drivers/gpio/gpio-pcf857x.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
   4  *
   5  * Copyright (C) 2007 David Brownell
   6  */
   7
   8 #include <linux/gpio/driver.h>
   9 #include <linux/i2c.h>
  10 #include <linux/platform_data/pcf857x.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/irq.h>
  13 #include <linux/irqdomain.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/of.h>
  17 #include <linux/of_device.h>
  18 #include <linux/slab.h>
  19 #include <linux/spinlock.h>
  20
  21
  22 static const struct i2c_device_id pcf857x_id[] = {
  23         { "pcf8574", 8 },
  24         { "pcf8574a", 8 },
  25         { "pca8574", 8 },
  26         { "pca9670", 8 },
  27         { "pca9672", 8 },
  28         { "pca9674", 8 },
  29         { "pcf8575", 16 },
  30         { "pca8575", 16 },
  31         { "pca9671", 16 },
  32         { "pca9673", 16 },
  33         { "pca9675", 16 },
  34         { "max7328", 8 },
  35         { "max7329", 8 },
  36         { }
  37 };
  38 MODULE_DEVICE_TABLE(i2c, pcf857x_id);
  39
  40 #ifdef CONFIG_OF
  41 static const struct of_device_id pcf857x_of_table[] = {
  42         { .compatible = "nxp,pcf8574" },
  43         { .compatible = "nxp,pcf8574a" },
  44         { .compatible = "nxp,pca8574" },
  45         { .compatible = "nxp,pca9670" },
  46         { .compatible = "nxp,pca9672" },
  47         { .compatible = "nxp,pca9674" },
  48         { .compatible = "nxp,pcf8575" },
  49         { .compatible = "nxp,pca8575" },
  50         { .compatible = "nxp,pca9671" },
  51         { .compatible = "nxp,pca9673" },
  52         { .compatible = "nxp,pca9675" },
  53         { .compatible = "maxim,max7328" },
  54         { .compatible = "maxim,max7329" },
  55         { }
  56 };
  57 MODULE_DEVICE_TABLE(of, pcf857x_of_table);
  58 #endif
  59
  60 /*
  61  * The pcf857x, pca857x, and pca967x chips only expose one read and one
  62  * write register.  Writing a "one" bit (to match the reset state) lets
  63  * that pin be used as an input; it's not an open-drain model, but acts
  64  * a bit like one.  This is described as "quasi-bidirectional"; read the
  65  * chip documentation for details.
  66  *
  67  * Many other I2C GPIO expander chips (like the pca953x models) have
  68  * more complex register models and more conventional circuitry using
  69  * push/pull drivers.  They often use the same 0x20..0x27 addresses as
  70  * pcf857x parts, making the "legacy" I2C driver model problematic.
