xref: /openbmc/linux/drivers/gpio/gpio-pcf857x.c (revision e2f1cf25) 
1 /*
2  * Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
3  *
4  * Copyright (C) 2007 David Brownell
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20 
21 #include <linux/gpio.h>
22 #include <linux/i2c.h>
23 #include <linux/i2c/pcf857x.h>
24 #include <linux/interrupt.h>
25 #include <linux/irq.h>
26 #include <linux/irqdomain.h>
27 #include <linux/kernel.h>
28 #include <linux/module.h>
29 #include <linux/of.h>
30 #include <linux/of_device.h>
31 #include <linux/slab.h>
32 #include <linux/spinlock.h>
33 
34 
35 static const struct i2c_device_id pcf857x_id[] = {
36 	{ "pcf8574", 8 },
37 	{ "pcf8574a", 8 },
38 	{ "pca8574", 8 },
39 	{ "pca9670", 8 },
40 	{ "pca9672", 8 },
41 	{ "pca9674", 8 },
42 	{ "pcf8575", 16 },
43 	{ "pca8575", 16 },
44 	{ "pca9671", 16 },
45 	{ "pca9673", 16 },
46 	{ "pca9675", 16 },
47 	{ "max7328", 8 },
48 	{ "max7329", 8 },
49 	{ "tca9554", 8 },
50 	{ }
51 };
52 MODULE_DEVICE_TABLE(i2c, pcf857x_id);
53 
54 #ifdef CONFIG_OF
55 static const struct of_device_id pcf857x_of_table[] = {
56 	{ .compatible = "nxp,pcf8574" },
57 	{ .compatible = "nxp,pcf8574a" },
58 	{ .compatible = "nxp,pca8574" },
59 	{ .compatible = "nxp,pca9670" },
60 	{ .compatible = "nxp,pca9672" },
61 	{ .compatible = "nxp,pca9674" },
62 	{ .compatible = "nxp,pcf8575" },
63 	{ .compatible = "nxp,pca8575" },
64 	{ .compatible = "nxp,pca9671" },
65 	{ .compatible = "nxp,pca9673" },
66 	{ .compatible = "nxp,pca9675" },
67 	{ .compatible = "maxim,max7328" },
68 	{ .compatible = "maxim,max7329" },
69 	{ .compatible = "ti,tca9554" },
70 	{ }
71 };
72 MODULE_DEVICE_TABLE(of, pcf857x_of_table);
73 #endif
74 
75 /*
76  * The pcf857x, pca857x, and pca967x chips only expose one read and one
77  * write register.  Writing a "one" bit (to match the reset state) lets
78  * that pin be used as an input; it's not an open-drain model, but acts
79  * a bit like one.  This is described as "quasi-bidirectional"; read the
80  * chip documentation for details.
81  *
82  * Many other I2C GPIO expander chips (like the pca953x models) have
83  * more complex register models and more conventional circuitry using
84  * push/pull drivers.  They often use the same 0x20..0x27 addresses as
85  * pcf857x parts, making the "legacy" I2C driver model problematic.
