2 * DAC driver for the Apex Embedded Systems STX104
3 * Copyright (C) 2016 William Breathitt Gray
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.
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.
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>
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>
27 #define STX104_NUM_CHAN 2
29 #define STX104_CHAN(chan) { \
30 .type = IIO_VOLTAGE, \
32 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
37 #define STX104_EXTENT 16
39 static unsigned int base[max_num_isa_dev(STX104_EXTENT)];
40 static unsigned int num_stx104;
41 module_param_array(base, uint, &num_stx104, 0);
42 MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
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
50 unsigned chan_out_states[STX104_NUM_CHAN];
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
62 struct gpio_chip chip;
65 unsigned int out_state;
69 * struct stx104_dev - STX104 device private data structure
70 * @indio_dev: IIO device
71 * @chip: instance of the gpio_chip
74 struct iio_dev *indio_dev;
75 struct gpio_chip *chip;
78 static int stx104_read_raw(struct iio_dev *indio_dev,
79 struct iio_chan_spec const *chan, int *val, int *val2, long mask)
81 struct stx104_iio *const priv = iio_priv(indio_dev);
83 if (mask != IIO_CHAN_INFO_RAW)
86 *val = priv->chan_out_states[chan->channel];
91 static int stx104_write_raw(struct iio_dev *indio_dev,
92 struct iio_chan_spec const *chan, int val, int val2, long mask)
94 struct stx104_iio *const priv = iio_priv(indio_dev);
95 const unsigned chan_addr_offset = 2 * chan->channel;
97 if (mask != IIO_CHAN_INFO_RAW)
100 priv->chan_out_states[chan->channel] = val;
101 outw(val, priv->base + 4 + chan_addr_offset);
106 static const struct iio_info stx104_info = {
107 .driver_module = THIS_MODULE,
108 .read_raw = stx104_read_raw,
109 .write_raw = stx104_write_raw
112 static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
117 static int stx104_gpio_get_direction(struct gpio_chip *chip,
120 /* GPIO 0-3 are input only, while the rest are output only */
127 static int stx104_gpio_direction_input(struct gpio_chip *chip,
136 static int stx104_gpio_direction_output(struct gpio_chip *chip,
137 unsigned int offset, int value)
142 chip->set(chip, offset, value);
146 static int stx104_gpio_get(struct gpio_chip *chip, unsigned int offset)
148 struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
153 return !!(inb(stx104gpio->base) & BIT(offset));
156 static void stx104_gpio_set(struct gpio_chip *chip, unsigned int offset,
159 struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
160 const unsigned int mask = BIT(offset) >> 4;
166 spin_lock_irqsave(&stx104gpio->lock, flags);
169 stx104gpio->out_state |= mask;
171 stx104gpio->out_state &= ~mask;
173 outb(stx104gpio->out_state, stx104gpio->base);
175 spin_unlock_irqrestore(&stx104gpio->lock, flags);
178 static int stx104_probe(struct device *dev, unsigned int id)
180 struct iio_dev *indio_dev;
181 struct stx104_iio *priv;
182 struct stx104_gpio *stx104gpio;
183 struct stx104_dev *stx104dev;
186 indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
190 stx104gpio = devm_kzalloc(dev, sizeof(*stx104gpio), GFP_KERNEL);
194 stx104dev = devm_kzalloc(dev, sizeof(*stx104dev), GFP_KERNEL);
198 if (!devm_request_region(dev, base[id], STX104_EXTENT,
200 dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
201 base[id], base[id] + STX104_EXTENT);
205 indio_dev->info = &stx104_info;
206 indio_dev->modes = INDIO_DIRECT_MODE;
207 indio_dev->channels = stx104_channels;
208 indio_dev->num_channels = STX104_NUM_CHAN;
209 indio_dev->name = dev_name(dev);
211 priv = iio_priv(indio_dev);
212 priv->base = base[id];
214 /* initialize DAC output to 0V */
215 outw(0, base[id] + 4);
216 outw(0, base[id] + 6);
218 stx104gpio->chip.label = dev_name(dev);
219 stx104gpio->chip.parent = dev;
220 stx104gpio->chip.owner = THIS_MODULE;
221 stx104gpio->chip.base = -1;
222 stx104gpio->chip.ngpio = 8;
223 stx104gpio->chip.get_direction = stx104_gpio_get_direction;
224 stx104gpio->chip.direction_input = stx104_gpio_direction_input;
225 stx104gpio->chip.direction_output = stx104_gpio_direction_output;
226 stx104gpio->chip.get = stx104_gpio_get;
227 stx104gpio->chip.set = stx104_gpio_set;
228 stx104gpio->base = base[id] + 3;
229 stx104gpio->out_state = 0x0;
231 spin_lock_init(&stx104gpio->lock);
233 stx104dev->indio_dev = indio_dev;
234 stx104dev->chip = &stx104gpio->chip;
235 dev_set_drvdata(dev, stx104dev);
237 err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
239 dev_err(dev, "GPIO registering failed (%d)\n", err);
243 err = iio_device_register(indio_dev);
245 dev_err(dev, "IIO device registering failed (%d)\n", err);
246 gpiochip_remove(&stx104gpio->chip);
253 static int stx104_remove(struct device *dev, unsigned int id)
255 struct stx104_dev *const stx104dev = dev_get_drvdata(dev);
257 iio_device_unregister(stx104dev->indio_dev);
258 gpiochip_remove(stx104dev->chip);
263 static struct isa_driver stx104_driver = {
264 .probe = stx104_probe,
268 .remove = stx104_remove
271 module_isa_driver(stx104_driver, num_stx104);
273 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
274 MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
275 MODULE_LICENSE("GPL v2");