922
 	  will be called mcp4922.
 
 config STX104
-	tristate "Apex Embedded Systems STX104 DAC driver"
+	tristate "Apex Embedded Systems STX104 driver"
 	depends on X86 && ISA_BUS_API
 	select GPIOLIB
 	help
-	  Say yes here to build support for the 2-channel DAC and GPIO on the
-	  Apex Embedded Systems STX104 integrated analog PC/104 card. The base
-	  port addresses for the devices may be configured via the base array
-	  module parameter.
+	  Say yes here to build support for the Apex Embedded Systems STX104
+	  integrated analog PC/104 card.
+
+	  This driver supports the 16 channels of single-ended (8 channels of
+	  differential) analog inputs, 2 channels of analog output, 4 digital
+	  inputs, and 4 digital outputs provided by the STX104.
+
+	  The base port addresses for the devices may be configured via the base
+	  array module parameter.
 
 config VF610_DAC
 	tristate "Vybrid vf610 DAC driver"
diff --git a/drivers/iio/dac/stx104.c b/drivers/iio/dac/stx104.c
index bebbd00..51f6534 100644
--- a/drivers/iio/dac/stx104.c
+++ b/drivers/iio/dac/stx104.c
@@ -1,5 +1,5 @@
 /*
- * DAC driver for the Apex Embedded Systems STX104
+ * IIO driver for the Apex Embedded Systems STX104
  * Copyright (C) 2016 William Breathitt Gray
  *
  * This program is free software; you can redistribute it and/or modify
@@ -20,21 +20,32 @@
 #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/spinlock.h>
 
-#define STX104_NUM_CHAN 2
+#define STX104_EXTENT 16
 
-#define STX104_CHAN(chan) {				\
+#define STX104_IO_CHAN(chan, dir) {			\
 	.type = IIO_VOLTAGE,				\
 	.channel = chan,				\
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
 	.indexed = 1,					\
-	.output = 1					\
+	.output = dir					\
+}
+#define STX104_GAIN_CHAN {					\
+	.type = IIO_VOLTAGE,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),	\
+	.output = 1						\
 }
+#define STX104_OUT_CHAN(chan) STX104_IO_CHAN(chan, 1)
+#define STX104_IN_CHAN(chan) STX104_IO_CHAN(chan, 0)
 
-#define STX104_EXTENT 16
+#define STX104_NUM_OUT_CHAN 2
+#define STX104_NUM_GAIN_CHAN 1
+#define STX104_NUM_IN_CHAN 16
+#define STX104_IN_CHAN_OFFSET (STX104_NUM_OUT_CHAN + STX104_NUM_GAIN_CHAN)
 
 static unsigned int base[max_num_isa_dev(STX104_EXTENT)];
 static unsigned int num_stx104;
@@ -47,7 +58,7 @@ MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
  * @base:		base port address of the IIO device
  */
 struct stx104_iio {
-	unsigned chan_out_states[STX104_NUM_CHAN];
+	unsigned int chan_out_states[STX104_NUM_OUT_CHAN];
 	unsigned base;
 };
 
@@ -79,39 +90,123 @@ static int stx104_read_raw(struct iio_dev *indio_dev,
 	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
 {
 	struct stx104_iio *const priv = iio_priv(indio_dev);
+	long adc_sample;
+	unsigned int adc_config;
+	long adbu;
+	unsigned int gain;
+
+	/* handle output channels */
+	if (chan->output) {
+		switch (mask) {
+		case IIO_CHAN_INFO_RAW:
+			*val = priv->chan_out_states[chan->channel];
+			return IIO_VAL_INT;
+		case IIO_CHAN_INFO_HARDWAREGAIN:
+			*val = 1 << (inb(priv->base + 11) & 0x3);
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	}
 
 	if (mask != IIO_CHAN_INFO_RAW)
 		return -EINVAL;
 
-	*val = priv->chan_out_states[chan->channel];
-
-	return IIO_VAL_INT;
+	/* select ADC channel */
+	outb(chan->channel | (chan->channel << 4), priv->base + 2);
+
+	/* trigger ADC sample capture and wait for completion */
+	outb(0, priv->base);
+	while (inb(priv->base + 8) & BIT(7));
+
+	adc_sample = inw(priv->base);
+
+	/* get ADC bipolar/unipolar and gain configuration */
+	adc_config = inb(priv->base + 11);
+	adbu = !(adc_config & BIT(2));
+	gain = adc_config & 0x3;
+
+	/* Value conversion math:
+	 * ----------------------
+	 * scale = adc_sample / 65536
+	 * range = 10 / (1 << gain)
+	 * voltage = scale * (range + adbu * range) - adbu * range
+	 *
+	 * Simplified:
+	 * -----------
+	 * voltage = 5 * (adc_sample * (1 + adbu) - adbu * 65536) /
+	 *	(1 << (15 + gain))
+	 *
+	 * Portability Caution:
+	 * --------------------
+	 * *val will be set to a value between -327680 and 327675; in order to
+	 * prevent integer underflow/overflow, the int data type of the
+	 * implementation should be capable of representing this value range.
+	 */
+	*val = 5 * (adc_sample * (1 + adbu) - adbu * 65536);
+	*val2 = 15 + gain;
+
+	return IIO_VAL_FRACTIONAL_LOG2;
 }
 
 static int stx104_write_raw(struct iio_dev *indio_dev,
 	struct iio_chan_spec const *chan, int val, int val2, long mask)
 {
 	struct stx104_iio *const priv = iio_priv(indio_dev);
-	const unsigned chan_addr_offset = 2 * chan->channel;
 
-	if (mask != IIO_CHAN_INFO_RAW)
-		return -EINVAL;
-
-	priv->chan_out_states[chan->channel] = val;
-	outw(val, priv->base + 4 + chan_addr_offset);
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/* DAC can only accept up to a 16-bit value */
+		if ((unsigned int)val > 65535)
+			return -EINVAL;
+
+		priv->chan_out_states[chan->channel] = val;
+		outw(val, priv->base + 4 + 2 * chan->channel);
+
+		return 0;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		/* Only four gain states (x1, x2, x4, x8) */
+		switch (val) {
+		case 1:
+			outb(0, priv->base + 11);
+			break;
+		case 2:
+			outb(1, priv->base + 11);
+			break;
+		case 4:
+			outb(2, priv->base + 11);
+			break;
+		case 8:
+			outb(3, priv->base + 11);
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		return 0;
+	}
 
-	return 0;
+	return -EINVAL;
 }
 
 static const struct iio_info stx104_info = {
 	.driver_module = THIS_MODULE,
 	.read_raw = stx104_read_raw,
-	.write_raw = stx104_write_raw
+	.write_raw = stx104_write_raw,
 };
 
-static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
-	STX104_CHAN(0),
-	STX104_CHAN(1)
+/* stx104_channels is not const in order to allow for the configuration of
+ * differential channels in the probe callback if a device is setup for such
+ */
+static struct iio_chan_spec stx104_channels[] = {
+	STX104_OUT_CHAN(0), STX104_OUT_CHAN(1),
+	STX104_GAIN_CHAN,
+	STX104_IN_CHAN(0), STX104_IN_CHAN(1), STX104_IN_CHAN(2),
+	STX104_IN_CHAN(3), STX104_IN_CHAN(4), STX104_IN_CHAN(5),
+	STX104_IN_CHAN(6), STX104_IN_CHAN(7), STX104_IN_CHAN(8),
+	STX104_IN_CHAN(9), STX104_IN_CHAN(10), STX104_IN_CHAN(11),
+	STX104_IN_CHAN(12), STX104_IN_CHAN(13), STX104_IN_CHAN(14),
+	STX104_IN_CHAN(15)
 };
 
 static int stx104_gpio_get_direction(struct gpio_chip *chip,
@@ -181,6 +276,8 @@ static int stx104_probe(struct device *dev, unsigned int id)
 	struct stx104_iio *priv;
 	struct stx104_gpio *stx104gpio;
 	struct stx104_dev *stx104dev;
+	struct iio_chan_spec *input_channel;
+	int i;
 	int err;
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
@@ -204,13 +301,31 @@ static int stx104_probe(struct device *dev, unsigned int id)
 
 	indio_dev->info = &stx104_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->num_channels = ARRAY_SIZE(stx104_channels);
+
+	/* determine if differential inputs */
+	if (inb(base[id] + 8) & BIT(5)) {
+		indio_dev->num_channels -= STX104_NUM_IN_CHAN / 2;
+
+		input_channel = stx104_channels + STX104_IN_CHAN_OFFSET;
+		for (i = 0; i < STX104_NUM_IN_CHAN / 2; input_channel++) {
+			input_channel->differential = 1;
+			input_channel->channel2 = i;
+		}
+	}
+
 	indio_dev->channels = stx104_channels;
-	indio_dev->num_channels = STX104_NUM_CHAN;
 	indio_dev->name = dev_name(dev);
 
 	priv = iio_priv(indio_dev);
 	priv->base = base[id];
 
+	/* configure device for software trigger operation */
+	outb(0, base[id] + 9);
+
+	/* initialize gain setting to x1 */
+	outb(0, base[id] + 11);
+
 	/* initialize DAC output to 0V */
 	outw(0, base[id] + 4);
 	outw(0, base[id] + 6);
@@ -271,5 +386,5 @@ static struct isa_driver stx104_driver = {
 module_isa_driver(stx104_driver, num_stx104);
 
 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
-MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
+MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
 MODULE_LICENSE("GPL v2");
-- 
2.7.3

[PATCH v2 3/3] iio: stx104: Move the STX104 IIO driver to the ADC directory

[William Breathitt Gray]

The Apex Embedded Systems STX104 is primarily an analog-to-digital
converter device. The STX104 IIO driver was initially placed in the DAC
directory because only the DAC portion of the STX104 was supported at
the time. Now that ADC support has been added to the STX104 IIO driver,
the driver should be moved to the more appropriate ADC directory.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 MAINTAINERS              |   2 +-
 drivers/iio/adc/Kconfig  |  15 ++
 drivers/iio/adc/Makefile |   1 +
 drivers/iio/adc/stx104.c | 390 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/iio/dac/Kconfig  |  15 --
 drivers/iio/dac/Makefile |   1 -
 drivers/iio/dac/stx104.c | 390 -----------------------------------------------
 7 files changed, 407 insertions(+), 407 deletions(-)
 create mode 100644 drivers/iio/adc/stx104.c
 delete mode 100644 drivers/iio/dac/stx104.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 345e757..95dd91b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -796,7 +796,7 @@ APEX EMBEDDED SYSTEMS STX104 DAC DRIVER
 M:	William Breathitt Gray <vilhelm.gray@gmail.com>
 L:	linux-iio@vger.kernel.org
 S:	Maintained
-F:	drivers/iio/dac/stx104.c
+F:	drivers/iio/adc/stx104.c
 
 APM DRIVER
 M:	Jiri Kosina <jikos@kernel.org>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 1de31bd..ec9ada8 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -396,6 +396,21 @@ config ROCKCHIP_SARADC
 	  To compile this driver as a module, choose M here: the
 	  module will be called rockchip_saradc.
 
