1/*
  2 * GPIO driver for the ACCES 104-IDIO-16 family
  3 * Copyright (C) 2015 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/io.h>
 19#include <linux/ioport.h>
 20#include <linux/interrupt.h>
 21#include <linux/irqdesc.h>
 22#include <linux/kernel.h>
 23#include <linux/module.h>
 24#include <linux/moduleparam.h>
 25#include <linux/platform_device.h>
 26#include <linux/spinlock.h>
 27
 28static unsigned idio_16_base;
 29module_param(idio_16_base, uint, 0);
 30MODULE_PARM_DESC(idio_16_base, "ACCES 104-IDIO-16 base address");
 31static unsigned idio_16_irq;
 32module_param(idio_16_irq, uint, 0);
 33MODULE_PARM_DESC(idio_16_irq, "ACCES 104-IDIO-16 interrupt line number");
 34
 35/**
 36 * struct idio_16_gpio - GPIO device private data structure
 37 * @chip:	instance of the gpio_chip
 38 * @lock:	synchronization lock to prevent I/O race conditions
 39 * @irq_mask:	I/O bits affected by interrupts
 40 * @base:	base port address of the GPIO device
 41 * @irq:	Interrupt line number
 42 * @out_state:	output bits state
 43 */
 44struct idio_16_gpio {
 45	struct gpio_chip chip;
 46	spinlock_t lock;
 47	unsigned long irq_mask;
 48	unsigned base;
 49	unsigned irq;
 50	unsigned out_state;
 51};
 52
 53static int idio_16_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
 54{
 55	if (offset > 15)
 56		return 1;
 57
 58	return 0;
 59}
 60
 61static int idio_16_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
 62{
 63	return 0;
 64}
 65
 66static int idio_16_gpio_direction_output(struct gpio_chip *chip,
 67	unsigned offset, int value)
 68{
 69	chip->set(chip, offset, value);
 70	return 0;
 71}
 72
 73static int idio_16_gpio_get(struct gpio_chip *chip, unsigned offset)
 74{
 75	struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip);
 76	const unsigned mask = BIT(offset-16);
 77
 78	if (offset < 16)
 79		return -EINVAL;
 80
 81	if (offset < 24)
 82		return !!(inb(idio16gpio->base + 1) & mask);
 83
 84	return !!(inb(idio16gpio->base + 5) & (mask>>8));
 85}
 86
 87static void idio_16_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
 88{
 89	struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip);
 90	const unsigned mask = BIT(offset);
 91	unsigned long flags;
 92
 93	if (offset > 15)
 94		return;
 95
 96	spin_lock_irqsave(&idio16gpio->lock, flags);
 97
 98	if (value)
 99		idio16gpio->out_state |= mask;
100	else
101		idio16gpio->out_state &= ~mask;
102
103	if (offset > 7)
104		outb(idio16gpio->out_state >> 8, idio16gpio->base + 4);
105	else
106		outb(idio16gpio->out_state, idio16gpio->base);
107
108	spin_unlock_irqrestore(&idio16gpio->lock, flags);
109}
110
111static void idio_16_irq_ack(struct irq_data *data)
112{
113}
114
115static void idio_16_irq_mask(struct irq_data *data)
116{
117	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
118	struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip);
119	const unsigned long mask = BIT(irqd_to_hwirq(data));
120	unsigned long flags;
121
122	idio16gpio->irq_mask &= ~mask;
123
124	if (!idio16gpio->irq_mask) {
125		spin_lock_irqsave(&idio16gpio->lock, flags);
126
127		outb(0, idio16gpio->base + 2);
128
129		spin_unlock_irqrestore(&idio16gpio->lock, flags);
130	}
131}
132
133static void idio_16_irq_unmask(struct irq_data *data)
134{
135	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
136	struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip);
137	const unsigned long mask = BIT(irqd_to_hwirq(data));
138	const unsigned long prev_irq_mask = idio16gpio->irq_mask;
139	unsigned long flags;
140
141	idio16gpio->irq_mask |= mask;
142
143	if (!prev_irq_mask) {
144		spin_lock_irqsave(&idio16gpio->lock, flags);
145
146		inb(idio16gpio->base + 2);
147
148		spin_unlock_irqrestore(&idio16gpio->lock, flags);
149	}
150}
151
152static int idio_16_irq_set_type(struct irq_data *data, unsigned flow_type)
153{
154	/* The only valid irq types are none and both-edges */
155	if (flow_type != IRQ_TYPE_NONE &&
156		(flow_type & IRQ_TYPE_EDGE_BOTH) != IRQ_TYPE_EDGE_BOTH)
157		return -EINVAL;
158
159	return 0;
160}
161
162static struct irq_chip idio_16_irqchip = {
