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/*
* DAC 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/iio/iio.h>
#include <linux/iio/types.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/isa.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#define STX104_NUM_CHAN 2
#define STX104_CHAN(chan) { \
.type = IIO_VOLTAGE, \
.channel = chan, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.indexed = 1, \
.output = 1 \
}
#define STX104_EXTENT 16
/**
* The highest base address possible for an ISA device is 0x3FF; this results in
* 1024 possible base addresses. Dividing the number of possible base addresses
* by the address extent taken by each device results in the maximum number of
* devices on a system.
*/
#define MAX_NUM_STX104 (1024 / STX104_EXTENT)
static unsigned base[MAX_NUM_STX104];
static unsigned 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 chan_out_states[STX104_NUM_CHAN];
unsigned base;
};
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);
if (mask != IIO_CHAN_INFO_RAW)
return -EINVAL;
*val = priv->chan_out_states[chan->channel];
return IIO_VAL_INT;
}
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);
return 0;
}
static const struct iio_info stx104_info = {
.driver_module = THIS_MODULE,
.read_raw = stx104_read_raw,
.write_raw = stx104_write_raw
};
static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
STX104_CHAN(0),
STX104_CHAN(1)
};
static int stx104_probe(struct device *dev, unsigned int id)
{
struct iio_dev *indio_dev;
struct stx104_iio *priv;
indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
if (!indio_dev)
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->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];
/* initialize DAC output to 0V */
outw(0, base[id] + 4);
outw(0, base[id] + 6);
return devm_iio_device_register(dev, indio_dev);
}
static struct isa_driver stx104_driver = {
.probe = stx104_probe,
.driver = {
.name = "stx104"
}
};
static void __exit stx104_exit(void)
{
isa_unregister_driver(&stx104_driver);
}
static int __init stx104_init(void)
{
return isa_register_driver(&stx104_driver, num_stx104);
}
module_init(stx104_init);
module_exit(stx104_exit);
MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
MODULE_LICENSE("GPL v2");
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