xref: /openbmc/linux/drivers/iio/dac/cio-dac.c (revision 89df62c3)
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 
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 #define CIO_DAC_BASE 0x00
38 #define CIO_DAC_CHANNEL_STRIDE 2
39 
40 static 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 
49 static 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  */
62 struct cio_dac_iio {
63 	struct regmap *map;
64 };
65 
66 static 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 
86 static 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 
102 static const struct iio_info cio_dac_info = {
103 	.read_raw = cio_dac_read_raw,
104 	.write_raw = cio_dac_write_raw
105 };
106 
107 static 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 
114 static 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 
150 static struct isa_driver cio_dac_driver = {
151 	.probe = cio_dac_probe,
152 	.driver = {
153 		.name = "cio-dac"
154 	}
155 };
156 
157 module_isa_driver(cio_dac_driver, num_cio_dac);
158 
159 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
160 MODULE_DESCRIPTION("Measurement Computing CIO-DAC IIO driver");
161 MODULE_LICENSE("GPL v2");
162