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 
34 static unsigned int base[MAX_NUM_IDI_48];
35 static unsigned int num_idi_48;
36 module_param_array(base, uint, &num_idi_48, 0);
37 MODULE_PARM_DESC(base, "ACCES 104-IDI-48 base addresses");
38 
39 static unsigned int irq[MAX_NUM_IDI_48];
40 module_param_array(irq, uint, NULL, 0);
41 MODULE_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  */
53 struct 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 
63 static int idi_48_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
64 {
65 	return 1;
66 }
67 
68 static int idi_48_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
69 {
70 	return 0;
71 }
72 
73 static 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 
93 static void idi_48_irq_ack(struct irq_data *data)
94 {
95 }
96 
97 static 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 
128 static 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 
161 static 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 
171 static 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 
179 static 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 
222 static 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 
280 err_gpiochip_remove:
281 	gpiochip_remove(&idi48gpio->chip);
282 	return err;
283 }
284 
285 static 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 
295 static 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 };
302 module_isa_driver(idi_48_driver, num_idi_48);
303 
304 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
305 MODULE_DESCRIPTION("ACCES 104-IDI-48 GPIO driver");
306 MODULE_LICENSE("GPL v2");
307