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
  32
  33 static const struct i2c_device_id pcf857x_id[] = {
  34         { "pcf8574", 8 },
  35         { "pcf8574a", 8 },
  36         { "pca8574", 8 },
  37         { "pca9670", 8 },
  38         { "pca9672", 8 },
  39         { "pca9674", 8 },
  40         { "pcf8575", 16 },
  41         { "pca8575", 16 },
  42         { "pca9671", 16 },
  43         { "pca9673", 16 },
  44         { "pca9675", 16 },
  45         { "max7328", 8 },
  46         { "max7329", 8 },
  47         { "tca9554", 8 },
  48         { }
  49 };
  50 MODULE_DEVICE_TABLE(i2c, pcf857x_id);
  51
  52 /*
  53  * The pcf857x, pca857x, and pca967x chips only expose one read and one
  54  * write register.  Writing a "one" bit (to match the reset state) lets
  55  * that pin be used as an input; it's not an open-drain model, but acts
  56  * a bit like one.  This is described as "quasi-bidirectional"; read the
  57  * chip documentation for details.
  58  *
  59  * Many other I2C GPIO expander chips (like the pca953x models) have
  60  * more complex register models and more conventional circuitry using
  61  * push/pull drivers.  They often use the same 0x20..0x27 addresses as
  62  * pcf857x parts, making the "legacy" I2C driver model problematic.
  63  */
  64 struct pcf857x {
  65         struct gpio_chip        chip;
  66         struct i2c_client       *client;
  67         struct mutex            lock;           /* protect 'out' */
  68         struct irq_domain       *irq_domain;    /* for irq demux  */
  69         spinlock_t              slock;          /* protect irq demux */
  70         unsigned                out;            /* software latch */
  71         unsigned                status;         /* current status */
  72         unsigned                irq_mapped;     /* mapped gpio irqs */
  73
  74         int (*write)(struct i2c_client *client, unsigned data);
  75         int (*read)(struct i2c_client *client);
  76 };
  77
  78 /*-------------------------------------------------------------------------*/
  79
  80 /* Talk to 8-bit I/O expander */
  81
  82 static int i2c_write_le8(struct i2c_client *client, unsigned data)
  83 {
  84         return i2c_smbus_write_byte(client, data);
  85 }
  86
  87 static int i2c_read_le8(struct i2c_client *client)
  88 {
  89         return (int)i2c_smbus_read_byte(client);
  90 }
  91
  92 /* Talk to 16-bit I/O expander */
  93
  94 static int i2c_write_le16(struct i2c_client *client, unsigned word)
  95 {
  96         u8 buf[2] = { word & 0xff, word >> 8, };
  97         int status;
  98
  99         status = i2c_master_send(client, buf, 2);
 100         return (status < 0) ? status : 0;
 101 }
 102
 103 static int i2c_read_le16(struct i2c_client *client)
 104 {
 105         u8 buf[2];
 106         int status;
 107
 108         status = i2c_master_recv(client, buf, 2);
 109         if (status < 0)
 110                 return status;
 111         return (buf[1] << 8) | buf[0];
 112 }
 113
 114 /*-------------------------------------------------------------------------*/
 115
 116 static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
 117 {
 118         struct pcf857x  *gpio = container_of(chip, struct pcf857x, chip);
 119         int             status;
 120
 121         mutex_lock(&gpio->lock);
 122         gpio->out |= (1 << offset);
 123         status = gpio->write(gpio->client, gpio->out);
 124         mutex_unlock(&gpio->lock);
 125
 126         return status;
 127 }
 128
 129 static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
 130 {
 131         struct pcf857x  *gpio = container_of(chip, struct pcf857x, chip);
 132         int             value;
 133
 134         value = gpio->read(gpio->client);
 135         return (value < 0) ? 0 : (value & (1 << offset));
 136 }
 137
 138 static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
 139 {
 140         struct pcf857x  *gpio = container_of(chip, struct pcf857x, chip);
 141         unsigned        bit = 1 << offset;
 142         int             status;
 143
 144         mutex_lock(&gpio->lock);
 145         if (value)
 146                 gpio->out |= bit;
 147         else
 148                 gpio->out &= ~bit;
 149         status = gpio->write(gpio->client, gpio->out);
 150         mutex_unlock(&gpio->lock);
 151
 152         return status;
 153 }
 154
 155 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
 156 {
 157         pcf857x_output(chip, offset, value);
 158 }
 159
 160 /*-------------------------------------------------------------------------*/
 161
 162 static int pcf857x_to_irq(struct gpio_chip *chip, unsigned offset)
 163 {
 164         struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
