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/slab.h> 30 #include <linux/spinlock.h> 31 #include <linux/workqueue.h> 32 33 34 static const struct i2c_device_id pcf857x_id[] = { 35 { "pcf8574", 8 }, 36 { "pcf8574a", 8 }, 37 { "pca8574", 8 }, 38 { "pca9670", 8 }, 39 { "pca9672", 8 }, 40 { "pca9674", 8 }, 41 { "pcf8575", 16 }, 42 { "pca8575", 16 }, 43 { "pca9671", 16 }, 44 { "pca9673", 16 }, 45 { "pca9675", 16 }, 46 { "max7328", 8 }, 47 { "max7329", 8 }, 48 { "tca9554", 8 }, 49 { } 50 }; 51 MODULE_DEVICE_TABLE(i2c, pcf857x_id); 52 53 /* 54 * The pcf857x, pca857x, and pca967x chips only expose one read and one 55 * write register. Writing a "one" bit (to match the reset state) lets 56 * that pin be used as an input; it's not an open-drain model, but acts 57 * a bit like one. This is described as "quasi-bidirectional"; read the 58 * chip documentation for details. 59 * 60 * Many other I2C GPIO expander chips (like the pca953x models) have 61 * more complex register models and more conventional circuitry using 62 * push/pull drivers. They often use the same 0x20..0x27 addresses as 63 * pcf857x parts, making the "legacy" I2C driver model problematic. 64 */ 65 struct pcf857x { 66 struct gpio_chip chip; 67 struct i2c_client *client; 68 struct mutex lock; /* protect 'out' */ 69 struct work_struct work; /* irq demux work */ 70 struct irq_domain *irq_domain; /* for irq demux */ 71 spinlock_t slock; /* protect irq demux */ 72 unsigned out; /* software latch */ 73 unsigned status; /* current status */ 74 int irq; /* real irq number */ 75 76 int (*write)(struct i2c_client *client, unsigned 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 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 (int)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 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 offset) 119 { 120 struct pcf857x *gpio = container_of(chip, struct pcf857x, 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 offset) 132 { 133 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); 134 int value; 135 136 value = gpio->read(gpio->client); 137 return (value < 0) ? 0 : (value & (1 << offset)); 138 } 139 140 static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value) 141 { 142 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); 143 unsigned bit = 1 << offset; 144 int status; 145 146 mutex_lock(&gpio->lock); 147 if (value) 148 gpio->out |= bit; 149 else 150 gpio->out &= ~bit; 151 status = gpio->write(gpio->client, gpio->out); 152 mutex_unlock(&gpio->lock); 153 154 return status; 155 } 156 157 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value) 158 { 159 pcf857x_output(chip, offset, value); 160 } 161 162 /*-------------------------------------------------------------------------*/ 163 164 static int pcf857x_to_irq(struct gpio_chip *chip, unsigned offset) 165 { 166 struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); 167 168 return irq_create_mapping(gpio->irq_domain, offset); 169 } 170 171 static void pcf857x_irq_demux_work(struct work_struct *work) 172 { 173 struct pcf857x *gpio = container_of(work, 174 struct pcf857x, 175 work); 176 unsigned long change, i, status, flags; 177 178 status = gpio->read(gpio->client); 179 180 spin_lock_irqsave(&gpio->slock, flags); 181 182 change = gpio->status ^ status; 183 for_each_set_bit(i, &change, gpio->chip.ngpio) 184 generic_handle_irq(irq_find_mapping(gpio->irq_domain, i)); 185 gpio->status = status; 186 187 spin_unlock_irqrestore(&gpio->slock, flags); 188 } 189 190 static irqreturn_t pcf857x_irq_demux(int irq, void *data) 191 { 192 struct pcf857x *gpio = data; 193 194 /* 195 * pcf857x can't read/write data here, 196 * since i2c data access might go to sleep. 