drivers/gpio/gpio-pcf857x.c

   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/platform_data/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         { }
  50 };
  51 MODULE_DEVICE_TABLE(i2c, pcf857x_id);
  52
  53 #ifdef CONFIG_OF
  54 static const struct of_device_id pcf857x_of_table[] = {
  55         { .compatible = "nxp,pcf8574" },
  56         { .compatible = "nxp,pcf8574a" },
  57         { .compatible = "nxp,pca8574" },
  58         { .compatible = "nxp,pca9670" },
  59         { .compatible = "nxp,pca9672" },
  60         { .compatible = "nxp,pca9674" },
  61         { .compatible = "nxp,pcf8575" },
  62         { .compatible = "nxp,pca8575" },
  63         { .compatible = "nxp,pca9671" },
  64         { .compatible = "nxp,pca9673" },
  65         { .compatible = "nxp,pca9675" },
  66         { .compatible = "maxim,max7328" },
  67         { .compatible = "maxim,max7329" },
  68         { }
  69 };
  70 MODULE_DEVICE_TABLE(of, pcf857x_of_table);
  71 #endif
  72
  73 /*
  74  * The pcf857x, pca857x, and pca967x chips only expose one read and one
  75  * write register.  Writing a "one" bit (to match the reset state) lets
  76  * that pin be used as an input; it's not an open-drain model, but acts
  77  * a bit like one.  This is described as "quasi-bidirectional"; read the
  78  * chip documentation for details.
  79  *
  80  * Many other I2C GPIO expander chips (like the pca953x models) have
  81  * more complex register models and more conventional circuitry using
  82  * push/pull drivers.  They often use the same 0x20..0x27 addresses as
  83  * pcf857x parts, making the "legacy" I2C driver model problematic.
  84  */
  85 struct pcf857x {
  86         struct gpio_chip        chip;
  87         struct irq_chip         irqchip;
  88         struct i2c_client       *client;
  89         struct mutex            lock;           /* protect 'out' */
  90         unsigned                out;            /* software latch */
  91         unsigned                status;         /* current status */
  92         unsigned int            irq_parent;
  93         unsigned                irq_enabled;    /* enabled irqs */
  94
  95         int (*write)(struct i2c_client *client, unsigned data);
  96         int (*read)(struct i2c_client *client);
  97 };
  98
  99 /*-------------------------------------------------------------------------*/
 100
 101 /* Talk to 8-bit I/O expander */
 102
 103 static int i2c_write_le8(struct i2c_client *client, unsigned data)
 104 {
 105         return i2c_smbus_write_byte(client, data);
 106 }
 107
 108 static int i2c_read_le8(struct i2c_client *client)
 109 {
 110         return (int)i2c_smbus_read_byte(client);
 111 }
 112
 113 /* Talk to 16-bit I/O expander */
 114
 115 static int i2c_write_le16(struct i2c_client *client, unsigned word)
 116 {
 117         u8 buf[2] = { word & 0xff, word >> 8, };
 118         int status;
 119
 120         status = i2c_master_send(client, buf, 2);
 121         return (status < 0) ? status : 0;
 122 }
 123
 124 static int i2c_read_le16(struct i2c_client *client)
 125 {
 126         u8 buf[2];
 127         int status;
 128
 129         status = i2c_master_recv(client, buf, 2);
 130         if (status < 0)
 131                 return status;
 132         return (buf[1] << 8) | buf[0];
 133 }
 134
 135 /*-------------------------------------------------------------------------*/
 136
 137 static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
 138 {
 139         struct pcf857x  *gpio = gpiochip_get_data(chip);
 140         int             status;
 141
 142         mutex_lock(&gpio->lock);
 143         gpio->out |= (1 << offset);
 144         status = gpio->write(gpio->client, gpio->out);
 145         mutex_unlock(&gpio->lock);
 146
 147         return status;
 148 }
 149
 150 static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
 151 {
 152         struct pcf857x  *gpio = gpiochip_get_data(chip);
 153         int             value;
 154
 155         value = gpio->read(gpio->client);
 156         return (value < 0) ? value : !!(value & (1 << offset));
 157 }
 158
 159 static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
 160 {
 161         struct pcf857x  *gpio = gpiochip_get_data(chip);
 162         unsigned        bit = 1 << offset;
 163         int             status;
 164
 165         mutex_lock(&gpio->lock);
 166         if (value)
 167                 gpio->out |= bit;
 168         else
 169                 gpio->out &= ~bit;
