1/*
  2 * GPIO driver for the WinSystems WS16C48
  3 * Copyright (C) 2016 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 ws16c48_base;
 29module_param(ws16c48_base, uint, 0);
 30MODULE_PARM_DESC(ws16c48_base, "WinSystems WS16C48 base address");
 31static unsigned ws16c48_irq;
 32module_param(ws16c48_irq, uint, 0);
 33MODULE_PARM_DESC(ws16c48_irq, "WinSystems WS16C48 interrupt line number");
 34
 35/**
 36 * struct ws16c48_gpio - GPIO device private data structure
 37 * @chip:	instance of the gpio_chip
 38 * @io_state:	bit I/O state (whether bit is set to input or output)
 39 * @out_state:	output bits state
 40 * @lock:	synchronization lock to prevent I/O race conditions
 41 * @irq_mask:	I/O bits affected by interrupts
 42 * @flow_mask:	IRQ flow type mask for the respective I/O bits
 43 * @base:	base port address of the GPIO device
 44 * @irq:	Interrupt line number
 45 */
 46struct ws16c48_gpio {
 47	struct gpio_chip chip;
 48	unsigned char io_state[6];
 49	unsigned char out_state[6];
 50	spinlock_t lock;
 51	unsigned long irq_mask;
 52	unsigned long flow_mask;
 53	unsigned base;
 54	unsigned irq;
 55};
 56
 57static int ws16c48_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
 58{
 59	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
 60	const unsigned port = offset / 8;
 61	const unsigned mask = BIT(offset % 8);
 62
 63	return !!(ws16c48gpio->io_state[port] & mask);
 64}
 65
 66static int ws16c48_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
 67{
 68	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
 69	const unsigned port = offset / 8;
 70	const unsigned mask = BIT(offset % 8);
 71	unsigned long flags;
 72
 73	spin_lock_irqsave(&ws16c48gpio->lock, flags);
 74
 75	ws16c48gpio->io_state[port] |= mask;
 76	ws16c48gpio->out_state[port] &= ~mask;
 77	outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
 78
 79	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
 80
 81	return 0;
 82}
 83
 84static int ws16c48_gpio_direction_output(struct gpio_chip *chip,
 85	unsigned offset, int value)
 86{
 87	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
 88	const unsigned port = offset / 8;
 89	const unsigned mask = BIT(offset % 8);
 90	unsigned long flags;
 91
 92	spin_lock_irqsave(&ws16c48gpio->lock, flags);
 93
 94	ws16c48gpio->io_state[port] &= ~mask;
 95	if (value)
 96		ws16c48gpio->out_state[port] |= mask;
 97	else
 98		ws16c48gpio->out_state[port] &= ~mask;
 99	outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
100
101	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
102
103	return 0;
104}
105
106static int ws16c48_gpio_get(struct gpio_chip *chip, unsigned offset)
107{
108	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
109	const unsigned port = offset / 8;
110	const unsigned mask = BIT(offset % 8);
111	unsigned long flags;
112	unsigned port_state;
113
114	spin_lock_irqsave(&ws16c48gpio->lock, flags);
115
116	/* ensure that GPIO is set for input */
117	if (!(ws16c48gpio->io_state[port] & mask)) {
118		spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
119		return -EINVAL;
120	}
121
122	port_state = inb(ws16c48gpio->base + port);
123
124	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
125
126	return !!(port_state & mask);
127}
128
129static void ws16c48_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
130{
131	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
132	const unsigned port = offset / 8;
133	const unsigned mask = BIT(offset % 8);
134	unsigned long flags;
135
136	spin_lock_irqsave(&ws16c48gpio->lock, flags);
137
138	/* ensure that GPIO is set for output */
139	if (ws16c48gpio->io_state[port] & mask) {
140		spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
141		return;
142	}
143
144	if (value)
145		ws16c48gpio->out_state[port] |= mask;
146	else
147		ws16c48gpio->out_state[port] &= ~mask;
148	outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
149
150	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