+config STX104
+	tristate "Apex Embedded Systems STX104 driver"
+	depends on X86 && ISA_BUS_API
+	select GPIOLIB
+	help
+	  Say yes here to build support for the Apex Embedded Systems STX104
+	  integrated analog PC/104 card.
+
+	  This driver supports the 16 channels of single-ended (8 channels of
+	  differential) analog inputs, 2 channels of analog output, 4 digital
+	  inputs, and 4 digital outputs provided by the STX104.
+
+	  The base port addresses for the devices may be configured via the base
+	  array module parameter.
+
 config TI_ADC081C
 	tristate "Texas Instruments ADC081C/ADC101C/ADC121C family"
 	depends on I2C
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 0ba0d50..d7b4a71 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
 obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
 obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
+obj-$(CONFIG_STX104) += stx104.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
 obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
 obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
diff --git a/drivers/iio/adc/stx104.c b/drivers/iio/adc/stx104.c
new file mode 100644
index 0000000..6f13d2c
--- /dev/null
+++ b/drivers/iio/adc/stx104.c
@@ -0,0 +1,390 @@
+/*
+ * IIO driver for the Apex Embedded Systems STX104
+ * 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.
+ */
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/gpio/driver.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/spinlock.h>
+
+#define STX104_EXTENT 16
+
+#define STX104_IO_CHAN(chan, dir) {			\
+	.type = IIO_VOLTAGE,				\
+	.channel = chan,				\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
+	.indexed = 1,					\
+	.output = dir					\
+}
+#define STX104_GAIN_CHAN {					\
+	.type = IIO_VOLTAGE,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),	\
+	.output = 1						\
+}
+#define STX104_OUT_CHAN(chan) STX104_IO_CHAN(chan, 1)
+#define STX104_IN_CHAN(chan) STX104_IO_CHAN(chan, 0)
+
+#define STX104_NUM_OUT_CHAN 2
+#define STX104_NUM_GAIN_CHAN 1
+#define STX104_NUM_IN_CHAN 16
+#define STX104_IN_CHAN_OFFSET (STX104_NUM_OUT_CHAN + STX104_NUM_GAIN_CHAN)
+
+static unsigned int base[max_num_isa_dev(STX104_EXTENT)];
+static unsigned int num_stx104;
+module_param_array(base, uint, &num_stx104, 0);
+MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
+
+/**
+ * struct stx104_iio - IIO device private data structure
+ * @chan_out_states:	channels' output states
+ * @base:		base port address of the IIO device
+ */
+struct stx104_iio {
+	unsigned int chan_out_states[STX104_NUM_OUT_CHAN];
+	unsigned int base;
+};
+
+/**
+ * struct stx104_gpio - GPIO device private data structure
+ * @chip:	instance of the gpio_chip
+ * @lock:	synchronization lock to prevent I/O race conditions
+ * @base:	base port address of the GPIO device
+ * @out_state:	output bits state
+ */
+struct stx104_gpio {
+	struct gpio_chip chip;
+	spinlock_t lock;
+	unsigned int base;
+	unsigned int out_state;
+};
+
+/**
+ * struct stx104_dev - STX104 device private data structure
+ * @indio_dev:	IIO device
+ * @chip:	instance of the gpio_chip
+ */
+struct stx104_dev {
+	struct iio_dev *indio_dev;
+	struct gpio_chip *chip;
+};
+
+static int stx104_read_raw(struct iio_dev *indio_dev,
+	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
+{
+	struct stx104_iio *const priv = iio_priv(indio_dev);
+	long adc_sample;
+	unsigned int adc_config;
+	long adbu;
+	unsigned int gain;
+
+	/* handle output channels */
+	if (chan->output) {
+		switch (mask) {
+		case IIO_CHAN_INFO_RAW:
+			*val = priv->chan_out_states[chan->channel];
+			return IIO_VAL_INT;
+		case IIO_CHAN_INFO_HARDWAREGAIN:
+			*val = 1 << (inb(priv->base + 11) & 0x3);
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	}
+
+	if (mask != IIO_CHAN_INFO_RAW)
+		return -EINVAL;
+
+	/* select ADC channel */
+	outb(chan->channel | (chan->channel << 4), priv->base + 2);
+
+	/* trigger ADC sample capture and wait for completion */
+	outb(0, priv->base);
+	while (inb(priv->base + 8) & BIT(7));
+
+	adc_sample = inw(priv->base);
+
+	/* get ADC bipolar/unipolar and gain configuration */
+	adc_config = inb(priv->base + 11);
+	adbu = !(adc_config & BIT(2));
+	gain = adc_config & 0x3;
+
+	/* Value conversion math:
+	 * ----------------------
+	 * scale = adc_sample / 65536
+	 * range = 10 / (1 << gain)
+	 * voltage = scale * (range + adbu * range) - adbu * range
+	 *
+	 * Simplified:
+	 * -----------
+	 * voltage = 5 * (adc_sample * (1 + adbu) - adbu * 65536) /
+	 *	(1 << (15 + gain))
+	 *
+	 * Portability Caution:
+	 * --------------------
+	 * *val will be set to a value between -327680 and 327675; in order to
+	 * prevent integer underflow/overflow, the int data type of the
+	 * implementation should be capable of representing this value range.
+	 */
+	*val = 5 * (adc_sample * (1 + adbu) - adbu * 65536);
+	*val2 = 15 + gain;
+
+	return IIO_VAL_FRACTIONAL_LOG2;
+}
+
+static int stx104_write_raw(struct iio_dev *indio_dev,
+	struct iio_chan_spec const *chan, int val, int val2, long mask)
+{
+	struct stx104_iio *const priv = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/* DAC can only accept up to a 16-bit value */
+		if ((unsigned int)val > 65535)
+			return -EINVAL;
+
+		priv->chan_out_states[chan->channel] = val;
+		outw(val, priv->base + 4 + 2 * chan->channel);
+
+		return 0;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		/* Only four gain states (x1, x2, x4, x8) */
+		switch (val) {
+		case 1:
+			outb(0, priv->base + 11);
+			break;
+		case 2:
+			outb(1, priv->base + 11);
+			break;
+		case 4:
+			outb(2, priv->base + 11);
+			break;
+		case 8:
+			outb(3, priv->base + 11);
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info stx104_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = stx104_read_raw,
+	.write_raw = stx104_write_raw,
+};
+
+/* stx104_channels is not const in order to allow for the configuration of
+ * differential channels in the probe callback if a device is setup for such
+ */
+static struct iio_chan_spec stx104_channels[] = {
+	STX104_OUT_CHAN(0), STX104_OUT_CHAN(1),
+	STX104_GAIN_CHAN,
+	STX104_IN_CHAN(0), STX104_IN_CHAN(1), STX104_IN_CHAN(2),
+	STX104_IN_CHAN(3), STX104_IN_CHAN(4), STX104_IN_CHAN(5),
+	STX104_IN_CHAN(6), STX104_IN_CHAN(7), STX104_IN_CHAN(8),
+	STX104_IN_CHAN(9), STX104_IN_CHAN(10), STX104_IN_CHAN(11),
+	STX104_IN_CHAN(12), STX104_IN_CHAN(13), STX104_IN_CHAN(14),
+	STX104_IN_CHAN(15)
+};
+
+static int stx104_gpio_get_direction(struct gpio_chip *chip,
+	unsigned int offset)
+{
+	/* GPIO 0-3 are input only, while the rest are output only */
+	if (offset < 4)
+		return 1;
+
+	return 0;
+}
+
+static int stx104_gpio_direction_input(struct gpio_chip *chip,
+	unsigned int offset)
+{
+	if (offset >= 4)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int stx104_gpio_direction_output(struct gpio_chip *chip,
+	unsigned int offset, int value)
+{
+	if (offset < 4)
+		return -EINVAL;
+
+	chip->set(chip, offset, value);
+	return 0;
+}
+
+static int stx104_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
+
+	if (offset >= 4)
+		return -EINVAL;
+
+	return !!(inb(stx104gpio->base) & BIT(offset));
+}
+
+static void stx104_gpio_set(struct gpio_chip *chip, unsigned int offset,
+	int value)
+{
+	struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
+	const unsigned int mask = BIT(offset) >> 4;
+	unsigned long flags;
+
+	if (offset < 4)
+		return;
+
+	spin_lock_irqsave(&stx104gpio->lock, flags);
+
+	if (value)
+		stx104gpio->out_state |= mask;
+	else
+		stx104gpio->out_state &= ~mask;
+
+	outb(stx104gpio->out_state, stx104gpio->base);
+
+	spin_unlock_irqrestore(&stx104gpio->lock, flags);
+}
+
+static int stx104_probe(struct device *dev, unsigned int id)
+{
+	struct iio_dev *indio_dev;
+	struct stx104_iio *priv;
+	struct stx104_gpio *stx104gpio;
+	struct stx104_dev *stx104dev;
+	struct iio_chan_spec *input_channel;
+	int i;
+	int err;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	stx104gpio = devm_kzalloc(dev, sizeof(*stx104gpio), GFP_KERNEL);
+	if (!stx104gpio)
+		return -ENOMEM;
+
+	stx104dev = devm_kzalloc(dev, sizeof(*stx104dev), GFP_KERNEL);
+	if (!stx104dev)
+		return -ENOMEM;
+
+	if (!devm_request_region(dev, base[id], STX104_EXTENT,
+		dev_name(dev))) {
+		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
+			base[id], base[id] + STX104_EXTENT);
+		return -EBUSY;
+	}
+
+	indio_dev->info = &stx104_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->num_channels = ARRAY_SIZE(stx104_channels);
+
+	/* determine if differential inputs */
+	if (inb(base[id] + 8) & BIT(5)) {
+		indio_dev->num_channels -= STX104_NUM_IN_CHAN / 2;
+
+		input_channel = stx104_channels + STX104_IN_CHAN_OFFSET;
+		for (i = 0; i < STX104_NUM_IN_CHAN / 2; input_channel++) {
+			input_channel->differential = 1;
+			input_channel->channel2 = i;
+		}
+	}
+
+	indio_dev->channels = stx104_channels;
+	indio_dev->name = dev_name(dev);
+
+	priv = iio_priv(indio_dev);
+	priv->base = base[id];
+
+	/* configure device for software trigger operation */
+	outb(0, base[id] + 9);
+
+	/* initialize gain setting to x1 */
+	outb(0, base[id] + 11);
+
+	/* initialize DAC output to 0V */
+	outw(0, base[id] + 4);
+	outw(0, base[id] + 6);
+
+	stx104gpio->chip.label = dev_name(dev);
+	stx104gpio->chip.parent = dev;
+	stx104gpio->chip.owner = THIS_MODULE;
+	stx104gpio->chip.base = -1;
+	stx104gpio->chip.ngpio = 8;
+	stx104gpio->chip.get_direction = stx104_gpio_get_direction;
+	stx104gpio->chip.direction_input = stx104_gpio_direction_input;
+	stx104gpio->chip.direction_output = stx104_gpio_direction_output;
+	stx104gpio->chip.get = stx104_gpio_get;
+	stx104gpio->chip.set = stx104_gpio_set;
+	stx104gpio->base = base[id] + 3;
+	stx104gpio->out_state = 0x0;
+
+	spin_lock_init(&stx104gpio->lock);
+
+	stx104dev->indio_dev = indio_dev;
+	stx104dev->chip = &stx104gpio->chip;
+	dev_set_drvdata(dev, stx104dev);
+
+	err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
+	if (err) {
+		dev_err(dev, "GPIO registering failed (%d)\n", err);
+		return err;
+	}
+
+	err = iio_device_register(indio_dev);
+	if (err) {
+		dev_err(dev, "IIO device registering failed (%d)\n", err);
+		gpiochip_remove(&stx104gpio->chip);
+		return err;
+	}
+
+	return 0;
+}
+
+static int stx104_remove(struct device *dev, unsigned int id)
+{
+	struct stx104_dev *const stx104dev = dev_get_drvdata(dev);
+
+	iio_device_unregister(stx104dev->indio_dev);
+	gpiochip_remove(stx104dev->chip);
+
+	return 0;
+}
+
+static struct isa_driver stx104_driver = {
+	.probe = stx104_probe,
+	.driver = {
+		.name = "stx104"
+	},
+	.remove = stx104_remove
+};
+
+module_isa_driver(stx104_driver, num_stx104);
+
+MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
+MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 60294ef..d359fef 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -245,21 +245,6 @@ config MCP4922
 	  To compile this driver as a module, choose M here: the module
 	  will be called mcp4922.
 
