2 * 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/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>
30 #include <linux/of_device.h>
31 #include <linux/slab.h>
32 #include <linux/spinlock.h>
35 static const struct i2c_device_id pcf857x_id[] = {
51 MODULE_DEVICE_TABLE(i2c, pcf857x_id);
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" },
70 MODULE_DEVICE_TABLE(of, pcf857x_of_table);
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.
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.
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 irq_enabled; /* enabled irqs */
94 int (*write)(struct i2c_client *client, unsigned data);
95 int (*read)(struct i2c_client *client);
98 /*-------------------------------------------------------------------------*/
100 /* Talk to 8-bit I/O expander */
102 static int i2c_write_le8(struct i2c_client *client, unsigned data)
104 return i2c_smbus_write_byte(client, data);
107 static int i2c_read_le8(struct i2c_client *client)
109 return (int)i2c_smbus_read_byte(client);
112 /* Talk to 16-bit I/O expander */
114 static int i2c_write_le16(struct i2c_client *client, unsigned word)
116 u8 buf[2] = { word & 0xff, word >> 8, };
119 status = i2c_master_send(client, buf, 2);
120 return (status < 0) ? status : 0;
123 static int i2c_read_le16(struct i2c_client *client)
128 status = i2c_master_recv(client, buf, 2);
131 return (buf[1] << 8) | buf[0];
134 /*-------------------------------------------------------------------------*/
136 static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
138 struct pcf857x *gpio = gpiochip_get_data(chip);
141 mutex_lock(&gpio->lock);
142 gpio->out |= (1 << offset);
143 status = gpio->write(gpio->client, gpio->out);
144 mutex_unlock(&gpio->lock);
149 static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
151 struct pcf857x *gpio = gpiochip_get_data(chip);
154 value = gpio->read(gpio->client);
155 return (value < 0) ? value : !!(value & (1 << offset));
158 static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
160 struct pcf857x *gpio = gpiochip_get_data(chip);
161 unsigned bit = 1 << offset;
164 mutex_lock(&gpio->lock);
169 status = gpio->write(gpio->client, gpio->out);
170 mutex_unlock(&gpio->lock);
175 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
177 pcf857x_output(chip, offset, value);
180 /*-------------------------------------------------------------------------*/
182 static irqreturn_t pcf857x_irq(int irq, void *data)
184 struct pcf857x *gpio = data;
185 unsigned long change, i, status;
187 status = gpio->read(gpio->client);
190 * call the interrupt handler iff gpio is used as
191 * interrupt source, just to avoid bad irqs
193 mutex_lock(&gpio->lock);
194 change = (gpio->status ^ status) & gpio->irq_enabled;
195 gpio->status = status;
196 mutex_unlock(&gpio->lock);
198 for_each_set_bit(i, &change, gpio->chip.ngpio)
199 handle_nested_irq(irq_find_mapping(gpio->chip.irq.domain, i));
207 static void noop(struct irq_data *data) { }
209 static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
211 struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
213 return irq_set_irq_wake(gpio->client->irq, on);
216 static void pcf857x_irq_enable(struct irq_data *data)
218 struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
220 gpio->irq_enabled |= (1 << data->hwirq);
223 static void pcf857x_irq_disable(struct irq_data *data)
225 struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
227 gpio->irq_enabled &= ~(1 << data->hwirq);
230 static void pcf857x_irq_bus_lock(struct irq_data *data)
232 struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
234 mutex_lock(&gpio->lock);
237 static void pcf857x_irq_bus_sync_unlock(struct irq_data *data)
239 struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
241 mutex_unlock(&gpio->lock);
244 /*-------------------------------------------------------------------------*/
246 static int pcf857x_probe(struct i2c_client *client,
247 const struct i2c_device_id *id)
249 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev);
250 struct device_node *np = client->dev.of_node;
251 struct pcf857x *gpio;
252 unsigned int n_latch = 0;
255 if (IS_ENABLED(CONFIG_OF) && np)
256 of_property_read_u32(np, "lines-initial-states", &n_latch);
258 n_latch = pdata->n_latch;
260 dev_dbg(&client->dev, "no platform data\n");
262 /* Allocate, initialize, and register this gpio_chip. */
263 gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
267 mutex_init(&gpio->lock);
269 gpio->chip.base = pdata ? pdata->gpio_base : -1;
270 gpio->chip.can_sleep = true;
271 gpio->chip.parent = &client->dev;
272 gpio->chip.owner = THIS_MODULE;
273 gpio->chip.get = pcf857x_get;
274 gpio->chip.set = pcf857x_set;
275 gpio->chip.direction_input = pcf857x_input;
276 gpio->chip.direction_output = pcf857x_output;
277 gpio->chip.ngpio = id->driver_data;
279 /* NOTE: the OnSemi jlc1562b is also largely compatible with
280 * these parts, notably for output. It has a low-resolution
281 * DAC instead of pin change IRQs; and its inputs can be the
282 * result of comparators.
