2 * pcf857x - driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
4 * Copyright (C) 2007 David Brownell
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.
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.
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.
21 #include <linux/kernel.h>
22 #include <linux/slab.h>
23 #include <linux/i2c.h>
24 #include <linux/i2c/pcf857x.h>
29 static const struct i2c_device_id pcf857x_id
[] = {
44 MODULE_DEVICE_TABLE(i2c
, pcf857x_id
);
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.
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.
59 struct gpio_chip chip
;
60 struct i2c_client
*client
;
61 struct mutex lock
; /* protect 'out' */
62 unsigned out
; /* software latch */
65 /*-------------------------------------------------------------------------*/
67 /* Talk to 8-bit I/O expander */
69 static int pcf857x_input8(struct gpio_chip
*chip
, unsigned offset
)
71 struct pcf857x
*gpio
= container_of(chip
, struct pcf857x
, chip
);
74 mutex_lock(&gpio
->lock
);
75 gpio
->out
|= (1 << offset
);
76 status
= i2c_smbus_write_byte(gpio
->client
, gpio
->out
);
77 mutex_unlock(&gpio
->lock
);
82 static int pcf857x_get8(struct gpio_chip
*chip
, unsigned offset
)
84 struct pcf857x
*gpio
= container_of(chip
, struct pcf857x
, chip
);
87 value
= i2c_smbus_read_byte(gpio
->client
);
88 return (value
< 0) ? 0 : (value
& (1 << offset
));
91 static int pcf857x_output8(struct gpio_chip
*chip
, unsigned offset
, int value
)
93 struct pcf857x
*gpio
= container_of(chip
, struct pcf857x
, chip
);
94 unsigned bit
= 1 << offset
;
97 mutex_lock(&gpio
->lock
);
102 status
= i2c_smbus_write_byte(gpio
->client
, gpio
->out
);
103 mutex_unlock(&gpio
->lock
);
108 static void pcf857x_set8(struct gpio_chip
*chip
, unsigned offset
, int value
)
110 pcf857x_output8(chip
, offset
, value
);
113 /*-------------------------------------------------------------------------*/
115 /* Talk to 16-bit I/O expander */
117 static int i2c_write_le16(struct i2c_client
*client
, u16 word
)
119 u8 buf
[2] = { word
& 0xff, word
>> 8, };
122 status
= i2c_master_send(client
, buf
, 2);
123 return (status
< 0) ? status
: 0;
126 static int i2c_read_le16(struct i2c_client
*client
)
131 status
= i2c_master_recv(client
, buf
, 2);
134 return (buf
[1] << 8) | buf
[0];
137 static int pcf857x_input16(struct gpio_chip
*chip
, unsigned offset
)
139 struct pcf857x
*gpio
= container_of(chip
, struct pcf857x
, chip
);
142 mutex_lock(&gpio
->lock
);
143 gpio
->out
|= (1 << offset
);
144 status
= i2c_write_le16(gpio
->client
, gpio
->out
);
145 mutex_unlock(&gpio
->lock
);
150 static int pcf857x_get16(struct gpio_chip
*chip
, unsigned offset
)
152 struct pcf857x
*gpio
= container_of(chip
, struct pcf857x
, chip
);
155 value
= i2c_read_le16(gpio
->client
);
156 return (value
< 0) ? 0 : (value
& (1 << offset
));
159 static int pcf857x_output16(struct gpio_chip
*chip
, unsigned offset
, int value
)
161 struct pcf857x
*gpio
= container_of(chip
, struct pcf857x
, chip
);
162 unsigned bit
= 1 << offset
;
165 mutex_lock(&gpio
->lock
);
170 status
= i2c_write_le16(gpio
->client
, gpio
->out
);
171 mutex_unlock(&gpio
->lock
);
176 static void pcf857x_set16(struct gpio_chip
*chip
, unsigned offset
, int value
)
178 pcf857x_output16(chip
, offset
, value
);
181 /*-------------------------------------------------------------------------*/
183 static int pcf857x_probe(struct i2c_client
*client
,
184 const struct i2c_device_id
*id
)
186 struct pcf857x_platform_data
*pdata
;
187 struct pcf857x
*gpio
;
190 pdata
= client
->dev
.platform_data
;
194 /* Allocate, initialize, and register this gpio_chip. */
195 gpio
= kzalloc(sizeof *gpio
, GFP_KERNEL
);
199 mutex_init(&gpio
->lock
);
201 gpio
->chip
.base
= pdata
->gpio_base
;
202 gpio
->chip
.can_sleep
= 1;
203 gpio
->chip
.dev
= &client
->dev
;
204 gpio
->chip
.owner
= THIS_MODULE
;
206 /* NOTE: the OnSemi jlc1562b is also largely compatible with
207 * these parts, notably for output. It has a low-resolution
208 * DAC instead of pin change IRQs; and its inputs can be the
209 * result of comparators.