  71  */
  72 struct pcf857x {
  73         struct gpio_chip        chip;
  74         struct irq_chip         irqchip;
  75         struct i2c_client       *client;
  76         struct mutex            lock;           /* protect 'out' */
  77         unsigned                out;            /* software latch */
  78         unsigned                status;         /* current status */
  79         unsigned                irq_enabled;    /* enabled irqs */
  80
  81         int (*write)(struct i2c_client *client, unsigned data);
  82         int (*read)(struct i2c_client *client);
  83 };
  84
  85 /*-------------------------------------------------------------------------*/
  86
  87 /* Talk to 8-bit I/O expander */
  88
  89 static int i2c_write_le8(struct i2c_client *client, unsigned data)
  90 {
  91         return i2c_smbus_write_byte(client, data);
  92 }
  93
  94 static int i2c_read_le8(struct i2c_client *client)
  95 {
  96         return (int)i2c_smbus_read_byte(client);
  97 }
  98
  99 /* Talk to 16-bit I/O expander */
 100
 101 static int i2c_write_le16(struct i2c_client *client, unsigned word)
 102 {
 103         u8 buf[2] = { word & 0xff, word >> 8, };
 104         int status;
 105
 106         status = i2c_master_send(client, buf, 2);
 107         return (status < 0) ? status : 0;
 108 }
 109
 110 static int i2c_read_le16(struct i2c_client *client)
 111 {
 112         u8 buf[2];
 113         int status;
 114
 115         status = i2c_master_recv(client, buf, 2);
 116         if (status < 0)
 117                 return status;
 118         return (buf[1] << 8) | buf[0];
 119 }
 120
 121 /*-------------------------------------------------------------------------*/
 122
 123 static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
 124 {
 125         struct pcf857x  *gpio = gpiochip_get_data(chip);
 126         int             status;
 127
 128         mutex_lock(&gpio->lock);
 129         gpio->out |= (1 << offset);
 130         status = gpio->write(gpio->client, gpio->out);
 131         mutex_unlock(&gpio->lock);
 132
 133         return status;
 134 }
 135
 136 static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
 137 {
 138         struct pcf857x  *gpio = gpiochip_get_data(chip);
 139         int             value;
 140
 141         value = gpio->read(gpio->client);
 142         return (value < 0) ? value : !!(value & (1 << offset));
 143 }
 144
 145 static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
 146 {
 147         struct pcf857x  *gpio = gpiochip_get_data(chip);
 148         unsigned        bit = 1 << offset;
 149         int             status;
 150
 151         mutex_lock(&gpio->lock);
 152         if (value)
 153                 gpio->out |= bit;
 154         else
 155                 gpio->out &= ~bit;
 156         status = gpio->write(gpio->client, gpio->out);
 157         mutex_unlock(&gpio->lock);
 158
 159         return status;
 160 }
 161
 162 static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
 163 {
 164         pcf857x_output(chip, offset, value);
 165 }
 166
 167 /*-------------------------------------------------------------------------*/
 168
 169 static irqreturn_t pcf857x_irq(int irq, void *data)
 170 {
 171         struct pcf857x  *gpio = data;
 172         unsigned long change, i, status;
 173
 174         status = gpio->read(gpio->client);
 175
 176         /*
 177          * call the interrupt handler iff gpio is used as
 178          * interrupt source, just to avoid bad irqs
 179          */
 180         mutex_lock(&gpio->lock);
 181         change = (gpio->status ^ status) & gpio->irq_enabled;
 182         gpio->status = status;
 183         mutex_unlock(&gpio->lock);
 184
 185         for_each_set_bit(i, &change, gpio->chip.ngpio)
 186                 handle_nested_irq(irq_find_mapping(gpio->chip.irq.domain, i));
 187
 188         return IRQ_HANDLED;
 189 }
 190
 191 /*
 192  * NOP functions
 193  */
 194 static void noop(struct irq_data *data) { }
 195
 196 static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
 197 {
 198         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 199
 200         return irq_set_irq_wake(gpio->client->irq, on);
 201 }
 202
 203 static void pcf857x_irq_enable(struct irq_data *data)
 204 {
 205         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 206
 207         gpio->irq_enabled |= (1 << data->hwirq);
 208 }
 209
 210 static void pcf857x_irq_disable(struct irq_data *data)
 211 {
 212         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 213
 214         gpio->irq_enabled &= ~(1 << data->hwirq);
 215 }
 216
 217 static void pcf857x_irq_bus_lock(struct irq_data *data)
 218 {
 219         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 220
 221         mutex_lock(&gpio->lock);
 222 }
 223
 224 static void pcf857x_irq_bus_sync_unlock(struct irq_data *data)
