1/*
  2 * GPIO driver for the ACCES 104-IDI-48 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 * This driver supports the following ACCES devices: 104-IDI-48A,
 15 * 104-IDI-48AC, 104-IDI-48B, and 104-IDI-48BC.
 16 */
 17#include <linux/bitops.h>
 18#include <linux/device.h>
 19#include <linux/errno.h>
 20#include <linux/gpio/driver.h>
 21#include <linux/io.h>
 22#include <linux/ioport.h>
 23#include <linux/interrupt.h>
 24#include <linux/irqdesc.h>
 25#include <linux/isa.h>
 26#include <linux/kernel.h>
 27#include <linux/module.h>
 28#include <linux/moduleparam.h>
 29#include <linux/spinlock.h>
 30
 31#define IDI_48_EXTENT 8
 32#define MAX_NUM_IDI_48 max_num_isa_dev(IDI_48_EXTENT)
 33
 34static unsigned int base[MAX_NUM_IDI_48];
 35static unsigned int num_idi_48;
 36module_param_array(base, uint, &num_idi_48, 0);
 37MODULE_PARM_DESC(base, "ACCES 104-IDI-48 base addresses");
 38
 39static unsigned int irq[MAX_NUM_IDI_48];
 40module_param_array(irq, uint, NULL, 0);
 41MODULE_PARM_DESC(irq, "ACCES 104-IDI-48 interrupt line numbers");
 42
 43/**
 44 * struct idi_48_gpio - GPIO device private data structure
 45 * @chip:	instance of the gpio_chip
 46 * @lock:	synchronization lock to prevent I/O race conditions
 47 * @ack_lock:	synchronization lock to prevent IRQ handler race conditions
 48 * @irq_mask:	input bits affected by interrupts
 49 * @base:	base port address of the GPIO device
 50 * @irq:	Interrupt line number
 51 * @cos_enb:	Change-Of-State IRQ enable boundaries mask
 52 */
 53struct idi_48_gpio {
 54	struct gpio_chip chip;
 55	spinlock_t lock;
 56	spinlock_t ack_lock;
 57	unsigned char irq_mask[6];
 58	unsigned base;
 59	unsigned irq;
 60	unsigned char cos_enb;
 61};
 62
 63static int idi_48_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
 64{
 65	return 1;
 66}
 67
 68static int idi_48_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
 69{
 70	return 0;
 71}
 72
 73static int idi_48_gpio_get(struct gpio_chip *chip, unsigned offset)
 74{
 75	struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
 76	unsigned i;
 77	const unsigned register_offset[6] = { 0, 1, 2, 4, 5, 6 };
 78	unsigned base_offset;
 79	unsigned mask;
 80
 81	for (i = 0; i < 48; i += 8)
 82		if (offset < i + 8) {
 83			base_offset = register_offset[i / 8];
 84			mask = BIT(offset - i);
 85
 86			return !!(inb(idi48gpio->base + base_offset) & mask);
 87		}
 88
 89	/* The following line should never execute since offset < 48 */
 90	return 0;
 91}
 92
 93static void idi_48_irq_ack(struct irq_data *data)
 94{
 95}
 96
 97static void idi_48_irq_mask(struct irq_data *data)
 98{
 99	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
100	struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
101	const unsigned offset = irqd_to_hwirq(data);
102	unsigned i;
103	unsigned mask;
104	unsigned boundary;
105	unsigned long flags;
106
107	for (i = 0; i < 48; i += 8)
108		if (offset < i + 8) {
109			mask = BIT(offset - i);
110			boundary = i / 8;
111
112			idi48gpio->irq_mask[boundary] &= ~mask;
113
114			if (!idi48gpio->irq_mask[boundary]) {
115				idi48gpio->cos_enb &= ~BIT(boundary);
116
117				spin_lock_irqsave(&idi48gpio->lock, flags);
118
119				outb(idi48gpio->cos_enb, idi48gpio->base + 7);
120
121				spin_unlock_irqrestore(&idi48gpio->lock, flags);
122			}
123
124			return;
125		}
126}
127
128static void idi_48_irq_unmask(struct irq_data *data)
129{
130	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
131	struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
132	const unsigned offset = irqd_to_hwirq(data);
133	unsigned i;
134	unsigned mask;
135	unsigned boundary;
136	unsigned prev_irq_mask;
137	unsigned long flags;
138
139	for (i = 0; i < 48; i += 8)
140		if (offset < i + 8) {
141			mask = BIT(offset - i);
142			boundary = i / 8;
143			prev_irq_mask = idi48gpio->irq_mask[boundary];
144
145			idi48gpio->irq_mask[boundary] |= mask;
146
147			if (!prev_irq_mask) {
148				idi48gpio->cos_enb |= BIT(boundary);
149
150				spin_lock_irqsave(&idi48gpio->lock, flags);
151
152				outb(idi48gpio->cos_enb, idi48gpio->base + 7);
153
