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/interrupt.h>
  11 #include <linux/irq.h>
  12 #include <linux/irqdomain.h>
  13 #include <linux/kernel.h>
  14 #include <linux/mod_devicetable.h>
  15 #include <linux/module.h>
  16 #include <linux/property.h>
  17 #include <linux/slab.h>
  18 #include <linux/spinlock.h>
  19
  20 static const struct i2c_device_id pcf857x_id[] = {
  21         { "pcf8574", 8 },
  22         { "pcf8574a", 8 },
  23         { "pca8574", 8 },
  24         { "pca9670", 8 },
  25         { "pca9672", 8 },
  26         { "pca9674", 8 },
  27         { "pcf8575", 16 },
  28         { "pca8575", 16 },
  29         { "pca9671", 16 },
  30         { "pca9673", 16 },
  31         { "pca9675", 16 },
  32         { "max7328", 8 },
  33         { "max7329", 8 },
  34         { }
  35 };
  36 MODULE_DEVICE_TABLE(i2c, pcf857x_id);
  37
  38 static const struct of_device_id pcf857x_of_table[] = {
  39         { .compatible = "nxp,pcf8574", (void *)8 },
  40         { .compatible = "nxp,pcf8574a", (void *)8 },
  41         { .compatible = "nxp,pca8574", (void *)8 },
  42         { .compatible = "nxp,pca9670", (void *)8 },
  43         { .compatible = "nxp,pca9672", (void *)8 },
  44         { .compatible = "nxp,pca9674", (void *)8 },
  45         { .compatible = "nxp,pcf8575", (void *)16 },
  46         { .compatible = "nxp,pca8575", (void *)16 },
  47         { .compatible = "nxp,pca9671", (void *)16 },
  48         { .compatible = "nxp,pca9673", (void *)16 },
  49         { .compatible = "nxp,pca9675", (void *)16 },
  50         { .compatible = "maxim,max7328", (void *)8 },
  51         { .compatible = "maxim,max7329", (void *)8 },
  52         { }
  53 };
  54 MODULE_DEVICE_TABLE(of, pcf857x_of_table);
  55
  56 /*
  57  * The pcf857x, pca857x, and pca967x chips only expose one read and one
  58  * write register.  Writing a "one" bit (to match the reset state) lets
  59  * that pin be used as an input; it's not an open-drain model, but acts
  60  * a bit like one.  This is described as "quasi-bidirectional"; read the
  61  * chip documentation for details.
  62  *
  63  * Many other I2C GPIO expander chips (like the pca953x models) have
  64  * more complex register models and more conventional circuitry using
  65  * push/pull drivers.  They often use the same 0x20..0x27 addresses as
  66  * pcf857x parts, making the "legacy" I2C driver model problematic.
  67  */
  68 struct pcf857x {
  69         struct gpio_chip        chip;
  70         struct i2c_client       *client;
  71         struct mutex            lock;           /* protect 'out' */
  72         unsigned int            out;            /* software latch */
  73         unsigned int            status;         /* current status */
  74         unsigned int            irq_enabled;    /* enabled irqs */
  75
  76         int (*write)(struct i2c_client *client, unsigned int 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 int 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 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 int 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 int offset)
 119 {
 120         struct pcf857x *gpio = gpiochip_get_data(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 int offset)
 132 {
 133         struct pcf857x *gpio = gpiochip_get_data(chip);
 134         int value;
 135
 136         value = gpio->read(gpio->client);
 137         return (value < 0) ? value : !!(value & (1 << offset));
 138 }
 139
 140 static int pcf857x_get_multiple(struct gpio_chip *chip, unsigned long *mask,
 141                                 unsigned long *bits)
 142 {
 143         struct pcf857x *gpio = gpiochip_get_data(chip);
 144         int value = gpio->read(gpio->client);
 145
 146         if (value < 0)
 147                 return value;
 148
 149         *bits &= ~*mask;
 150         *bits |= value & *mask;
 151
 152         return 0;
 153 }
 154
 155 static int pcf857x_output(struct gpio_chip *chip, unsigned int offset, int value)
 156 {
 157         struct pcf857x *gpio = gpiochip_get_data(chip);
 158         unsigned int bit = 1 << offset;
 159         int status;
 160
 161         mutex_lock(&gpio->lock);
 162         if (value)
 163                 gpio->out |= bit;
 164         else
 165                 gpio->out &= ~bit;
 166         status = gpio->write(gpio->client, gpio->out);
 167         mutex_unlock(&gpio->lock);
 168
 169         return status;
 170 }
 171
 172 static void pcf857x_set(struct gpio_chip *chip, unsigned int offset, int value)
 173 {
 174         pcf857x_output(chip, offset, value);
 175 }
 176
 177 static void pcf857x_set_multiple(struct gpio_chip *chip, unsigned long *mask,
 178                                  unsigned long *bits)
 179 {
 180         struct pcf857x *gpio = gpiochip_get_data(chip);
 181
