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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
35static 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};
52MODULE_DEVICE_TABLE(i2c, pcf857x_id);
53
54#ifdef CONFIG_OF
55static 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};
72MODULE_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 */
87struct pcf857x {
88 struct gpio_chip chip;
89 struct i2c_client *client;
90 struct mutex lock; /* protect 'out' */
91 struct irq_domain *irq_domain; /* for irq demux */
92 spinlock_t slock; /* protect irq demux */
93 unsigned out; /* software latch */
94 unsigned status; /* current status */
95 unsigned irq_mapped; /* mapped gpio 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
105static int i2c_write_le8(struct i2c_client *client, unsigned data)
106{
107 return i2c_smbus_write_byte(client, data);
108}
109
110static 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
117static 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
126static 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
139static 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
152static 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
161static 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
178static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
179{
180 pcf857x_output(chip, offset, value);
181}
182
183/*-------------------------------------------------------------------------*/
184
185static int pcf857x_to_irq(struct gpio_chip *chip, unsigned offset)
186{
187 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
188 int ret;
189
190 ret = irq_create_mapping(gpio->irq_domain, offset);
191 if (ret > 0)
192 gpio->irq_mapped |= (1 << offset);
193
194 return ret;
195}
196
197static irqreturn_t pcf857x_irq(int irq, void *data)
198{
199 struct pcf857x *gpio = data;
200 unsigned long change, i, status, flags;
201
202 status = gpio->read(gpio->client);
203
204 spin_lock_irqsave(&gpio->slock, flags);
205
206 /*
207 * call the interrupt handler iff gpio is used as
208 * interrupt source, just to avoid bad irqs
209 */
210
211 change = ((gpio->status ^ status) & gpio->irq_mapped);
212 for_each_set_bit(i, &change, gpio->chip.ngpio)
213 generic_handle_irq(irq_find_mapping(gpio->irq_domain, i));
214 gpio->status = status;
215
216 spin_unlock_irqrestore(&gpio->slock, flags);
217
218 return IRQ_HANDLED;
219}
220
221static int pcf857x_irq_domain_map(struct irq_domain *domain, unsigned int irq,
222 irq_hw_number_t hw)
223{
224 struct pcf857x *gpio = domain->host_data;
225
226 irq_set_chip_and_handler(irq,
227 &dummy_irq_chip,
228 handle_level_irq);
229#ifdef CONFIG_ARM
230 set_irq_flags(irq, IRQF_VALID);
231#else
232 irq_set_noprobe(irq);
233#endif
234 gpio->irq_mapped |= (1 << hw);
235
236 return 0;
237}
238
239static struct irq_domain_ops pcf857x_irq_domain_ops = {
240 .map = pcf857x_irq_domain_map,
241};
242
243static void pcf857x_irq_domain_cleanup(struct pcf857x *gpio)
244{
245 if (gpio->irq_domain)
246 irq_domain_remove(gpio->irq_domain);
247
248}
249
250static int pcf857x_irq_domain_init(struct pcf857x *gpio,
251 struct i2c_client *client)
252{
253 int status;
254
255 gpio->irq_domain = irq_domain_add_linear(client->dev.of_node,
256 gpio->chip.ngpio,
257 &pcf857x_irq_domain_ops,
258 gpio);
259 if (!gpio->irq_domain)
260 goto fail;
261
262 /* enable real irq */
263 status = devm_request_threaded_irq(&client->dev, client->irq,
264 NULL, pcf857x_irq, IRQF_ONESHOT |
265 IRQF_TRIGGER_FALLING,
266 dev_name(&client->dev), gpio);
267
268 if (status)
269 goto fail;
270
271 /* enable gpio_to_irq() */
272 gpio->chip.to_irq = pcf857x_to_irq;
273
274 return 0;
275
276fail:
277 pcf857x_irq_domain_cleanup(gpio);
278 return -EINVAL;
279}
280
281/*-------------------------------------------------------------------------*/
282
283static int pcf857x_probe(struct i2c_client *client,
