1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders 4 * 5 * Copyright (C) 2007 David Brownell 6 */ 7 8 #include <linux/gpio/driver.h> 9 #include <linux/i2c.h> 10 #include <linux/interrupt.h> 11 #include <linux/irq.h> 12 #include <linux/irqdomain.h> 13 #include <linux/kernel.h> 14 #include <linux/mod_devicetable.h> 15 #include <linux/module.h> 16 #include <linux/property.h> 17 #include <linux/slab.h> 18 #include <linux/spinlock.h> 19 20 static const struct i2c_device_id pcf857x_id[] = { 21 { "pcf8574", 8 }, 22 { "pcf8574a", 8 }, 23 { "pca8574", 8 }, 24 { "pca9670", 8 }, 25 { "pca9672", 8 }, 26 { "pca9674", 8 }, 27 { "pcf8575", 16 }, 28 { "pca8575", 16 }, 29 { "pca9671", 16 }, 30 { "pca9673", 16 }, 31 { "pca9675", 16 }, 32 { "max7328", 8 }, 33 { "max7329", 8 }, 34 { } 35 }; 36 MODULE_DEVICE_TABLE(i2c, pcf857x_id); 37 38 static const struct of_device_id pcf857x_of_table[] = { 39 { .compatible = "nxp,pcf8574", (void *)8 }, 40 { .compatible = "nxp,pcf8574a", (void *)8 }, 41 { .compatible = "nxp,pca8574", (void *)8 }, 42 { .compatible = "nxp,pca9670", (void *)8 }, 43 { .compatible = "nxp,pca9672", (void *)8 }, 44 { .compatible = "nxp,pca9674", (void *)8 }, 45 { .compatible = "nxp,pcf8575", (void *)16 }, 46 { .compatible = "nxp,pca8575", (void *)16 }, 47 { .compatible = "nxp,pca9671", (void *)16 }, 48 { .compatible = "nxp,pca9673", (void *)16 }, 49 { .compatible = "nxp,pca9675", (void *)16 }, 50 { .compatible = "maxim,max7328", (void *)8 }, 51 { .compatible = "maxim,max7329", (void *)8 }, 52 { } 53 }; 54 MODULE_DEVICE_TABLE(of, pcf857x_of_table); 55 56 /* 57 * The pcf857x, pca857x, and pca967x chips only expose one read and one 58 * write register. Writing a "one" bit (to match the reset state) lets 59 * that pin be used as an input; it's not an open-drain model, but acts 60 * a bit like one. This is described as "quasi-bidirectional"; read the 61 * chip documentation for details. 62 * 63 * Many other I2C GPIO expander chips (like the pca953x models) have 64 * more complex register models and more conventional circuitry using 65 * push/pull drivers. They often use the same 0x20..0x27 addresses as 66 * pcf857x parts, making the "legacy" I2C driver model problematic. 67 */ 68 struct pcf857x { 69 struct gpio_chip chip; 70 struct i2c_client *client; 71 struct mutex lock; /* protect 'out' */ 72 unsigned int out; /* software latch */ 73 unsigned int status; /* current status */ 74 unsigned int irq_enabled; /* enabled irqs */ 75 76 int (*write)(struct i2c_client *client, unsigned int data); 77 int (*read)(struct i2c_client *client); 78 }; 79 80 /*-------------------------------------------------------------------------*/ 81 82 /* Talk to 8-bit I/O expander */ 83 84 static int i2c_write_le8(struct i2c_client *client, unsigned int data) 85 { 86 return i2c_smbus_write_byte(client, data); 87 } 88 89 static int i2c_read_le8(struct i2c_client *client) 90 { 91 return i2c_smbus_read_byte(client); 92 } 93 94 /* Talk to 16-bit I/O expander */ 95 96 static int i2c_write_le16(struct i2c_client *client, unsigned int word) 97 { 98 u8 buf[2] = { word & 0xff, word >> 8, }; 99 int status; 100 101 status = i2c_master_send(client, buf, 2); 102 return (status < 0) ? status : 0; 103 } 104 105 static