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 * The highest base address possible for an ISA device is 0x3FF; this results in
40 * 1024 possible base addresses. Dividing the number of possible base addresses
41 * by the address extent taken by each device results in the maximum number of
42 * devices on a system.
44 #define MAX_NUM_STX104 (1024 / STX104_EXTENT)
46 static unsigned base[MAX_NUM_STX104];
47 static unsigned num_stx104;
48 module_param_array(base, uint, &num_stx104, 0);
49 MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
52 * struct stx104_iio - IIO device private data structure
53 * @chan_out_states: channels' output states
54 * @base: base port address of the IIO device
57 unsigned chan_out_states[STX104_NUM_CHAN];
62 * struct stx104_gpio - GPIO device private data structure
63 * @chip: instance of the gpio_chip
64 * @lock: synchronization lock to prevent I/O race conditions
65 * @base: base port address of the GPIO device
66 * @out_state: output bits state
69 struct gpio_chip chip;
72 unsigned int out_state;
75 static int stx104_read_raw(struct iio_dev *indio_dev,
76 struct iio_chan_spec const *chan, int *val, int *val2, long mask)
78 struct stx104_iio *const priv = iio_priv(indio_dev);
80 if (mask != IIO_CHAN_INFO_RAW)
83 *val = priv->chan_out_states[chan->channel];
88 static int stx104_write_raw(struct iio_dev *indio_dev,
89 struct iio_chan_spec const *chan, int val, int val2, long mask)
91 struct stx104_iio *const priv = iio_priv(indio_dev);
92 const unsigned chan_addr_offset = 2 * chan->channel;
94 if (mask != IIO_CHAN_INFO_RAW)
97 priv->chan_out_states[chan->channel] = val;
98 outw(val, priv->base + 4 + chan_addr_offset);
103 static const struct iio_info stx104_info = {
104 .driver_module = THIS_MODULE,
105 .read_raw = stx104_read_raw,
106 .write_raw = stx104_write_raw
109 static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
114 static int stx104_gpio_get_direction(struct gpio_chip *chip,
123 static int stx104_gpio_direction_input(struct gpio_chip *chip,
132 static int stx104_gpio_direction_output(struct gpio_chip *chip,
133 unsigned int offset, int value)
138 chip->set(chip, offset, value);
142 static int stx104_gpio_get(struct gpio_chip *chip, unsigned int offset)
144 struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
149 return !!(inb(stx104gpio->base) & BIT(offset));
152 static void stx104_gpio_set(struct gpio_chip *chip, unsigned int offset,
155 struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
156 const unsigned int mask = BIT(offset) >> 4;
162 spin_lock_irqsave(&stx104gpio->lock, flags);
165 stx104gpio->out_state |= mask;
167 stx104gpio->out_state &= ~mask;
169 outb(stx104gpio->out_state, stx104gpio->base);
171 spin_unlock_irqrestore(&stx104gpio->lock, flags);
174 static int stx104_probe(struct device *dev, unsigned int id)
176 struct iio_dev *indio_dev;
177 struct stx104_iio *priv;
178 struct stx104_gpio *stx104gpio;
181 indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
185 stx104gpio = devm_kzalloc(dev, sizeof(*stx104gpio), GFP_KERNEL);
189 if (!devm_request_region(dev, base[id], STX104_EXTENT,
191 dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
192 base[id], base[id] + STX104_EXTENT);
196 indio_dev->info = &stx104_info;
197 indio_dev->modes = INDIO_DIRECT_MODE;
198 indio_dev->channels = stx104_channels;
199 indio_dev->num_channels = STX104_NUM_CHAN;
200 indio_dev->name = dev_name(dev);
202 priv = iio_priv(indio_dev);
203 priv->base = base[id];
205 /* initialize DAC output to 0V */
206 outw(0, base[id] + 4);
207 outw(0, base[id] + 6);
209 err = devm_iio_device_register(dev, indio_dev);
211 dev_err(dev, "IIO device registering failed (%d)\n", err);
215 stx104gpio->chip.label = dev_name(dev);
216 stx104gpio->chip.parent = dev;
217 stx104gpio->chip.owner = THIS_MODULE;
218 stx104gpio->chip.base = -1;
219 stx104gpio->chip.ngpio = 8;
220 stx104gpio->chip.get_direction = stx104_gpio_get_direction;
221 stx104gpio->chip.direction_input = stx104_gpio_direction_input;
222 stx104gpio->chip.direction_output = stx104_gpio_direction_output;
223 stx104gpio->chip.get = stx104_gpio_get;
224 stx104gpio->chip.set = stx104_gpio_set;
225 stx104gpio->base = base[id] + 3;
226 stx104gpio->out_state = 0x0;
228 spin_lock_init(&stx104gpio->lock);
230 dev_set_drvdata(dev, stx104gpio);
232 err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
234 dev_err(dev, "GPIO registering failed (%d)\n", err);
241 static int stx104_remove(struct device *dev, unsigned int id)
243 struct stx104_gpio *const stx104gpio = dev_get_drvdata(dev);
245 gpiochip_remove(&stx104gpio->chip);
250 static struct isa_driver stx104_driver = {
251 .probe = stx104_probe,
255 .remove = stx104_remove
258 static void __exit stx104_exit(void)
260 isa_unregister_driver(&stx104_driver);
263 static int __init stx104_init(void)
265 return isa_register_driver(&stx104_driver, num_stx104);
268 module_init(stx104_init);
269 module_exit(stx104_exit);
271 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
272 MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
273 MODULE_LICENSE("GPL v2");