 225 {
 226         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 227
 228         mutex_unlock(&gpio->lock);
 229 }
 230
 231 /*-------------------------------------------------------------------------*/
 232
 233 static int pcf857x_probe(struct i2c_client *client,
 234                          const struct i2c_device_id *id)
 235 {
 236         struct pcf857x_platform_data    *pdata = dev_get_platdata(&client->dev);
 237         struct device_node              *np = client->dev.of_node;
 238         struct pcf857x                  *gpio;
 239         unsigned int                    n_latch = 0;
 240         int                             status;
 241
 242         if (IS_ENABLED(CONFIG_OF) && np)
 243                 of_property_read_u32(np, "lines-initial-states", &n_latch);
 244         else if (pdata)
 245                 n_latch = pdata->n_latch;
 246         else
 247                 dev_dbg(&client->dev, "no platform data\n");
 248
 249         /* Allocate, initialize, and register this gpio_chip. */
 250         gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
 251         if (!gpio)
 252                 return -ENOMEM;
 253
 254         mutex_init(&gpio->lock);
 255
 256         gpio->chip.base                 = pdata ? pdata->gpio_base : -1;
 257         gpio->chip.can_sleep            = true;
 258         gpio->chip.parent               = &client->dev;
 259         gpio->chip.owner                = THIS_MODULE;
 260         gpio->chip.get                  = pcf857x_get;
 261         gpio->chip.set                  = pcf857x_set;
 262         gpio->chip.direction_input      = pcf857x_input;
 263         gpio->chip.direction_output     = pcf857x_output;
 264         gpio->chip.ngpio                = id->driver_data;
 265
 266         /* NOTE:  the OnSemi jlc1562b is also largely compatible with
 267          * these parts, notably for output.  It has a low-resolution
 268          * DAC instead of pin change IRQs; and its inputs can be the
 269          * result of comparators.
 270          */
 271
 272         /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
 273          * 9670, 9672, 9764, and 9764a use quite a variety.
 274          *
 275          * NOTE: we don't distinguish here between *4 and *4a parts.
 276          */
 277         if (gpio->chip.ngpio == 8) {
 278                 gpio->write     = i2c_write_le8;
 279                 gpio->read      = i2c_read_le8;
 280
 281                 if (!i2c_check_functionality(client->adapter,
 282                                 I2C_FUNC_SMBUS_BYTE))
 283                         status = -EIO;
 284
 285                 /* fail if there's no chip present */
 286                 else
 287                         status = i2c_smbus_read_byte(client);
 288
 289         /* '75/'75c addresses are 0x20..0x27, just like the '74;
 290          * the '75c doesn't have a current source pulling high.
 291          * 9671, 9673, and 9765 use quite a variety of addresses.
 292          *
 293          * NOTE: we don't distinguish here between '75 and '75c parts.
 294          */
 295         } else if (gpio->chip.ngpio == 16) {
 296                 gpio->write     = i2c_write_le16;
 297                 gpio->read      = i2c_read_le16;
 298
 299                 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 300                         status = -EIO;
 301
 302                 /* fail if there's no chip present */
 303                 else
 304                         status = i2c_read_le16(client);
 305
 306         } else {
 307                 dev_dbg(&client->dev, "unsupported number of gpios\n");
 308                 status = -EINVAL;
 309         }
 310
 311         if (status < 0)
 312                 goto fail;
 313
 314         gpio->chip.label = client->name;
 315
 316         gpio->client = client;
 317         i2c_set_clientdata(client, gpio);
 318
 319         /* NOTE:  these chips have strange "quasi-bidirectional" I/O pins.
 320          * We can't actually know whether a pin is configured (a) as output
 321          * and driving the signal low, or (b) as input and reporting a low
 322          * value ... without knowing the last value written since the chip
 323          * came out of reset (if any).  We can't read the latched output.
 324          *
 325          * In short, the only reliable solution for setting up pin direction
 326          * is to do it explicitly.  The setup() method can do that, but it
 327          * may cause transient glitching since it can't know the last value
 328          * written (some pins may need to be driven low).
 329          *
 330          * Using n_latch avoids that trouble.  When left initialized to zero,
 331          * our software copy of the "latch" then matches the chip's all-ones
 332          * reset state.  Otherwise it flags pins to be driven low.