163	.name = "104-idio-16",
164	.irq_ack = idio_16_irq_ack,
165	.irq_mask = idio_16_irq_mask,
166	.irq_unmask = idio_16_irq_unmask,
167	.irq_set_type = idio_16_irq_set_type
168};
169
170static irqreturn_t idio_16_irq_handler(int irq, void *dev_id)
171{
172	struct idio_16_gpio *const idio16gpio = dev_id;
173	struct gpio_chip *const chip = &idio16gpio->chip;
174	int gpio;
175
176	for_each_set_bit(gpio, &idio16gpio->irq_mask, chip->ngpio)
177		generic_handle_irq(irq_find_mapping(chip->irqdomain, gpio));
178
179	spin_lock(&idio16gpio->lock);
180
181	outb(0, idio16gpio->base + 1);
182
183	spin_unlock(&idio16gpio->lock);
184
185	return IRQ_HANDLED;
186}
187
188static int __init idio_16_probe(struct platform_device *pdev)
189{
190	struct device *dev = &pdev->dev;
191	struct idio_16_gpio *idio16gpio;
192	const unsigned base = idio_16_base;
193	const unsigned extent = 8;
194	const char *const name = dev_name(dev);
195	int err;
196	const unsigned irq = idio_16_irq;
197
198	idio16gpio = devm_kzalloc(dev, sizeof(*idio16gpio), GFP_KERNEL);
199	if (!idio16gpio)
200		return -ENOMEM;
201
202	if (!devm_request_region(dev, base, extent, name)) {
203		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
204			base, base + extent);
205		return -EBUSY;
206	}
207
208	idio16gpio->chip.label = name;
209	idio16gpio->chip.parent = dev;
210	idio16gpio->chip.owner = THIS_MODULE;
211	idio16gpio->chip.base = -1;
212	idio16gpio->chip.ngpio = 32;
213	idio16gpio->chip.get_direction = idio_16_gpio_get_direction;
214	idio16gpio->chip.direction_input = idio_16_gpio_direction_input;
215	idio16gpio->chip.direction_output = idio_16_gpio_direction_output;
216	idio16gpio->chip.get = idio_16_gpio_get;
217	idio16gpio->chip.set = idio_16_gpio_set;
218	idio16gpio->base = base;
219	idio16gpio->irq = irq;
220	idio16gpio->out_state = 0xFFFF;
221
222	spin_lock_init(&idio16gpio->lock);
223
224	dev_set_drvdata(dev, idio16gpio);
225
226	err = gpiochip_add_data(&idio16gpio->chip, idio16gpio);
227	if (err) {
228		dev_err(dev, "GPIO registering failed (%d)\n", err);
229		return err;
230	}
231
232	/* Disable IRQ by default */
233	outb(0, base + 2);
234	outb(0, base + 1);
235
236	err = gpiochip_irqchip_add(&idio16gpio->chip, &idio_16_irqchip, 0,
237		handle_edge_irq, IRQ_TYPE_NONE);
238	if (err) {
239		dev_err(dev, "Could not add irqchip (%d)\n", err);
240		goto err_gpiochip_remove;
241	}
242
243	err = request_irq(irq, idio_16_irq_handler, 0, name, idio16gpio);
244	if (err) {
245		dev_err(dev, "IRQ handler registering failed (%d)\n", err);
246		goto err_gpiochip_remove;
247	}
248
249	return 0;
250
251err_gpiochip_remove:
252	gpiochip_remove(&idio16gpio->chip);
253	return err;
254}
255
256static int idio_16_remove(struct platform_device *pdev)
257{
258	struct idio_16_gpio *const idio16gpio = platform_get_drvdata(pdev);
259
260	free_irq(idio16gpio->irq, idio16gpio);
261	gpiochip_remove(&idio16gpio->chip);
262
263	return 0;
264}
265
266static struct platform_device *idio_16_device;
267
268static struct platform_driver idio_16_driver = {
269	.driver = {
270		.name = "104-idio-16"
271	},
272	.remove = idio_16_remove
273};
274
275static void __exit idio_16_exit(void)
276{
277	platform_device_unregister(idio_16_device);
278	platform_driver_unregister(&idio_16_driver);
279}
280
281static int __init idio_16_init(void)
282{
283	int err;
284
285	idio_16_device = platform_device_alloc(idio_16_driver.driver.name, -1);
286	if (!idio_16_device)
287		return -ENOMEM;
288
289	err = platform_device_add(idio_16_device);
290	if (err)
291		goto err_platform_device;
292
293	err = platform_driver_probe(&idio_16_driver, idio_16_probe);
294	if (err)
295		goto err_platform_driver;
296
297	return 0;
298
299err_platform_driver:
300	platform_device_del(idio_16_device);
301err_platform_device:
302	platform_device_put(idio_16_device);
303	return err;
304}
305
306module_init(idio_16_init);
307module_exit(idio_16_exit);
308
309MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
310MODULE_DESCRIPTION("ACCES 104-IDIO-16 GPIO driver");
311MODULE_LICENSE("GPL v2");