154				spin_unlock_irqrestore(&idi48gpio->lock, flags);
155			}
156
157			return;
158		}
159}
160
161static int idi_48_irq_set_type(struct irq_data *data, unsigned flow_type)
162{
163	/* The only valid irq types are none and both-edges */
164	if (flow_type != IRQ_TYPE_NONE &&
165		(flow_type & IRQ_TYPE_EDGE_BOTH) != IRQ_TYPE_EDGE_BOTH)
166		return -EINVAL;
167
168	return 0;
169}
170
171static struct irq_chip idi_48_irqchip = {
172	.name = "104-idi-48",
173	.irq_ack = idi_48_irq_ack,
174	.irq_mask = idi_48_irq_mask,
175	.irq_unmask = idi_48_irq_unmask,
176	.irq_set_type = idi_48_irq_set_type
177};
178
179static irqreturn_t idi_48_irq_handler(int irq, void *dev_id)
180{
181	struct idi_48_gpio *const idi48gpio = dev_id;
182	unsigned long cos_status;
183	unsigned long boundary;
184	unsigned long irq_mask;
185	unsigned long bit_num;
186	unsigned long gpio;
187	struct gpio_chip *const chip = &idi48gpio->chip;
188
189	spin_lock(&idi48gpio->ack_lock);
190
191	spin_lock(&idi48gpio->lock);
192
193	cos_status = inb(idi48gpio->base + 7);
194
195	spin_unlock(&idi48gpio->lock);
196
197	/* IRQ Status (bit 6) is active low (0 = IRQ generated by device) */
198	if (cos_status & BIT(6)) {
199		spin_unlock(&idi48gpio->ack_lock);
200		return IRQ_NONE;
201	}
202
203	/* Bit 0-5 indicate which Change-Of-State boundary triggered the IRQ */
204	cos_status &= 0x3F;
205
206	for_each_set_bit(boundary, &cos_status, 6) {
207		irq_mask = idi48gpio->irq_mask[boundary];
208
209		for_each_set_bit(bit_num, &irq_mask, 8) {
210			gpio = bit_num + boundary * 8;
211
212			generic_handle_irq(irq_find_mapping(chip->irqdomain,
213				gpio));
214		}
215	}
216
217	spin_unlock(&idi48gpio->ack_lock);
218
219	return IRQ_HANDLED;
220}
221
222static int idi_48_probe(struct device *dev, unsigned int id)
223{
224	struct idi_48_gpio *idi48gpio;
225	const char *const name = dev_name(dev);
226	int err;
227
228	idi48gpio = devm_kzalloc(dev, sizeof(*idi48gpio), GFP_KERNEL);
229	if (!idi48gpio)
230		return -ENOMEM;
231
232	if (!devm_request_region(dev, base[id], IDI_48_EXTENT, name)) {
233		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
234			base[id], base[id] + IDI_48_EXTENT);
235		return -EBUSY;
236	}
237
238	idi48gpio->chip.label = name;
239	idi48gpio->chip.parent = dev;
240	idi48gpio->chip.owner = THIS_MODULE;
241	idi48gpio->chip.base = -1;
242	idi48gpio->chip.ngpio = 48;
243	idi48gpio->chip.get_direction = idi_48_gpio_get_direction;
244	idi48gpio->chip.direction_input = idi_48_gpio_direction_input;
245	idi48gpio->chip.get = idi_48_gpio_get;
246	idi48gpio->base = base[id];
247	idi48gpio->irq = irq[id];
248
249	spin_lock_init(&idi48gpio->lock);
250	spin_lock_init(&idi48gpio->ack_lock);
251
252	dev_set_drvdata(dev, idi48gpio);
253
254	err = gpiochip_add_data(&idi48gpio->chip, idi48gpio);
255	if (err) {
256		dev_err(dev, "GPIO registering failed (%d)\n", err);
257		return err;
258	}
259
260	/* Disable IRQ by default */
261	outb(0, base[id] + 7);
262	inb(base[id] + 7);
263
264	err = gpiochip_irqchip_add(&idi48gpio->chip, &idi_48_irqchip, 0,
265		handle_edge_irq, IRQ_TYPE_NONE);
266	if (err) {
267		dev_err(dev, "Could not add irqchip (%d)\n", err);
268		goto err_gpiochip_remove;
269	}
270
271	err = request_irq(irq[id], idi_48_irq_handler, IRQF_SHARED, name,
272		idi48gpio);
273	if (err) {
274		dev_err(dev, "IRQ handler registering failed (%d)\n", err);
275		goto err_gpiochip_remove;
276	}
277
278	return 0;
279
280err_gpiochip_remove:
281	gpiochip_remove(&idi48gpio->chip);
282	return err;
283}
284
285static int idi_48_remove(struct device *dev, unsigned int id)
286{
287	struct idi_48_gpio *const idi48gpio = dev_get_drvdata(dev);
288
289	free_irq(idi48gpio->irq, idi48gpio);
290	gpiochip_remove(&idi48gpio->chip);
291
292	return 0;
293}
294
295static struct isa_driver idi_48_driver = {
296	.probe = idi_48_probe,
297	.driver = {
298		.name = "104-idi-48"
299	},
300	.remove = idi_48_remove
301};
302module_isa_driver(idi_48_driver, num_idi_48);
303
304MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
305MODULE_DESCRIPTION("ACCES 104-IDI-48 GPIO driver");
306MODULE_LICENSE("GPL v2");