 333          */
 334         gpio->out = ~n_latch;
 335         gpio->status = gpio->read(gpio->client);
 336
 337         /* Enable irqchip if we have an interrupt */
 338         if (client->irq) {
 339                 struct gpio_irq_chip *girq;
 340
 341                 gpio->irqchip.name = "pcf857x";
 342                 gpio->irqchip.irq_enable = pcf857x_irq_enable;
 343                 gpio->irqchip.irq_disable = pcf857x_irq_disable;
 344                 gpio->irqchip.irq_ack = noop;
 345                 gpio->irqchip.irq_mask = noop;
 346                 gpio->irqchip.irq_unmask = noop;
 347                 gpio->irqchip.irq_set_wake = pcf857x_irq_set_wake;
 348                 gpio->irqchip.irq_bus_lock = pcf857x_irq_bus_lock;
 349                 gpio->irqchip.irq_bus_sync_unlock = pcf857x_irq_bus_sync_unlock;
 350
 351                 status = devm_request_threaded_irq(&client->dev, client->irq,
 352                                         NULL, pcf857x_irq, IRQF_ONESHOT |
 353                                         IRQF_TRIGGER_FALLING | IRQF_SHARED,
 354                                         dev_name(&client->dev), gpio);
 355                 if (status)
 356                         goto fail;
 357
 358                 girq = &gpio->chip.irq;
 359                 girq->chip = &gpio->irqchip;
 360                 /* This will let us handle the parent IRQ in the driver */
 361                 girq->parent_handler = NULL;
 362                 girq->num_parents = 0;
 363                 girq->parents = NULL;
 364                 girq->default_type = IRQ_TYPE_NONE;
 365                 girq->handler = handle_level_irq;
 366                 girq->threaded = true;
 367         }
 368
 369         status = devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio);
 370         if (status < 0)
 371                 goto fail;
 372
 373         /* Let platform code set up the GPIOs and their users.
 374          * Now is the first time anyone could use them.
 375          */
 376         if (pdata && pdata->setup) {
 377                 status = pdata->setup(client,
 378                                 gpio->chip.base, gpio->chip.ngpio,
 379                                 pdata->context);
 380                 if (status < 0)
 381                         dev_warn(&client->dev, "setup --> %d\n", status);
 382         }
 383
 384         dev_info(&client->dev, "probed\n");
 385
 386         return 0;
 387
 388 fail:
 389         dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
 390                 client->name);
 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         return status;
 413 }
 414
 415 static void pcf857x_shutdown(struct i2c_client *client)
 416 {
 417         struct pcf857x *gpio = i2c_get_clientdata(client);
 418
 419         /* Drive all the I/O lines high */
 420         gpio->write(gpio->client, BIT(gpio->chip.ngpio) - 1);
 421 }
 422
 423 static struct i2c_driver pcf857x_driver = {
 424         .driver = {
 425                 .name   = "pcf857x",
 426                 .of_match_table = of_match_ptr(pcf857x_of_table),
 427         },
 428         .probe  = pcf857x_probe,
 429         .remove = pcf857x_remove,
 430         .shutdown = pcf857x_shutdown,
 431         .id_table = pcf857x_id,
 432 };
 433
 434 static int __init pcf857x_init(void)
 435 {
 436         return i2c_add_driver(&pcf857x_driver);
 437 }
 438 /* register after i2c postcore initcall and before
 439  * subsys initcalls that may rely on these GPIOs
 440  */
 441 subsys_initcall(pcf857x_init);
 442
 443 static void __exit pcf857x_exit(void)
 444 {
 445         i2c_del_driver(&pcf857x_driver);
 446 }
 447 module_exit(pcf857x_exit);
 448
 449 MODULE_LICENSE("GPL");
 450 MODULE_AUTHOR("David Brownell");