 182         mutex_lock(&gpio->lock);
 183         gpio->out &= ~*mask;
 184         gpio->out |= *bits & *mask;
 185         gpio->write(gpio->client, gpio->out);
 186         mutex_unlock(&gpio->lock);
 187 }
 188
 189 /*-------------------------------------------------------------------------*/
 190
 191 static irqreturn_t pcf857x_irq(int irq, void *data)
 192 {
 193         struct pcf857x *gpio = data;
 194         unsigned long change, i, status;
 195
 196         status = gpio->read(gpio->client);
 197
 198         /*
 199          * call the interrupt handler iff gpio is used as
 200          * interrupt source, just to avoid bad irqs
 201          */
 202         mutex_lock(&gpio->lock);
 203         change = (gpio->status ^ status) & gpio->irq_enabled;
 204         gpio->status = status;
 205         mutex_unlock(&gpio->lock);
 206
 207         for_each_set_bit(i, &change, gpio->chip.ngpio)
 208                 handle_nested_irq(irq_find_mapping(gpio->chip.irq.domain, i));
 209
 210         return IRQ_HANDLED;
 211 }
 212
 213 /*
 214  * NOP functions
 215  */
 216 static void noop(struct irq_data *data) { }
 217
 218 static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
 219 {
 220         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 221
 222         return irq_set_irq_wake(gpio->client->irq, on);
 223 }
 224
 225 static void pcf857x_irq_enable(struct irq_data *data)
 226 {
 227         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 228         irq_hw_number_t hwirq = irqd_to_hwirq(data);
 229
 230         gpiochip_enable_irq(&gpio->chip, hwirq);
 231         gpio->irq_enabled |= (1 << hwirq);
 232 }
 233
 234 static void pcf857x_irq_disable(struct irq_data *data)
 235 {
 236         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 237         irq_hw_number_t hwirq = irqd_to_hwirq(data);
 238
 239         gpio->irq_enabled &= ~(1 << hwirq);
 240         gpiochip_disable_irq(&gpio->chip, hwirq);
 241 }
 242
 243 static void pcf857x_irq_bus_lock(struct irq_data *data)
 244 {
 245         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 246
 247         mutex_lock(&gpio->lock);
 248 }
 249
 250 static void pcf857x_irq_bus_sync_unlock(struct irq_data *data)
 251 {
 252         struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 253
 254         mutex_unlock(&gpio->lock);
 255 }
 256
 257 static const struct irq_chip pcf857x_irq_chip = {
 258         .name                   = "pcf857x",
 259         .irq_enable             = pcf857x_irq_enable,
 260         .irq_disable            = pcf857x_irq_disable,
 261         .irq_ack                = noop,
 262         .irq_mask               = noop,
 263         .irq_unmask             = noop,
 264         .irq_set_wake           = pcf857x_irq_set_wake,
 265         .irq_bus_lock           = pcf857x_irq_bus_lock,
 266         .irq_bus_sync_unlock    = pcf857x_irq_bus_sync_unlock,
 267         .flags                  = IRQCHIP_IMMUTABLE,
 268         GPIOCHIP_IRQ_RESOURCE_HELPERS,
 269 };
 270
 271 /*-------------------------------------------------------------------------*/
 272
 273 static int pcf857x_probe(struct i2c_client *client)
 274 {
 275         struct pcf857x *gpio;
 276         unsigned int n_latch = 0;
 277         int status;
 278
 279         device_property_read_u32(&client->dev, "lines-initial-states", &n_latch);
 280
 281         /* Allocate, initialize, and register this gpio_chip. */
 282         gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
 283         if (!gpio)
 284                 return -ENOMEM;
 285
 286         mutex_init(&gpio->lock);
 287
 288         gpio->chip.base                 = -1;
 289         gpio->chip.can_sleep            = true;
 290         gpio->chip.parent               = &client->dev;
 291         gpio->chip.owner                = THIS_MODULE;
 292         gpio->chip.get                  = pcf857x_get;
 293         gpio->chip.get_multiple         = pcf857x_get_multiple;
 294         gpio->chip.set                  = pcf857x_set;
 295         gpio->chip.set_multiple         = pcf857x_set_multiple;
 296         gpio->chip.direction_input      = pcf857x_input;
 297         gpio->chip.direction_output     = pcf857x_output;
 298         gpio->chip.ngpio                = (uintptr_t)i2c_get_match_data(client);
 299
 300         /* NOTE:  the OnSemi jlc1562b is also largely compatible with
 301          * these parts, notably for output.  It has a low-resolution
 302          * DAC instead of pin change IRQs; and its inputs can be the
 303          * result of comparators.
 304          */
 305
 306         /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
 307          * 9670, 9672, 9764, and 9764a use quite a variety.
 308          *
 309          * NOTE: we don't distinguish here between *4 and *4a parts.