 165         int ret;
 166
 167         ret = irq_create_mapping(gpio->irq_domain, offset);
 168         if (ret > 0)
 169                 gpio->irq_mapped |= (1 << offset);
 170
 171         return ret;
 172 }
 173
 174 static irqreturn_t pcf857x_irq(int irq, void *data)
 175 {
 176         struct pcf857x  *gpio = data;
 177         unsigned long change, i, status, flags;
 178
 179         status = gpio->read(gpio->client);
 180
 181         spin_lock_irqsave(&gpio->slock, flags);
 182
 183         /*
 184          * call the interrupt handler iff gpio is used as
 185          * interrupt source, just to avoid bad irqs
 186          */
 187
 188         change = ((gpio->status ^ status) & gpio->irq_mapped);
 189         for_each_set_bit(i, &change, gpio->chip.ngpio)
 190                 generic_handle_irq(irq_find_mapping(gpio->irq_domain, i));
 191         gpio->status = status;
 192
 193         spin_unlock_irqrestore(&gpio->slock, flags);
 194
 195         return IRQ_HANDLED;
 196 }
 197
 198 static int pcf857x_irq_domain_map(struct irq_domain *domain, unsigned int virq,
 199                                  irq_hw_number_t hw)
 200 {
 201         struct pcf857x *gpio = domain->host_data;
 202
 203         irq_set_chip_and_handler(virq,
 204                                  &dummy_irq_chip,
 205                                  handle_level_irq);
 206         set_irq_flags(virq, IRQF_VALID);
 207         gpio->irq_mapped |= (1 << hw);
 208
 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 }
 222
 223 static int pcf857x_irq_domain_init(struct pcf857x *gpio,
 224                                    struct i2c_client *client)
 225 {
 226         int status;
 227
 228         gpio->irq_domain = irq_domain_add_linear(client->dev.of_node,
 229                                                  gpio->chip.ngpio,
 230                                                  &pcf857x_irq_domain_ops,
 231                                                  gpio);
 232         if (!gpio->irq_domain)
 233                 goto fail;
 234
 235         /* enable real irq */
 236         status = devm_request_threaded_irq(&client->dev, client->irq,
 237                                 NULL, pcf857x_irq, IRQF_ONESHOT |
 238                                 IRQF_TRIGGER_FALLING,
 239                                 dev_name(&client->dev), gpio);
 240
 241         if (status)
 242                 goto fail;
 243
 244         /* enable gpio_to_irq() */
 245         gpio->chip.to_irq       = pcf857x_to_irq;
 246
 247         return 0;
 248
 249 fail:
 250         pcf857x_irq_domain_cleanup(gpio);
 251         return -EINVAL;
 252 }
 253
 254 /*-------------------------------------------------------------------------*/
 255
 256 static int pcf857x_probe(struct i2c_client *client,
 257                          const struct i2c_device_id *id)
 258 {
 259         struct pcf857x_platform_data    *pdata;
 260         struct pcf857x                  *gpio;
 261         int                             status;
 262
 263         pdata = dev_get_platdata(&client->dev);
 264         if (!pdata) {
 265                 dev_dbg(&client->dev, "no platform data\n");
 266         }
 267
 268         /* Allocate, initialize, and register this gpio_chip. */
 269         gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
 270         if (!gpio)
 271                 return -ENOMEM;
 272
 273         mutex_init(&gpio->lock);
 274         spin_lock_init(&gpio->slock);
 275
 276         gpio->chip.base                 = pdata ? pdata->gpio_base : -1;
 277         gpio->chip.can_sleep            = 1;
 278         gpio->chip.dev                  = &client->dev;
 279         gpio->chip.owner                = THIS_MODULE;
 280         gpio->chip.get                  = pcf857x_get;
 281         gpio->chip.set                  = pcf857x_set;
 282         gpio->chip.direction_input      = pcf857x_input;
 283         gpio->chip.direction_output     = pcf857x_output;
 284         gpio->chip.ngpio                = id->driver_data;
 285
 286         /* enable gpio_to_irq() if platform has settings */
 287         if (client->irq) {
 288                 status = pcf857x_irq_domain_init(gpio, client);
 289                 if (status < 0) {
 290                         dev_err(&client->dev, "irq_domain init failed\n");
 291                         goto fail;
 292                 }
 293         }
 294
 295         /* NOTE:  the OnSemi jlc1562b is also largely compatible with
 296          * these parts, notably for output.  It has a low-resolution
 297          * DAC instead of pin change IRQs; and its inputs can be the
 298          * result of comparators.