-config STX104
-	tristate "Apex Embedded Systems STX104 driver"
-	depends on X86 && ISA_BUS_API
-	select GPIOLIB
-	help
-	  Say yes here to build support for the Apex Embedded Systems STX104
-	  integrated analog PC/104 card.
-
-	  This driver supports the 16 channels of single-ended (8 channels of
-	  differential) analog inputs, 2 channels of analog output, 4 digital
-	  inputs, and 4 digital outputs provided by the STX104.
-
-	  The base port addresses for the devices may be configured via the base
-	  array module parameter.
-
 config VF610_DAC
 	tristate "Vybrid vf610 DAC driver"
 	depends on OF
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 8b78d5c..7acb05d 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -26,5 +26,4 @@ obj-$(CONFIG_MAX517) += max517.o
 obj-$(CONFIG_MAX5821) += max5821.o
 obj-$(CONFIG_MCP4725) += mcp4725.o
 obj-$(CONFIG_MCP4922) += mcp4922.o
-obj-$(CONFIG_STX104) += stx104.o
 obj-$(CONFIG_VF610_DAC) += vf610_dac.o
diff --git a/drivers/iio/dac/stx104.c b/drivers/iio/dac/stx104.c
deleted file mode 100644
index 51f6534..0000000
--- a/drivers/iio/dac/stx104.c
+++ /dev/null
@@ -1,390 +0,0 @@
-/*
- * IIO driver for the Apex Embedded Systems STX104
- * 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.
- */
-#include <linux/bitops.h>
-#include <linux/device.h>
-#include <linux/errno.h>
-#include <linux/gpio/driver.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/spinlock.h>
-
-#define STX104_EXTENT 16
-
-#define STX104_IO_CHAN(chan, dir) {			\
-	.type = IIO_VOLTAGE,				\
-	.channel = chan,				\
-	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
-	.indexed = 1,					\
-	.output = dir					\
-}
-#define STX104_GAIN_CHAN {					\
-	.type = IIO_VOLTAGE,					\
-	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),	\
-	.output = 1						\
-}
-#define STX104_OUT_CHAN(chan) STX104_IO_CHAN(chan, 1)
-#define STX104_IN_CHAN(chan) STX104_IO_CHAN(chan, 0)
-
-#define STX104_NUM_OUT_CHAN 2
-#define STX104_NUM_GAIN_CHAN 1
-#define STX104_NUM_IN_CHAN 16
-#define STX104_IN_CHAN_OFFSET (STX104_NUM_OUT_CHAN + STX104_NUM_GAIN_CHAN)
-
-static unsigned int base[max_num_isa_dev(STX104_EXTENT)];
-static unsigned int num_stx104;
-module_param_array(base, uint, &num_stx104, 0);
-MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
-
-/**
- * struct stx104_iio - IIO device private data structure
- * @chan_out_states:	channels' output states
- * @base:		base port address of the IIO device
- */
-struct stx104_iio {
-	unsigned int chan_out_states[STX104_NUM_OUT_CHAN];
-	unsigned base;
-};
-
-/**
- * struct stx104_gpio - GPIO device private data structure
- * @chip:	instance of the gpio_chip
- * @lock:	synchronization lock to prevent I/O race conditions
- * @base:	base port address of the GPIO device
- * @out_state:	output bits state
- */
-struct stx104_gpio {
-	struct gpio_chip chip;
-	spinlock_t lock;
-	unsigned int base;
-	unsigned int out_state;
-};
-
-/**
- * struct stx104_dev - STX104 device private data structure
- * @indio_dev:	IIO device
- * @chip:	instance of the gpio_chip
- */
-struct stx104_dev {
-	struct iio_dev *indio_dev;
-	struct gpio_chip *chip;
-};
-
-static int stx104_read_raw(struct iio_dev *indio_dev,
-	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
-{
-	struct stx104_iio *const priv = iio_priv(indio_dev);
-	long adc_sample;
-	unsigned int adc_config;
-	long adbu;
-	unsigned int gain;
-
-	/* handle output channels */
-	if (chan->output) {
-		switch (mask) {
-		case IIO_CHAN_INFO_RAW:
-			*val = priv->chan_out_states[chan->channel];
-			return IIO_VAL_INT;
-		case IIO_CHAN_INFO_HARDWAREGAIN:
-			*val = 1 << (inb(priv->base + 11) & 0x3);
-			return IIO_VAL_INT;
-		default:
-			return -EINVAL;
-		}
-	}
-
-	if (mask != IIO_CHAN_INFO_RAW)
-		return -EINVAL;
-
-	/* select ADC channel */
-	outb(chan->channel | (chan->channel << 4), priv->base + 2);
-
-	/* trigger ADC sample capture and wait for completion */
-	outb(0, priv->base);
-	while (inb(priv->base + 8) & BIT(7));
-
-	adc_sample = inw(priv->base);
-
-	/* get ADC bipolar/unipolar and gain configuration */
-	adc_config = inb(priv->base + 11);
-	adbu = !(adc_config & BIT(2));
-	gain = adc_config & 0x3;
-
-	/* Value conversion math:
-	 * ----------------------
-	 * scale = adc_sample / 65536
-	 * range = 10 / (1 << gain)
-	 * voltage = scale * (range + adbu * range) - adbu * range
-	 *
-	 * Simplified:
-	 * -----------
-	 * voltage = 5 * (adc_sample * (1 + adbu) - adbu * 65536) /
-	 *	(1 << (15 + gain))
-	 *
-	 * Portability Caution:
-	 * --------------------
-	 * *val will be set to a value between -327680 and 327675; in order to
-	 * prevent integer underflow/overflow, the int data type of the
-	 * implementation should be capable of representing this value range.
-	 */
-	*val = 5 * (adc_sample * (1 + adbu) - adbu * 65536);
-	*val2 = 15 + gain;
-
-	return IIO_VAL_FRACTIONAL_LOG2;
-}
-
-static int stx104_write_raw(struct iio_dev *indio_dev,
-	struct iio_chan_spec const *chan, int val, int val2, long mask)
-{
-	struct stx104_iio *const priv = iio_priv(indio_dev);
-
-	switch (mask) {
-	case IIO_CHAN_INFO_RAW:
-		/* DAC can only accept up to a 16-bit value */
-		if ((unsigned int)val > 65535)
-			return -EINVAL;
-
-		priv->chan_out_states[chan->channel] = val;
-		outw(val, priv->base + 4 + 2 * chan->channel);
-
-		return 0;
-	case IIO_CHAN_INFO_HARDWAREGAIN:
-		/* Only four gain states (x1, x2, x4, x8) */
-		switch (val) {
-		case 1:
-			outb(0, priv->base + 11);
-			break;
-		case 2:
-			outb(1, priv->base + 11);
-			break;
-		case 4:
-			outb(2, priv->base + 11);
-			break;
-		case 8:
-			outb(3, priv->base + 11);
-			break;
-		default:
-			return -EINVAL;
-		}
-
-		return 0;
-	}
-
-	return -EINVAL;
-}
-
-static const struct iio_info stx104_info = {
-	.driver_module = THIS_MODULE,
-	.read_raw = stx104_read_raw,
-	.write_raw = stx104_write_raw,
-};
-
-/* stx104_channels is not const in order to allow for the configuration of
- * differential channels in the probe callback if a device is setup for such
- */
-static struct iio_chan_spec stx104_channels[] = {
-	STX104_OUT_CHAN(0), STX104_OUT_CHAN(1),
-	STX104_GAIN_CHAN,
-	STX104_IN_CHAN(0), STX104_IN_CHAN(1), STX104_IN_CHAN(2),
-	STX104_IN_CHAN(3), STX104_IN_CHAN(4), STX104_IN_CHAN(5),
-	STX104_IN_CHAN(6), STX104_IN_CHAN(7), STX104_IN_CHAN(8),
-	STX104_IN_CHAN(9), STX104_IN_CHAN(10), STX104_IN_CHAN(11),
-	STX104_IN_CHAN(12), STX104_IN_CHAN(13), STX104_IN_CHAN(14),
-	STX104_IN_CHAN(15)
-};
-
-static int stx104_gpio_get_direction(struct gpio_chip *chip,
-	unsigned int offset)
-{
-	/* GPIO 0-3 are input only, while the rest are output only */
-	if (offset < 4)
-		return 1;
-
-	return 0;
-}
-
-static int stx104_gpio_direction_input(struct gpio_chip *chip,
-	unsigned int offset)
-{
-	if (offset >= 4)
-		return -EINVAL;
-
-	return 0;
-}
-
-static int stx104_gpio_direction_output(struct gpio_chip *chip,
-	unsigned int offset, int value)
-{
-	if (offset < 4)
-		return -EINVAL;
-
-	chip->set(chip, offset, value);
-	return 0;
-}
-
-static int stx104_gpio_get(struct gpio_chip *chip, unsigned int offset)
-{
-	struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
-
-	if (offset >= 4)
-		return -EINVAL;
-
-	return !!(inb(stx104gpio->base) & BIT(offset));
-}
-
-static void stx104_gpio_set(struct gpio_chip *chip, unsigned int offset,
-	int value)
-{
-	struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
-	const unsigned int mask = BIT(offset) >> 4;
-	unsigned long flags;
-
-	if (offset < 4)
-		return;
-
-	spin_lock_irqsave(&stx104gpio->lock, flags);
-
-	if (value)
-		stx104gpio->out_state |= mask;
-	else
-		stx104gpio->out_state &= ~mask;
-
-	outb(stx104gpio->out_state, stx104gpio->base);
-
-	spin_unlock_irqrestore(&stx104gpio->lock, flags);
-}
-
-static int stx104_probe(struct device *dev, unsigned int id)
-{
-	struct iio_dev *indio_dev;
-	struct stx104_iio *priv;
-	struct stx104_gpio *stx104gpio;
-	struct stx104_dev *stx104dev;
-	struct iio_chan_spec *input_channel;
-	int i;
-	int err;
-
-	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
-	if (!indio_dev)
-		return -ENOMEM;
-
-	stx104gpio = devm_kzalloc(dev, sizeof(*stx104gpio), GFP_KERNEL);
-	if (!stx104gpio)
-		return -ENOMEM;
-
-	stx104dev = devm_kzalloc(dev, sizeof(*stx104dev), GFP_KERNEL);
-	if (!stx104dev)
-		return -ENOMEM;
-
-	if (!devm_request_region(dev, base[id], STX104_EXTENT,
-		dev_name(dev))) {
-		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
-			base[id], base[id] + STX104_EXTENT);
-		return -EBUSY;
-	}
-
-	indio_dev->info = &stx104_info;
-	indio_dev->modes = INDIO_DIRECT_MODE;
-	indio_dev->num_channels = ARRAY_SIZE(stx104_channels);
-
-	/* determine if differential inputs */
-	if (inb(base[id] + 8) & BIT(5)) {
-		indio_dev->num_channels -= STX104_NUM_IN_CHAN / 2;
-
-		input_channel = stx104_channels + STX104_IN_CHAN_OFFSET;
-		for (i = 0; i < STX104_NUM_IN_CHAN / 2; input_channel++) {
-			input_channel->differential = 1;
-			input_channel->channel2 = i;
-		}
-	}
-
-	indio_dev->channels = stx104_channels;
-	indio_dev->name = dev_name(dev);
-
-	priv = iio_priv(indio_dev);
-	priv->base = base[id];
-
-	/* configure device for software trigger operation */
-	outb(0, base[id] + 9);
-
-	/* initialize gain setting to x1 */
-	outb(0, base[id] + 11);
-
-	/* initialize DAC output to 0V */
-	outw(0, base[id] + 4);
-	outw(0, base[id] + 6);
-
-	stx104gpio->chip.label = dev_name(dev);
-	stx104gpio->chip.parent = dev;
-	stx104gpio->chip.owner = THIS_MODULE;
-	stx104gpio->chip.base = -1;
-	stx104gpio->chip.ngpio = 8;
-	stx104gpio->chip.get_direction = stx104_gpio_get_direction;
-	stx104gpio->chip.direction_input = stx104_gpio_direction_input;
-	stx104gpio->chip.direction_output = stx104_gpio_direction_output;
-	stx104gpio->chip.get = stx104_gpio_get;
-	stx104gpio->chip.set = stx104_gpio_set;
-	stx104gpio->base = base[id] + 3;
-	stx104gpio->out_state = 0x0;
-
-	spin_lock_init(&stx104gpio->lock);
-
-	stx104dev->indio_dev = indio_dev;
-	stx104dev->chip = &stx104gpio->chip;
-	dev_set_drvdata(dev, stx104dev);
-
-	err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
-	if (err) {
-		dev_err(dev, "GPIO registering failed (%d)\n", err);
-		return err;
-	}
-
-	err = iio_device_register(indio_dev);
-	if (err) {
-		dev_err(dev, "IIO device registering failed (%d)\n", err);
-		gpiochip_remove(&stx104gpio->chip);
-		return err;
-	}
-
-	return 0;
-}
-
-static int stx104_remove(struct device *dev, unsigned int id)
-{
-	struct stx104_dev *const stx104dev = dev_get_drvdata(dev);
-
-	iio_device_unregister(stx104dev->indio_dev);
-	gpiochip_remove(stx104dev->chip);
-
-	return 0;
-}
-
-static struct isa_driver stx104_driver = {
-	.probe = stx104_probe,
-	.driver = {
-		.name = "stx104"
-	},
-	.remove = stx104_remove
-};
-
-module_isa_driver(stx104_driver, num_stx104);
-
-MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
-MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
-MODULE_LICENSE("GPL v2");
-- 
2.7.3

