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/platform_data/pcf857x.h> 11 #include <linux/interrupt.h> 12 #include <linux/irq.h> 13 #include <linux/irqdomain.h> 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/of.h> 17 #include <linux/of_device.h> 18 #include <linux/slab.h> 19 #include <linux/spinlock.h> 20 21 22 static const struct i2c_device_id pcf857x_id[] = { 23 { "pcf8574", 8 }, 24 { "pcf8574a", 8 }, 25 { "pca8574", 8 }, 26 { "pca9670", 8 }, 27 { "pca9672", 8 }, 28 { "pca9674", 8 }, 29 { "pcf8575", 16 }, 30 { "pca8575", 16 }, 31 { "pca9671", 16 }, 32 { "pca9673", 16 }, 33 { "pca9675", 16 }, 34 { "max7328", 8 }, 35 { "max7329", 8 }, 36 { } 37 }; 38 MODULE_DEVICE_TABLE(i2c, pcf857x_id); 39 40 #ifdef CONFIG_OF 41 static const struct of_device_id pcf857x_of_table[] = { 42 { .compatible = "nxp,pcf8574" }, 43 { .compatible = "nxp,pcf8574a" }, 44 { .compatible = "nxp,pca8574" }, 45 { .compatible = "nxp,pca9670" }, 46 { .compatible = "nxp,pca9672" }, 47 { .compatible = "nxp,pca9674" }, 48 { .compatible = "nxp,pcf8575" }, 49 { .compatible = "nxp,pca8575" }, 50 { .compatible = "nxp,pca9671" }, 51 { .compatible = "nxp,pca9673" }, 52 { .compatible = "nxp,pca9675" }, 53 { .compatible = "maxim,max7328" }, 54 { .compatible = "maxim,max7329" }, 55 { } 56 }; 57 MODULE_DEVICE_TABLE(of, pcf857x_of_table); 58 #endif 59 60 /* 61 * The pcf857x, pca857x, and pca967x chips only expose one read and one 62 * write register. Writing a "one" bit (to match the reset state) lets 63 * that pin be used as an input; it's not an open-drain model, but acts 64 * a bit like one. This is described as "quasi-bidirectional"; read the 65 * chip documentation for details. 66 * 67 * Many other I2C GPIO expander chips (like the pca953x models) have 68 * more complex register models and more conventional circuitry using 69 * push/pull drivers. They often use the same 0x20..0x27 addresses as 70 * pcf857x parts, making the "legacy" I2C driver model problematic. 71 */ 72 struct pcf857x { 73 struct gpio_chip chip; 74 struct irq_chip irqchip; 75 struct i2c_client *client; 76 struct mutex lock; /* protect 'out' */ 77 unsigned out; /* software latch */ 78 unsigned status; /* current status */ 79 unsigned irq_enabled; /* enabled irqs */ 80 81 int (*write)(struct i2c_client *client, unsigned data); 82 int (*read)(struct i2c_client *client); 83 }; 84 85 /*-------------------------------------------------------------------------*/ 86 87 /* Talk to 8-bit I/O expander */ 88 89 static int i2c_write_le8(struct i2c_client *client, unsigned data) 90 { 91 return i2c_smbus_write_byte(client, data); 92 } 93 94 static int i2c_read_le8(struct i2c_client *client) 95 { 96 return (int)i2c_smbus_read_byte(client); 97 } 98 99 /* Talk to 16-bit I/O expander */ 100 101 static int i2c_write_le16(struct i2c_client *client, unsigned word) 102 { 103 u8 buf[2] = { word & 0xff, word >> 8, }; 104 int status; 105 106 status = i2c_master_send(client, buf, 2); 107 return (status < 0) ? status : 0; 108 } 109 110 static int i2c_read_le16(struct i2c_client *client) 111 { 112 u8 buf[2]; 113 int status; 114 115 status = i2c_master_recv(client, buf, 2); 116 if (status < 0) 117 return status; 118 return (buf[1] << 8) | buf[0]; 119 } 120 121 /*-------------------------------------------------------------------------*/ 122 123 static int pcf857x_input(struct gpio_chip *chip, unsigned offset) 124 { 125 struct pcf857x *gpio = gpiochip_get_data(chip); 126 int status; 127 128 mutex_lock(&gpio->lock); 129 gpio->out |= (1 << offset); 130 status = gpio->write(gpio->client, gpio->out); 131 mutex_unlock(&gpio->lock); 132 133 return status; 134 } 135 136 static int pcf857x_get(struct gpio_chip *chip, unsigned offset) 137 { 138 struct pcf857x *gpio = gpiochip_get_data(chip); 139 int value; 140 141 value = gpio->read(gpio->client); 142 return (value < 0) ? value : !!