 310          */
 311         if (gpio->chip.ngpio == 8) {
 312                 gpio->write     = i2c_write_le8;
 313                 gpio->read      = i2c_read_le8;
 314
 315                 if (!i2c_check_functionality(client->adapter,
 316                                 I2C_FUNC_SMBUS_BYTE))
 317                         status = -EIO;
 318
 319                 /* fail if there's no chip present */
 320                 else
 321                         status = i2c_smbus_read_byte(client);
 322
 323         /* '75/'75c addresses are 0x20..0x27, just like the '74;
 324          * the '75c doesn't have a current source pulling high.
 325          * 9671, 9673, and 9765 use quite a variety of addresses.
 326          *
 327          * NOTE: we don't distinguish here between '75 and '75c parts.
 328          */
 329         } else if (gpio->chip.ngpio == 16) {
 330                 gpio->write     = i2c_write_le16;
 331                 gpio->read      = i2c_read_le16;
 332
 333                 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 334                         status = -EIO;
 335
 336                 /* fail if there's no chip present */
 337                 else
 338                         status = i2c_read_le16(client);
 339
 340         } else {
 341                 dev_dbg(&client->dev, "unsupported number of gpios\n");
 342                 status = -EINVAL;
 343         }
 344
 345         if (status < 0)
 346                 goto fail;
 347
 348         gpio->chip.label = client->name;
 349
 350         gpio->client = client;
 351         i2c_set_clientdata(client, gpio);
 352
 353         /* NOTE:  these chips have strange "quasi-bidirectional" I/O pins.
 354          * We can't actually know whether a pin is configured (a) as output
 355          * and driving the signal low, or (b) as input and reporting a low
 356          * value ... without knowing the last value written since the chip
 357          * came out of reset (if any).  We can't read the latched output.
 358          *
 359          * In short, the only reliable solution for setting up pin direction
 360          * is to do it explicitly.  The setup() method can do that, but it
 361          * may cause transient glitching since it can't know the last value
 362          * written (some pins may need to be driven low).
 363          *
 364          * Using n_latch avoids that trouble.  When left initialized to zero,
 365          * our software copy of the "latch" then matches the chip's all-ones
 366          * reset state.  Otherwise it flags pins to be driven low.
 367          */
 368         gpio->out = ~n_latch;
 369         gpio->status = gpio->read(gpio->client);
 370
 371         /* Enable irqchip if we have an interrupt */
 372         if (client->irq) {
 373                 struct gpio_irq_chip *girq;
 374
 375                 status = devm_request_threaded_irq(&client->dev, client->irq,
 376                                         NULL, pcf857x_irq, IRQF_ONESHOT |
 377                                         IRQF_TRIGGER_FALLING | IRQF_SHARED,
 378                                         dev_name(&client->dev), gpio);
 379                 if (status)
 380                         goto fail;
 381
 382                 girq = &gpio->chip.irq;
 383                 gpio_irq_chip_set_chip(girq, &pcf857x_irq_chip);
 384                 /* This will let us handle the parent IRQ in the driver */
 385                 girq->parent_handler = NULL;
 386                 girq->num_parents = 0;
 387                 girq->parents = NULL;
 388                 girq->default_type = IRQ_TYPE_NONE;
 389                 girq->handler = handle_level_irq;
 390                 girq->threaded = true;
 391         }
 392
 393         status = devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio);
 394         if (status < 0)
 395                 goto fail;
 396
 397         dev_info(&client->dev, "probed\n");
 398
 399         return 0;
 400
 401 fail:
 402         dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
 403                 client->name);
 404
 405         return status;
 406 }
 407
 408 static void pcf857x_shutdown(struct i2c_client *client)
 409 {
 410         struct pcf857x *gpio = i2c_get_clientdata(client);
 411
 412         /* Drive all the I/O lines high */
 413         gpio->write(gpio->client, BIT(gpio->chip.ngpio) - 1);
 414 }
 415
 416 static struct i2c_driver pcf857x_driver = {
 417         .driver = {
 418                 .name   = "pcf857x",
 419                 .of_match_table = pcf857x_of_table,
 420         },
 421         .probe = pcf857x_probe,
 422         .shutdown = pcf857x_shutdown,
 423         .id_table = pcf857x_id,
 424 };
 425
 426 static int __init pcf857x_init(void)
 427 {
 428         return i2c_add_driver(&pcf857x_driver);
 429 }
 430 /* register after i2c postcore initcall and before
 431  * subsys initcalls that may rely on these GPIOs
 432  */
 433 subsys_initcall(pcf857x_init);
 434
 435 static void __exit pcf857x_exit(void)
 436 {
 437         i2c_del_driver(&pcf857x_driver);
 438 }
 439 module_exit(pcf857x_exit);
 440
 441 MODULE_DESCRIPTION("Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders");
 442 MODULE_LICENSE("GPL");
 443 MODULE_AUTHOR("David Brownell");