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Date: Tue, 19 Jul 2016 12:25:11 -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 2/3] iio: stx104: Add IIO support for the ADC channels
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@...il.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@...il.com>");
-MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
+MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
MODULE_LICENSE("GPL v2");
--
2.7.3
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