197 */ 198 schedule_work(&gpio->work); 199 200 return IRQ_HANDLED; 201 } 202 203 static int pcf857x_irq_domain_map(struct irq_domain *domain, unsigned int virq, 204 irq_hw_number_t hw) 205 { 206 irq_set_chip_and_handler(virq, 207 &dummy_irq_chip, 208 handle_level_irq); 209 return 0; 210 } 211 212 static struct irq_domain_ops pcf857x_irq_domain_ops = { 213 .map = pcf857x_irq_domain_map, 214 }; 215 216 static void pcf857x_irq_domain_cleanup(struct pcf857x *gpio) 217 { 218 if (gpio->irq_domain) 219 irq_domain_remove(gpio->irq_domain); 220 221 if (gpio->irq) 222 free_irq(gpio->irq, gpio); 223 } 224 225 static int pcf857x_irq_domain_init(struct pcf857x *gpio, 226 struct i2c_client *client) 227 { 228 int status; 229 230 gpio->irq_domain = irq_domain_add_linear(client->dev.of_node, 231 gpio->chip.ngpio, 232 &pcf857x_irq_domain_ops, 233 NULL); 234 if (!gpio->irq_domain) 235 goto fail; 236 237 /* enable real irq */ 238 status = request_irq(client->irq, pcf857x_irq_demux, 0, 239 dev_name(&client->dev), gpio); 240 if (status) 241 goto fail; 242 243 /* enable gpio_to_irq() */ 244 INIT_WORK(&gpio->work, pcf857x_irq_demux_work); 245 gpio->chip.to_irq = pcf857x_to_irq; 246 gpio->irq = client->irq; 247 248 return 0; 249 250 fail: 251 pcf857x_irq_domain_cleanup(gpio); 252 return -EINVAL; 253 } 254 255 /*-------------------------------------------------------------------------*/ 256 257 static int pcf857x_probe(struct i2c_client *client, 258 const struct i2c_device_id *id) 259 { 260 struct pcf857x_platform_data *pdata; 261 struct pcf857x *gpio; 262 int status; 263 264 pdata = dev_get_platdata(&client->dev); 265 if (!pdata) { 266 dev_dbg(&client->dev, "no platform data\n"); 267 } 268 269 /* Allocate, initialize, and register this gpio_chip. */ 270 gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL); 271 if (!gpio) 272 return -ENOMEM; 273 274 mutex_init(&gpio->lock); 275 spin_lock_init(&gpio->slock); 276 277 gpio->chip.base = pdata ? pdata->gpio_base : -1; 278 gpio->chip.can_sleep = 1; 279 gpio->chip.dev = &client->dev; 280 gpio->chip.owner = THIS_MODULE; 281 gpio->chip.get = pcf857x_get; 282 gpio->chip.set = pcf857x_set; 283 gpio->chip.direction_input = pcf857x_input; 284 gpio->chip.direction_output = pcf857x_output; 285 gpio->chip.ngpio = id->driver_data; 286 287 /* enable gpio_to_irq() if platform has settings */ 288 if (client->irq) { 289 status = pcf857x_irq_domain_init(gpio, client); 290 if (status < 0) { 291 dev_err(&client->dev, "irq_domain init failed\n"); 292 goto fail; 293 } 294 } 295 296 /* NOTE: the OnSemi jlc1562b is also largely compatible with 297 * these parts, notably for output. It has a low-resolution 298 * DAC instead of pin change IRQs; and its inputs can be the 299 * result of comparators. 300 */ 301 302 /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f; 303 * 9670, 9672, 9764, and 9764a use quite a variety. 304 * 305 * NOTE: we don't distinguish here between *4 and *4a parts. 306 */ 307 if (gpio->chip.ngpio == 8) { 308 gpio->write = i2c_write_le8; 309 gpio->read = i2c_read_le8; 310 311 if (!i2c_check_functionality(client->adapter, 312 I2C_FUNC_SMBUS_BYTE)) 313 status = -EIO; 314 315 /* fail if there's no chip present */ 316 else 317 status = i2c_smbus_read_byte(client); 318 319 /* '75/'75c addresses are 0x20..0x27, just like the '74; 320 * the '75c doesn't have a current source pulling high. 321 * 9671, 9673, and 9765 use quite a variety of addresses. 