 170         status = gpio->write(gpio->client, gpio->out);
 171         mutex_unlock(&gpio->lock);
 172
 173         return status;
 174 }
 175
 176 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
 177 {
 178         pcf857x_output(chip, offset, value);
 179 }
 180
 181 /*-------------------------------------------------------------------------*/
 182
 183 static irqreturn_t pcf857x_irq(int irq, void *data)
 184 {
 185         struct pcf857x  *gpio = data;
 186         unsigned long change, i, status;
 187
 188         status = gpio->read(gpio->client);
 189
 190         /*
 191          * call the interrupt handler iff gpio is used as
 192          * interrupt source, just to avoid bad irqs
 193          */
 194         mutex_lock(&gpio->lock);
 195         change = (gpio->status ^ status) & gpio->irq_enabled;
 196         gpio->status = status;
 197         mutex_unlock(&gpio->lock);
 198
 199         for_each_set_bit(i, &change, gpio->chip.ngpio)
 200                 handle_nested_irq(irq_find_mapping(gpio->chip.irqdomain, i));
 201
 202         return IRQ_HANDLED;
 203 }
 204
 205 /*
 206  * NOP functions
 207  */
 208 static void noop(struct irq_data *data) { }
 209
 210 static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
 211 {
 212         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 213
 214         int error = 0;
 215
 216         if (gpio->irq_parent) {
 217                 error = irq_set_irq_wake(gpio->irq_parent, on);
 218                 if (error) {
 219                         dev_dbg(&gpio->client->dev,
 220                                 "irq %u doesn't support irq_set_wake\n",
 221                                 gpio->irq_parent);
 222                         gpio->irq_parent = 0;
 223                 }
 224         }
 225         return error;
 226 }
 227
 228 static void pcf857x_irq_enable(struct irq_data *data)
 229 {
 230         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 231
 232         gpio->irq_enabled |= (1 << data->hwirq);
 233 }
 234
 235 static void pcf857x_irq_disable(struct irq_data *data)
 236 {
 237         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 238
 239         gpio->irq_enabled &= ~(1 << data->hwirq);
 240 }
 241
 242 static void pcf857x_irq_bus_lock(struct irq_data *data)
 243 {
 244         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 245
 246         mutex_lock(&gpio->lock);
 247 }
 248
 249 static void pcf857x_irq_bus_sync_unlock(struct irq_data *data)
 250 {
 251         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 252
 253         mutex_unlock(&gpio->lock);
 254 }
 255
 256 /*-------------------------------------------------------------------------*/
 257
 258 static int pcf857x_probe(struct i2c_client *client,
 259                          const struct i2c_device_id *id)
 260 {
 261         struct pcf857x_platform_data    *pdata = dev_get_platdata(&client->dev);
 262         struct device_node              *np = client->dev.of_node;
 263         struct pcf857x                  *gpio;
 264         unsigned int                    n_latch = 0;
 265         int                             status;
 266
 267         if (IS_ENABLED(CONFIG_OF) && np)
 268                 of_property_read_u32(np, "lines-initial-states", &n_latch);
 269         else if (pdata)
 270                 n_latch = pdata->n_latch;
 271         else
 272                 dev_dbg(&client->dev, "no platform data\n");
 273
 274         /* Allocate, initialize, and register this gpio_chip. */
 275         gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
 276         if (!gpio)
 277                 return -ENOMEM;
 278
 279         mutex_init(&gpio->lock);
 280
 281         gpio->chip.base                 = pdata ? pdata->gpio_base : -1;
 282         gpio->chip.can_sleep            = true;
 283         gpio->chip.parent               = &client->dev;
 284         gpio->chip.owner                = THIS_MODULE;
 285         gpio->chip.get                  = pcf857x_get;
 286         gpio->chip.set                  = pcf857x_set;
 287         gpio->chip.direction_input      = pcf857x_input;
 288         gpio->chip.direction_output     = pcf857x_output;
 289         gpio->chip.ngpio                = id->driver_data;
 290
 291         /* NOTE:  the OnSemi jlc1562b is also largely compatible with
 292          * these parts, notably for output.  It has a low-resolution
 293          * DAC instead of pin change IRQs; and its inputs can be the
 294          * result of comparators.
