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/driver.h>
22 #include <linux/i2c.h>
23 #include <linux/platform_data/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 { }
50 };
51 MODULE_DEVICE_TABLE(i2c, pcf857x_id);
52
53 #ifdef CONFIG_OF
54 static const struct of_device_id pcf857x_of_table[] = {
55 { .compatible = "nxp,pcf8574" },
56 { .compatible = "nxp,pcf8574a" },
57 { .compatible = "nxp,pca8574" },
58 { .compatible = "nxp,pca9670" },
59 { .compatible = "nxp,pca9672" },
60 { .compatible = "nxp,pca9674" },
61 { .compatible = "nxp,pcf8575" },
62 { .compatible = "nxp,pca8575" },
63 { .compatible = "nxp,pca9671" },
64 { .compatible = "nxp,pca9673" },
65 { .compatible = "nxp,pca9675" },
66 { .compatible = "maxim,max7328" },
67 { .compatible = "maxim,max7329" },
68 { }
69 };
70 MODULE_DEVICE_TABLE(of, pcf857x_of_table);
71 #endif
72
73 /*
74 * The pcf857x, pca857x, and pca967x chips only expose one read and one
75 * write register. Writing a "one" bit (to match the reset state) lets
76 * that pin be used as an input; it's not an open-drain model, but acts
77 * a bit like one. This is described as "quasi-bidirectional"; read the
78 * chip documentation for details.
79 *
80 * Many other I2C GPIO expander chips (like the pca953x models) have
81 * more complex register models and more conventional circuitry using
82 * push/pull drivers. They often use the same 0x20..0x27 addresses as
83 * pcf857x parts, making the "legacy" I2C driver model problematic.
84 */
85 struct pcf857x {
86 struct gpio_chip chip;
87 struct irq_chip irqchip;
88 struct i2c_client *client;
89 struct mutex lock; /* protect 'out' */
90 unsigned out; /* software latch */
91 unsigned status; /* current status */
92 unsigned int irq_parent;
93 unsigned irq_enabled; /* enabled irqs */
94
95 int (*write)(struct i2c_client *client, unsigned data);
96 int (*read)(struct i2c_client *client);
97 };
98
99 /*-------------------------------------------------------------------------*/
100
101 /* Talk to 8-bit I/O expander */
102
i2c_write_le8(struct i2c_client * client,unsigned data)103 static int i2c_write_le8(struct i2c_client *client, unsigned data)
104 {
105 return i2c_smbus_write_byte(client, data);
106 }
107
i2c_read_le8(struct i2c_client * client)108 static int i2c_read_le8(struct i2c_client *client)
109 {
110 return (int)i2c_smbus_read_byte(client);
111 }
112
113 /* Talk to 16-bit I/O expander */
114
i2c_write_le16(struct i2c_client * client,unsigned word)115 static int i2c_write_le16(struct i2c_client *client, unsigned word)
116 {
117 u8 buf[2] = { word & 0xff, word >> 8, };
118 int status;
119
120 status = i2c_master_send(client, buf, 2);
121 return (status < 0) ? status : 0;
122 }
123
i2c_read_le16(struct i2c_client * client)124 static int i2c_read_le16(struct i2c_client *client)
125 {
126 u8 buf[2];
127 int status;
128
129 status = i2c_master_recv(client, buf, 2);
130 if (status < 0)
131 return status;
132 return (buf[1] << 8) | buf[0];
133 }
134
135 /*-------------------------------------------------------------------------*/
136
pcf857x_input(struct gpio_chip * chip,unsigned offset)137 static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
138 {
139 struct pcf857x *gpio = gpiochip_get_data(chip);
140 int status;
141
142 mutex_lock(&gpio->lock);
143 gpio->out |= (1 << offset);
144 status = gpio->write(gpio->client, gpio->out);
145 mutex_unlock(&gpio->lock);
146
147 return status;
148 }
149
pcf857x_get(struct gpio_chip * chip,unsigned offset)150 static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
151 {
152 struct pcf857x *gpio = gpiochip_get_data(chip);
153 int value;
154
155 value = gpio->read(gpio->client);
156 return (value < 0) ? value : !!(value & (1 << offset));
157 }
158
pcf857x_output(struct gpio_chip * chip,unsigned offset,int value)159 static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
160 {
161 struct pcf857x *gpio = gpiochip_get_data(chip);
162 unsigned bit = 1 << offset;
163 int status;
164
165 mutex_lock(&gpio->lock);
166 if (value)
167 gpio->out |= bit;
168 else
169 gpio->out &= ~bit;
170 status = gpio->write(gpio->client, gpio->out);
171 mutex_unlock(&gpio->lock);
172
173 return status;
174 }
175
pcf857x_set(struct gpio_chip * chip,unsigned offset,int value)176 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
177 {
178 pcf857x_output(chip, offset, value);
179 }
180