86  */
87 struct pcf857x {
88 	struct gpio_chip	chip;
89 	struct i2c_client	*client;
90 	struct mutex		lock;		/* protect 'out' */
91 	spinlock_t		slock;		/* protect irq demux */
92 	unsigned		out;		/* software latch */
93 	unsigned		status;		/* current status */
94 	unsigned int		irq_parent;
95 	unsigned		irq_enabled;	/* enabled irqs */
96 
97 	int (*write)(struct i2c_client *client, unsigned data);
98 	int (*read)(struct i2c_client *client);
99 };
100 
101 /*-------------------------------------------------------------------------*/
102 
103 /* Talk to 8-bit I/O expander */
104 
105 static int i2c_write_le8(struct i2c_client *client, unsigned data)
106 {
107 	return i2c_smbus_write_byte(client, data);
108 }
109 
110 static int i2c_read_le8(struct i2c_client *client)
111 {
112 	return (int)i2c_smbus_read_byte(client);
113 }
114 
115 /* Talk to 16-bit I/O expander */
116 
117 static int i2c_write_le16(struct i2c_client *client, unsigned word)
118 {
119 	u8 buf[2] = { word & 0xff, word >> 8, };
120 	int status;
121 
122 	status = i2c_master_send(client, buf, 2);
123 	return (status < 0) ? status : 0;
124 }
125 
126 static int i2c_read_le16(struct i2c_client *client)
127 {
128 	u8 buf[2];
129 	int status;
130 
131 	status = i2c_master_recv(client, buf, 2);
132 	if (status < 0)
133 		return status;
134 	return (buf[1] << 8) | buf[0];
135 }
136 
137 /*-------------------------------------------------------------------------*/
138 
139 static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
140 {
141 	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
142 	int		status;
143 
144 	mutex_lock(&gpio->lock);
145 	gpio->out |= (1 << offset);
146 	status = gpio->write(gpio->client, gpio->out);
147 	mutex_unlock(&gpio->lock);
148 
149 	return status;
150 }
151 
152 static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
153 {
154 	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
155 	int		value;
156 
157 	value = gpio->read(gpio->client);
158 	return (value < 0) ? 0 : (value & (1 << offset));
159 }
160 
161 static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
162 {
163 	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
164 	unsigned	bit = 1 << offset;
165 	int		status;
166 
167 	mutex_lock(&gpio->lock);
168 	if (value)
169 		gpio->out |= bit;
170 	else
171 		gpio->out &= ~bit;
172 	status = gpio->write(gpio->client, gpio->out);
173 	mutex_unlock(&gpio->lock);
174 
175 	return status;
176 }
177 
178 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
179 {
180 	pcf857x_output(chip, offset, value);
181 }
182 
183 /*-------------------------------------------------------------------------*/
184 
185 static irqreturn_t pcf857x_irq(int irq, void *data)
186 {
187 	struct pcf857x  *gpio = data;
188 	unsigned long change, i, status, flags;
189 
190 	status = gpio->read(gpio->client);
191 
192 	spin_lock_irqsave(&gpio->slock, flags);
193 
194 	/*
195 	 * call the interrupt handler iff gpio is used as
196 	 * interrupt source, just to avoid bad irqs
197 	 */
198 
199 	change = (gpio->status ^ status) & gpio->irq_enabled;
200 	for_each_set_bit(i, &change, gpio->chip.ngpio)
201 		handle_nested_irq(irq_find_mapping(gpio->chip.irqdomain, i));
202 	gpio->status = status;
203 
204 	spin_unlock_irqrestore(&gpio->slock, flags);
205 
206 	return IRQ_HANDLED;
207 }
208 
209 /*
210  * NOP functions
211  */
212 static void noop(struct irq_data *data) { }
213 
214 static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
215 {
216 	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
217 
218 	int error = 0;
219 
220 	if (gpio->irq_parent) {
221 		error = irq_set_irq_wake(gpio->irq_parent, on);
222 		if (error) {
223 			dev_dbg(&gpio->client->dev,
224 				"irq %u doesn't support irq_set_wake\n",
225 				gpio->irq_parent);
226 			gpio->irq_parent = 0;
227 		}
228 	}
229 	return error;
230 }
231 
232 static void pcf857x_irq_enable(struct irq_data *data)
233 {
234 	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
235 
236 	gpio->irq_enabled |= (1 << data->hwirq);
237 }
238 
239 static void pcf857x_irq_disable(struct irq_data *data)