(value & (1 << offset)); 143 } 144 145 static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value) 146 { 147 struct pcf857x *gpio = gpiochip_get_data(chip); 148 unsigned bit = 1 << offset; 149 int status; 150 151 mutex_lock(&gpio->lock); 152 if (value) 153 gpio->out |= bit; 154 else 155 gpio->out &= ~bit; 156 status = gpio->write(gpio->client, gpio->out); 157 mutex_unlock(&gpio->lock); 158 159 return status; 160 } 161 162 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value) 163 { 164 pcf857x_output(chip, offset, value); 165 } 166 167 /*-------------------------------------------------------------------------*/ 168 169 static irqreturn_t pcf857x_irq(int irq, void *data) 170 { 171 struct pcf857x *gpio = data; 172 unsigned long change, i, status; 173 174 status = gpio->read(gpio->client); 175 176 /* 177 * call the interrupt handler iff gpio is used as 178 * interrupt source, just to avoid bad irqs 179 */ 180 mutex_lock(&gpio->lock); 181 change = (gpio->status ^ status) & gpio->irq_enabled; 182 gpio->status = status; 183 mutex_unlock(&gpio->lock); 184 185 for_each_set_bit(i, &change, gpio->chip.ngpio) 186 handle_nested_irq(irq_find_mapping(gpio->chip.irq.domain, i)); 187 188 return IRQ_HANDLED; 189 } 190 191 /* 192 * NOP functions 193 */ 194 static void noop(struct irq_data *data) { } 195 196 static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on) 197 { 198 struct pcf857x *gpio = irq_data_get_irq_chip_data(data); 199 200 return irq_set_irq_wake(gpio->client->irq, on); 201 } 202 203 static void pcf857x_irq_enable(struct irq_data *data) 204 { 205 struct pcf857x *gpio = irq_data_get_irq_chip_data(data); 206 207 gpio->irq_enabled |= (1 << data->hwirq); 208 } 209 210 static void pcf857x_irq_disable(struct irq_data *data) 211 { 212 struct pcf857x *gpio = irq_data_get_irq_chip_data(data); 213 214 gpio->irq_enabled &= ~(1 << data->hwirq); 215 } 216 217 static void pcf857x_irq_bus_lock(struct irq_data *data) 218 { 219 struct pcf857x *gpio = irq_data_get_irq_chip_data(data); 220 221 mutex_lock(&gpio->lock); 222 } 223 224 static void pcf857x_irq_bus_sync_unlock(struct irq_data *data) 225 { 226 struct pcf857x *gpio = irq_data_get_irq_chip_data(data); 227 228 mutex_unlock(&gpio->lock); 229 } 230 231 /*-------------------------------------------------------------------------*/ 232 233 static int pcf857x_probe(struct i2c_client *client, 234 const struct i2c_device_id *id) 235 { 236 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev); 237 struct device_node *np = client->dev.of_node; 238 struct pcf857x *gpio; 239 unsigned int n_latch = 0; 240 int status; 241 242 if (IS_ENABLED(CONFIG_OF) && np) 243 of_property_read_u32(np, "lines-initial-states", &n_latch); 244 else if (pdata) 245 n_latch = pdata->n_latch; 246 else 247 dev_dbg(&client->dev, "no platform data\n"); 248 249 /* Allocate, initialize, and register this gpio_chip. */ 250 gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL); 251 if (!gpio) 252 return -ENOMEM; 253 254 mutex_init(&gpio->lock); 255 256 gpio->chip.base = pdata ? pdata->gpio_base : -1; 257 gpio->chip.can_sleep = true; 258 gpio->chip.parent = &client->dev; 259 gpio->chip.owner = THIS_MODULE; 260 gpio->chip.get = pcf857x_get; 261 gpio->chip.set = pcf857x_set; 262 gpio->chip.direction_input = pcf857x_input; 263 gpio->chip.direction_output = pcf857x_output; 264 gpio->chip.ngpio = id->driver_data; 265 266 /* NOTE: the OnSemi jlc1562b is also largely compatible with 267 * these parts, notably for output. It has a low-resolution 268 * DAC instead of pin change IRQs; and its inputs can be the 269 * result of comparators. 270 */ 271 272 /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f; 273 * 9670, 9672, 9764, and 9764a use quite a variety. 274 * 275 * NOTE: we don't distinguish here between *4 and *4a parts. 276 */ 277 if (gpio->chip.ngpio == 8) { 278 gpio->write = i2c_write_le8; 279 gpio->read = i2c_read_le8; 280 281 if (!i2c_check_functionality(client->adapter, 282 I2C_FUNC_SMBUS_BYTE)) 283 status = -EIO; 284 285 /* fail if there's no chip present */ 286 else 287 status = i2c_smbus_read_byte(client); 288 289 /* '75/'75c addresses are 0x20..0x27, just like the '74; 290 * the '75c doesn't have a current source pulling high. 291 * 9671, 9673, and 9765 use quite a variety of addresses. 292 * 293 * NOTE: we don't distinguish here between '75 and '75c parts. 