Re: [PATCH v2 2/3] iio: stx104: Add IIO support for the ADC channels

[Jonathan Cameron]

On 19/07/16 17:25, William Breathitt Gray wrote:
> The Apex Embedded Systems STX104 features 16 channels of single-ended (8
> channels of true differential) 16-bit analog input. Differential input
> configuration may be selected via a physical jumper on the device.
> Similarly, input polarity (unipolar/bipolar) is configured via a
> physical jumper on the device.
> 
> Input gain selection is available to the user via software, thus
> allowing eight possible input ranges: +-10V, +-5V, +-2.5V, +-1.25V,
> 0 to 10V, 0 to 5V, 0 to 2.5V, and 0 to 1.25V. Four input gain
> configurations are supported: x1, x2, x4, and x8.
> 
> This ADC resolution is 16-bits (1/65536 of full scale). Analog input
> samples are taken on software trigger; neither FIFO sampling nor
> interrupt triggering is supported by this driver.
> 
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
A few bits inline.

Jonathan
> ---
>  drivers/iio/dac/Kconfig  |  15 +++--
>  drivers/iio/dac/stx104.c | 159 ++++++++++++++++++++++++++++++++++++++++-------
>  2 files changed, 147 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index ca81447..60294ef 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -246,14 +246,19 @@ config MCP4922
>  	  will be called mcp4922.
>  
>  config STX104
> -	tristate "Apex Embedded Systems STX104 DAC driver"
> +	tristate "Apex Embedded Systems STX104 driver"
>  	depends on X86 && ISA_BUS_API
>  	select GPIOLIB
>  	help
> -	  Say yes here to build support for the 2-channel DAC and GPIO on the
> -	  Apex Embedded Systems STX104 integrated analog PC/104 card. The base
> -	  port addresses for the devices may be configured via the base array
> -	  module parameter.
> +	  Say yes here to build support for the Apex Embedded Systems STX104
> +	  integrated analog PC/104 card.
> +
> +	  This driver supports the 16 channels of single-ended (8 channels of
> +	  differential) analog inputs, 2 channels of analog output, 4 digital
> +	  inputs, and 4 digital outputs provided by the STX104.
> +
> +	  The base port addresses for the devices may be configured via the base
> +	  array module parameter.
>  
>  config VF610_DAC
>  	tristate "Vybrid vf610 DAC driver"
> diff --git a/drivers/iio/dac/stx104.c b/drivers/iio/dac/stx104.c
> index bebbd00..51f6534 100644
> --- a/drivers/iio/dac/stx104.c
> +++ b/drivers/iio/dac/stx104.c
> @@ -1,5 +1,5 @@
>  /*
> - * DAC driver for the Apex Embedded Systems STX104
> + * IIO driver for the Apex Embedded Systems STX104
>   * Copyright (C) 2016 William Breathitt Gray
>   *
>   * This program is free software; you can redistribute it and/or modify
> @@ -20,21 +20,32 @@
>  #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/spinlock.h>
>  
> -#define STX104_NUM_CHAN 2
> +#define STX104_EXTENT 16
>  
> -#define STX104_CHAN(chan) {				\
> +#define STX104_IO_CHAN(chan, dir) {			\
>  	.type = IIO_VOLTAGE,				\
>  	.channel = chan,				\
>  	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
>  	.indexed = 1,					\
> -	.output = 1					\
> +	.output = dir					\
> +}
> +#define STX104_GAIN_CHAN {					\
> +	.type = IIO_VOLTAGE,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),	\
> +	.output = 1						\
>  }
> +#define STX104_OUT_CHAN(chan) STX104_IO_CHAN(chan, 1)
> +#define STX104_IN_CHAN(chan) STX104_IO_CHAN(chan, 0)
>  
> -#define STX104_EXTENT 16
> +#define STX104_NUM_OUT_CHAN 2
> +#define STX104_NUM_GAIN_CHAN 1
> +#define STX104_NUM_IN_CHAN 16
> +#define STX104_IN_CHAN_OFFSET (STX104_NUM_OUT_CHAN + STX104_NUM_GAIN_CHAN)
>  
>  static unsigned int base[max_num_isa_dev(STX104_EXTENT)];
>  static unsigned int num_stx104;
> @@ -47,7 +58,7 @@ MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
>   * @base:		base port address of the IIO device
>   */
>  struct stx104_iio {
> -	unsigned chan_out_states[STX104_NUM_CHAN];
> +	unsigned int chan_out_states[STX104_NUM_OUT_CHAN];
>  	unsigned base;
>  };
>  
> @@ -79,39 +90,123 @@ static int stx104_read_raw(struct iio_dev *indio_dev,
>  	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
>  {
>  	struct stx104_iio *const priv = iio_priv(indio_dev);
> +	long adc_sample;
> +	unsigned int adc_config;
> +	long adbu;
> +	unsigned int gain;
> +
> +	/* handle output channels */
> +	if (chan->output) {
> +		switch (mask) {
> +		case IIO_CHAN_INFO_RAW:
> +			*val = priv->chan_out_states[chan->channel];
> +			return IIO_VAL_INT;
> +		case IIO_CHAN_INFO_HARDWAREGAIN:
> +			*val = 1 << (inb(priv->base + 11) & 0x3);
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	}
>  
>  	if (mask != IIO_CHAN_INFO_RAW)
>  		return -EINVAL;
>  
> -	*val = priv->chan_out_states[chan->channel];
> -
> -	return IIO_VAL_INT;
> +	/* select ADC channel */
> +	outb(chan->channel | (chan->channel << 4), priv->base + 2);
> +
> +	/* trigger ADC sample capture and wait for completion */
> +	outb(0, priv->base);
> +	while (inb(priv->base + 8) & BIT(7));
> +
> +	adc_sample = inw(priv->base);
> +
> +	/* get ADC bipolar/unipolar and gain configuration */
> +	adc_config = inb(priv->base + 11);
> +	adbu = !(adc_config & BIT(2));
> +	gain = adc_config & 0x3;
> +
> +	/* Value conversion math:
Fix the multiline comment syntax please.
/*
 * Value...
> +	 * ----------------------
> +	 * scale = adc_sample / 65536
> +	 * range = 10 / (1 << gain)
> +	 * voltage = scale * (range + adbu * range) - adbu * range
> +	 *
> +	 * Simplified:
> +	 * -----------
> +	 * voltage = 5 * (adc_sample * (1 + adbu) - adbu * 65536) /
> +	 *	(1 << (15 + gain))
> +	 *
> +	 * Portability Caution:
> +	 * --------------------
> +	 * *val will be set to a value between -327680 and 327675; in order to
> +	 * prevent integer underflow/overflow, the int data type of the
> +	 * implementation should be capable of representing this value range.
32 bits should easily do this.... Which is the kernel minimum size for int...