 299          */
 300
 301         /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
 302          * 9670, 9672, 9764, and 9764a use quite a variety.
 303          *
 304          * NOTE: we don't distinguish here between *4 and *4a parts.
 305          */
 306         if (gpio->chip.ngpio == 8) {
 307                 gpio->write     = i2c_write_le8;
 308                 gpio->read      = i2c_read_le8;
 309
 310                 if (!i2c_check_functionality(client->adapter,
 311                                 I2C_FUNC_SMBUS_BYTE))
 312                         status = -EIO;
 313
 314                 /* fail if there's no chip present */
 315                 else
 316                         status = i2c_smbus_read_byte(client);
 317
 318         /* '75/'75c addresses are 0x20..0x27, just like the '74;
 319          * the '75c doesn't have a current source pulling high.
 320          * 9671, 9673, and 9765 use quite a variety of addresses.
 321          *
 322          * NOTE: we don't distinguish here between '75 and '75c parts.
 323          */
 324         } else if (gpio->chip.ngpio == 16) {
 325                 gpio->write     = i2c_write_le16;
 326                 gpio->read      = i2c_read_le16;
 327
 328                 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 329                         status = -EIO;
 330
 331                 /* fail if there's no chip present */
 332                 else
 333                         status = i2c_read_le16(client);
 334
 335         } else {
 336                 dev_dbg(&client->dev, "unsupported number of gpios\n");
 337                 status = -EINVAL;
 338         }
 339
 340         if (status < 0)
 341                 goto fail;
 342
 343         gpio->chip.label = client->name;
 344
 345         gpio->client = client;
 346         i2c_set_clientdata(client, gpio);
 347
 348         /* NOTE:  these chips have strange "quasi-bidirectional" I/O pins.
 349          * We can't actually know whether a pin is configured (a) as output
 350          * and driving the signal low, or (b) as input and reporting a low
 351          * value ... without knowing the last value written since the chip
 352          * came out of reset (if any).  We can't read the latched output.
 353          *
 354          * In short, the only reliable solution for setting up pin direction
 355          * is to do it explicitly.  The setup() method can do that, but it
 356          * may cause transient glitching since it can't know the last value
 357          * written (some pins may need to be driven low).
 358          *
 359          * Using pdata->n_latch avoids that trouble.  When left initialized
 360          * to zero, our software copy of the "latch" then matches the chip's
 361          * all-ones reset state.  Otherwise it flags pins to be driven low.
 362          */
 363         gpio->out = pdata ? ~pdata->n_latch : ~0;
 364         gpio->status = gpio->out;
 365
 366         status = gpiochip_add(&gpio->chip);
 367         if (status < 0)
 368                 goto fail;
 369
 370         /* Let platform code set up the GPIOs and their users.
 371          * Now is the first time anyone could use them.
 372          */
 373         if (pdata && pdata->setup) {
 374                 status = pdata->setup(client,
 375                                 gpio->chip.base, gpio->chip.ngpio,
 376                                 pdata->context);
 377                 if (status < 0)
 378                         dev_warn(&client->dev, "setup --> %d\n", status);
 379         }
 380
 381         dev_info(&client->dev, "probed\n");
 382
 383         return 0;
 384
 385 fail:
 386         dev_dbg(&client->dev, "probe error %d for '%s'\n",
 387                         status, client->name);
 388
 389         if (client->irq)
 390                 pcf857x_irq_domain_cleanup(gpio);
 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         if (client->irq)
 413                 pcf857x_irq_domain_cleanup(gpio);
 414
 415         status = gpiochip_remove(&gpio->chip);
 416         if (status)
 417                 dev_err(&client->dev, "%s --> %d\n", "remove", status);
 418         return status;
 419 }
 420
 421 static struct i2c_driver pcf857x_driver = {
 422         .driver = {
 423                 .name   = "pcf857x",
 424                 .owner  = THIS_MODULE,
 425         },
 426         .probe  = pcf857x_probe,
 427         .remove = pcf857x_remove,
 428         .id_table = pcf857x_id,
 429 };
 430
 431 static int __init pcf857x_init(void)
 432 {
 433         return i2c_add_driver(&pcf857x_driver);
 434 }
 435 /* register after i2c postcore initcall and before
 436  * subsys initcalls that may rely on these GPIOs
 437  */
 438 subsys_initcall(pcf857x_init);
 439
 440 static void __exit pcf857x_exit(void)
 441 {
 442         i2c_del_driver(&pcf857x_driver);
 443 }
 444 module_exit(pcf857x_exit);
 445
 446 MODULE_LICENSE("GPL");
 447 MODULE_AUTHOR("David Brownell");