294 */ 295 } else if (gpio->chip.ngpio == 16) { 296 gpio->write = i2c_write_le16; 297 gpio->read = i2c_read_le16; 298 299 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 300 status = -EIO; 301 302 /* fail if there's no chip present */ 303 else 304 status = i2c_read_le16(client); 305 306 } else { 307 dev_dbg(&client->dev, "unsupported number of gpios\n"); 308 status = -EINVAL; 309 } 310 311 if (status < 0) 312 goto fail; 313 314 gpio->chip.label = client->name; 315 316 gpio->client = client; 317 i2c_set_clientdata(client, gpio); 318 319 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins. 320 * We can't actually know whether a pin is configured (a) as output 321 * and driving the signal low, or (b) as input and reporting a low 322 * value ... without knowing the last value written since the chip 323 * came out of reset (if any). We can't read the latched output. 324 * 325 * In short, the only reliable solution for setting up pin direction 326 * is to do it explicitly. The setup() method can do that, but it 327 * may cause transient glitching since it can't know the last value 328 * written (some pins may need to be driven low). 329 * 330 * Using n_latch avoids that trouble. When left initialized to zero, 331 * our software copy of the "latch" then matches the chip's all-ones 332 * reset state. Otherwise it flags pins to be driven low. 333 */ 334 gpio->out = ~n_latch; 335 gpio->status = gpio->out; 336 337 /* Enable irqchip if we have an interrupt */ 338 if (client->irq) { 339 struct gpio_irq_chip *girq; 340 341 gpio->irqchip.name = "pcf857x"; 342 gpio->irqchip.irq_enable = pcf857x_irq_enable; 343 gpio->irqchip.irq_disable = pcf857x_irq_disable; 344 gpio->irqchip.irq_ack = noop; 345 gpio->irqchip.irq_mask = noop; 346 gpio->irqchip.irq_unmask = noop; 347 gpio->irqchip.irq_set_wake = pcf857x_irq_set_wake; 348 gpio->irqchip.irq_bus_lock = pcf857x_irq_bus_lock; 349 gpio->irqchip.irq_bus_sync_unlock = pcf857x_irq_bus_sync_unlock; 350 351 status = devm_request_threaded_irq(&client->dev, client->irq, 352 NULL, pcf857x_irq, IRQF_ONESHOT | 353 IRQF_TRIGGER_FALLING | IRQF_SHARED, 354 dev_name(&client->dev), gpio); 355 if (status) 356 goto fail; 357 358 girq = &gpio->chip.irq; 359 girq->chip = &gpio->irqchip; 360 /* This will let us handle the parent IRQ in the driver */ 361 girq->parent_handler = NULL; 362 girq->num_parents = 0; 363 girq->parents = NULL; 364 girq->default_type = IRQ_TYPE_NONE; 365 girq->handler = handle_level_irq; 366 girq->threaded = true; 367 } 368 369 status = devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio); 370 if (status < 0) 371 goto fail; 372 373 /* Let platform code set up the GPIOs and their users. 374 * Now is the first time anyone could use them. 375 */ 376 if (pdata && pdata->setup) { 377 status = pdata->setup(client, 378 gpio->chip.base, gpio->chip.ngpio, 379 pdata->context); 380 if (status < 0) 381 dev_warn(&client->dev, "setup --> %d\n", status); 382 } 383 384 dev_info(&client->dev, "probed\n"); 385 386 return 0; 387 388 fail: 389 dev_dbg(&client->dev, "probe error %d for '%s'\n", status, 390 client->name); 391 392 return status; 393 } 394 395 static int pcf857x_remove(struct i2c_client *client) 396 { 397 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev); 398 struct pcf857x *gpio = i2c_get_clientdata(client); 399 int status = 0; 400 401 if (pdata && pdata->teardown) { 402 status = pdata->teardown(client, 403 gpio->chip.base, gpio->chip.ngpio, 404 pdata->context); 405 if (status < 0) { 406 dev_err(&client->dev, "%s --> %d\n", 407 "teardown", status); 408 return status; 409 } 410 } 411 412 return status; 413 } 414 415 static void pcf857x_shutdown(struct i2c_client *client) 416 { 417 struct pcf857x *gpio = i2c_get_clientdata(client); 418 419 /* Drive all the I/O lines high */ 420 gpio->write(gpio->client, BIT(gpio->chip.ngpio) - 1); 421 } 422 423 static struct i2c_driver pcf857x_driver = { 424 .driver = { 425 .name = "pcf857x", 426 .of_match_table = of_match_ptr(pcf857x_of_table), 427 }, 428 .probe = pcf857x_probe, 429 .remove = pcf857x_remove, 430 .shutdown = pcf857x_shutdown, 431 .id_table = pcf857x_id, 432 }; 433 434 static int __init pcf857x_init(void) 435 { 436 return i2c_add_driver(&pcf857x_driver); 437 } 438 /* register after i2c postcore initcall and before 439 * subsys initcalls that may rely on these GPIOs 440 */ 441 subsys_initcall(pcf857x_init); 442 443 static void __exit pcf857x_exit(void) 444 { 445 i2c_del_driver(&pcf857x_driver); 446 } 447 module_exit(pcf857x_exit); 448 449 MODULE_LICENSE("GPL"); 450 MODULE_AUTHOR("David Brownell"); 451