xref: /openbmc/linux/drivers/iio/dac/cio-dac.c (revision dbf563ee)
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-DAC06, and PC104-DAC06.
8  */
9 #include <linux/bitops.h>
10 #include <linux/device.h>
11 #include <linux/errno.h>
12 #include <linux/iio/iio.h>
13 #include <linux/iio/types.h>
14 #include <linux/io.h>
15 #include <linux/ioport.h>
16 #include <linux/isa.h>
17 #include <linux/module.h>
18 #include <linux/moduleparam.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 
32 static unsigned int base[max_num_isa_dev(CIO_DAC_EXTENT)];
33 static unsigned int num_cio_dac;
34 module_param_hw_array(base, uint, ioport, &num_cio_dac, 0);
35 MODULE_PARM_DESC(base, "Measurement Computing CIO-DAC base addresses");
36 
37 /**
38  * struct cio_dac_iio - IIO device private data structure
39  * @chan_out_states:	channels' output states
40  * @base:		base port address of the IIO device
41  */
42 struct cio_dac_iio {
43 	int chan_out_states[CIO_DAC_NUM_CHAN];
44 	unsigned int base;
45 };
46 
47 static int cio_dac_read_raw(struct iio_dev *indio_dev,
48 	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
49 {
50 	struct cio_dac_iio *const priv = iio_priv(indio_dev);
51 
52 	if (mask != IIO_CHAN_INFO_RAW)
53 		return -EINVAL;
54 
55 	*val = priv->chan_out_states[chan->channel];
56 
57 	return IIO_VAL_INT;
58 }
59 
60 static int cio_dac_write_raw(struct iio_dev *indio_dev,
61 	struct iio_chan_spec const *chan, int val, int val2, long mask)
62 {
63 	struct cio_dac_iio *const priv = iio_priv(indio_dev);
64 	const unsigned int chan_addr_offset = 2 * chan->channel;
65 
66 	if (mask != IIO_CHAN_INFO_RAW)
67 		return -EINVAL;
68 
69 	/* DAC can only accept up to a 16-bit value */
70 	if ((unsigned int)val > 65535)
71 		return -EINVAL;
72 
73 	priv->chan_out_states[chan->channel] = val;
74 	outw(val, priv->base + chan_addr_offset);
75 
76 	return 0;
77 }
78 
79 static const struct iio_info cio_dac_info = {
80 	.read_raw = cio_dac_read_raw,
81 	.write_raw = cio_dac_write_raw
82 };
83 
84 static const struct iio_chan_spec cio_dac_channels[CIO_DAC_NUM_CHAN] = {
85 	CIO_DAC_CHAN(0), CIO_DAC_CHAN(1), CIO_DAC_CHAN(2), CIO_DAC_CHAN(3),
86 	CIO_DAC_CHAN(4), CIO_DAC_CHAN(5), CIO_DAC_CHAN(6), CIO_DAC_CHAN(7),
87 	CIO_DAC_CHAN(8), CIO_DAC_CHAN(9), CIO_DAC_CHAN(10), CIO_DAC_CHAN(11),
88 	CIO_DAC_CHAN(12), CIO_DAC_CHAN(13), CIO_DAC_CHAN(14), CIO_DAC_CHAN(15)
89 };
90 
91 static int cio_dac_probe(struct device *dev, unsigned int id)
92 {
93 	struct iio_dev *indio_dev;
94 	struct cio_dac_iio *priv;
95 	unsigned int i;
96 
97 	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
98 	if (!indio_dev)
99 		return -ENOMEM;
100 
101 	if (!devm_request_region(dev, base[id], CIO_DAC_EXTENT,
102 		dev_name(dev))) {
103 		dev_err(dev, "Unable to request port addresses (0x%X-0x%X)\n",
104 			base[id], base[id] + CIO_DAC_EXTENT);
105 		return -EBUSY;
106 	}
107 
108 	indio_dev->info = &cio_dac_info;
109 	indio_dev->modes = INDIO_DIRECT_MODE;
110 	indio_dev->channels = cio_dac_channels;
111 	indio_dev->num_channels = CIO_DAC_NUM_CHAN;
112 	indio_dev->name = dev_name(dev);
113 
114 	priv = iio_priv(indio_dev);
115 	priv->base = base[id];
116 
117 	/* initialize DAC outputs to 0V */
118 	for (i = 0; i < 32; i += 2)
119 		outw(0, base[id] + i);
120 
121 	return devm_iio_device_register(dev, indio_dev);
122 }
123 
124 static struct isa_driver cio_dac_driver = {
125 	.probe = cio_dac_probe,
126 	.driver = {
127 		.name = "cio-dac"
128 	}
129 };
130 
131 module_isa_driver(cio_dac_driver, num_cio_dac);
132 
133 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
134 MODULE_DESCRIPTION("Measurement Computing CIO-DAC IIO driver");
135 MODULE_LICENSE("GPL v2");
136