> +	 */
> +	*val = 5 * (adc_sample * (1 + adbu) - adbu * 65536);
> +	*val2 = 15 + gain;
> +
> +	return IIO_VAL_FRACTIONAL_LOG2;
>  }
>  
>  static int stx104_write_raw(struct iio_dev *indio_dev,
>  	struct iio_chan_spec const *chan, int val, int val2, long mask)
>  {
>  	struct stx104_iio *const priv = iio_priv(indio_dev);
> -	const unsigned chan_addr_offset = 2 * chan->channel;
>  
> -	if (mask != IIO_CHAN_INFO_RAW)
> -		return -EINVAL;
> -
> -	priv->chan_out_states[chan->channel] = val;
> -	outw(val, priv->base + 4 + chan_addr_offset);
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		/* DAC can only accept up to a 16-bit value */
> +		if ((unsigned int)val > 65535)
> +			return -EINVAL;
> +
> +		priv->chan_out_states[chan->channel] = val;
> +		outw(val, priv->base + 4 + 2 * chan->channel);
> +
> +		return 0;
> +	case IIO_CHAN_INFO_HARDWAREGAIN:
> +		/* Only four gain states (x1, x2, x4, x8) */
> +		switch (val) {
> +		case 1:
> +			outb(0, priv->base + 11);
> +			break;
> +		case 2:
> +			outb(1, priv->base + 11);
> +			break;
> +		case 4:
> +			outb(2, priv->base + 11);
> +			break;
> +		case 8:
> +			outb(3, priv->base + 11);
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +
> +		return 0;
> +	}
>  
> -	return 0;
> +	return -EINVAL;
>  }
>  
>  static const struct iio_info stx104_info = {
>  	.driver_module = THIS_MODULE,
>  	.read_raw = stx104_read_raw,
> -	.write_raw = stx104_write_raw
> +	.write_raw = stx104_write_raw,
>  };
>  
> -static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
> -	STX104_CHAN(0),
> -	STX104_CHAN(1)
> +/* stx104_channels is not const in order to allow for the configuration of
> + * differential channels in the probe callback if a device is setup for such
> + */
> +static struct iio_chan_spec stx104_channels[] = {
> +	STX104_OUT_CHAN(0), STX104_OUT_CHAN(1),
> +	STX104_GAIN_CHAN,
> +	STX104_IN_CHAN(0), STX104_IN_CHAN(1), STX104_IN_CHAN(2),
> +	STX104_IN_CHAN(3), STX104_IN_CHAN(4), STX104_IN_CHAN(5),
> +	STX104_IN_CHAN(6), STX104_IN_CHAN(7), STX104_IN_CHAN(8),
> +	STX104_IN_CHAN(9), STX104_IN_CHAN(10), STX104_IN_CHAN(11),
> +	STX104_IN_CHAN(12), STX104_IN_CHAN(13), STX104_IN_CHAN(14),
> +	STX104_IN_CHAN(15)
>  };
Presumably we have the potential for more than one of these boards in a
machine?  If so you'll need to take a copy of this array for each
of them as you modify it.  If not all the devices will share this
one copy..

As there only seem to be a couple of options, I'd select between
two different iio_chan_spec arrays instead of modifying them 
during probe.
>  
>  static int stx104_gpio_get_direction(struct gpio_chip *chip,
> @@ -181,6 +276,8 @@ static int stx104_probe(struct device *dev, unsigned int id)
>  	struct stx104_iio *priv;
>  	struct stx104_gpio *stx104gpio;
>  	struct stx104_dev *stx104dev;
> +	struct iio_chan_spec *input_channel;
> +	int i;
>  	int err;
>  
>  	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
> @@ -204,13 +301,31 @@ static int stx104_probe(struct device *dev, unsigned int id)
>  
>  	indio_dev->info = &stx104_info;
>  	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->num_channels = ARRAY_SIZE(stx104_channels);
> +
> +	/* determine if differential inputs */
> +	if (inb(base[id] + 8) & BIT(5)) {
> +		indio_dev->num_channels -= STX104_NUM_IN_CHAN / 2;
> +
> +		input_channel = stx104_channels + STX104_IN_CHAN_OFFSET;
> +		for (i = 0; i < STX104_NUM_IN_CHAN / 2; input_channel++) {
> +			input_channel->differential = 1;
> +			input_channel->channel2 = i;
> +		}
> +	}
> +
>  	indio_dev->channels = stx104_channels;
> -	indio_dev->num_channels = STX104_NUM_CHAN;
>  	indio_dev->name = dev_name(dev);
>  
>  	priv = iio_priv(indio_dev);
>  	priv->base = base[id];
>  
> +	/* configure device for software trigger operation */
> +	outb(0, base[id] + 9);
> +
> +	/* initialize gain setting to x1 */
> +	outb(0, base[id] + 11);
> +
>  	/* initialize DAC output to 0V */
>  	outw(0, base[id] + 4);
>  	outw(0, base[id] + 6);
> @@ -271,5 +386,5 @@ static struct isa_driver stx104_driver = {
>  module_isa_driver(stx104_driver, num_stx104);
>  
>  MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
> -MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
> +MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
>  MODULE_LICENSE("GPL v2");
> 

Re: [PATCH v2 1/3] iio: stx104: Unregister IIO device on remove callback

[Jonathan Cameron]

On 19/07/16 17:25, William Breathitt Gray wrote:
> The devm_iio_device_register function should not be used if custom
> operations must be performed in the remove callback. This patch replaces
> the dem_iio_device_register call with a iio_device_register call and
> respective iio_device_unregister call in the remove callback.
> 
> Fixes: 765550e4d98d ("iio: stx104: Add GPIO support for the Apex Embedded Systems STX104")
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Applied to the fixes-togreg-post-rc1 branch (it's more convenient
right now than the fixes-togreg branch) and marked for stable.

These will go upstream in a few weeks after I'm back from travelling
and the merge windows has closed.

Thanks,

Jonathan
> ---
>  drivers/iio/dac/stx104.c | 38 +++++++++++++++++++++++++++++---------
>  1 file changed, 29 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/iio/dac/stx104.c b/drivers/iio/dac/stx104.c
> index 792a971..bebbd00 100644
> --- a/drivers/iio/dac/stx104.c
> +++ b/drivers/iio/dac/stx104.c
> @@ -65,6 +65,16 @@ struct stx104_gpio {
>  	unsigned int out_state;
>  };
>  
> +/**
> + * struct stx104_dev - STX104 device private data structure
> + * @indio_dev:	IIO device
> + * @chip:	instance of the gpio_chip
> + */
> +struct stx104_dev {
> +	struct iio_dev *indio_dev;
> +	struct gpio_chip *chip;
> +};
> +
>  static int stx104_read_raw(struct iio_dev *indio_dev,
>  	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
>  {
> @@ -107,6 +117,7 @@ static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
>  static int stx104_gpio_get_direction(struct gpio_chip *chip,
>  	unsigned int offset)
>  {
> +	/* GPIO 0-3 are input only, while the rest are output only */
>  	if (offset < 4)
>  		return 1;
>  
> @@ -169,6 +180,7 @@ static int stx104_probe(struct device *dev, unsigned int id)
>  	struct iio_dev *indio_dev;
>  	struct stx104_iio *priv;
>  	struct stx104_gpio *stx104gpio;
> +	struct stx104_dev *stx104dev;
>  	int err;
>  
>  	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
> @@ -179,6 +191,10 @@ static int stx104_probe(struct device *dev, unsigned int id)
>  	if (!stx104gpio)
>  		return -ENOMEM;
>  
> +	stx104dev = devm_kzalloc(dev, sizeof(*stx104dev), GFP_KERNEL);
> +	if (!stx104dev)
> +		return -ENOMEM;
> +
>  	if (!devm_request_region(dev, base[id], STX104_EXTENT,
>  		dev_name(dev))) {
>  		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
> @@ -199,12 +215,6 @@ static int stx104_probe(struct device *dev, unsigned int id)
>  	outw(0, base[id] + 4);
>  	outw(0, base[id] + 6);
>  
> -	err = devm_iio_device_register(dev, indio_dev);
> -	if (err) {
> -		dev_err(dev, "IIO device registering failed (%d)\n", err);
> -		return err;
> -	}
> -
>  	stx104gpio->chip.label = dev_name(dev);
>  	stx104gpio->chip.parent = dev;
>  	stx104gpio->chip.owner = THIS_MODULE;
> @@ -220,7 +230,9 @@ static int stx104_probe(struct device *dev, unsigned int id)
>  
>  	spin_lock_init(&stx104gpio->lock);
>  
> -	dev_set_drvdata(dev, stx104gpio);
> +	stx104dev->indio_dev = indio_dev;
> +	stx104dev->chip = &stx104gpio->chip;
> +	dev_set_drvdata(dev, stx104dev);
>  
>  	err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
>  	if (err) {
> @@ -228,14 +240,22 @@ static int stx104_probe(struct device *dev, unsigned int id)
>  		return err;
>  	}
>  
> +	err = iio_device_register(indio_dev);
> +	if (err) {
> +		dev_err(dev, "IIO device registering failed (%d)\n", err);
> +		gpiochip_remove(&stx104gpio->chip);
> +		return err;
> +	}
> +
>  	return 0;
>  }
>  
>  static int stx104_remove(struct device *dev, unsigned int id)
>  {
> -	struct stx104_gpio *const stx104gpio = dev_get_drvdata(dev);
> +	struct stx104_dev *const stx104dev = dev_get_drvdata(dev);
>  
> -	gpiochip_remove(&stx104gpio->chip);
> +	iio_device_unregister(stx104dev->indio_dev);
> +	gpiochip_remove(stx104dev->chip);
>  
>  	return 0;
>  }
> 

