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/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");