212 /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
213 * 9670, 9672, 9764, and 9764a use quite a variety.
215 * NOTE: we don't distinguish here between *4 and *4a parts.
217 gpio
->chip
.ngpio
= id
->driver_data
;
218 if (gpio
->chip
.ngpio
== 8) {
219 gpio
->chip
.direction_input
= pcf857x_input8
;
220 gpio
->chip
.get
= pcf857x_get8
;
221 gpio
->chip
.direction_output
= pcf857x_output8
;
222 gpio
->chip
.set
= pcf857x_set8
;
224 if (!i2c_check_functionality(client
->adapter
,
225 I2C_FUNC_SMBUS_BYTE
))
228 /* fail if there's no chip present */
230 status
= i2c_smbus_read_byte(client
);
232 /* '75/'75c addresses are 0x20..0x27, just like the '74;
233 * the '75c doesn't have a current source pulling high.
234 * 9671, 9673, and 9765 use quite a variety of addresses.
236 * NOTE: we don't distinguish here between '75 and '75c parts.
238 } else if (gpio
->chip
.ngpio
== 16) {
239 gpio
->chip
.direction_input
= pcf857x_input16
;
240 gpio
->chip
.get
= pcf857x_get16
;
241 gpio
->chip
.direction_output
= pcf857x_output16
;
242 gpio
->chip
.set
= pcf857x_set16
;
244 if (!i2c_check_functionality(client
->adapter
, I2C_FUNC_I2C
))
247 /* fail if there's no chip present */
249 status
= i2c_read_le16(client
);
257 gpio
->chip
.label
= client
->name
;
259 gpio
->client
= client
;
260 i2c_set_clientdata(client
, gpio
);
262 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
263 * We can't actually know whether a pin is configured (a) as output
264 * and driving the signal low, or (b) as input and reporting a low
265 * value ... without knowing the last value written since the chip
266 * came out of reset (if any). We can't read the latched output.
268 * In short, the only reliable solution for setting up pin direction
269 * is to do it explicitly. The setup() method can do that, but it
270 * may cause transient glitching since it can't know the last value
271 * written (some pins may need to be driven low).
273 * Using pdata->n_latch avoids that trouble. When left initialized
274 * to zero, our software copy of the "latch" then matches the chip's
275 * all-ones reset state. Otherwise it flags pins to be driven low.
277 gpio
->out
= ~pdata
->n_latch
;
279 status
= gpiochip_add(&gpio
->chip
);
283 /* NOTE: these chips can issue "some pin-changed" IRQs, which we
284 * don't yet even try to use. Among other issues, the relevant
285 * genirq state isn't available to modular drivers; and most irq
286 * methods can't be called from sleeping contexts.
289 dev_info(&client
->dev
, "gpios %d..%d on a %s%s\n",
291 gpio
->chip
.base
+ gpio
->chip
.ngpio
- 1,
293 client
->irq
? " (irq ignored)" : "");
295 /* Let platform code set up the GPIOs and their users.
296 * Now is the first time anyone could use them.
299 status
= pdata
->setup(client
,
300 gpio
->chip
.base
, gpio
->chip
.ngpio
,
303 dev_warn(&client
->dev
, "setup --> %d\n", status
);
309 dev_dbg(&client
->dev
, "probe error %d for '%s'\n",
310 status
, client
->name
);
315 static int pcf857x_remove(struct i2c_client
*client
)
317 struct pcf857x_platform_data
*pdata
= client
->dev
.platform_data
;
318 struct pcf857x
*gpio
= i2c_get_clientdata(client
);
321 if (pdata
->teardown
) {
322 status
= pdata
->teardown(client
,
323 gpio
->chip
.base
, gpio
->chip
.ngpio
,
326 dev_err(&client
->dev
, "%s --> %d\n",
332 status
= gpiochip_remove(&gpio
->chip
);
336 dev_err(&client
->dev
, "%s --> %d\n", "remove", status
);
340 static struct i2c_driver pcf857x_driver
= {
343 .owner
= THIS_MODULE
,
345 .probe
= pcf857x_probe
,
346 .remove
= pcf857x_remove
,
347 .id_table
= pcf857x_id
,
350 static int __init
pcf857x_init(void)
352 return i2c_add_driver(&pcf857x_driver
);
354 /* register after i2c postcore initcall and before
355 * subsys initcalls that may rely on these GPIOs
357 subsys_initcall(pcf857x_init
);
359 static void __exit
pcf857x_exit(void)
361 i2c_del_driver(&pcf857x_driver
);
363 module_exit(pcf857x_exit
);
365 MODULE_LICENSE("GPL");
366 MODULE_AUTHOR("David Brownell");