cio-dac.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * IIO driver for the Measurement Computing CIO-DAC
  4 * Copyright (C) 2016 William Breathitt Gray
  5 *
  6 * This driver supports the following Measurement Computing devices: CIO-DAC16,
  7 * CIO-DAC08, and PC104-DAC06.
  8 */
  9#include <linux/bits.h>
 10#include <linux/device.h>
 11#include <linux/err.h>
 12#include <linux/iio/iio.h>
 13#include <linux/iio/types.h>
 14#include <linux/isa.h>
 15#include <linux/module.h>
 16#include <linux/moduleparam.h>
 17#include <linux/regmap.h>
 18#include <linux/types.h>
 19
 20#define CIO_DAC_NUM_CHAN 16
 21
 22#define CIO_DAC_CHAN(chan) {				\
 23	.type = IIO_VOLTAGE,				\
 24	.channel = chan,				\
 25	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
 26	.indexed = 1,					\
 27	.output = 1					\
 28}
 29
 30#define CIO_DAC_EXTENT 32
 31
 32static unsigned int base[max_num_isa_dev(CIO_DAC_EXTENT)];
 33static unsigned int num_cio_dac;
 34module_param_hw_array(base, uint, ioport, &num_cio_dac, 0);
 35MODULE_PARM_DESC(base, "Measurement Computing CIO-DAC base addresses");
 36
 37#define CIO_DAC_BASE 0x00
 38#define CIO_DAC_CHANNEL_STRIDE 2
 39
 40static bool cio_dac_precious_reg(struct device *dev, unsigned int reg)
 41{
 42	/*
 43	 * All registers are considered precious; if the XFER jumper is set on
 44	 * the device, then no update occurs until a DAC register is read.
 45	 */
 46	return true;
 47}
 48
 49static const struct regmap_config cio_dac_regmap_config = {
 50	.reg_bits = 16,
 51	.reg_stride = 2,
 52	.val_bits = 16,
 53	.io_port = true,
 54	.max_register = 0x1F,
 55	.precious_reg = cio_dac_precious_reg,
 56};
 57
 58/**
 59 * struct cio_dac_iio - IIO device private data structure
 60 * @map: Regmap for the device
 61 */
 62struct cio_dac_iio {
 63	struct regmap *map;
 64};
 65
 66static int cio_dac_read_raw(struct iio_dev *indio_dev,
 67	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
 68{
 69	struct cio_dac_iio *const priv = iio_priv(indio_dev);
 70	const unsigned int offset = chan->channel * CIO_DAC_CHANNEL_STRIDE;
 71	int err;
 72	unsigned int dac_val;
 73
 74	if (mask != IIO_CHAN_INFO_RAW)
 75		return -EINVAL;
 76
 77	err = regmap_read(priv->map, CIO_DAC_BASE + offset, &dac_val);
 78	if (err)
 79		return err;
 80
 81	*val = dac_val;
 82
 83	return IIO_VAL_INT;
 84}
 85
 86static int cio_dac_write_raw(struct iio_dev *indio_dev,
 87	struct iio_chan_spec const *chan, int val, int val2, long mask)
 88{
 89	struct cio_dac_iio *const priv = iio_priv(indio_dev);
 90	const unsigned int offset = chan->channel * CIO_DAC_CHANNEL_STRIDE;
 91
 92	if (mask != IIO_CHAN_INFO_RAW)
 93		return -EINVAL;
 94
 95	/* DAC can only accept up to a 12-bit value */
 96	if ((unsigned int)val > 4095)
 97		return -EINVAL;
 98
 99	return regmap_write(priv->map, CIO_DAC_BASE + offset, val);
100}
101
102static const struct iio_info cio_dac_info = {
103	.read_raw = cio_dac_read_raw,
104	.write_raw = cio_dac_write_raw
105};
106
107static const struct iio_chan_spec cio_dac_channels[CIO_DAC_NUM_CHAN] = {
108	CIO_DAC_CHAN(0), CIO_DAC_CHAN(1), CIO_DAC_CHAN(2), CIO_DAC_CHAN(3),
109	CIO_DAC_CHAN(4), CIO_DAC_CHAN(5), CIO_DAC_CHAN(6), CIO_DAC_CHAN(7),
110	CIO_DAC_CHAN(8), CIO_DAC_CHAN(9), CIO_DAC_CHAN(10), CIO_DAC_CHAN(11),
111	CIO_DAC_CHAN(12), CIO_DAC_CHAN(13), CIO_DAC_CHAN(14), CIO_DAC_CHAN(15)
112};
113
114static int cio_dac_probe(struct device *dev, unsigned int id)
115{
116	struct iio_dev *indio_dev;
117	struct cio_dac_iio *priv;
118	void __iomem *regs;
119
120	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
121	if (!indio_dev)
122		return -ENOMEM;
123
124	if (!devm_request_region(dev, base[id], CIO_DAC_EXTENT,
125		dev_name(dev))) {
126		dev_err(dev, "Unable to request port addresses (0x%X-0x%X)\n",
127			base[id], base[id] + CIO_DAC_EXTENT);
128		return -EBUSY;
129	}
130
131	regs = devm_ioport_map(dev, base[id], CIO_DAC_EXTENT);
132	if (!regs)
133		return -ENOMEM;
134
135	priv = iio_priv(indio_dev);
136	priv->map = devm_regmap_init_mmio(dev, regs, &cio_dac_regmap_config);
137	if (IS_ERR(priv->map))
138		return dev_err_probe(dev, PTR_ERR(priv->map),
139				     "Unable to initialize register map\n");
140
141	indio_dev->info = &cio_dac_info;
142	indio_dev->modes = INDIO_DIRECT_MODE;
143	indio_dev->channels = cio_dac_channels;
144	indio_dev->num_channels = CIO_DAC_NUM_CHAN;
145	indio_dev->name = dev_name(dev);
146
147	return devm_iio_device_register(dev, indio_dev);
148}
149
150static struct isa_driver cio_dac_driver = {
151	.probe = cio_dac_probe,
152	.driver = {
153		.name = "cio-dac"
154	}
155};
156
157module_isa_driver(cio_dac_driver, num_cio_dac);
158
159MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
160MODULE_DESCRIPTION("Measurement Computing CIO-DAC IIO driver");
161MODULE_LICENSE("GPL v2");