tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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/gpio/driver.h>
18#include <linux/iio/iio.h>
19#include <linux/iio/types.h>
20#include <linux/io.h>
21#include <linux/ioport.h>
22#include <linux/isa.h>
23#include <linux/module.h>
24#include <linux/moduleparam.h>
25#include <linux/spinlock.h>
26
27#define STX104_NUM_CHAN 2
28
29#define STX104_CHAN(chan) { \
30 .type = IIO_VOLTAGE, \
31 .channel = chan, \
32 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
33 .indexed = 1, \
34 .output = 1 \
35}
36
37#define STX104_EXTENT 16
38
39static unsigned int base[max_num_isa_dev(STX104_EXTENT)];
40static unsigned int num_stx104;
41module_param_array(base, uint, &num_stx104, 0);
42MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
43
44/**
45 * struct stx104_iio - IIO device private data structure
46 * @chan_out_states: channels' output states
47 * @base: base port address of the IIO device
48 */
49struct stx104_iio {
50 unsigned chan_out_states[STX104_NUM_CHAN];
51 unsigned base;
52};
53
54/**
55 * struct stx104_gpio - GPIO device private data structure
56 * @chip: instance of the gpio_chip
57 * @lock: synchronization lock to prevent I/O race conditions
58 * @base: base port address of the GPIO device
59 * @out_state: output bits state
60 */
61struct stx104_gpio {
62 struct gpio_chip chip;
63 spinlock_t lock;
64 unsigned int base;
65 unsigned int out_state;
66};
67
68static int stx104_read_raw(struct iio_dev *indio_dev,
69 struct iio_chan_spec const *chan, int *val, int *val2, long mask)
70{
71 struct stx104_iio *const priv = iio_priv(indio_dev);
72
73 if (mask != IIO_CHAN_INFO_RAW)
74 return -EINVAL;
75
76 *val = priv->chan_out_states[chan->channel];
77
78 return IIO_VAL_INT;
79}
80
81static int stx104_write_raw(struct iio_dev *indio_dev,
82 struct iio_chan_spec const *chan, int val, int val2, long mask)
83{
84 struct stx104_iio *const priv = iio_priv(indio_dev);
85 const unsigned chan_addr_offset = 2 * chan->channel;
86
87 if (mask != IIO_CHAN_INFO_RAW)
88 return -EINVAL;
89
90 priv->chan_out_states[chan->channel] = val;
91 outw(val, priv->base + 4 + chan_addr_offset);
92
93 return 0;
94}
95
96static const struct iio_info stx104_info = {
97 .driver_module = THIS_MODULE,
98 .read_raw = stx104_read_raw,
99 .write_raw = stx104_write_raw
100};
101
102static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
103 STX104_CHAN(0),
104 STX104_CHAN(1)
105};
106
107static int stx104_gpio_get_direction(struct gpio_chip *chip,
108 unsigned int offset)
109{
110 if (offset < 4)
111 return 1;
112
113 return 0;
114}
115
116static int stx104_gpio_direction_input(struct gpio_chip *chip,
117 unsigned int offset)
118{
119 if (offset >= 4)
120 return -EINVAL;
121
122 return 0;
123}
124
125static int stx104_gpio_direction_output(struct gpio_chip *chip,
126 unsigned int offset, int value)
127{
128 if (offset < 4)
129 return -EINVAL;
130
131 chip->set(chip, offset, value);
132 return 0;
133}
134
135static int stx104_gpio_get(struct gpio_chip *chip, unsigned int offset)
136{
137 struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
138
139 if (offset >= 4)
140 return -EINVAL;
141
142 return !!(inb(stx104gpio->base) & BIT(offset));
143}
144
145static void stx104_gpio_set(struct gpio_chip *chip, unsigned int offset,
146 int value)
147{
148 struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
149 const unsigned int mask = BIT(offset) >> 4;
150 unsigned long flags;
151
152 if (offset < 4)
153 return;
154
155 spin_lock_irqsave(&stx104gpio->lock, flags);
156
157 if (value)
158 stx104gpio->out_state |= mask;
159 else
160 stx104gpio->out_state &= ~mask;
161
162 outb(stx104gpio->out_state, stx104gpio->base);
163
164 spin_unlock_irqrestore(&stx104gpio->lock, flags);
165}
166
167static int stx104_probe(struct device *dev, unsigned int id)
168{
169 struct iio_dev *indio_dev;
170 struct stx104_iio *priv;
171 struct stx104_gpio *stx104gpio;
172 int err;
173
174 indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
175 if (!indio_dev)
176 return -ENOMEM;
177
178 stx104gpio = devm_kzalloc(dev, sizeof(*stx104gpio), GFP_KERNEL);
179 if (!stx104gpio)
180 return -ENOMEM;
181
182 if (!devm_request_region(dev, base[id], STX104_EXTENT,
183 dev_name(dev))) {
184 dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
185 base[id], base[id] + STX104_EXTENT);
186 return -EBUSY;
187 }
188
189 indio_dev->info = &stx104_info;
190 indio_dev->modes = INDIO_DIRECT_MODE;
191 indio_dev->channels = stx104_channels;
192 indio_dev->num_channels = STX104_NUM_CHAN;
193 indio_dev->name = dev_name(dev);
194
195 priv = iio_priv(indio_dev);
196 priv->base = base[id];
197
198 /* initialize DAC output to 0V */
199 outw(0, base[id] + 4);
200 outw(0, base[id] + 6);
201
202 err = devm_iio_device_register(dev, indio_dev);
203 if (err) {
204 dev_err(dev, "IIO device registering failed (%d)\n", err);
205 return err;
206 }
207
208 stx104gpio->chip.label = dev_name(dev);
209 stx104gpio->chip.parent = dev;
210 stx104gpio->chip.owner = THIS_MODULE;
211 stx104gpio->chip.base = -1;
212 stx104gpio->chip.ngpio = 8;
213 stx104gpio->chip.get_direction = stx104_gpio_get_direction;
214 stx104gpio->chip.direction_input = stx104_gpio_direction_input;
215 stx104gpio->chip.direction_output = stx104_gpio_direction_output;
216 stx104gpio->chip.get = stx104_gpio_get;
217 stx104gpio->chip.set = stx104_gpio_set;
218 stx104gpio->base = base[id] + 3;
219 stx104gpio->out_state = 0x0;
220
221 spin_lock_init(&stx104gpio->lock);
222
223 dev_set_drvdata(dev, stx104gpio);
224
225 err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
226 if (err) {
227 dev_err(dev, "GPIO registering failed (%d)\n", err);
228 return err;
229 }
230
231 return 0;
232}
233
234static int stx104_remove(struct device *dev, unsigned int id)
235{
236 struct stx104_gpio *const stx104gpio = dev_get_drvdata(dev);
237
238 gpiochip_remove(&stx104gpio->chip);
239
240 return 0;
241}
242
243static struct isa_driver stx104_driver = {
244 .probe = stx104_probe,
245 .driver = {
246 .name = "stx104"
247 },
248 .remove = stx104_remove
249};
250
251module_isa_driver(stx104_driver, num_stx104);
252
253MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
254MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
255MODULE_LICENSE("GPL v2");