181 /*-------------------------------------------------------------------------*/
182
pcf857x_irq(int irq,void * data)183 static irqreturn_t pcf857x_irq(int irq, void *data)
184 {
185 struct pcf857x *gpio = data;
186 unsigned long change, i, status;
187
188 status = gpio->read(gpio->client);
189
190 /*
191 * call the interrupt handler iff gpio is used as
192 * interrupt source, just to avoid bad irqs
193 */
194 mutex_lock(&gpio->lock);
195 change = (gpio->status ^ status) & gpio->irq_enabled;
196 gpio->status = status;
197 mutex_unlock(&gpio->lock);
198
199 for_each_set_bit(i, &change, gpio->chip.ngpio)
200 handle_nested_irq(irq_find_mapping(gpio->chip.irq.domain, i));
201
202 return IRQ_HANDLED;
203 }
204
205 /*
206 * NOP functions
207 */
noop(struct irq_data * data)208 static void noop(struct irq_data *data) { }
209
pcf857x_irq_set_wake(struct irq_data * data,unsigned int on)210 static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
211 {
212 struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
213
214 int error = 0;
215
216 if (gpio->irq_parent) {
217 error = irq_set_irq_wake(gpio->irq_parent, on);
218 if (error) {
219 dev_dbg(&gpio->client->dev,
220 "irq %u doesn't support irq_set_wake\n",
221 gpio->irq_parent);
222 gpio->irq_parent = 0;
223 }
224 }
225 return error;
226 }
227
pcf857x_irq_enable(struct irq_data * data)228 static void pcf857x_irq_enable(struct irq_data *data)
229 {
230 struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
231
232 gpio->irq_enabled |= (1 << data->hwirq);
233 }
234
pcf857x_irq_disable(struct irq_data * data)235 static void pcf857x_irq_disable(struct irq_data *data)
236 {
237 struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
238
239 gpio->irq_enabled &= ~(1 << data->hwirq);
240 }
241
pcf857x_irq_bus_lock(struct irq_data * data)242 static void pcf857x_irq_bus_lock(struct irq_data *data)
243 {
244 struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
245
246 mutex_lock(&gpio->lock);
247 }
248
pcf857x_irq_bus_sync_unlock(struct irq_data * data)249 static void pcf857x_irq_bus_sync_unlock(struct irq_data *data)
250 {
251 struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
252
253 mutex_unlock(&gpio->lock);
254 }
255
256 /*-------------------------------------------------------------------------*/
257
pcf857x_probe(struct i2c_client * client,const struct i2c_device_id * id)258 static int pcf857x_probe(struct i2c_client *client,
259 const struct i2c_device_id *id)
260 {
261 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev);
262 struct device_node *np = client->dev.of_node;
263 struct pcf857x *gpio;
264 unsigned int n_latch = 0;
265 int status;
266
267 if (IS_ENABLED(CONFIG_OF) && np)
268 of_property_read_u32(np, "lines-initial-states", &n_latch);
269 else if (pdata)
270 n_latch = pdata->n_latch;
271 else
272 dev_dbg(&client->dev, "no platform data\n");
273
274 /* Allocate, initialize, and register this gpio_chip. */
275 gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
276 if (!gpio)
277 return -ENOMEM;
278
279 mutex_init(&gpio->lock);
280
281 gpio->chip.base = pdata ? pdata->gpio_base : -1;
282 gpio->chip.can_sleep = true;
283 gpio->chip.parent = &client->dev;
284 gpio->chip.owner = THIS_MODULE;
285 gpio->chip.get = pcf857x_get;
286 gpio->chip.set = pcf857x_set;
287 gpio->chip.direction_input = pcf857x_input;
288 gpio->chip.direction_output = pcf857x_output;
289 gpio->chip.ngpio = id->driver_data;
290
291 /* NOTE: the OnSemi jlc1562b is also largely compatible with
292 * these parts, notably for output. It has a low-resolution
293 * DAC instead of pin change IRQs; and its inputs can be the
294 * result of comparators.
295 */
296
297 /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
298 * 9670, 9672, 9764, and 9764a use quite a variety.
299 *
300 * NOTE: we don't distinguish here between *4 and *4a parts.
301 */
302 if (gpio->chip.ngpio == 8) {
303 gpio->write = i2c_write_le8;
304 gpio->read = i2c_read_le8;
305
306 if (!i2c_check_functionality(client->adapter,
307 I2C_FUNC_SMBUS_BYTE))
308 status = -EIO;
309
310 /* fail if there's no chip present */
311 else
312 status = i2c_smbus_read_byte(client);
313
314 /* '75/'75c addresses are 0x20..0x27, just like the '74;
315 * the '75c doesn't have a current source pulling high.
316 * 9671, 9673, and 9765 use quite a variety of addresses.
317 *
318 * NOTE: we don't distinguish here between '75 and '75c parts.