int i2c_read_le16(struct i2c_client *client) 106 { 107 u8 buf[2]; 108 int status; 109 110 status = i2c_master_recv(client, buf, 2); 111 if (status < 0) 112 return status; 113 return (buf[1] << 8) | buf[0]; 114 } 115 116 /*-------------------------------------------------------------------------*/ 117 118 static int pcf857x_input(struct gpio_chip *chip, unsigned int offset) 119 { 120 struct pcf857x *gpio = gpiochip_get_data(chip); 121 int status; 122 123 mutex_lock(&gpio->lock); 124 gpio->out |= (1 << offset); 125 status = gpio->write(gpio->client, gpio->out); 126 mutex_unlock(&gpio->lock); 127 128 return status; 129 } 130 131 static int pcf857x_get(struct gpio_chip *chip, unsigned int offset) 132 { 133 struct pcf857x *gpio = gpiochip_get_data(chip); 134 int value; 135 136 value = gpio->read(gpio->client); 137 return (value < 0) ? value : !!(value & (1 << offset)); 138 } 139 140 static int pcf857x_get_multiple(struct gpio_chip *chip, unsigned long *mask, 141 unsigned long *bits) 142 { 143 struct pcf857x *gpio = gpiochip_get_data(chip); 144 int value = gpio->read(gpio->client); 145 146 if (value < 0) 147 return value; 148 149 *bits &= ~*mask; 150 *bits |= value & *mask; 151 152 return 0; 153 } 154 155 static int pcf857x_output(struct gpio_chip *chip, unsigned int offset, int value) 156 { 157 struct pcf857x *gpio = gpiochip_get_data(chip); 158 unsigned int bit = 1 << offset; 159 int status; 160 161 mutex_lock(&gpio->lock); 162 if (value) 163 gpio->out |= bit; 164 else 165 gpio->out &= ~bit; 166 status = gpio->write(gpio->client, gpio->out); 167 mutex_unlock(&gpio->lock); 168 169 return status; 170 } 171 172 static void pcf857x_set(struct gpio_chip *chip, unsigned int offset, int value) 173 { 174 pcf857x_output(chip, offset, value); 175 } 176 177 static void pcf857x_set_multiple(struct gpio_chip *chip, unsigned long *mask, 178 unsigned long *bits) 179 { 180 struct pcf857x *gpio = gpiochip_get_data(chip); 181 182 mutex_lock(&gpio->lock); 183 gpio->out &= ~*mask; 184 gpio->out |= *bits & *mask; 185 gpio->write(gpio->client, gpio->out); 186 mutex_unlock(&gpio->lock); 187 } 188 189 /*-------------------------------------------------------------------------*/ 190 191 static irqreturn_t pcf857x_irq(int irq, void *data) 192 { 193 struct pcf857x *gpio = data; 194 unsigned long change, i, status; 195 196 status = gpio->read(gpio->client); 197 198 /* 199 * call the interrupt handler iff gpio is used as 200 * interrupt source, just to avoid bad irqs 201 */ 202 mutex_lock(&gpio->lock); 203 change = (gpio->status ^ status) & gpio->irq_enabled; 204 gpio->status = status; 205 mutex_unlock(&gpio->lock); 206 207 for_each_set_bit(i, &change, gpio->chip.ngpio) 208 handle_nested_irq(irq_find_mapping(gpio->chip.irq.domain, i)); 209 210 return IRQ_HANDLED; 211 } 212 213 /* 214 * NOP functions 215 */ 216 static void noop(struct irq_data *data) { } 217 218 static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on) 219 { 220 struct pcf857x *gpio = irq_data_get_irq_chip_data(data); 221 222 return irq_set_irq_wake(gpio->client->irq, on); 223 } 224 225 static void pcf857x_irq_enable(struct irq_data *data) 226 { 227 struct pcf857x *gpio = irq_data_get_irq_chip_data(data); 228 irq_hw_number_t hwirq = irqd_to_hwirq(data); 229 230 gpiochip_enable_irq(&gpio->chip, hwirq); 231 gpio->irq_enabled |= (1 << hwirq); 232 } 233 234 static void pcf857x_irq_disable(struct irq_data *data) 235 { 236 struct pcf857x *gpio = irq_data_get_irq_chip_data(data); 237 irq_hw_number_t hwirq = irqd_to_hwirq(data); 238 239 gpio->irq_enabled &= ~(1 << hwirq); 240 gpiochip_disable_irq(&gpio->chip, hwirq); 241 } 242 243 static void pcf857x_irq_bus_lock(struct irq_data *data) 244 { 245 struct pcf857x *gpio = irq_data_get_irq_chip_data(data); 246 247 mutex_lock(&gpio->lock); 248 } 249 250 static void pcf857x_irq_bus_sync_unlock(struct irq_data *data) 251 { 252 struct pcf857x *gpio = irq_data_get_irq_chip_data(data); 253 254 mutex_unlock(&gpio->lock); 255 } 256 257 static const struct irq_chip pcf857x_irq_chip = { 258 .name = "pcf857x", 259 .irq_enable = pcf857x_irq_enable, 260 .irq_disable = pcf857x_irq_disable, 261 .irq_ack = noop, 262 .irq_mask = noop, 263 .irq_unmask = noop, 264 .irq_set_wake = pcf857x_irq_set_wake, 265 .irq_bus_lock = pcf857x_irq_bus_lock, 266 .irq_bus_sync_unlock = pcf857x_irq_bus_sync_unlock, 267 .flags = IRQCHIP_IMMUTABLE, 268 GPIOCHIP_IRQ_RESOURCE_HELPERS, 269 }; 270 271 /*-------------------------------------------------------------------------*/ 272 273 static int pcf857x_probe(struct i2c_client *client) 274 { 275 struct pcf857x *gpio; 276 unsigned int n_latch = 0; 277 int status; 278 279 device_property_read_u32(&client->dev, "lines-initial-states", &n_latch); 280 281 /* Allocate, initialize, and register this gpio_chip. */ 282 gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL); 283 if (!gpio) 284 return -ENOMEM; 285 286 mutex_init(&gpio->lock); 287 288 gpio->chip.base = -1; 289 gpio->chip.can_sleep = true; 290 gpio->chip.parent = &client->dev; 291 gpio->chip.owner = THIS_MODULE; 292 gpio->chip.get = pcf857x_get; 293 gpio->chip.get_multiple = pcf857x_get_multiple; 294 gpio->chip.set = pcf857x_set; 295 gpio->chip.set_multiple = pcf857x_set_multiple; 296 gpio->chip.direction_input = pcf857x_input; 297 gpio->chip.direction_output = pcf857x_output; 298 gpio->chip.ngpio = (uintptr_t)i2c_get_match_data(client); 299 300 /* NOTE: the OnSemi jlc1562b is also largely compatible with 301 * these parts, notably for output. It has a low-resolution 302 * DAC instead of pin change IRQs; and its inputs can be the 303 * result of comparators. 304 */ 305 306 /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f; 307 * 9670, 9672, 9764, and 9764a use quite a variety. 308 * 309 * NOTE: we don't distinguish here between *4 and *4a parts. 310 */ 311 if (gpio->chip.ngpio == 8) { 312 gpio->write = i2c_write_le8; 313 gpio->read = i2c_read_le8; 314 315 if (!i2c_check_functionality(client->adapter, 316 I2C_FUNC_SMBUS_BYTE)) 317 status = -EIO; 318 319 /* fail if there's no chip present */ 320 else 321 status = i2c_smbus_read_byte(client); 322 323 /* '75/'75c addresses are 0x20..0x27, just like the '74; 324 * the '75c doesn't have a current source pulling high. 325 * 9671, 9673, and 9765 use quite a variety of addresses. 326 * 327 * NOTE: we don't distinguish here between '75 and '75c parts. 