Re: [PATCH v2 3/3] iio: stx104: Move the STX104 IIO driver to the ADC directory

[Jonathan Cameron]

On 19/07/16 17:25, William Breathitt Gray wrote:
> The Apex Embedded Systems STX104 is primarily an analog-to-digital
> converter device. The STX104 IIO driver was initially placed in the DAC
> directory because only the DAC portion of the STX104 was supported at
> the time. Now that ADC support has been added to the STX104 IIO driver,
> the driver should be moved to the more appropriate ADC directory.
> 
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
For a clean move this this, use git format-patch -M which will then
avoid putting all the file being deleted and the one being added
in the patch.

It's a different matter if you are making any changes (which I
assume you aren't here!)

Thanks,

Jonathan
> ---
>  MAINTAINERS              |   2 +-
>  drivers/iio/adc/Kconfig  |  15 ++
>  drivers/iio/adc/Makefile |   1 +
>  drivers/iio/adc/stx104.c | 390 +++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/iio/dac/Kconfig  |  15 --
>  drivers/iio/dac/Makefile |   1 -
>  drivers/iio/dac/stx104.c | 390 -----------------------------------------------
>  7 files changed, 407 insertions(+), 407 deletions(-)
>  create mode 100644 drivers/iio/adc/stx104.c
>  delete mode 100644 drivers/iio/dac/stx104.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 345e757..95dd91b 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -796,7 +796,7 @@ APEX EMBEDDED SYSTEMS STX104 DAC DRIVER
>  M:	William Breathitt Gray <vilhelm.gray@gmail.com>
>  L:	linux-iio@vger.kernel.org
>  S:	Maintained
> -F:	drivers/iio/dac/stx104.c
> +F:	drivers/iio/adc/stx104.c
>  
>  APM DRIVER
>  M:	Jiri Kosina <jikos@kernel.org>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 1de31bd..ec9ada8 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -396,6 +396,21 @@ config ROCKCHIP_SARADC
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called rockchip_saradc.
>  
> +config STX104
> +	tristate "Apex Embedded Systems STX104 driver"
> +	depends on X86 && ISA_BUS_API
> +	select GPIOLIB
> +	help
> +	  Say yes here to build support for the Apex Embedded Systems STX104
> +	  integrated analog PC/104 card.
> +
> +	  This driver supports the 16 channels of single-ended (8 channels of
> +	  differential) analog inputs, 2 channels of analog output, 4 digital
> +	  inputs, and 4 digital outputs provided by the STX104.
> +
> +	  The base port addresses for the devices may be configured via the base
> +	  array module parameter.
> +
>  config TI_ADC081C
>  	tristate "Texas Instruments ADC081C/ADC101C/ADC121C family"
>  	depends on I2C
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 0ba0d50..d7b4a71 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -38,6 +38,7 @@ obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
>  obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
>  obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
>  obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
> +obj-$(CONFIG_STX104) += stx104.o
>  obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
>  obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
>  obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
> diff --git a/drivers/iio/adc/stx104.c b/drivers/iio/adc/stx104.c
> new file mode 100644
> index 0000000..6f13d2c
> --- /dev/null
> +++ b/drivers/iio/adc/stx104.c
> @@ -0,0 +1,390 @@
> +/*
> + * IIO driver for the Apex Embedded Systems STX104
> + * 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.
> + */
> +#include <linux/bitops.h>
> +#include <linux/device.h>
> +#include <linux/errno.h>
> +#include <linux/gpio/driver.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/spinlock.h>
> +
> +#define STX104_EXTENT 16
> +
> +#define STX104_IO_CHAN(chan, dir) {			\
> +	.type = IIO_VOLTAGE,				\
> +	.channel = chan,				\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
> +	.indexed = 1,					\
> +	.output = dir					\
> +}
> +#define STX104_GAIN_CHAN {					\
> +	.type = IIO_VOLTAGE,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),	\
> +	.output = 1						\
> +}
> +#define STX104_OUT_CHAN(chan) STX104_IO_CHAN(chan, 1)
> +#define STX104_IN_CHAN(chan) STX104_IO_CHAN(chan, 0)
> +
> +#define STX104_NUM_OUT_CHAN 2
> +#define STX104_NUM_GAIN_CHAN 1
> +#define STX104_NUM_IN_CHAN 16
> +#define STX104_IN_CHAN_OFFSET (STX104_NUM_OUT_CHAN + STX104_NUM_GAIN_CHAN)
> +
> +static unsigned int base[max_num_isa_dev(STX104_EXTENT)];
> +static unsigned int num_stx104;
> +module_param_array(base, uint, &num_stx104, 0);
> +MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
> +
> +/**
> + * struct stx104_iio - IIO device private data structure
> + * @chan_out_states:	channels' output states
> + * @base:		base port address of the IIO device
> + */
> +struct stx104_iio {
> +	unsigned int chan_out_states[STX104_NUM_OUT_CHAN];
> +	unsigned int base;
> +};
> +
> +/**
> + * struct stx104_gpio - GPIO device private data structure
> + * @chip:	instance of the gpio_chip
> + * @lock:	synchronization lock to prevent I/O race conditions
> + * @base:	base port address of the GPIO device
> + * @out_state:	output bits state
> + */
> +struct stx104_gpio {
> +	struct gpio_chip chip;
> +	spinlock_t lock;
> +	unsigned int base;
> +	unsigned int out_state;
> +};
> +
> +/**
> + * struct stx104_dev - STX104 device private data structure
> + * @indio_dev:	IIO device
> + * @chip:	instance of the gpio_chip
> + */
> +struct stx104_dev {
> +	struct iio_dev *indio_dev;
> +	struct gpio_chip *chip;
> +};
> +
> +static int stx104_read_raw(struct iio_dev *indio_dev,
> +	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
> +{
> +	struct stx104_iio *const priv = iio_priv(indio_dev);
> +	long adc_sample;
> +	unsigned int adc_config;
> +	long adbu;
> +	unsigned int gain;
> +
> +	/* handle output channels */
> +	if (chan->output) {
> +		switch (mask) {
> +		case IIO_CHAN_INFO_RAW:
> +			*val = priv->chan_out_states[chan->channel];
> +			return IIO_VAL_INT;
> +		case IIO_CHAN_INFO_HARDWAREGAIN:
> +			*val = 1 << (inb(priv->base + 11) & 0x3);
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	}
> +
> +	if (mask != IIO_CHAN_INFO_RAW)
> +		return -EINVAL;
> +
> +	/* select ADC channel */
> +	outb(chan->channel | (chan->channel << 4), priv->base + 2);
> +
> +	/* trigger ADC sample capture and wait for completion */
> +	outb(0, priv->base);
> +	while (inb(priv->base + 8) & BIT(7));
> +
> +	adc_sample = inw(priv->base);
> +
> +	/* get ADC bipolar/unipolar and gain configuration */
> +	adc_config = inb(priv->base + 11);
> +	adbu = !(adc_config & BIT(2));
> +	gain = adc_config & 0x3;
> +
> +	/* Value conversion math:
> +	 * ----------------------
> +	 * scale = adc_sample / 65536
> +	 * range = 10 / (1 << gain)
> +	 * voltage = scale * (range + adbu * range) - adbu * range
> +	 *
> +	 * Simplified:
> +	 * -----------
> +	 * voltage = 5 * (adc_sample * (1 + adbu) - adbu * 65536) /
> +	 *	(1 << (15 + gain))
> +	 *
> +	 * Portability Caution:
> +	 * --------------------
> +	 * *val will be set to a value between -327680 and 327675; in order to
> +	 * prevent integer underflow/overflow, the int data type of the
> +	 * implementation should be capable of representing this value range.
> +	 */
> +	*val = 5 * (adc_sample * (1 + adbu) - adbu * 65536);
> +	*val2 = 15 + gain;
> +
> +	return IIO_VAL_FRACTIONAL_LOG2;
> +}
> +
> +static int stx104_write_raw(struct iio_dev *indio_dev,
> +	struct iio_chan_spec const *chan, int val, int val2, long mask)
> +{
> +	struct stx104_iio *const priv = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		/* DAC can only accept up to a 16-bit value */
> +		if ((unsigned int)val > 65535)
> +			return -EINVAL;
> +
> +		priv->chan_out_states[chan->channel] = val;
> +		outw(val, priv->base + 4 + 2 * chan->channel);
> +
> +		return 0;
> +	case IIO_CHAN_INFO_HARDWAREGAIN:
> +		/* Only four gain states (x1, x2, x4, x8) */
> +		switch (val) {
> +		case 1:
> +			outb(0, priv->base + 11);
> +			break;
> +		case 2:
> +			outb(1, priv->base + 11);
> +			break;
> +		case 4:
> +			outb(2, priv->base + 11);
> +			break;
> +		case 8:
> +			outb(3, priv->base + 11);
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +
> +		return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info stx104_info = {
> +	.driver_module = THIS_MODULE,
> +	.read_raw = stx104_read_raw,
> +	.write_raw = stx104_write_raw,
> +};
> +
> +/* stx104_channels is not const in order to allow for the configuration of
> + * differential channels in the probe callback if a device is setup for such