322 * 323 * NOTE: we don't distinguish here between '75 and '75c parts. 324 */ 325 } else if (gpio->chip.ngpio == 16) { 326 gpio->write = i2c_write_le16; 327 gpio->read = i2c_read_le16; 328 329 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 330 status = -EIO; 331 332 /* fail if there's no chip present */ 333 else 334 status = i2c_read_le16(client); 335 336 } else { 337 dev_dbg(&client->dev, "unsupported number of gpios\n"); 338 status = -EINVAL; 339 } 340 341 if (status < 0) 342 goto fail; 343 344 gpio->chip.label = client->name; 345 346 gpio->client = client; 347 i2c_set_clientdata(client, gpio); 348 349 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins. 350 * We can't actually know whether a pin is configured (a) as output 351 * and driving the signal low, or (b) as input and reporting a low 352 * value ... without knowing the last value written since the chip 353 * came out of reset (if any). We can't read the latched output. 354 * 355 * In short, the only reliable solution for setting up pin direction 356 * is to do it explicitly. The setup() method can do that, but it 357 * may cause transient glitching since it can't know the last value 358 * written (some pins may need to be driven low). 359 * 360 * Using pdata->n_latch avoids that trouble. When left initialized 361 * to zero, our software copy of the "latch" then matches the chip's 362 * all-ones reset state. Otherwise it flags pins to be driven low. 363 */ 364 gpio->out = pdata ? ~pdata->n_latch : ~0; 365 gpio->status = gpio->out; 366 367 status = gpiochip_add(&gpio->chip); 368 if (status < 0) 369 goto fail; 370 371 /* Let platform code set up the GPIOs and their users. 372 * Now is the first time anyone could use them. 373 */ 374 if (pdata && pdata->setup) { 375 status = pdata->setup(client, 376 gpio->chip.base, gpio->chip.ngpio, 377 pdata->context); 378 if (status < 0) 379 dev_warn(&client->dev, "setup --> %d\n", status); 380 } 381 382 dev_info(&client->dev, "probed\n"); 383 384 return 0; 385 386 fail: 387 dev_dbg(&client->dev, "probe error %d for '%s'\n", 388 status, client->name); 389 390 if (client->irq) 391 pcf857x_irq_domain_cleanup(gpio); 392 393 return status; 394 } 395 396 static int pcf857x_remove(struct i2c_client *client) 397 { 398 struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev); 399 struct pcf857x *gpio = i2c_get_clientdata(client); 400 int status = 0; 401 402 if (pdata && pdata->teardown) { 403 status = pdata->teardown(client, 404 gpio->chip.base, gpio->chip.ngpio, 405 pdata->context); 406 if (status < 0) { 407 dev_err(&client->dev, "%s --> %d\n", 408 "teardown", status); 409 return status; 410 } 411 } 412 413 if (client->irq) 414 pcf857x_irq_domain_cleanup(gpio); 415 416 status = gpiochip_remove(&gpio->chip); 417 if (status) 418 dev_err(&client->dev, "%s --> %d\n", "remove", status); 419 return status; 420 } 421 422 static struct i2c_driver pcf857x_driver = { 423 .driver = { 424 .name = "pcf857x", 425 .owner = THIS_MODULE, 426 }, 427 .probe = pcf857x_probe, 428 .remove = pcf857x_remove, 429 .id_table = pcf857x_id, 430 }; 431 432 static int __init pcf857x_init(void) 433 { 434 return i2c_add_driver(&pcf857x_driver); 435 } 436 /* register after i2c postcore initcall and before 437 * subsys initcalls that may rely on these GPIOs 438 */ 439 subsys_initcall(pcf857x_init); 440 441 static void __exit pcf857x_exit(void) 442 { 443 i2c_del_driver(&pcf857x_driver); 444 } 445 module_exit(pcf857x_exit); 446 447 MODULE_LICENSE("GPL"); 448 MODULE_AUTHOR("David Brownell"); 449