151}
152
153static void ws16c48_irq_ack(struct irq_data *data)
154{
155	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
156	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
157	const unsigned long offset = irqd_to_hwirq(data);
158	const unsigned port = offset / 8;
159	const unsigned mask = BIT(offset % 8);
160	unsigned long flags;
161	unsigned port_state;
162
163	/* only the first 3 ports support interrupts */
164	if (port > 2)
165		return;
166
167	spin_lock_irqsave(&ws16c48gpio->lock, flags);
168
169	port_state = ws16c48gpio->irq_mask >> (8*port);
170
171	outb(0x80, ws16c48gpio->base + 7);
172	outb(port_state & ~mask, ws16c48gpio->base + 8 + port);
173	outb(port_state | mask, ws16c48gpio->base + 8 + port);
174	outb(0xC0, ws16c48gpio->base + 7);
175
176	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
177}
178
179static void ws16c48_irq_mask(struct irq_data *data)
180{
181	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
182	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
183	const unsigned long offset = irqd_to_hwirq(data);
184	const unsigned long mask = BIT(offset);
185	const unsigned port = offset / 8;
186	unsigned long flags;
187
188	/* only the first 3 ports support interrupts */
189	if (port > 2)
190		return;
191
192	spin_lock_irqsave(&ws16c48gpio->lock, flags);
193
194	ws16c48gpio->irq_mask &= ~mask;
195
196	outb(0x80, ws16c48gpio->base + 7);
197	outb(ws16c48gpio->irq_mask >> (8*port), ws16c48gpio->base + 8 + port);
198	outb(0xC0, ws16c48gpio->base + 7);
199
200	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
201}
202
203static void ws16c48_irq_unmask(struct irq_data *data)
204{
205	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
206	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
207	const unsigned long offset = irqd_to_hwirq(data);
208	const unsigned long mask = BIT(offset);
209	const unsigned port = offset / 8;
210	unsigned long flags;
211
212	/* only the first 3 ports support interrupts */
213	if (port > 2)
214		return;
215
216	spin_lock_irqsave(&ws16c48gpio->lock, flags);
217
218	ws16c48gpio->irq_mask |= mask;
219
220	outb(0x80, ws16c48gpio->base + 7);
221	outb(ws16c48gpio->irq_mask >> (8*port), ws16c48gpio->base + 8 + port);
222	outb(0xC0, ws16c48gpio->base + 7);
223
224	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
225}
226
227static int ws16c48_irq_set_type(struct irq_data *data, unsigned flow_type)
228{
229	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
230	struct ws16c48_gpio *const ws16c48gpio = gpiochip_get_data(chip);
231	const unsigned long offset = irqd_to_hwirq(data);
232	const unsigned long mask = BIT(offset);
233	const unsigned port = offset / 8;
234	unsigned long flags;
235
236	/* only the first 3 ports support interrupts */
237	if (port > 2)
238		return -EINVAL;
239
240	spin_lock_irqsave(&ws16c48gpio->lock, flags);
241
242	switch (flow_type) {
243	case IRQ_TYPE_NONE:
244		break;
245	case IRQ_TYPE_EDGE_RISING:
246		ws16c48gpio->flow_mask |= mask;
247		break;
248	case IRQ_TYPE_EDGE_FALLING:
249		ws16c48gpio->flow_mask &= ~mask;
250		break;
251	default:
252		spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
253		return -EINVAL;
254	}
255
256	outb(0x40, ws16c48gpio->base + 7);
257	outb(ws16c48gpio->flow_mask >> (8*port), ws16c48gpio->base + 8 + port);
258	outb(0xC0, ws16c48gpio->base + 7);
259
260	spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
261
262	return 0;
263}
264
265static struct irq_chip ws16c48_irqchip = {
266	.name = "ws16c48",
267	.irq_ack = ws16c48_irq_ack,
268	.irq_mask = ws16c48_irq_mask,
269	.irq_unmask = ws16c48_irq_unmask,
270	.irq_set_type = ws16c48_irq_set_type
271};
272
273static irqreturn_t ws16c48_irq_handler(int irq, void *dev_id)
274{
275	struct ws16c48_gpio *const ws16c48gpio = dev_id;
276	struct gpio_chip *const chip = &ws16c48gpio->chip;
277	unsigned long int_pending;
278	unsigned long port;
279	unsigned long int_id;
280	unsigned long gpio;
281
