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