> + */
> +static struct iio_chan_spec stx104_channels[] = {
> +	STX104_OUT_CHAN(0), STX104_OUT_CHAN(1),
> +	STX104_GAIN_CHAN,
> +	STX104_IN_CHAN(0), STX104_IN_CHAN(1), STX104_IN_CHAN(2),
> +	STX104_IN_CHAN(3), STX104_IN_CHAN(4), STX104_IN_CHAN(5),
> +	STX104_IN_CHAN(6), STX104_IN_CHAN(7), STX104_IN_CHAN(8),
> +	STX104_IN_CHAN(9), STX104_IN_CHAN(10), STX104_IN_CHAN(11),
> +	STX104_IN_CHAN(12), STX104_IN_CHAN(13), STX104_IN_CHAN(14),
> +	STX104_IN_CHAN(15)
> +};
> +
> +static int stx104_gpio_get_direction(struct gpio_chip *chip,
> +	unsigned int offset)
> +{
> +	/* GPIO 0-3 are input only, while the rest are output only */
> +	if (offset < 4)
> +		return 1;
> +
> +	return 0;
> +}
> +
> +static int stx104_gpio_direction_input(struct gpio_chip *chip,
> +	unsigned int offset)
> +{
> +	if (offset >= 4)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int stx104_gpio_direction_output(struct gpio_chip *chip,
> +	unsigned int offset, int value)
> +{
> +	if (offset < 4)
> +		return -EINVAL;
> +
> +	chip->set(chip, offset, value);
> +	return 0;
> +}
> +
> +static int stx104_gpio_get(struct gpio_chip *chip, unsigned int offset)
> +{
> +	struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
> +
> +	if (offset >= 4)
> +		return -EINVAL;
> +
> +	return !!(inb(stx104gpio->base) & BIT(offset));
> +}
> +
> +static void stx104_gpio_set(struct gpio_chip *chip, unsigned int offset,
> +	int value)
> +{
> +	struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
> +	const unsigned int mask = BIT(offset) >> 4;
> +	unsigned long flags;
> +
> +	if (offset < 4)
> +		return;
> +
> +	spin_lock_irqsave(&stx104gpio->lock, flags);
> +
> +	if (value)
> +		stx104gpio->out_state |= mask;
> +	else
> +		stx104gpio->out_state &= ~mask;
> +
> +	outb(stx104gpio->out_state, stx104gpio->base);
> +
> +	spin_unlock_irqrestore(&stx104gpio->lock, flags);
> +}
> +
> +static int stx104_probe(struct device *dev, unsigned int id)
> +{
> +	struct iio_dev *indio_dev;
> +	struct stx104_iio *priv;
> +	struct stx104_gpio *stx104gpio;
> +	struct stx104_dev *stx104dev;
> +	struct iio_chan_spec *input_channel;
> +	int i;
> +	int err;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	stx104gpio = devm_kzalloc(dev, sizeof(*stx104gpio), GFP_KERNEL);
> +	if (!stx104gpio)
> +		return -ENOMEM;
> +
> +	stx104dev = devm_kzalloc(dev, sizeof(*stx104dev), GFP_KERNEL);
> +	if (!stx104dev)
> +		return -ENOMEM;
> +
> +	if (!devm_request_region(dev, base[id], STX104_EXTENT,
> +		dev_name(dev))) {
> +		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
> +			base[id], base[id] + STX104_EXTENT);
> +		return -EBUSY;
> +	}
> +
> +	indio_dev->info = &stx104_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->num_channels = ARRAY_SIZE(stx104_channels);
> +
> +	/* determine if differential inputs */
> +	if (inb(base[id] + 8) & BIT(5)) {
> +		indio_dev->num_channels -= STX104_NUM_IN_CHAN / 2;
> +
> +		input_channel = stx104_channels + STX104_IN_CHAN_OFFSET;
> +		for (i = 0; i < STX104_NUM_IN_CHAN / 2; input_channel++) {
> +			input_channel->differential = 1;
> +			input_channel->channel2 = i;
> +		}
> +	}
> +
> +	indio_dev->channels = stx104_channels;
> +	indio_dev->name = dev_name(dev);
> +
> +	priv = iio_priv(indio_dev);
> +	priv->base = base[id];
> +
> +	/* configure device for software trigger operation */
> +	outb(0, base[id] + 9);
> +
> +	/* initialize gain setting to x1 */
> +	outb(0, base[id] + 11);
> +
> +	/* initialize DAC output to 0V */
> +	outw(0, base[id] + 4);
> +	outw(0, base[id] + 6);
> +
> +	stx104gpio->chip.label = dev_name(dev);
> +	stx104gpio->chip.parent = dev;
> +	stx104gpio->chip.owner = THIS_MODULE;
> +	stx104gpio->chip.base = -1;
> +	stx104gpio->chip.ngpio = 8;
> +	stx104gpio->chip.get_direction = stx104_gpio_get_direction;
> +	stx104gpio->chip.direction_input = stx104_gpio_direction_input;
> +	stx104gpio->chip.direction_output = stx104_gpio_direction_output;
> +	stx104gpio->chip.get = stx104_gpio_get;
> +	stx104gpio->chip.set = stx104_gpio_set;
> +	stx104gpio->base = base[id] + 3;
> +	stx104gpio->out_state = 0x0;
> +
> +	spin_lock_init(&stx104gpio->lock);
> +
> +	stx104dev->indio_dev = indio_dev;
> +	stx104dev->chip = &stx104gpio->chip;
> +	dev_set_drvdata(dev, stx104dev);
> +
> +	err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
> +	if (err) {
> +		dev_err(dev, "GPIO registering failed (%d)\n", err);
> +		return err;
> +	}
> +
> +	err = iio_device_register(indio_dev);
> +	if (err) {
> +		dev_err(dev, "IIO device registering failed (%d)\n", err);
> +		gpiochip_remove(&stx104gpio->chip);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static int stx104_remove(struct device *dev, unsigned int id)
> +{
> +	struct stx104_dev *const stx104dev = dev_get_drvdata(dev);
> +
> +	iio_device_unregister(stx104dev->indio_dev);
> +	gpiochip_remove(stx104dev->chip);
> +
> +	return 0;
> +}
> +
> +static struct isa_driver stx104_driver = {
> +	.probe = stx104_probe,
> +	.driver = {
> +		.name = "stx104"
> +	},
> +	.remove = stx104_remove
> +};
> +
> +module_isa_driver(stx104_driver, num_stx104);
> +
> +MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
> +MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index 60294ef..d359fef 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -245,21 +245,6 @@ config MCP4922
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called mcp4922.
>  
> -config STX104
> -	tristate "Apex Embedded Systems STX104 driver"
> -	depends on X86 && ISA_BUS_API
> -	select GPIOLIB
> -	help
> -	  Say yes here to build support for the Apex Embedded Systems STX104
> -	  integrated analog PC/104 card.
> -
> -	  This driver supports the 16 channels of single-ended (8 channels of
> -	  differential) analog inputs, 2 channels of analog output, 4 digital
> -	  inputs, and 4 digital outputs provided by the STX104.
> -
> -	  The base port addresses for the devices may be configured via the base
> -	  array module parameter.
> -
>  config VF610_DAC
>  	tristate "Vybrid vf610 DAC driver"
>  	depends on OF
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 8b78d5c..7acb05d 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -26,5 +26,4 @@ obj-$(CONFIG_MAX517) += max517.o
>  obj-$(CONFIG_MAX5821) += max5821.o
>  obj-$(CONFIG_MCP4725) += mcp4725.o
>  obj-$(CONFIG_MCP4922) += mcp4922.o
> -obj-$(CONFIG_STX104) += stx104.o
>  obj-$(CONFIG_VF610_DAC) += vf610_dac.o
> diff --git a/drivers/iio/dac/stx104.c b/drivers/iio/dac/stx104.c
> deleted file mode 100644
> index 51f6534..0000000
> --- a/drivers/iio/dac/stx104.c
> +++ /dev/null
> @@ -1,390 +0,0 @@
> -/*
> - * IIO driver for the Apex Embedded Systems STX104
> - * 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.
> - */
> -#include <linux/bitops.h>
> -#include <linux/device.h>
> -#include <linux/errno.h>
> -#include <linux/gpio/driver.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/spinlock.h>
> -
> -#define STX104_EXTENT 16
> -
> -#define STX104_IO_CHAN(chan, dir) {			\
> -	.type = IIO_VOLTAGE,				\
> -	.channel = chan,				\
> -	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
> -	.indexed = 1,					\
> -	.output = dir					\
> -}
> -#define STX104_GAIN_CHAN {					\
> -	.type = IIO_VOLTAGE,					\
> -	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),	\
> -	.output = 1						\
> -}
> -#define STX104_OUT_CHAN(chan) STX104_IO_CHAN(chan, 1)
> -#define STX104_IN_CHAN(chan) STX104_IO_CHAN(chan, 0)
> -
> -#define STX104_NUM_OUT_CHAN 2
> -#define STX104_NUM_GAIN_CHAN 1
> -#define STX104_NUM_IN_CHAN 16
> -#define STX104_IN_CHAN_OFFSET (STX104_NUM_OUT_CHAN + STX104_NUM_GAIN_CHAN)
> -
> -static unsigned int base[max_num_isa_dev(STX104_EXTENT)];
> -static unsigned int num_stx104;
> -module_param_array(base, uint, &num_stx104, 0);
> -MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
> -
> -/**
> - * struct stx104_iio - IIO device private data structure
> - * @chan_out_states:	channels' output states
> - * @base:		base port address of the IIO device
> - */
> -struct stx104_iio {
> -	unsigned int chan_out_states[STX104_NUM_OUT_CHAN];
> -	unsigned base;
> -};
> -
> -/**
> - * struct stx104_gpio - GPIO device private data structure
> - * @chip:	instance of the gpio_chip
> - * @lock:	synchronization lock to prevent I/O race conditions
> - * @base:	base port address of the GPIO device
> - * @out_state:	output bits state
> - */
> -struct stx104_gpio {
> -	struct gpio_chip chip;
> -	spinlock_t lock;
> -	unsigned int base;
> -	unsigned int out_state;
> -};
> -
> -/**
> - * struct stx104_dev - STX104 device private data structure
