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@xxxxxxxxx>
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@xxxxxxxxx>");
> -MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
> +MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
> MODULE_LICENSE("GPL v2");
>
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