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 35 static 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 }; 52 MODULE_DEVICE_TABLE(i2c, pcf857x_id); 53 54 #ifdef CONFIG_OF 55 static 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 }; 72 MODULE_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 */ 87 struct 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 */ 104 105 static int i2c_write_le8(struct i2c_client *client, unsigned data) 106 { 107 return i2c_smbus_write_byte(client, data); 108 } 109 110 static 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 */ 116 117 static 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 } 125 126 static 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 /*-------------------------------------------------------------------------*/ 138 139 static 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 } 151 152 static 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 } 160 161 static 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 } 177 178 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value) 179 { 180 pcf857x_output(chip, offset, value); 181 } 182 183 /*-------------------------------------------------------------------------*/ 184 185 static 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 } 196 197 static 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 } 220 221 static 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 } 238 239 static struct irq_domain_ops pcf857x_irq_domain_ops = { 240 .map = pcf857x_irq_domain_map, 241 }; 242 243 static void pcf857x_irq_domain_cleanup(struct pcf857x *gpio) 244 { 245 if (gpio->irq_domain) 246 irq_domain_remove(gpio->irq_domain); 247 248 } 249 250 static 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 | IRQF_SHARED, 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; 275 276 fail: 277 pcf857x_irq_domain_cleanup(gpio); 278 return -EINVAL; 279 } 280 281 /*-------------------------------------------------------------------------*/ 282 283 static 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_irq_domain; 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; 415 416 fail: 417 if (client->irq) 418 pcf857x_irq_domain_cleanup(gpio); 419 420 fail_irq_domain: 421 dev_dbg(&client->dev, "probe error %d for '%s'\n", 422 status, client->name); 423 424 return status; 425 } 426 427 static int pcf857x_remove(struct i2c_client *client) 428 { 429 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev); 430 struct pcf857x *gpio = i2c_get_clientdata(client); 431 int status = 0; 432 433 if (pdata && pdata->teardown) { 434 status = pdata->teardown(client, 435 gpio->chip.base, gpio->chip.ngpio, 436 pdata->context); 437 if (status < 0) { 438 dev_err(&client->dev, "%s --> %d\n", 439 "teardown", status); 440 return status; 441 } 442 } 443 444 if (client->irq) 445 pcf857x_irq_domain_cleanup(gpio); 446 447 gpiochip_remove(&gpio->chip); 448 return status; 449 } 450 451 static struct i2c_driver pcf857x_driver = { 452 .driver = { 453 .name = "pcf857x", 454 .owner = THIS_MODULE, 455 .of_match_table = of_match_ptr(pcf857x_of_table), 456 }, 457 .probe = pcf857x_probe, 458 .remove = pcf857x_remove, 459 .id_table = pcf857x_id, 460 }; 461 462 static int __init pcf857x_init(void) 463 { 464 return i2c_add_driver(&pcf857x_driver); 465 } 466 /* register after i2c postcore initcall and before 467 * subsys initcalls that may rely on these GPIOs 468 */ 469 subsys_initcall(pcf857x_init); 470 471 static void __exit pcf857x_exit(void) 472 { 473 i2c_del_driver(&pcf857x_driver); 474 } 475 module_exit(pcf857x_exit); 476 477 MODULE_LICENSE("GPL"); 478 MODULE_AUTHOR("David Brownell"); 479