240 {
241 	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
242 
243 	gpio->irq_enabled &= ~(1 << data->hwirq);
244 }
245 
246 static void pcf857x_irq_bus_lock(struct irq_data *data)
247 {
248 	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
249 
250 	mutex_lock(&gpio->lock);
251 }
252 
253 static void pcf857x_irq_bus_sync_unlock(struct irq_data *data)
254 {
255 	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
256 
257 	mutex_unlock(&gpio->lock);
258 }
259 
260 static struct irq_chip pcf857x_irq_chip = {
261 	.name		= "pcf857x",
262 	.irq_enable	= pcf857x_irq_enable,
263 	.irq_disable	= pcf857x_irq_disable,
264 	.irq_ack	= noop,
265 	.irq_mask	= noop,
266 	.irq_unmask	= noop,
267 	.irq_set_wake	= pcf857x_irq_set_wake,
268 	.irq_bus_lock		= pcf857x_irq_bus_lock,
269 	.irq_bus_sync_unlock	= pcf857x_irq_bus_sync_unlock,
270 };
271 
272 /*-------------------------------------------------------------------------*/
273 
274 static int pcf857x_probe(struct i2c_client *client,
275 			 const struct i2c_device_id *id)
276 {
277 	struct pcf857x_platform_data	*pdata = dev_get_platdata(&client->dev);
278 	struct device_node		*np = client->dev.of_node;
279 	struct pcf857x			*gpio;
280 	unsigned int			n_latch = 0;
281 	int				status;
282 
283 	if (IS_ENABLED(CONFIG_OF) && np)
284 		of_property_read_u32(np, "lines-initial-states", &n_latch);
285 	else if (pdata)
286 		n_latch = pdata->n_latch;
287 	else
288 		dev_dbg(&client->dev, "no platform data\n");
289 
290 	/* Allocate, initialize, and register this gpio_chip. */
291 	gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
292 	if (!gpio)
293 		return -ENOMEM;
294 
295 	mutex_init(&gpio->lock);
296 	spin_lock_init(&gpio->slock);
297 
298 	gpio->chip.base			= pdata ? pdata->gpio_base : -1;
299 	gpio->chip.can_sleep		= true;
300 	gpio->chip.dev			= &client->dev;
301 	gpio->chip.owner		= THIS_MODULE;
302 	gpio->chip.get			= pcf857x_get;
303 	gpio->chip.set			= pcf857x_set;
304 	gpio->chip.direction_input	= pcf857x_input;
305 	gpio->chip.direction_output	= pcf857x_output;
306 	gpio->chip.ngpio		= id->driver_data;
307 
308 	/* NOTE:  the OnSemi jlc1562b is also largely compatible with
309 	 * these parts, notably for output.  It has a low-resolution
310 	 * DAC instead of pin change IRQs; and its inputs can be the
311 	 * result of comparators.
312 	 */
313 
314 	/* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
315 	 * 9670, 9672, 9764, and 9764a use quite a variety.
316 	 *
317 	 * NOTE: we don't distinguish here between *4 and *4a parts.
318 	 */
319 	if (gpio->chip.ngpio == 8) {
320 		gpio->write	= i2c_write_le8;
321 		gpio->read	= i2c_read_le8;
322 
323 		if (!i2c_check_functionality(client->adapter,
324 				I2C_FUNC_SMBUS_BYTE))
325 			status = -EIO;
326 
327 		/* fail if there's no chip present */
328 		else
329 			status = i2c_smbus_read_byte(client);
330 
331 	/* '75/'75c addresses are 0x20..0x27, just like the '74;
332 	 * the '75c doesn't have a current source pulling high.
333 	 * 9671, 9673, and 9765 use quite a variety of addresses.
334 	 *
335 	 * NOTE: we don't distinguish here between '75 and '75c parts.
336 	 */
337 	} else if (gpio->chip.ngpio == 16) {
338 		gpio->write	= i2c_write_le16;
339 		gpio->read	= i2c_read_le16;
340 
341 		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
342 			status = -EIO;
343 
344 		/* fail if there's no chip present */
345 		else
346 			status = i2c_read_le16(client);
347 
348 	} else {
349 		dev_dbg(&client->dev, "unsupported number of gpios\n");
350 		status = -EINVAL;
351 	}
352 
353 	if (status < 0)
354 		goto fail;
355 
356 	gpio->chip.label = client->name;
357 
358 	gpio->client = client;
359 	i2c_set_clientdata(client, gpio);
360 
361 	/* NOTE:  these chips have strange "quasi-bidirectional" I/O pins.
362 	 * We can't actually know whether a pin is configured (a) as output
363 	 * and driving the signal low, or (b) as input and reporting a low
364 	 * value ... without knowing the last value written since the chip
365 	 * came out of reset (if any).  We can't read the latched output.
