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David Brownell15fae372008-02-04 22:28:24 -08001/*
2 * pcf857x - 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>
H Hartley Sweetend120c172009-09-22 16:46:37 -070023#include <linux/gpio.h>
David Brownell15fae372008-02-04 22:28:24 -080024#include <linux/i2c.h>
25#include <linux/i2c/pcf857x.h>
26
David Brownell15fae372008-02-04 22:28:24 -080027
Jean Delvare3760f732008-04-29 23:11:40 +020028static const struct i2c_device_id pcf857x_id[] = {
29 { "pcf8574", 8 },
Wolfram Sang4ba2ccb2009-09-18 22:45:47 +020030 { "pcf8574a", 8 },
Jean Delvare3760f732008-04-29 23:11:40 +020031 { "pca8574", 8 },
32 { "pca9670", 8 },
33 { "pca9672", 8 },
34 { "pca9674", 8 },
35 { "pcf8575", 16 },
36 { "pca8575", 16 },
37 { "pca9671", 16 },
38 { "pca9673", 16 },
39 { "pca9675", 16 },
David Brownell1673ad52008-07-21 14:21:34 -070040 { "max7328", 8 },
41 { "max7329", 8 },
Jean Delvare3760f732008-04-29 23:11:40 +020042 { }
43};
44MODULE_DEVICE_TABLE(i2c, pcf857x_id);
45
David Brownell15fae372008-02-04 22:28:24 -080046/*
47 * The pcf857x, pca857x, and pca967x chips only expose one read and one
48 * write register. Writing a "one" bit (to match the reset state) lets
49 * that pin be used as an input; it's not an open-drain model, but acts
50 * a bit like one. This is described as "quasi-bidirectional"; read the
51 * chip documentation for details.
52 *
53 * Many other I2C GPIO expander chips (like the pca953x models) have
54 * more complex register models and more conventional circuitry using
55 * push/pull drivers. They often use the same 0x20..0x27 addresses as
56 * pcf857x parts, making the "legacy" I2C driver model problematic.
57 */
58struct pcf857x {
59 struct gpio_chip chip;
60 struct i2c_client *client;
David Brownell1673ad52008-07-21 14:21:34 -070061 struct mutex lock; /* protect 'out' */
David Brownell15fae372008-02-04 22:28:24 -080062 unsigned out; /* software latch */
63};
64
65/*-------------------------------------------------------------------------*/
66
67/* Talk to 8-bit I/O expander */
68
69static int pcf857x_input8(struct gpio_chip *chip, unsigned offset)
70{
71 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
David Brownell1673ad52008-07-21 14:21:34 -070072 int status;
David Brownell15fae372008-02-04 22:28:24 -080073
David Brownell1673ad52008-07-21 14:21:34 -070074 mutex_lock(&gpio->lock);
David Brownell15fae372008-02-04 22:28:24 -080075 gpio->out |= (1 << offset);
David Brownell1673ad52008-07-21 14:21:34 -070076 status = i2c_smbus_write_byte(gpio->client, gpio->out);
77 mutex_unlock(&gpio->lock);
78
79 return status;
David Brownell15fae372008-02-04 22:28:24 -080080}
81
82static int pcf857x_get8(struct gpio_chip *chip, unsigned offset)
83{
84 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
85 s32 value;
86
87 value = i2c_smbus_read_byte(gpio->client);
88 return (value < 0) ? 0 : (value & (1 << offset));
89}
90
91static int pcf857x_output8(struct gpio_chip *chip, unsigned offset, int value)
92{
93 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
94 unsigned bit = 1 << offset;
David Brownell1673ad52008-07-21 14:21:34 -070095 int status;
David Brownell15fae372008-02-04 22:28:24 -080096
David Brownell1673ad52008-07-21 14:21:34 -070097 mutex_lock(&gpio->lock);
David Brownell15fae372008-02-04 22:28:24 -080098 if (value)
99 gpio->out |= bit;
100 else
101 gpio->out &= ~bit;
David Brownell1673ad52008-07-21 14:21:34 -0700102 status = i2c_smbus_write_byte(gpio->client, gpio->out);
103 mutex_unlock(&gpio->lock);
104
105 return status;
David Brownell15fae372008-02-04 22:28:24 -0800106}
107
108static void pcf857x_set8(struct gpio_chip *chip, unsigned offset, int value)
109{
110 pcf857x_output8(chip, offset, value);
111}
112
113/*-------------------------------------------------------------------------*/
114
115/* Talk to 16-bit I/O expander */
116
117static int i2c_write_le16(struct i2c_client *client, u16 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
137static int pcf857x_input16(struct gpio_chip *chip, unsigned offset)
138{
139 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
David Brownell1673ad52008-07-21 14:21:34 -0700140 int status;
David Brownell15fae372008-02-04 22:28:24 -0800141
David Brownell1673ad52008-07-21 14:21:34 -0700142 mutex_lock(&gpio->lock);
David Brownell15fae372008-02-04 22:28:24 -0800143 gpio->out |= (1 << offset);
David Brownell1673ad52008-07-21 14:21:34 -0700144 status = i2c_write_le16(gpio->client, gpio->out);
145 mutex_unlock(&gpio->lock);
146
147 return status;
David Brownell15fae372008-02-04 22:28:24 -0800148}
149
150static int pcf857x_get16(struct gpio_chip *chip, unsigned offset)
151{
152 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
153 int value;
154
155 value = i2c_read_le16(gpio->client);
156 return (value < 0) ? 0 : (value & (1 << offset));
157}
158
