Message-Id: <7ed650b4f54533c4e867a2419e2f860412d36b83.1468944073.git.vilhelm.gray@gmail.com>
Date:	Tue, 19 Jul 2016 12:25:22 -0400
From:	William Breathitt Gray <vilhelm.gray@...il.com>
To:	jic23@...nel.org, knaack.h@....de, lars@...afoo.de,
	pmeerw@...erw.net
Cc:	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
	William Breathitt Gray <vilhelm.gray@...il.com>
Subject: [PATCH v2 3/3] iio: stx104: Move the STX104 IIO driver to the ADC directory

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@...il.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@...il.com>
 L:	linux-iio@...r.kernel.org
 S:	Maintained
-F:	drivers/iio/dac/stx104.c
+F:	drivers/iio/adc/stx104.c
 
 APM DRIVER
 M:	Jiri Kosina <jikos@...nel.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@...il.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@...il.com>");
-MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
-MODULE_LICENSE("GPL v2");
-- 
2.7.3

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