366 	 *
367 	 * In short, the only reliable solution for setting up pin direction
368 	 * is to do it explicitly.  The setup() method can do that, but it
369 	 * may cause transient glitching since it can't know the last value
370 	 * written (some pins may need to be driven low).
371 	 *
372 	 * Using n_latch avoids that trouble.  When left initialized to zero,
373 	 * our software copy of the "latch" then matches the chip's all-ones
374 	 * reset state.  Otherwise it flags pins to be driven low.
375 	 */
376 	gpio->out = ~n_latch;
377 	gpio->status = gpio->out;
378 
379 	status = gpiochip_add(&gpio->chip);
380 	if (status < 0)
381 		goto fail;
382 
383 	/* Enable irqchip if we have an interrupt */
384 	if (client->irq) {
385 		status = gpiochip_irqchip_add(&gpio->chip, &pcf857x_irq_chip,
386 					      0, handle_level_irq,
387 					      IRQ_TYPE_NONE);
388 		if (status) {
389 			dev_err(&client->dev, "cannot add irqchip\n");
390 			goto fail_irq;
391 		}
392 
393 		status = devm_request_threaded_irq(&client->dev, client->irq,
394 					NULL, pcf857x_irq, IRQF_ONESHOT |
395 					IRQF_TRIGGER_FALLING | IRQF_SHARED,
396 					dev_name(&client->dev), gpio);
397 		if (status)
398 			goto fail_irq;
399 
400 		gpiochip_set_chained_irqchip(&gpio->chip, &pcf857x_irq_chip,
401 					     client->irq, NULL);
402 		gpio->irq_parent = client->irq;
403 	}
404 
405 	/* Let platform code set up the GPIOs and their users.
406 	 * Now is the first time anyone could use them.
407 	 */
408 	if (pdata && pdata->setup) {
409 		status = pdata->setup(client,
410 				gpio->chip.base, gpio->chip.ngpio,
411 				pdata->context);
412 		if (status < 0)
413 			dev_warn(&client->dev, "setup --> %d\n", status);
414 	}
415 
416 	dev_info(&client->dev, "probed\n");
417 
418 	return 0;
419 
420 fail_irq:
421 	gpiochip_remove(&gpio->chip);
422 
423 fail:
424 	dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
425 		client->name);
426 
427 	return status;
428 }
429 
430 static int pcf857x_remove(struct i2c_client *client)
431 {
432 	struct pcf857x_platform_data	*pdata = dev_get_platdata(&client->dev);
433 	struct pcf857x			*gpio = i2c_get_clientdata(client);
434 	int				status = 0;
435 
436 	if (pdata && pdata->teardown) {
437 		status = pdata->teardown(client,
438 				gpio->chip.base, gpio->chip.ngpio,
439 				pdata->context);
440 		if (status < 0) {
441 			dev_err(&client->dev, "%s --> %d\n",
442 					"teardown", status);
443 			return status;
444 		}
445 	}
446 
447 	gpiochip_remove(&gpio->chip);
448 	return status;
449 }
450 
451 static struct i2c_driver pcf857x_driver = {
452 	.driver = {
453 		.name	= "pcf857x",
454 		.owner	= THIS_MODULE,
455 		.of_match_table = of_match_ptr(pcf857x_of_table),
456 	},
457 	.probe	= pcf857x_probe,
458 	.remove	= pcf857x_remove,
459 	.id_table = pcf857x_id,
460 };
461 
462 static int __init pcf857x_init(void)
463 {
464 	return i2c_add_driver(&pcf857x_driver);
465 }
466 /* register after i2c postcore initcall and before
467  * subsys initcalls that may rely on these GPIOs
468  */
469 subsys_initcall(pcf857x_init);
470 
471 static void __exit pcf857x_exit(void)
472 {
473 	i2c_del_driver(&pcf857x_driver);
474 }
475 module_exit(pcf857x_exit);
476 
477 MODULE_LICENSE("GPL");
478 MODULE_AUTHOR("David Brownell");
479