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97a445da WBG |
1 | /* |
2 | * DAC driver for the Apex Embedded Systems STX104 | |
3 | * Copyright (C) 2016 William Breathitt Gray | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License, version 2, as | |
7 | * published by the Free Software Foundation. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, but | |
10 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | * General Public License for more details. | |
13 | */ | |
14 | #include <linux/bitops.h> | |
15 | #include <linux/device.h> | |
16 | #include <linux/errno.h> | |
17 | #include <linux/iio/iio.h> | |
18 | #include <linux/iio/types.h> | |
19 | #include <linux/io.h> | |
20 | #include <linux/ioport.h> | |
21 | #include <linux/isa.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/moduleparam.h> | |
24 | ||
25 | #define STX104_NUM_CHAN 2 | |
26 | ||
27 | #define STX104_CHAN(chan) { \ | |
28 | .type = IIO_VOLTAGE, \ | |
29 | .channel = chan, \ | |
30 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ | |
31 | .indexed = 1, \ | |
32 | .output = 1 \ | |
33 | } | |
34 | ||
35 | #define STX104_EXTENT 16 | |
36 | /** | |
37 | * The highest base address possible for an ISA device is 0x3FF; this results in | |
38 | * 1024 possible base addresses. Dividing the number of possible base addresses | |
39 | * by the address extent taken by each device results in the maximum number of | |
40 | * devices on a system. | |
41 | */ | |
42 | #define MAX_NUM_STX104 (1024 / STX104_EXTENT) | |
43 | ||
44 | static unsigned base[MAX_NUM_STX104]; | |
45 | static unsigned num_stx104; | |
46 | module_param_array(base, uint, &num_stx104, 0); | |
47 | MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses"); | |
48 | ||
49 | /** | |
50 | * struct stx104_iio - IIO device private data structure | |
51 | * @chan_out_states: channels' output states | |
52 | * @base: base port address of the IIO device | |
53 | */ | |
54 | struct stx104_iio { | |
55 | unsigned chan_out_states[STX104_NUM_CHAN]; | |
56 | unsigned base; | |
57 | }; | |
58 | ||
59 | static int stx104_read_raw(struct iio_dev *indio_dev, | |
60 | struct iio_chan_spec const *chan, int *val, int *val2, long mask) | |
61 | { | |
62 | struct stx104_iio *const priv = iio_priv(indio_dev); | |
63 | ||
64 | if (mask != IIO_CHAN_INFO_RAW) | |
65 | return -EINVAL; | |
66 | ||
67 | *val = priv->chan_out_states[chan->channel]; | |
68 | ||
69 | return IIO_VAL_INT; | |
70 | } | |
71 | ||
72 | static int stx104_write_raw(struct iio_dev *indio_dev, | |
73 | struct iio_chan_spec const *chan, int val, int val2, long mask) | |
74 | { | |
75 | struct stx104_iio *const priv = iio_priv(indio_dev); | |
76 | const unsigned chan_addr_offset = 2 * chan->channel; | |
77 | ||
78 | if (mask != IIO_CHAN_INFO_RAW) | |
79 | return -EINVAL; | |
80 | ||
81 | priv->chan_out_states[chan->channel] = val; | |
82 | outw(val, priv->base + 4 + chan_addr_offset); | |
83 | ||
84 | return 0; | |
85 | } | |
86 | ||
87 | static const struct iio_info stx104_info = { | |
88 | .driver_module = THIS_MODULE, | |
89 | .read_raw = stx104_read_raw, | |
90 | .write_raw = stx104_write_raw | |
91 | }; | |
92 | ||
93 | static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = { | |
94 | STX104_CHAN(0), | |
95 | STX104_CHAN(1) | |
96 | }; | |
97 | ||
98 | static int stx104_probe(struct device *dev, unsigned int id) | |
99 | { | |
100 | struct iio_dev *indio_dev; | |
101 | struct stx104_iio *priv; | |
102 | ||
103 | indio_dev = devm_iio_device_alloc(dev, sizeof(*priv)); | |
104 | if (!indio_dev) | |
105 | return -ENOMEM; | |
106 | ||
107 | if (!devm_request_region(dev, base[id], STX104_EXTENT, | |
108 | dev_name(dev))) { | |
109 | dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n", | |
110 | base[id], base[id] + STX104_EXTENT); | |
111 | return -EBUSY; | |
112 | } | |
113 | ||
114 | indio_dev->info = &stx104_info; | |
115 | indio_dev->modes = INDIO_DIRECT_MODE; | |
116 | indio_dev->channels = stx104_channels; | |
117 | indio_dev->num_channels = STX104_NUM_CHAN; | |
118 | indio_dev->name = dev_name(dev); | |
119 | ||
120 | priv = iio_priv(indio_dev); | |
121 | priv->base = base[id]; | |
122 | ||
123 | /* initialize DAC output to 0V */ | |
124 | outw(0, base[id] + 4); | |
125 | outw(0, base[id] + 6); | |
126 | ||
127 | return devm_iio_device_register(dev, indio_dev); | |
128 | } | |
129 | ||
130 | static struct isa_driver stx104_driver = { | |
131 | .probe = stx104_probe, | |
132 | .driver = { | |
133 | .name = "stx104" | |
134 | } | |
135 | }; | |
136 | ||
137 | static void __exit stx104_exit(void) | |
138 | { | |
139 | isa_unregister_driver(&stx104_driver); | |
140 | } | |
141 | ||
142 | static int __init stx104_init(void) | |
143 | { | |
144 | return isa_register_driver(&stx104_driver, num_stx104); | |
145 | } | |
146 | ||
147 | module_init(stx104_init); | |
148 | module_exit(stx104_exit); | |
149 | ||
150 | MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>"); | |
151 | MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver"); | |
152 | MODULE_LICENSE("GPL v2"); |