153 lines
3.9 KiB
C
153 lines
3.9 KiB
C
/*
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* DAC driver for the Apex Embedded Systems STX104
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* Copyright (C) 2016 William Breathitt Gray
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License, version 2, as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/bitops.h>
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#include <linux/device.h>
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#include <linux/errno.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/types.h>
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#include <linux/io.h>
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#include <linux/ioport.h>
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#include <linux/isa.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#define STX104_NUM_CHAN 2
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#define STX104_CHAN(chan) { \
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.type = IIO_VOLTAGE, \
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.channel = chan, \
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
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.indexed = 1, \
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.output = 1 \
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}
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#define STX104_EXTENT 16
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/**
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* The highest base address possible for an ISA device is 0x3FF; this results in
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* 1024 possible base addresses. Dividing the number of possible base addresses
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* by the address extent taken by each device results in the maximum number of
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* devices on a system.
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*/
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#define MAX_NUM_STX104 (1024 / STX104_EXTENT)
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static unsigned base[MAX_NUM_STX104];
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static unsigned num_stx104;
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module_param_array(base, uint, &num_stx104, 0);
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MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
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/**
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* struct stx104_iio - IIO device private data structure
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* @chan_out_states: channels' output states
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* @base: base port address of the IIO device
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*/
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struct stx104_iio {
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unsigned chan_out_states[STX104_NUM_CHAN];
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unsigned base;
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};
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static int stx104_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int *val, int *val2, long mask)
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{
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struct stx104_iio *const priv = iio_priv(indio_dev);
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if (mask != IIO_CHAN_INFO_RAW)
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return -EINVAL;
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*val = priv->chan_out_states[chan->channel];
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return IIO_VAL_INT;
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}
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static int stx104_write_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int val, int val2, long mask)
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{
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struct stx104_iio *const priv = iio_priv(indio_dev);
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const unsigned chan_addr_offset = 2 * chan->channel;
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if (mask != IIO_CHAN_INFO_RAW)
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return -EINVAL;
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priv->chan_out_states[chan->channel] = val;
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outw(val, priv->base + 4 + chan_addr_offset);
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return 0;
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}
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static const struct iio_info stx104_info = {
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.driver_module = THIS_MODULE,
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.read_raw = stx104_read_raw,
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.write_raw = stx104_write_raw
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};
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static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
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STX104_CHAN(0),
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STX104_CHAN(1)
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};
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static int stx104_probe(struct device *dev, unsigned int id)
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{
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struct iio_dev *indio_dev;
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struct stx104_iio *priv;
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indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
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if (!indio_dev)
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return -ENOMEM;
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if (!devm_request_region(dev, base[id], STX104_EXTENT,
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dev_name(dev))) {
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dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
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base[id], base[id] + STX104_EXTENT);
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return -EBUSY;
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}
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indio_dev->info = &stx104_info;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = stx104_channels;
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indio_dev->num_channels = STX104_NUM_CHAN;
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indio_dev->name = dev_name(dev);
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priv = iio_priv(indio_dev);
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priv->base = base[id];
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/* initialize DAC output to 0V */
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outw(0, base[id] + 4);
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outw(0, base[id] + 6);
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return devm_iio_device_register(dev, indio_dev);
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}
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static struct isa_driver stx104_driver = {
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.probe = stx104_probe,
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.driver = {
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.name = "stx104"
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}
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};
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static void __exit stx104_exit(void)
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{
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isa_unregister_driver(&stx104_driver);
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}
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static int __init stx104_init(void)
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{
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return isa_register_driver(&stx104_driver, num_stx104);
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}
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module_init(stx104_init);
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module_exit(stx104_exit);
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MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
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MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
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MODULE_LICENSE("GPL v2");
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