282	int_pending = inb(ws16c48gpio->base + 6) & 0x7;
283	if (!int_pending)
284		return IRQ_NONE;
285
286	/* loop until all pending interrupts are handled */
287	do {
288		for_each_set_bit(port, &int_pending, 3) {
289			int_id = inb(ws16c48gpio->base + 8 + port);
290			for_each_set_bit(gpio, &int_id, 8)
291				generic_handle_irq(irq_find_mapping(
292					chip->irqdomain, gpio + 8*port));
293		}
294
295		int_pending = inb(ws16c48gpio->base + 6) & 0x7;
296	} while (int_pending);
297
298	return IRQ_HANDLED;
299}
300
301static int __init ws16c48_probe(struct platform_device *pdev)
302{
303	struct device *dev = &pdev->dev;
304	struct ws16c48_gpio *ws16c48gpio;
305	const unsigned base = ws16c48_base;
306	const unsigned extent = 16;
307	const char *const name = dev_name(dev);
308	int err;
309	const unsigned irq = ws16c48_irq;
310
311	ws16c48gpio = devm_kzalloc(dev, sizeof(*ws16c48gpio), GFP_KERNEL);
312	if (!ws16c48gpio)
313		return -ENOMEM;
314
315	if (!devm_request_region(dev, base, extent, name)) {
316		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
317			base, base + extent);
318		return -EBUSY;
319	}
320
321	ws16c48gpio->chip.label = name;
322	ws16c48gpio->chip.parent = dev;
323	ws16c48gpio->chip.owner = THIS_MODULE;
324	ws16c48gpio->chip.base = -1;
325	ws16c48gpio->chip.ngpio = 48;
326	ws16c48gpio->chip.get_direction = ws16c48_gpio_get_direction;
327	ws16c48gpio->chip.direction_input = ws16c48_gpio_direction_input;
328	ws16c48gpio->chip.direction_output = ws16c48_gpio_direction_output;
329	ws16c48gpio->chip.get = ws16c48_gpio_get;
330	ws16c48gpio->chip.set = ws16c48_gpio_set;
331	ws16c48gpio->base = base;
332	ws16c48gpio->irq = irq;
333
334	spin_lock_init(&ws16c48gpio->lock);
335
336	dev_set_drvdata(dev, ws16c48gpio);
337
338	err = gpiochip_add_data(&ws16c48gpio->chip, ws16c48gpio);
339	if (err) {
340		dev_err(dev, "GPIO registering failed (%d)\n", err);
341		return err;
342	}
343
344	/* Disable IRQ by default */
345	outb(0x80, base + 7);
346	outb(0, base + 8);
347	outb(0, base + 9);
348	outb(0, base + 10);
349	outb(0xC0, base + 7);
350
351	err = gpiochip_irqchip_add(&ws16c48gpio->chip, &ws16c48_irqchip, 0,
352		handle_edge_irq, IRQ_TYPE_NONE);
353	if (err) {
354		dev_err(dev, "Could not add irqchip (%d)\n", err);
355		goto err_gpiochip_remove;
356	}
357
358	err = request_irq(irq, ws16c48_irq_handler, IRQF_SHARED, name,
359		ws16c48gpio);
360	if (err) {
361		dev_err(dev, "IRQ handler registering failed (%d)\n", err);
362		goto err_gpiochip_remove;
363	}
364
365	return 0;
366
367err_gpiochip_remove:
368	gpiochip_remove(&ws16c48gpio->chip);
369	return err;
370}
371
372static int ws16c48_remove(struct platform_device *pdev)
373{
374	struct ws16c48_gpio *const ws16c48gpio = platform_get_drvdata(pdev);
375
376	free_irq(ws16c48gpio->irq, ws16c48gpio);
377	gpiochip_remove(&ws16c48gpio->chip);
378
379	return 0;
380}
381
382static struct platform_device *ws16c48_device;
383
384static struct platform_driver ws16c48_driver = {
385	.driver = {
386		.name = "ws16c48"
387	},
388	.remove = ws16c48_remove
389};
390
391static void __exit ws16c48_exit(void)
392{
393	platform_device_unregister(ws16c48_device);
394	platform_driver_unregister(&ws16c48_driver);
395}
396
397static int __init ws16c48_init(void)
398{
399	int err;
400
401	ws16c48_device = platform_device_alloc(ws16c48_driver.driver.name, -1);
402	if (!ws16c48_device)
403		return -ENOMEM;
404
405	err = platform_device_add(ws16c48_device);
406	if (err)
407		goto err_platform_device;
408
409	err = platform_driver_probe(&ws16c48_driver, ws16c48_probe);
410	if (err)
411		goto err_platform_driver;
412
413	return 0;
414
415err_platform_driver:
416	platform_device_del(ws16c48_device);
417err_platform_device:
418	platform_device_put(ws16c48_device);
419	return err;
420}
421
422module_init(ws16c48_init);
423module_exit(ws16c48_exit);
424
425MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
426MODULE_DESCRIPTION("WinSystems WS16C48 GPIO driver");
427MODULE_LICENSE("GPL v2");