284 const struct i2c_device_id *id)
285{
286 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev);
287 struct device_node *np = client->dev.of_node;
288 struct pcf857x *gpio;
289 unsigned int n_latch = 0;
290 int status;
291
292 if (IS_ENABLED(CONFIG_OF) && np)
293 of_property_read_u32(np, "lines-initial-states", &n_latch);
294 else if (pdata)
295 n_latch = pdata->n_latch;
296 else
297 dev_dbg(&client->dev, "no platform data\n");
298
299 /* Allocate, initialize, and register this gpio_chip. */
300 gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
301 if (!gpio)
302 return -ENOMEM;
303
304 mutex_init(&gpio->lock);
305 spin_lock_init(&gpio->slock);
306
307 gpio->chip.base = pdata ? pdata->gpio_base : -1;
308 gpio->chip.can_sleep = true;
309 gpio->chip.dev = &client->dev;
310 gpio->chip.owner = THIS_MODULE;
311 gpio->chip.get = pcf857x_get;
312 gpio->chip.set = pcf857x_set;
313 gpio->chip.direction_input = pcf857x_input;
314 gpio->chip.direction_output = pcf857x_output;
315 gpio->chip.ngpio = id->driver_data;
316
317 /* enable gpio_to_irq() if platform has settings */
318 if (client->irq) {
319 status = pcf857x_irq_domain_init(gpio, client);
320 if (status < 0) {
321 dev_err(&client->dev, "irq_domain init failed\n");
322 goto fail;
323 }
324 }
325
326 /* NOTE: the OnSemi jlc1562b is also largely compatible with
327 * these parts, notably for output. It has a low-resolution
328 * DAC instead of pin change IRQs; and its inputs can be the
329 * result of comparators.
330 */
331
332 /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
333 * 9670, 9672, 9764, and 9764a use quite a variety.
334 *
335 * NOTE: we don't distinguish here between *4 and *4a parts.
336 */
337 if (gpio->chip.ngpio == 8) {
338 gpio->write = i2c_write_le8;
339 gpio->read = i2c_read_le8;
340
341 if (!i2c_check_functionality(client->adapter,
342 I2C_FUNC_SMBUS_BYTE))
343 status = -EIO;
344
345 /* fail if there's no chip present */
346 else
347 status = i2c_smbus_read_byte(client);
348
349 /* '75/'75c addresses are 0x20..0x27, just like the '74;
350 * the '75c doesn't have a current source pulling high.
351 * 9671, 9673, and 9765 use quite a variety of addresses.
352 *
353 * NOTE: we don't distinguish here between '75 and '75c parts.
354 */
355 } else if (gpio->chip.ngpio == 16) {
356 gpio->write = i2c_write_le16;
357 gpio->read = i2c_read_le16;
358
359 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
360 status = -EIO;
361
362 /* fail if there's no chip present */
363 else
364 status = i2c_read_le16(client);
365
366 } else {
367 dev_dbg(&client->dev, "unsupported number of gpios\n");
368 status = -EINVAL;
369 }
370
371 if (status < 0)
372 goto fail;
373
374 gpio->chip.label = client->name;
375
376 gpio->client = client;
377 i2c_set_clientdata(client, gpio);
378
379 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
380 * We can't actually know whether a pin is configured (a) as output
381 * and driving the signal low, or (b) as input and reporting a low
382 * value ... without knowing the last value written since the chip
383 * came out of reset (if any). We can't read the latched output.
384 *
385 * In short, the only reliable solution for setting up pin direction
386 * is to do it explicitly. The setup() method can do that, but it
387 * may cause transient glitching since it can't know the last value
388 * written (some pins may need to be driven low).
389 *
390 * Using n_latch avoids that trouble. When left initialized to zero,
391 * our software copy of the "latch" then matches the chip's all-ones
392 * reset state. Otherwise it flags pins to be driven low.
393 */
394 gpio->out = ~n_latch;
395 gpio->status = gpio->out;
396
397 status = gpiochip_add(&gpio->chip);
398 if (status < 0)
399 goto fail;
400
401 /* Let platform code set up the GPIOs and their users.
402 * Now is the first time anyone could use them.