159static int pcf857x_output16(struct gpio_chip *chip, unsigned offset, int value)
160{
161 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
162 unsigned bit = 1 << offset;
David Brownell1673ad52008-07-21 14:21:34 -0700163 int status;
David Brownell15fae372008-02-04 22:28:24 -0800164
David Brownell1673ad52008-07-21 14:21:34 -0700165 mutex_lock(&gpio->lock);
David Brownell15fae372008-02-04 22:28:24 -0800166 if (value)
167 gpio->out |= bit;
168 else
169 gpio->out &= ~bit;
David Brownell1673ad52008-07-21 14:21:34 -0700170 status = i2c_write_le16(gpio->client, gpio->out);
171 mutex_unlock(&gpio->lock);
172
173 return status;
David Brownell15fae372008-02-04 22:28:24 -0800174}
175
176static void pcf857x_set16(struct gpio_chip *chip, unsigned offset, int value)
177{
178 pcf857x_output16(chip, offset, value);
179}
180
181/*-------------------------------------------------------------------------*/
182
Jean Delvared2653e92008-04-29 23:11:39 +0200183static int pcf857x_probe(struct i2c_client *client,
184 const struct i2c_device_id *id)
David Brownell15fae372008-02-04 22:28:24 -0800185{
186 struct pcf857x_platform_data *pdata;
187 struct pcf857x *gpio;
188 int status;
189
190 pdata = client->dev.platform_data;
Ben Dooksa342d212009-01-15 13:50:45 -0800191 if (!pdata) {
192 dev_dbg(&client->dev, "no platform data\n");
193 return -EINVAL;
194 }
David Brownell15fae372008-02-04 22:28:24 -0800195
196 /* Allocate, initialize, and register this gpio_chip. */
197 gpio = kzalloc(sizeof *gpio, GFP_KERNEL);
198 if (!gpio)
199 return -ENOMEM;
200
David Brownell1673ad52008-07-21 14:21:34 -0700201 mutex_init(&gpio->lock);
202
David Brownell15fae372008-02-04 22:28:24 -0800203 gpio->chip.base = pdata->gpio_base;
204 gpio->chip.can_sleep = 1;
David Brownelld8f388d2008-07-25 01:46:07 -0700205 gpio->chip.dev = &client->dev;
Guennadi Liakhovetskid72cbed2008-04-28 02:14:45 -0700206 gpio->chip.owner = THIS_MODULE;
David Brownell15fae372008-02-04 22:28:24 -0800207
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 */
Jean Delvare3760f732008-04-29 23:11:40 +0200219 gpio->chip.ngpio = id->driver_data;
220 if (gpio->chip.ngpio == 8) {
David Brownell15fae372008-02-04 22:28:24 -0800221 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 */
Jean Delvare3760f732008-04-29 23:11:40 +0200240 } else if (gpio->chip.ngpio == 16) {
David Brownell15fae372008-02-04 22:28:24 -0800241 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
Ben Dooksa342d212009-01-15 13:50:45 -0800253 } else {
254 dev_dbg(&client->dev, "unsupported number of gpios\n");
255 status = -EINVAL;
256 }
David Brownell15fae372008-02-04 22:28:24 -0800257
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->n_latch;
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, "gpios %d..%d on a %s%s\n",
294 gpio->chip.base,
295 gpio->chip.base + gpio->chip.ngpio - 1,
296 client->name,
297 client->irq ? " (irq ignored)" : "");
298
299 /* Let platform code set up the GPIOs and their users.
300 * Now is the first time anyone could use them.
301 */
302 if (pdata->setup) {
303 status = pdata->setup(client,
304 gpio->chip.base, gpio->chip.ngpio,
305 pdata->context);
306 if (status < 0)
307 dev_warn(&client->dev, "setup --> %d\n", status);
308 }
309
310 return 0;
311
312fail:
313 dev_dbg(&client->dev, "probe error %d for '%s'\n",
314 status, client->name);
315 kfree(gpio);
316 return status;
317}
318
319static int pcf857x_remove(struct i2c_client *client)
320{
321 struct pcf857x_platform_data *pdata = client->dev.platform_data;
322 struct pcf857x *gpio = i2c_get_clientdata(client);
323 int status = 0;
324
325 if (pdata->teardown) {
326 status = pdata->teardown(client,
327 gpio->chip.base, gpio->chip.ngpio,
328 pdata->context);
329 if (status < 0) {
330 dev_err(&client->dev, "%s --> %d\n",
331 "teardown", status);
332 return status;
333 }
334 }
335
336 status = gpiochip_remove(&gpio->chip);
337 if (status == 0)
338 kfree(gpio);
339 else
340 dev_err(&client->dev, "%s --> %d\n", "remove", status);
341 return status;
342}
343
344static struct i2c_driver pcf857x_driver = {
345 .driver = {
346 .name = "pcf857x",
347 .owner = THIS_MODULE,
348 },
349 .probe = pcf857x_probe,
350 .remove = pcf857x_remove,
Jean Delvare3760f732008-04-29 23:11:40 +0200351 .id_table = pcf857x_id,
David Brownell15fae372008-02-04 22:28:24 -0800352};
353
354static int __init pcf857x_init(void)
355{
356 return i2c_add_driver(&pcf857x_driver);
357}
David Brownell2f8d1192008-10-15 22:03:13 -0700358/* register after i2c postcore initcall and before
359 * subsys initcalls that may rely on these GPIOs
360 */
361subsys_initcall(pcf857x_init);
David Brownell15fae372008-02-04 22:28:24 -0800362
363static void __exit pcf857x_exit(void)
364{
365 i2c_del_driver(&pcf857x_driver);
366}
367module_exit(pcf857x_exit);
368
369MODULE_LICENSE("GPL");
370MODULE_AUTHOR("David Brownell");