gpio-pcf857x.c 12.3 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479
/*
 * Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
 *
 * Copyright (C) 2007 David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/gpio.h>
#include <linux/i2c.h>
#include <linux/i2c/pcf857x.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>


static const struct i2c_device_id pcf857x_id[] = {
	{ "pcf8574", 8 },
	{ "pcf8574a", 8 },
	{ "pca8574", 8 },
	{ "pca9670", 8 },
	{ "pca9672", 8 },
	{ "pca9674", 8 },
	{ "pcf8575", 16 },
	{ "pca8575", 16 },
	{ "pca9671", 16 },
	{ "pca9673", 16 },
	{ "pca9675", 16 },
	{ "max7328", 8 },
	{ "max7329", 8 },
	{ "tca9554", 8 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, pcf857x_id);

#ifdef CONFIG_OF
static const struct of_device_id pcf857x_of_table[] = {
	{ .compatible = "nxp,pcf8574" },
	{ .compatible = "nxp,pcf8574a" },
	{ .compatible = "nxp,pca8574" },
	{ .compatible = "nxp,pca9670" },
	{ .compatible = "nxp,pca9672" },
	{ .compatible = "nxp,pca9674" },
	{ .compatible = "nxp,pcf8575" },
	{ .compatible = "nxp,pca8575" },
	{ .compatible = "nxp,pca9671" },
	{ .compatible = "nxp,pca9673" },
	{ .compatible = "nxp,pca9675" },
	{ .compatible = "maxim,max7328" },
	{ .compatible = "maxim,max7329" },
	{ .compatible = "ti,tca9554" },
	{ }
};
MODULE_DEVICE_TABLE(of, pcf857x_of_table);
#endif

/*
 * The pcf857x, pca857x, and pca967x chips only expose one read and one
 * write register.  Writing a "one" bit (to match the reset state) lets
 * that pin be used as an input; it's not an open-drain model, but acts
 * a bit like one.  This is described as "quasi-bidirectional"; read the
 * chip documentation for details.
 *
 * Many other I2C GPIO expander chips (like the pca953x models) have
 * more complex register models and more conventional circuitry using
 * push/pull drivers.  They often use the same 0x20..0x27 addresses as
 * pcf857x parts, making the "legacy" I2C driver model problematic.
 */
struct pcf857x {
	struct gpio_chip	chip;
	struct i2c_client	*client;
	struct mutex		lock;		/* protect 'out' */
	struct irq_domain	*irq_domain;	/* for irq demux  */
	spinlock_t		slock;		/* protect irq demux */
	unsigned		out;		/* software latch */
	unsigned		status;		/* current status */
	unsigned		irq_mapped;	/* mapped gpio irqs */

	int (*write)(struct i2c_client *client, unsigned data);
	int (*read)(struct i2c_client *client);
};

/*-------------------------------------------------------------------------*/

/* Talk to 8-bit I/O expander */

static int i2c_write_le8(struct i2c_client *client, unsigned data)
{
	return i2c_smbus_write_byte(client, data);
}

static int i2c_read_le8(struct i2c_client *client)
{
	return (int)i2c_smbus_read_byte(client);
}

/* Talk to 16-bit I/O expander */

static int i2c_write_le16(struct i2c_client *client, unsigned word)
{
	u8 buf[2] = { word & 0xff, word >> 8, };
	int status;

	status = i2c_master_send(client, buf, 2);
	return (status < 0) ? status : 0;
}

static int i2c_read_le16(struct i2c_client *client)
{
	u8 buf[2];
	int status;

	status = i2c_master_recv(client, buf, 2);
	if (status < 0)
		return status;
	return (buf[1] << 8) | buf[0];
}

/*-------------------------------------------------------------------------*/

static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
{
	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
	int		status;

	mutex_lock(&gpio->lock);
	gpio->out |= (1 << offset);
	status = gpio->write(gpio->client, gpio->out);
	mutex_unlock(&gpio->lock);

	return status;
}

static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
{
	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
	int		value;

	value = gpio->read(gpio->client);
	return (value < 0) ? 0 : (value & (1 << offset));
}

static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
{
	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
	unsigned	bit = 1 << offset;
	int		status;

	mutex_lock(&gpio->lock);
	if (value)
		gpio->out |= bit;
	else
		gpio->out &= ~bit;
	status = gpio->write(gpio->client, gpio->out);
	mutex_unlock(&gpio->lock);

	return status;
}

static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
{
	pcf857x_output(chip, offset, value);
}