285 /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
286 * 9670, 9672, 9764, and 9764a use quite a variety.
288 * NOTE: we don't distinguish here between *4 and *4a parts.
290 if (gpio->chip.ngpio == 8) {
291 gpio->write = i2c_write_le8;
292 gpio->read = i2c_read_le8;
294 if (!i2c_check_functionality(client->adapter,
295 I2C_FUNC_SMBUS_BYTE))
298 /* fail if there's no chip present */
300 status = i2c_smbus_read_byte(client);
302 /* '75/'75c addresses are 0x20..0x27, just like the '74;
303 * the '75c doesn't have a current source pulling high.
304 * 9671, 9673, and 9765 use quite a variety of addresses.
306 * NOTE: we don't distinguish here between '75 and '75c parts.
308 } else if (gpio->chip.ngpio == 16) {
309 gpio->write = i2c_write_le16;
310 gpio->read = i2c_read_le16;
312 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
315 /* fail if there's no chip present */
317 status = i2c_read_le16(client);
320 dev_dbg(&client->dev, "unsupported number of gpios\n");
327 gpio->chip.label = client->name;
329 gpio->client = client;
330 i2c_set_clientdata(client, gpio);
332 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
333 * We can't actually know whether a pin is configured (a) as output
334 * and driving the signal low, or (b) as input and reporting a low
335 * value ... without knowing the last value written since the chip
336 * came out of reset (if any). We can't read the latched output.
338 * In short, the only reliable solution for setting up pin direction
339 * is to do it explicitly. The setup() method can do that, but it
340 * may cause transient glitching since it can't know the last value
341 * written (some pins may need to be driven low).
343 * Using n_latch avoids that trouble. When left initialized to zero,
344 * our software copy of the "latch" then matches the chip's all-ones
345 * reset state. Otherwise it flags pins to be driven low.
347 gpio->out = ~n_latch;
348 gpio->status = gpio->out;
350 status = devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio);
354 /* Enable irqchip if we have an interrupt */
356 gpio->irqchip.name = "pcf857x",
357 gpio->irqchip.irq_enable = pcf857x_irq_enable,
358 gpio->irqchip.irq_disable = pcf857x_irq_disable,
359 gpio->irqchip.irq_ack = noop,
360 gpio->irqchip.irq_mask = noop,
361 gpio->irqchip.irq_unmask = noop,
362 gpio->irqchip.irq_set_wake = pcf857x_irq_set_wake,
363 gpio->irqchip.irq_bus_lock = pcf857x_irq_bus_lock,
364 gpio->irqchip.irq_bus_sync_unlock = pcf857x_irq_bus_sync_unlock,
365 status = gpiochip_irqchip_add_nested(&gpio->chip,
370 dev_err(&client->dev, "cannot add irqchip\n");
374 status = devm_request_threaded_irq(&client->dev, client->irq,
375 NULL, pcf857x_irq, IRQF_ONESHOT |
376 IRQF_TRIGGER_FALLING | IRQF_SHARED,
377 dev_name(&client->dev), gpio);
381 gpiochip_set_nested_irqchip(&gpio->chip, &gpio->irqchip,
385 /* Let platform code set up the GPIOs and their users.
386 * Now is the first time anyone could use them.
388 if (pdata && pdata->setup) {
389 status = pdata->setup(client,
390 gpio->chip.base, gpio->chip.ngpio,
393 dev_warn(&client->dev, "setup --> %d\n", status);
396 dev_info(&client->dev, "probed\n");
401 dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
407 static int pcf857x_remove(struct i2c_client *client)
409 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev);
410 struct pcf857x *gpio = i2c_get_clientdata(client);
413 if (pdata && pdata->teardown) {
414 status = pdata->teardown(client,
415 gpio->chip.base, gpio->chip.ngpio,
418 dev_err(&client->dev, "%s --> %d\n",
427 static void pcf857x_shutdown(struct i2c_client *client)
429 struct pcf857x *gpio = i2c_get_clientdata(client);
431 /* Drive all the I/O lines high */
432 gpio->write(gpio->client, BIT(gpio->chip.ngpio) - 1);
435 static struct i2c_driver pcf857x_driver = {
438 .of_match_table = of_match_ptr(pcf857x_of_table),
440 .probe = pcf857x_probe,
441 .remove = pcf857x_remove,
442 .shutdown = pcf857x_shutdown,
443 .id_table = pcf857x_id,
446 static int __init pcf857x_init(void)
448 return i2c_add_driver(&pcf857x_driver);
450 /* register after i2c postcore initcall and before
451 * subsys initcalls that may rely on these GPIOs
453 subsys_initcall(pcf857x_init);
455 static void __exit pcf857x_exit(void)
457 i2c_del_driver(&pcf857x_driver);
459 module_exit(pcf857x_exit);
461 MODULE_LICENSE("GPL");
462 MODULE_AUTHOR("David Brownell");