403 */
404 if (pdata && pdata->setup) {
405 status = pdata->setup(client,
406 gpio->chip.base, gpio->chip.ngpio,
407 pdata->context);
408 if (status < 0)
409 dev_warn(&client->dev, "setup --> %d\n", status);
410 }
411
412 dev_info(&client->dev, "probed\n");
413
414 return 0;
415
416fail:
417 dev_dbg(&client->dev, "probe error %d for '%s'\n",
418 status, client->name);
419
420 if (client->irq)
421 pcf857x_irq_domain_cleanup(gpio);
422
423 return status;
424}
425
426static int pcf857x_remove(struct i2c_client *client)
427{
428 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev);
429 struct pcf857x *gpio = i2c_get_clientdata(client);
430 int status = 0;
431
432 if (pdata && pdata->teardown) {
433 status = pdata->teardown(client,
434 gpio->chip.base, gpio->chip.ngpio,
435 pdata->context);
436 if (status < 0) {
437 dev_err(&client->dev, "%s --> %d\n",
438 "teardown", status);
439 return status;
440 }
441 }
442
443 if (client->irq)
444 pcf857x_irq_domain_cleanup(gpio);
445
446 status = gpiochip_remove(&gpio->chip);
447 if (status)
448 dev_err(&client->dev, "%s --> %d\n", "remove", status);
449 return status;
450}
451
452static struct i2c_driver pcf857x_driver = {
453 .driver = {
454 .name = "pcf857x",
455 .owner = THIS_MODULE,
456 .of_match_table = of_match_ptr(pcf857x_of_table),
457 },
458 .probe = pcf857x_probe,
459 .remove = pcf857x_remove,
460 .id_table = pcf857x_id,
461};
462
463static int __init pcf857x_init(void)
464{
465 return i2c_add_driver(&pcf857x_driver);
466}
467/* register after i2c postcore initcall and before
468 * subsys initcalls that may rely on these GPIOs
469 */
470subsys_initcall(pcf857x_init);
471
472static void __exit pcf857x_exit(void)
473{
474 i2c_del_driver(&pcf857x_driver);
475}
476module_exit(pcf857x_exit);
477
478MODULE_LICENSE("GPL");
479MODULE_AUTHOR("David Brownell");
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/kernel.h>
22#include <linux/slab.h>
23#include <linux/gpio.h>
24#include <linux/i2c.h>
25#include <linux/i2c/pcf857x.h>
26#include <linux/module.h>
27
28
29static const struct i2c_device_id pcf857x_id[] = {
30 { "pcf8574", 8 },
31 { "pcf8574a", 8 },
32 { "pca8574", 8 },
33 { "pca9670", 8 },
34 { "pca9672", 8 },
35 { "pca9674", 8 },
36 { "pcf8575", 16 },
37 { "pca8575", 16 },
38 { "pca9671", 16 },
39 { "pca9673", 16 },
40 { "pca9675", 16 },
41 { "max7328", 8 },
42 { "max7329", 8 },
43 { }
44};
45MODULE_DEVICE_TABLE(i2c, pcf857x_id);
46
47/*
48 * The pcf857x, pca857x, and pca967x chips only expose one read and one
49 * write register. Writing a "one" bit (to match the reset state) lets
50 * that pin be used as an input; it's not an open-drain model, but acts
51 * a bit like one. This is described as "quasi-bidirectional"; read the
52 * chip documentation for details.
53 *
54 * Many other I2C GPIO expander chips (like the pca953x models) have
55 * more complex register models and more conventional circuitry using
56 * push/pull drivers. They often use the same 0x20..0x27 addresses as
57 * pcf857x parts, making the "legacy" I2C driver model problematic.