 295          */
 296
 297         /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
 298          * 9670, 9672, 9764, and 9764a use quite a variety.
 299          *
 300          * NOTE: we don't distinguish here between *4 and *4a parts.
 301          */
 302         if (gpio->chip.ngpio == 8) {
 303                 gpio->write     = i2c_write_le8;
 304                 gpio->read      = i2c_read_le8;
 305
 306                 if (!i2c_check_functionality(client->adapter,
 307                                 I2C_FUNC_SMBUS_BYTE))
 308                         status = -EIO;
 309
 310                 /* fail if there's no chip present */
 311                 else
 312                         status = i2c_smbus_read_byte(client);
 313
 314         /* '75/'75c addresses are 0x20..0x27, just like the '74;
 315          * the '75c doesn't have a current source pulling high.
 316          * 9671, 9673, and 9765 use quite a variety of addresses.
 317          *
 318          * NOTE: we don't distinguish here between '75 and '75c parts.
 319          */
 320         } else if (gpio->chip.ngpio == 16) {
 321                 gpio->write     = i2c_write_le16;
 322                 gpio->read      = i2c_read_le16;
 323
 324                 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 325                         status = -EIO;
 326
 327                 /* fail if there's no chip present */
 328                 else
 329                         status = i2c_read_le16(client);
 330
 331         } else {
 332                 dev_dbg(&client->dev, "unsupported number of gpios\n");
 333                 status = -EINVAL;
 334         }
 335
 336         if (status < 0)
 337                 goto fail;
 338
 339         gpio->chip.label = client->name;
 340
 341         gpio->client = client;
 342         i2c_set_clientdata(client, gpio);
 343
 344         /* NOTE:  these chips have strange "quasi-bidirectional" I/O pins.
 345          * We can't actually know whether a pin is configured (a) as output
 346          * and driving the signal low, or (b) as input and reporting a low
 347          * value ... without knowing the last value written since the chip
 348          * came out of reset (if any).  We can't read the latched output.
 349          *
 350          * In short, the only reliable solution for setting up pin direction
 351          * is to do it explicitly.  The setup() method can do that, but it
 352          * may cause transient glitching since it can't know the last value
 353          * written (some pins may need to be driven low).
 354          *
 355          * Using n_latch avoids that trouble.  When left initialized to zero,
 356          * our software copy of the "latch" then matches the chip's all-ones
 357          * reset state.  Otherwise it flags pins to be driven low.