328 */ 329 } else if (gpio->chip.ngpio == 16) { 330 gpio->write = i2c_write_le16; 331 gpio->read = i2c_read_le16; 332 333 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 334 status = -EIO; 335 336 /* fail if there's no chip present */ 337 else 338 status = i2c_read_le16(client); 339 340 } else { 341 dev_dbg(&client->dev, "unsupported number of gpios\n"); 342 status = -EINVAL; 343 } 344 345 if (status < 0) 346 goto fail; 347 348 gpio->chip.label = client->name; 349 350 gpio->client = client; 351 i2c_set_clientdata(client, gpio); 352 353 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins. 354 * We can't actually know whether a pin is configured (a) as output 355 * and driving the signal low, or (b) as input and reporting a low 356 * value ... without knowing the last value written since the chip 357 * came out of reset (if any). We can't read the latched output. 358 * 359 * In short, the only reliable solution for setting up pin direction 360 * is to do it explicitly. The setup() method can do that, but it 361 * may cause transient glitching since it can't know the last value 362 * written (some pins may need to be driven low). 363 * 364 * Using n_latch avoids that trouble. When left initialized to zero, 365 * our software copy of the "latch" then matches the chip's all-ones 366 * reset state. Otherwise it flags pins to be driven low. 367 */ 368 gpio->out = ~n_latch; 369 gpio->status = gpio->read(gpio->client); 370 371 /* Enable irqchip if we have an interrupt */ 372 if (client->irq) { 373 struct gpio_irq_chip *girq; 374 375 status = devm_request_threaded_irq(&client->dev, client->irq, 376 NULL, pcf857x_irq, IRQF_ONESHOT | 377 IRQF_TRIGGER_FALLING | IRQF_SHARED, 378 dev_name(&client->dev), gpio); 379 if (status) 380 goto fail; 381 382 girq = &gpio->chip.irq; 383 gpio_irq_chip_set_chip(girq, &pcf857x_irq_chip); 384 /* This will let us handle the parent IRQ in the driver */ 385 girq->parent_handler = NULL; 386 girq->num_parents = 0; 387 girq->parents = NULL; 388 girq->default_type = IRQ_TYPE_NONE; 389 girq->handler = handle_level_irq; 390 girq->threaded = true; 391 } 392 393 status = devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio); 394 if (status < 0) 395 goto fail; 396 397 dev_info(&client->dev, "probed\n"); 398 399 return 0; 400 401 fail: 402 dev_dbg(&client->dev, "probe error %d for '%s'\n", status, 403 client->name); 404 405 return status; 406 } 407 408 static void pcf857x_shutdown(struct i2c_client *client) 409 { 410 struct pcf857x *gpio = i2c_get_clientdata(client); 411 412 /* Drive all the I/O lines high */ 413 gpio->write(gpio->client, BIT(gpio->chip.ngpio) - 1); 414 } 415 416 static struct i2c_driver pcf857x_driver = { 417 .driver = { 418 .name = "pcf857x", 419 .of_match_table = pcf857x_of_table, 420 }, 421 .probe = pcf857x_probe, 422 .shutdown = pcf857x_shutdown, 423 .id_table = pcf857x_id, 424 }; 425 426 static int __init pcf857x_init(void) 427 { 428 return i2c_add_driver(&pcf857x_driver); 429 } 430 /* register after i2c postcore initcall and before 431 * subsys initcalls that may rely on these GPIOs 432 */ 433 subsys_initcall(pcf857x_init); 434 435 static void __exit pcf857x_exit(void) 436 { 437 i2c_del_driver(&pcf857x_driver); 438 } 439 module_exit(pcf857x_exit); 440 441 MODULE_LICENSE("GPL"); 442 MODULE_AUTHOR("David Brownell"); 443