58 */
59struct pcf857x {
60 struct gpio_chip chip;
61 struct i2c_client *client;
62 struct mutex lock; /* protect 'out' */
63 unsigned out; /* software latch */
64};
65
66/*-------------------------------------------------------------------------*/
67
68/* Talk to 8-bit I/O expander */
69
70static int pcf857x_input8(struct gpio_chip *chip, unsigned offset)
71{
72 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
73 int status;
74
75 mutex_lock(&gpio->lock);
76 gpio->out |= (1 << offset);
77 status = i2c_smbus_write_byte(gpio->client, gpio->out);
78 mutex_unlock(&gpio->lock);
79
80 return status;
81}
82
83static int pcf857x_get8(struct gpio_chip *chip, unsigned offset)
84{
85 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
86 s32 value;
87
88 value = i2c_smbus_read_byte(gpio->client);
89 return (value < 0) ? 0 : (value & (1 << offset));
90}
91
92static int pcf857x_output8(struct gpio_chip *chip, unsigned offset, int value)
93{
94 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
95 unsigned bit = 1 << offset;
96 int status;
97
98 mutex_lock(&gpio->lock);
99 if (value)
100 gpio->out |= bit;
101 else
102 gpio->out &= ~bit;
103 status = i2c_smbus_write_byte(gpio->client, gpio->out);
104 mutex_unlock(&gpio->lock);
105
106 return status;
107}
108
109static void pcf857x_set8(struct gpio_chip *chip, unsigned offset, int value)
110{
111 pcf857x_output8(chip, offset, value);
112}
113
114/*-------------------------------------------------------------------------*/
115
116/* Talk to 16-bit I/O expander */
117
118static int i2c_write_le16(struct i2c_client *client, u16 word)
119{
120 u8 buf[2] = { word & 0xff, word >> 8, };
121 int status;
122
123 status = i2c_master_send(client, buf, 2);
124 return (status < 0) ? status : 0;
125}
126
127static int i2c_read_le16(struct i2c_client *client)
128{
129 u8 buf[2];
130 int status;
131
132 status = i2c_master_recv(client, buf, 2);
133 if (status < 0)
134 return status;
135 return (buf[1] << 8) | buf[0];
136}
137
138static int pcf857x_input16(struct gpio_chip *chip, unsigned offset)
139{
140 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
141 int status;
142
143 mutex_lock(&gpio->lock);
144 gpio->out |= (1 << offset);
145 status = i2c_write_le16(gpio->client, gpio->out);
146 mutex_unlock(&gpio->lock);
147
148 return status;
149}
150
151static int pcf857x_get16(struct gpio_chip *chip, unsigned offset)
152{
153 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
154 int value;
155
156 value = i2c_read_le16(gpio->client);
157 return (value < 0) ? 0 : (value & (1 << offset));
158}
159
160static int pcf857x_output16(struct gpio_chip *chip, unsigned offset, int value)
161{
162 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
163 unsigned bit = 1 << offset;
164 int status;
165
166 mutex_lock(&gpio->lock);
167 if (value)
168 gpio->out |= bit;
169 else
170 gpio->out &= ~bit;
171 status = i2c_write_le16(gpio->client, gpio->out);
172 mutex_unlock(&gpio->lock);
173
174 return status;
175}
176
177static void pcf857x_set16(struct gpio_chip *chip, unsigned offset, int value)
178{
179 pcf857x_output16(chip, offset, value);
180}
181
182/*-------------------------------------------------------------------------*/
183
184static int pcf857x_probe(struct i2c_client *client,
185 const struct i2c_device_id *id)
186{
187 struct pcf857x_platform_data *pdata;
188 struct pcf857x *gpio;
189 int status;
190
191 pdata = client->dev.platform_data;
192 if (!pdata) {
193 dev_dbg(&client->dev, "no platform data\n");
194 }
195
196 /* Allocate, initialize, and register this gpio_chip. */
197 gpio = kzalloc(sizeof *gpio, GFP_KERNEL);
198 if (!gpio)
199 return -ENOMEM;
200
201 mutex_init(&gpio->lock);
202
203 gpio->chip.base = pdata ? pdata->gpio_base : -1;
204 gpio->chip.can_sleep = 1;
205 gpio->chip.dev = &client->dev;
206 gpio->chip.owner = THIS_MODULE;
207
208 /* NOTE: the OnSemi jlc1562b is also largely compatible with
209 * these parts, notably for output. It has a low-resolution
210 * DAC instead of pin change IRQs; and its inputs can be the
211 * result of comparators.
212 */
213
214 /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
215 * 9670, 9672, 9764, and 9764a use quite a variety.
216 *
217 * NOTE: we don't distinguish here between *4 and *4a parts.
218 */
219 gpio->chip.ngpio = id->driver_data;
220 if (gpio->chip.ngpio == 8) {
221 gpio->chip.direction_input = pcf857x_input8;
222 gpio->chip.get = pcf857x_get8;
223 gpio->chip.direction_output = pcf857x_output8;
224 gpio->chip.set = pcf857x_set8;
225
226 if (!i2c_check_functionality(client->adapter,
227 I2C_FUNC_SMBUS_BYTE))
228 status = -EIO;
229
230 /* fail if there's no chip present */
231 else
232 status = i2c_smbus_read_byte(client);
233
234 /* '75/'75c addresses are 0x20..0x27, just like the '74;
235 * the '75c doesn't have a current source pulling high.