/*-------------------------------------------------------------------------*/

static int pcf857x_to_irq(struct gpio_chip *chip, unsigned offset)
{
	struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
	int ret;

	ret = irq_create_mapping(gpio->irq_domain, offset);
	if (ret > 0)
		gpio->irq_mapped |= (1 << offset);

	return ret;
}

static irqreturn_t pcf857x_irq(int irq, void *data)
{
	struct pcf857x  *gpio = data;
	unsigned long change, i, status, flags;

	status = gpio->read(gpio->client);

	spin_lock_irqsave(&gpio->slock, flags);

	/*
	 * call the interrupt handler iff gpio is used as
	 * interrupt source, just to avoid bad irqs
	 */

	change = ((gpio->status ^ status) & gpio->irq_mapped);
	for_each_set_bit(i, &change, gpio->chip.ngpio)
		generic_handle_irq(irq_find_mapping(gpio->irq_domain, i));
	gpio->status = status;

	spin_unlock_irqrestore(&gpio->slock, flags);

	return IRQ_HANDLED;
}

static int pcf857x_irq_domain_map(struct irq_domain *domain, unsigned int irq,
				 irq_hw_number_t hw)
{
	struct pcf857x *gpio = domain->host_data;

	irq_set_chip_and_handler(irq,
				 &dummy_irq_chip,
				 handle_level_irq);
#ifdef CONFIG_ARM
	set_irq_flags(irq, IRQF_VALID);
#else
	irq_set_noprobe(irq);
#endif
	gpio->irq_mapped |= (1 << hw);

	return 0;
}

static struct irq_domain_ops pcf857x_irq_domain_ops = {
	.map	= pcf857x_irq_domain_map,
};

static void pcf857x_irq_domain_cleanup(struct pcf857x *gpio)
{
	if (gpio->irq_domain)
		irq_domain_remove(gpio->irq_domain);

}

static int pcf857x_irq_domain_init(struct pcf857x *gpio,
				   struct i2c_client *client)
{
	int status;

	gpio->irq_domain = irq_domain_add_linear(client->dev.of_node,
						 gpio->chip.ngpio,
						 &pcf857x_irq_domain_ops,
						 gpio);
	if (!gpio->irq_domain)
		goto fail;

	/* enable real irq */
	status = devm_request_threaded_irq(&client->dev, client->irq,
				NULL, pcf857x_irq, IRQF_ONESHOT |
				IRQF_TRIGGER_FALLING,
				dev_name(&client->dev), gpio);

	if (status)
		goto fail;

	/* enable gpio_to_irq() */
	gpio->chip.to_irq	= pcf857x_to_irq;

	return 0;

fail:
	pcf857x_irq_domain_cleanup(gpio);
	return -EINVAL;
}

/*-------------------------------------------------------------------------*/

static int pcf857x_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct pcf857x_platform_data	*pdata = dev_get_platdata(&client->dev);
	struct device_node		*np = client->dev.of_node;
	struct pcf857x			*gpio;
	unsigned int			n_latch = 0;
	int				status;

	if (IS_ENABLED(CONFIG_OF) && np)
		of_property_read_u32(np, "lines-initial-states", &n_latch);
	else if (pdata)
		n_latch = pdata->n_latch;
	else
		dev_dbg(&client->dev, "no platform data\n");

	/* Allocate, initialize, and register this gpio_chip. */
	gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
	if (!gpio)
		return -ENOMEM;

	mutex_init(&gpio->lock);
	spin_lock_init(&gpio->slock);

	gpio->chip.base			= pdata ? pdata->gpio_base : -1;
	gpio->chip.can_sleep		= true;
	gpio->chip.dev			= &client->dev;
	gpio->chip.owner		= THIS_MODULE;
	gpio->chip.get			= pcf857x_get;
	gpio->chip.set			= pcf857x_set;
	gpio->chip.direction_input	= pcf857x_input;
	gpio->chip.direction_output	= pcf857x_output;
	gpio->chip.ngpio		= id->driver_data;

	/* enable gpio_to_irq() if platform has settings */
	if (client->irq) {
		status = pcf857x_irq_domain_init(gpio, client);
		if (status < 0) {
			dev_err(&client->dev, "irq_domain init failed\n");
			goto fail;
		}
	}

	/* NOTE:  the OnSemi jlc1562b is also largely compatible with
	 * these parts, notably for output.  It has a low-resolution
	 * DAC instead of pin change IRQs; and its inputs can be the
	 * result of comparators.
	 */