 358          */
 359         gpio->out = ~n_latch;
 360         gpio->status = gpio->out;
 361
 362         status = devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio);
 363         if (status < 0)
 364                 goto fail;
 365
 366         /* Enable irqchip if we have an interrupt */
 367         if (client->irq) {
 368                 gpio->irqchip.name = "pcf857x",
 369                 gpio->irqchip.irq_enable = pcf857x_irq_enable,
 370                 gpio->irqchip.irq_disable = pcf857x_irq_disable,
 371                 gpio->irqchip.irq_ack = noop,
 372                 gpio->irqchip.irq_mask = noop,
 373                 gpio->irqchip.irq_unmask = noop,
 374                 gpio->irqchip.irq_set_wake = pcf857x_irq_set_wake,
 375                 gpio->irqchip.irq_bus_lock = pcf857x_irq_bus_lock,
 376                 gpio->irqchip.irq_bus_sync_unlock = pcf857x_irq_bus_sync_unlock,
 377                 status = gpiochip_irqchip_add_nested(&gpio->chip,
 378                                                      &gpio->irqchip,
 379                                                      0, handle_level_irq,
 380                                                      IRQ_TYPE_NONE);
 381                 if (status) {
 382                         dev_err(&client->dev, "cannot add irqchip\n");
 383                         goto fail;
 384                 }
 385
 386                 status = devm_request_threaded_irq(&client->dev, client->irq,
 387                                         NULL, pcf857x_irq, IRQF_ONESHOT |
 388                                         IRQF_TRIGGER_FALLING | IRQF_SHARED,
 389                                         dev_name(&client->dev), gpio);
 390                 if (status)
 391                         goto fail;
 392
 393                 gpiochip_set_nested_irqchip(&gpio->chip, &gpio->irqchip,
 394                                             client->irq);
 395                 gpio->irq_parent = client->irq;
 396         }
 397
 398         /* Let platform code set up the GPIOs and their users.
 399          * Now is the first time anyone could use them.
 400          */
 401         if (pdata && pdata->setup) {
 402                 status = pdata->setup(client,
 403                                 gpio->chip.base, gpio->chip.ngpio,
 404                                 pdata->context);
 405                 if (status < 0)
 406                         dev_warn(&client->dev, "setup --> %d\n", status);
 407         }
 408
 409         dev_info(&client->dev, "probed\n");
 410
 411         return 0;
 412
 413 fail:
 414         dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
 415                 client->name);
 416
 417         return status;
 418 }
 419
 420 static int pcf857x_remove(struct i2c_client *client)
 421 {
 422         struct pcf857x_platform_data    *pdata = dev_get_platdata(&client->dev);
 423         struct pcf857x                  *gpio = i2c_get_clientdata(client);
 424         int                             status = 0;
 425
 426         if (pdata && pdata->teardown) {
 427                 status = pdata->teardown(client,
 428                                 gpio->chip.base, gpio->chip.ngpio,
 429                                 pdata->context);
 430                 if (status < 0) {
 431                         dev_err(&client->dev, "%s --> %d\n",
 432                                         "teardown", status);
 433                         return status;
 434                 }
 435         }
 436
 437         return status;
 438 }
 439
 440 static void pcf857x_shutdown(struct i2c_client *client)
 441 {
 442         struct pcf857x *gpio = i2c_get_clientdata(client);
 443
 444         /* Drive all the I/O lines high */
 445         gpio->write(gpio->client, BIT(gpio->chip.ngpio) - 1);
 446 }
 447
 448 static struct i2c_driver pcf857x_driver = {
 449         .driver = {
 450                 .name   = "pcf857x",
 451                 .of_match_table = of_match_ptr(pcf857x_of_table),
 452         },
 453         .probe  = pcf857x_probe,
 454         .remove = pcf857x_remove,
 455         .shutdown = pcf857x_shutdown,
 456         .id_table = pcf857x_id,
 457 };
 458
 459 static int __init pcf857x_init(void)
 460 {
 461         return i2c_add_driver(&pcf857x_driver);
 462 }
 463 /* register after i2c postcore initcall and before
 464  * subsys initcalls that may rely on these GPIOs
 465  */
 466 subsys_initcall(pcf857x_init);
 467
 468 static void __exit pcf857x_exit(void)
 469 {
 470         i2c_del_driver(&pcf857x_driver);
 471 }
 472 module_exit(pcf857x_exit);
 473
 474 MODULE_LICENSE("GPL");
 475 MODULE_AUTHOR("David Brownell");