236 * 9671, 9673, and 9765 use quite a variety of addresses.
237 *
238 * NOTE: we don't distinguish here between '75 and '75c parts.
239 */
240 } else if (gpio->chip.ngpio == 16) {
241 gpio->chip.direction_input = pcf857x_input16;
242 gpio->chip.get = pcf857x_get16;
243 gpio->chip.direction_output = pcf857x_output16;
244 gpio->chip.set = pcf857x_set16;
245
246 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
247 status = -EIO;
248
249 /* fail if there's no chip present */
250 else
251 status = i2c_read_le16(client);
252
253 } else {
254 dev_dbg(&client->dev, "unsupported number of gpios\n");
255 status = -EINVAL;
256 }
257
258 if (status < 0)
259 goto fail;
260
261 gpio->chip.label = client->name;
262
263 gpio->client = client;
264 i2c_set_clientdata(client, gpio);
265
266 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
267 * We can't actually know whether a pin is configured (a) as output
268 * and driving the signal low, or (b) as input and reporting a low
269 * value ... without knowing the last value written since the chip
270 * came out of reset (if any). We can't read the latched output.
271 *
272 * In short, the only reliable solution for setting up pin direction
273 * is to do it explicitly. The setup() method can do that, but it
274 * may cause transient glitching since it can't know the last value
275 * written (some pins may need to be driven low).
276 *
277 * Using pdata->n_latch avoids that trouble. When left initialized
278 * to zero, our software copy of the "latch" then matches the chip's
279 * all-ones reset state. Otherwise it flags pins to be driven low.
280 */
281 gpio->out = pdata ? ~pdata->n_latch : ~0;
282
283 status = gpiochip_add(&gpio->chip);
284 if (status < 0)
285 goto fail;
286
287 /* NOTE: these chips can issue "some pin-changed" IRQs, which we
288 * don't yet even try to use. Among other issues, the relevant
289 * genirq state isn't available to modular drivers; and most irq
290 * methods can't be called from sleeping contexts.
291 */
292
293 dev_info(&client->dev, "%s\n",
294 client->irq ? " (irq ignored)" : "");
295
296 /* Let platform code set up the GPIOs and their users.
297 * Now is the first time anyone could use them.
298 */
299 if (pdata && pdata->setup) {
300 status = pdata->setup(client,
301 gpio->chip.base, gpio->chip.ngpio,
302 pdata->context);
303 if (status < 0)
304 dev_warn(&client->dev, "setup --> %d\n", status);
305 }
306
307 return 0;
308
309fail:
310 dev_dbg(&client->dev, "probe error %d for '%s'\n",
311 status, client->name);
312 kfree(gpio);
313 return status;
314}
315
316static int pcf857x_remove(struct i2c_client *client)
317{
318 struct pcf857x_platform_data *pdata = client->dev.platform_data;
319 struct pcf857x *gpio = i2c_get_clientdata(client);
320 int status = 0;
321
322 if (pdata && pdata->teardown) {
323 status = pdata->teardown(client,
324 gpio->chip.base, gpio->chip.ngpio,
325 pdata->context);
326 if (status < 0) {
327 dev_err(&client->dev, "%s --> %d\n",
328 "teardown", status);
329 return status;
330 }
331 }
332
333 status = gpiochip_remove(&gpio->chip);
334 if (status == 0)
335 kfree(gpio);
336 else
337 dev_err(&client->dev, "%s --> %d\n", "remove", status);
338 return status;
339}
340
341static struct i2c_driver pcf857x_driver = {
342 .driver = {
343 .name = "pcf857x",
344 .owner = THIS_MODULE,
345 },
346 .probe = pcf857x_probe,
347 .remove = pcf857x_remove,
348 .id_table = pcf857x_id,
349};
350
351static int __init pcf857x_init(void)
352{
353 return i2c_add_driver(&pcf857x_driver);
354}
355/* register after i2c postcore initcall and before
356 * subsys initcalls that may rely on these GPIOs
357 */
358subsys_initcall(pcf857x_init);
359
360static void __exit pcf857x_exit(void)
361{
362 i2c_del_driver(&pcf857x_driver);
363}
364module_exit(pcf857x_exit);
365
366MODULE_LICENSE("GPL");
367MODULE_AUTHOR("David Brownell");