	/* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
	 * 9670, 9672, 9764, and 9764a use quite a variety.
	 *
	 * NOTE: we don't distinguish here between *4 and *4a parts.
	 */
	if (gpio->chip.ngpio == 8) {
		gpio->write	= i2c_write_le8;
		gpio->read	= i2c_read_le8;

		if (!i2c_check_functionality(client->adapter,
				I2C_FUNC_SMBUS_BYTE))
			status = -EIO;

		/* fail if there's no chip present */
		else
			status = i2c_smbus_read_byte(client);

	/* '75/'75c addresses are 0x20..0x27, just like the '74;
	 * the '75c doesn't have a current source pulling high.
	 * 9671, 9673, and 9765 use quite a variety of addresses.
	 *
	 * NOTE: we don't distinguish here between '75 and '75c parts.
	 */
	} else if (gpio->chip.ngpio == 16) {
		gpio->write	= i2c_write_le16;
		gpio->read	= i2c_read_le16;

		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
			status = -EIO;

		/* fail if there's no chip present */
		else
			status = i2c_read_le16(client);

	} else {
		dev_dbg(&client->dev, "unsupported number of gpios\n");
		status = -EINVAL;
	}

	if (status < 0)
		goto fail;

	gpio->chip.label = client->name;

	gpio->client = client;
	i2c_set_clientdata(client, gpio);

	/* NOTE:  these chips have strange "quasi-bidirectional" I/O pins.
	 * We can't actually know whether a pin is configured (a) as output
	 * and driving the signal low, or (b) as input and reporting a low
	 * value ... without knowing the last value written since the chip
	 * came out of reset (if any).  We can't read the latched output.
	 *
	 * In short, the only reliable solution for setting up pin direction
	 * is to do it explicitly.  The setup() method can do that, but it
	 * may cause transient glitching since it can't know the last value
	 * written (some pins may need to be driven low).
	 *
	 * Using n_latch avoids that trouble.  When left initialized to zero,
	 * our software copy of the "latch" then matches the chip's all-ones
	 * reset state.  Otherwise it flags pins to be driven low.
	 */
	gpio->out = ~n_latch;
	gpio->status = gpio->out;

	status = gpiochip_add(&gpio->chip);
	if (status < 0)
		goto fail;

	/* Let platform code set up the GPIOs and their users.
	 * Now is the first time anyone could use them.
	 */
	if (pdata && pdata->setup) {
		status = pdata->setup(client,
				gpio->chip.base, gpio->chip.ngpio,
				pdata->context);
		if (status < 0)
			dev_warn(&client->dev, "setup --> %d\n", status);
	}

	dev_info(&client->dev, "probed\n");

	return 0;

fail:
	dev_dbg(&client->dev, "probe error %d for '%s'\n",
			status, client->name);

	if (client->irq)
		pcf857x_irq_domain_cleanup(gpio);

	return status;
}

static int pcf857x_remove(struct i2c_client *client)
{
	struct pcf857x_platform_data	*pdata = dev_get_platdata(&client->dev);
	struct pcf857x			*gpio = i2c_get_clientdata(client);
	int				status = 0;

	if (pdata && pdata->teardown) {
		status = pdata->teardown(client,
				gpio->chip.base, gpio->chip.ngpio,
				pdata->context);
		if (status < 0) {
			dev_err(&client->dev, "%s --> %d\n",
					"teardown", status);
			return status;
		}
	}

	if (client->irq)
		pcf857x_irq_domain_cleanup(gpio);

	status = gpiochip_remove(&gpio->chip);
	if (status)
		dev_err(&client->dev, "%s --> %d\n", "remove", status);
	return status;
}

static struct i2c_driver pcf857x_driver = {
	.driver = {
		.name	= "pcf857x",
		.owner	= THIS_MODULE,
		.of_match_table = of_match_ptr(pcf857x_of_table),
	},
	.probe	= pcf857x_probe,
	.remove	= pcf857x_remove,
	.id_table = pcf857x_id,
};

static int __init pcf857x_init(void)
{
	return i2c_add_driver(&pcf857x_driver);
}
/* register after i2c postcore initcall and before
 * subsys initcalls that may rely on these GPIOs
 */
subsys_initcall(pcf857x_init);

static void __exit pcf857x_exit(void)
{
	i2c_del_driver(&pcf857x_driver);
}
module_exit(pcf857x_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Brownell");