319 */
320 } else if (gpio->chip.ngpio == 16) {
321 gpio->write = i2c_write_le16;
322 gpio->read = i2c_read_le16;
323
324 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
325 status = -EIO;
326
327 /* fail if there's no chip present */
328 else
329 status = i2c_read_le16(client);
330
331 } else {
332 dev_dbg(&client->dev, "unsupported number of gpios\n");
333 status = -EINVAL;
334 }
335
336 if (status < 0)
337 goto fail;
338
339 gpio->chip.label = client->name;
340
341 gpio->client = client;
342 i2c_set_clientdata(client, gpio);
343
344 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
345 * We can't actually know whether a pin is configured (a) as output
346 * and driving the signal low, or (b) as input and reporting a low
347 * value ... without knowing the last value written since the chip
348 * came out of reset (if any). We can't read the latched output.
349 *
350 * In short, the only reliable solution for setting up pin direction
351 * is to do it explicitly. The setup() method can do that, but it
352 * may cause transient glitching since it can't know the last value
353 * written (some pins may need to be driven low).
354 *
355 * Using n_latch avoids that trouble. When left initialized to zero,
356 * our software copy of the "latch" then matches the chip's all-ones
357 * reset state. Otherwise it flags pins to be driven low.
358 */
359 gpio->out = ~n_latch;
360 gpio->status = gpio->read(gpio->client);
361
362 status = devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio);
363 if (status < 0)
364 goto fail;
365
366 /* Enable irqchip if we have an interrupt */
367 if (client->irq) {
368 gpio->irqchip.name = "pcf857x",
369 gpio->irqchip.irq_enable = pcf857x_irq_enable,
370 gpio->irqchip.irq_disable = pcf857x_irq_disable,
371 gpio->irqchip.irq_ack = noop,
372 gpio->irqchip.irq_mask = noop,
373 gpio->irqchip.irq_unmask = noop,
374 gpio->irqchip.irq_set_wake = pcf857x_irq_set_wake,
375 gpio->irqchip.irq_bus_lock = pcf857x_irq_bus_lock,
376 gpio->irqchip.irq_bus_sync_unlock = pcf857x_irq_bus_sync_unlock,
377 status = gpiochip_irqchip_add_nested(&gpio->chip,
378 &gpio->irqchip,
379 0, handle_level_irq,
380 IRQ_TYPE_NONE);
381 if (status) {
382 dev_err(&client->dev, "cannot add irqchip\n");
383 goto fail;
384 }
385
386 status = devm_request_threaded_irq(&client->dev, client->irq,
387 NULL, pcf857x_irq, IRQF_ONESHOT |
388 IRQF_TRIGGER_FALLING | IRQF_SHARED,
389 dev_name(&client->dev), gpio);
390 if (status)
391 goto fail;
392
393 gpiochip_set_nested_irqchip(&gpio->chip, &gpio->irqchip,
394 client->irq);
395 gpio->irq_parent = client->irq;
396 }
397
398 /* Let platform code set up the GPIOs and their users.
399 * Now is the first time anyone could use them.
400 */
401 if (pdata && pdata->setup) {
402 status = pdata->setup(client,
403 gpio->chip.base, gpio->chip.ngpio,
404 pdata->context);
405 if (status < 0)
406 dev_warn(&client->dev, "setup --> %d\n", status);
407 }
408
409 dev_info(&client->dev, "probed\n");
410
411 return 0;
412
413 fail:
414 dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
415 client->name);
416
417 return status;
418 }
419
pcf857x_remove(struct i2c_client * client)420 static int pcf857x_remove(struct i2c_client *client)
421 {
422 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev);
423 struct pcf857x *gpio = i2c_get_clientdata(client);
424 int status = 0;
425
426 if (pdata && pdata->teardown) {
427 status = pdata->teardown(client,
428 gpio->chip.base, gpio->chip.ngpio,
429 pdata->context);
430 if (status < 0) {
431 dev_err(&client->dev, "%s --> %d\n",
432 "teardown", status);
433 return status;
434 }
435 }
436
437 return status;
438 }
439
pcf857x_shutdown(struct i2c_client * client)440 static void pcf857x_shutdown(struct i2c_client *client)
441 {
442 struct pcf857x *gpio = i2c_get_clientdata(client);
443
444 /* Drive all the I/O lines high */
445 gpio->write(gpio->client, BIT(gpio->chip.ngpio) - 1);
446 }
447
448 static struct i2c_driver pcf857x_driver = {
449 .driver = {
450 .name = "pcf857x",
451 .of_match_table = of_match_ptr(pcf857x_of_table),
452 },
453 .probe = pcf857x_probe,
454 .remove = pcf857x_remove,
455 .shutdown = pcf857x_shutdown,
456 .id_table = pcf857x_id,
457 };
458
pcf857x_init(void)459 static int __init pcf857x_init(void)
460 {
461 return i2c_add_driver(&pcf857x_driver);
462 }
463 /* register after i2c postcore initcall and before
464 * subsys initcalls that may rely on these GPIOs
465 */
466 subsys_initcall(pcf857x_init);
467
pcf857x_exit(void)468 static void __exit pcf857x_exit(void)
469 {
470 i2c_del_driver(&pcf857x_driver);
471 }
472 module_exit(pcf857x_exit);
473
474 MODULE_LICENSE("GPL");
475 MODULE_AUTHOR("David Brownell");
476