> - * @indio_dev:	IIO device
> - * @chip:	instance of the gpio_chip
> - */
> -struct stx104_dev {
> -	struct iio_dev *indio_dev;
> -	struct gpio_chip *chip;
> -};
> -
> -static int stx104_read_raw(struct iio_dev *indio_dev,
> -	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
> -{
> -	struct stx104_iio *const priv = iio_priv(indio_dev);
> -	long adc_sample;
> -	unsigned int adc_config;
> -	long adbu;
> -	unsigned int gain;
> -
> -	/* handle output channels */
> -	if (chan->output) {
> -		switch (mask) {
> -		case IIO_CHAN_INFO_RAW:
> -			*val = priv->chan_out_states[chan->channel];
> -			return IIO_VAL_INT;
> -		case IIO_CHAN_INFO_HARDWAREGAIN:
> -			*val = 1 << (inb(priv->base + 11) & 0x3);
> -			return IIO_VAL_INT;
> -		default:
> -			return -EINVAL;
> -		}
> -	}
> -
> -	if (mask != IIO_CHAN_INFO_RAW)
> -		return -EINVAL;
> -
> -	/* select ADC channel */
> -	outb(chan->channel | (chan->channel << 4), priv->base + 2);
> -
> -	/* trigger ADC sample capture and wait for completion */
> -	outb(0, priv->base);
> -	while (inb(priv->base + 8) & BIT(7));
> -
> -	adc_sample = inw(priv->base);
> -
> -	/* get ADC bipolar/unipolar and gain configuration */
> -	adc_config = inb(priv->base + 11);
> -	adbu = !(adc_config & BIT(2));
> -	gain = adc_config & 0x3;
> -
> -	/* Value conversion math:
> -	 * ----------------------
> -	 * scale = adc_sample / 65536
> -	 * range = 10 / (1 << gain)
> -	 * voltage = scale * (range + adbu * range) - adbu * range
> -	 *
> -	 * Simplified:
> -	 * -----------
> -	 * voltage = 5 * (adc_sample * (1 + adbu) - adbu * 65536) /
> -	 *	(1 << (15 + gain))
> -	 *
> -	 * Portability Caution:
> -	 * --------------------
> -	 * *val will be set to a value between -327680 and 327675; in order to
> -	 * prevent integer underflow/overflow, the int data type of the
> -	 * implementation should be capable of representing this value range.
> -	 */
> -	*val = 5 * (adc_sample * (1 + adbu) - adbu * 65536);
> -	*val2 = 15 + gain;
> -
> -	return IIO_VAL_FRACTIONAL_LOG2;
> -}
> -
> -static int stx104_write_raw(struct iio_dev *indio_dev,
> -	struct iio_chan_spec const *chan, int val, int val2, long mask)
> -{
> -	struct stx104_iio *const priv = iio_priv(indio_dev);
> -
> -	switch (mask) {
> -	case IIO_CHAN_INFO_RAW:
> -		/* DAC can only accept up to a 16-bit value */
> -		if ((unsigned int)val > 65535)
> -			return -EINVAL;
> -
> -		priv->chan_out_states[chan->channel] = val;
> -		outw(val, priv->base + 4 + 2 * chan->channel);
> -
> -		return 0;
> -	case IIO_CHAN_INFO_HARDWAREGAIN:
> -		/* Only four gain states (x1, x2, x4, x8) */
> -		switch (val) {
> -		case 1:
> -			outb(0, priv->base + 11);
> -			break;
> -		case 2:
> -			outb(1, priv->base + 11);
> -			break;
> -		case 4:
> -			outb(2, priv->base + 11);
> -			break;
> -		case 8:
> -			outb(3, priv->base + 11);
> -			break;
> -		default:
> -			return -EINVAL;
> -		}
> -
> -		return 0;
> -	}
> -
> -	return -EINVAL;
> -}
> -
> -static const struct iio_info stx104_info = {
> -	.driver_module = THIS_MODULE,
> -	.read_raw = stx104_read_raw,
> -	.write_raw = stx104_write_raw,
> -};
> -
> -/* stx104_channels is not const in order to allow for the configuration of
> - * differential channels in the probe callback if a device is setup for such
> - */
> -static struct iio_chan_spec stx104_channels[] = {
> -	STX104_OUT_CHAN(0), STX104_OUT_CHAN(1),
> -	STX104_GAIN_CHAN,
> -	STX104_IN_CHAN(0), STX104_IN_CHAN(1), STX104_IN_CHAN(2),
> -	STX104_IN_CHAN(3), STX104_IN_CHAN(4), STX104_IN_CHAN(5),
> -	STX104_IN_CHAN(6), STX104_IN_CHAN(7), STX104_IN_CHAN(8),
> -	STX104_IN_CHAN(9), STX104_IN_CHAN(10), STX104_IN_CHAN(11),
> -	STX104_IN_CHAN(12), STX104_IN_CHAN(13), STX104_IN_CHAN(14),
> -	STX104_IN_CHAN(15)
> -};
> -
> -static int stx104_gpio_get_direction(struct gpio_chip *chip,
> -	unsigned int offset)
> -{
> -	/* GPIO 0-3 are input only, while the rest are output only */
> -	if (offset < 4)
> -		return 1;
> -
> -	return 0;
> -}
> -
> -static int stx104_gpio_direction_input(struct gpio_chip *chip,
> -	unsigned int offset)
> -{
> -	if (offset >= 4)
> -		return -EINVAL;
> -
> -	return 0;
> -}
> -
> -static int stx104_gpio_direction_output(struct gpio_chip *chip,
> -	unsigned int offset, int value)
> -{
> -	if (offset < 4)
> -		return -EINVAL;
> -
> -	chip->set(chip, offset, value);
> -	return 0;
> -}
> -
> -static int stx104_gpio_get(struct gpio_chip *chip, unsigned int offset)
> -{
> -	struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
> -
> -	if (offset >= 4)
> -		return -EINVAL;
> -
> -	return !!(inb(stx104gpio->base) & BIT(offset));
> -}
> -
> -static void stx104_gpio_set(struct gpio_chip *chip, unsigned int offset,
> -	int value)
> -{
> -	struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
> -	const unsigned int mask = BIT(offset) >> 4;
> -	unsigned long flags;
> -
> -	if (offset < 4)
> -		return;
> -
> -	spin_lock_irqsave(&stx104gpio->lock, flags);
> -
> -	if (value)
> -		stx104gpio->out_state |= mask;
> -	else
> -		stx104gpio->out_state &= ~mask;
> -
> -	outb(stx104gpio->out_state, stx104gpio->base);
> -
> -	spin_unlock_irqrestore(&stx104gpio->lock, flags);
> -}
> -
> -static int stx104_probe(struct device *dev, unsigned int id)
> -{
> -	struct iio_dev *indio_dev;
> -	struct stx104_iio *priv;
> -	struct stx104_gpio *stx104gpio;
> -	struct stx104_dev *stx104dev;
> -	struct iio_chan_spec *input_channel;
> -	int i;
> -	int err;
> -
> -	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
> -	if (!indio_dev)
> -		return -ENOMEM;
> -
> -	stx104gpio = devm_kzalloc(dev, sizeof(*stx104gpio), GFP_KERNEL);
> -	if (!stx104gpio)
> -		return -ENOMEM;
> -
> -	stx104dev = devm_kzalloc(dev, sizeof(*stx104dev), GFP_KERNEL);
> -	if (!stx104dev)
> -		return -ENOMEM;
> -
> -	if (!devm_request_region(dev, base[id], STX104_EXTENT,
> -		dev_name(dev))) {
> -		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
> -			base[id], base[id] + STX104_EXTENT);
> -		return -EBUSY;
> -	}
> -
> -	indio_dev->info = &stx104_info;
> -	indio_dev->modes = INDIO_DIRECT_MODE;
> -	indio_dev->num_channels = ARRAY_SIZE(stx104_channels);
> -
> -	/* determine if differential inputs */
> -	if (inb(base[id] + 8) & BIT(5)) {
> -		indio_dev->num_channels -= STX104_NUM_IN_CHAN / 2;
> -
> -		input_channel = stx104_channels + STX104_IN_CHAN_OFFSET;
> -		for (i = 0; i < STX104_NUM_IN_CHAN / 2; input_channel++) {
> -			input_channel->differential = 1;
> -			input_channel->channel2 = i;
> -		}
> -	}
> -
> -	indio_dev->channels = stx104_channels;
> -	indio_dev->name = dev_name(dev);
> -
> -	priv = iio_priv(indio_dev);
> -	priv->base = base[id];
> -
> -	/* configure device for software trigger operation */
> -	outb(0, base[id] + 9);
> -
> -	/* initialize gain setting to x1 */
> -	outb(0, base[id] + 11);
> -
> -	/* initialize DAC output to 0V */
> -	outw(0, base[id] + 4);
> -	outw(0, base[id] + 6);
> -
> -	stx104gpio->chip.label = dev_name(dev);
> -	stx104gpio->chip.parent = dev;
> -	stx104gpio->chip.owner = THIS_MODULE;
> -	stx104gpio->chip.base = -1;
> -	stx104gpio->chip.ngpio = 8;
> -	stx104gpio->chip.get_direction = stx104_gpio_get_direction;
> -	stx104gpio->chip.direction_input = stx104_gpio_direction_input;
> -	stx104gpio->chip.direction_output = stx104_gpio_direction_output;
> -	stx104gpio->chip.get = stx104_gpio_get;
> -	stx104gpio->chip.set = stx104_gpio_set;
> -	stx104gpio->base = base[id] + 3;
> -	stx104gpio->out_state = 0x0;
> -
> -	spin_lock_init(&stx104gpio->lock);
> -
> -	stx104dev->indio_dev = indio_dev;
> -	stx104dev->chip = &stx104gpio->chip;
> -	dev_set_drvdata(dev, stx104dev);
> -
> -	err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
> -	if (err) {
> -		dev_err(dev, "GPIO registering failed (%d)\n", err);
> -		return err;
> -	}
> -
> -	err = iio_device_register(indio_dev);
> -	if (err) {
> -		dev_err(dev, "IIO device registering failed (%d)\n", err);
> -		gpiochip_remove(&stx104gpio->chip);
> -		return err;
> -	}
> -
> -	return 0;
> -}
> -
> -static int stx104_remove(struct device *dev, unsigned int id)
> -{
> -	struct stx104_dev *const stx104dev = dev_get_drvdata(dev);
> -
> -	iio_device_unregister(stx104dev->indio_dev);
> -	gpiochip_remove(stx104dev->chip);
> -
> -	return 0;
> -}
> -
> -static struct isa_driver stx104_driver = {
> -	.probe = stx104_probe,
> -	.driver = {
> -		.name = "stx104"
> -	},
> -	.remove = stx104_remove
> -};
> -
> -module_isa_driver(stx104_driver, num_stx104);
> -
> -MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
> -MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
> -MODULE_LICENSE("GPL v2");
>