| 1 | /* |
| 2 | * pcf857x - 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/kernel.h> |
| 22 | #include <linux/slab.h> |
| 23 | #include <linux/i2c.h> |
| 24 | #include <linux/i2c/pcf857x.h> |
| 25 | |
| 26 | #include <asm/gpio.h> |
| 27 | |
| 28 | |
| 29 | static const struct i2c_device_id pcf857x_id[] = { |
| 30 | { "pcf8574", 8 }, |
| 31 | { "pca8574", 8 }, |
| 32 | { "pca9670", 8 }, |
| 33 | { "pca9672", 8 }, |
| 34 | { "pca9674", 8 }, |
| 35 | { "pcf8575", 16 }, |
| 36 | { "pca8575", 16 }, |
| 37 | { "pca9671", 16 }, |
| 38 | { "pca9673", 16 }, |
| 39 | { "pca9675", 16 }, |
| 40 | { "max7328", 8 }, |
| 41 | { "max7329", 8 }, |
| 42 | { } |
| 43 | }; |
| 44 | MODULE_DEVICE_TABLE(i2c, pcf857x_id); |
| 45 | |
| 46 | /* |
| 47 | * The pcf857x, pca857x, and pca967x chips only expose one read and one |
| 48 | * write register. Writing a "one" bit (to match the reset state) lets |
| 49 | * that pin be used as an input; it's not an open-drain model, but acts |
| 50 | * a bit like one. This is described as "quasi-bidirectional"; read the |
| 51 | * chip documentation for details. |
| 52 | * |
| 53 | * Many other I2C GPIO expander chips (like the pca953x models) have |
| 54 | * more complex register models and more conventional circuitry using |
| 55 | * push/pull drivers. They often use the same 0x20..0x27 addresses as |
| 56 | * pcf857x parts, making the "legacy" I2C driver model problematic. |
| 57 | */ |
| 58 | struct pcf857x { |
| 59 | struct gpio_chip chip; |
| 60 | struct i2c_client *client; |
| 61 | struct mutex lock; /* protect 'out' */ |
| 62 | unsigned out; /* software latch */ |
| 63 | }; |
| 64 | |
| 65 | /*-------------------------------------------------------------------------*/ |
| 66 | |
| 67 | /* Talk to 8-bit I/O expander */ |
| 68 | |
| 69 | static int pcf857x_input8(struct gpio_chip *chip, unsigned offset) |
| 70 | { |
| 71 | struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); |
| 72 | int status; |
| 73 | |
| 74 | mutex_lock(&gpio->lock); |
| 75 | gpio->out |= (1 << offset); |
| 76 | status = i2c_smbus_write_byte(gpio->client, gpio->out); |
| 77 | mutex_unlock(&gpio->lock); |
| 78 | |
| 79 | return status; |
| 80 | } |
| 81 | |
| 82 | static int pcf857x_get8(struct gpio_chip *chip, unsigned offset) |
| 83 | { |
| 84 | struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); |
| 85 | s32 value; |
| 86 | |
| 87 | value = i2c_smbus_read_byte(gpio->client); |
| 88 | return (value < 0) ? 0 : (value & (1 << offset)); |
| 89 | } |
| 90 | |
| 91 | static int pcf857x_output8(struct gpio_chip *chip, unsigned offset, int value) |
| 92 | { |
| 93 | struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); |
| 94 | unsigned bit = 1 << offset; |
| 95 | int status; |
| 96 | |
| 97 | mutex_lock(&gpio->lock); |
| 98 | if (value) |
| 99 | gpio->out |= bit; |
| 100 | else |
| 101 | gpio->out &= ~bit; |
| 102 | status = i2c_smbus_write_byte(gpio->client, gpio->out); |
| 103 | mutex_unlock(&gpio->lock); |
| 104 | |
| 105 | return status; |
| 106 | } |
| 107 | |
| 108 | static void pcf857x_set8(struct gpio_chip *chip, unsigned offset, int value) |
| 109 | { |
| 110 | pcf857x_output8(chip, offset, value); |
| 111 | } |
| 112 | |
| 113 | /*-------------------------------------------------------------------------*/ |
| 114 | |
| 115 | /* Talk to 16-bit I/O expander */ |
| 116 | |
| 117 | static int i2c_write_le16(struct i2c_client *client, u16 word) |
| 118 | { |
| 119 | u8 buf[2] = { word & 0xff, word >> 8, }; |
| 120 | int status; |
| 121 | |
| 122 | status = i2c_master_send(client, buf, 2); |
| 123 | return (status < 0) ? status : 0; |
| 124 | } |
| 125 | |
| 126 | static int i2c_read_le16(struct i2c_client *client) |
| 127 | { |
| 128 | u8 buf[2]; |
| 129 | int status; |
| 130 | |
| 131 | status = i2c_master_recv(client, buf, 2); |
| 132 | if (status < 0) |
| 133 | return status; |
| 134 | return (buf[1] << 8) | buf[0]; |
| 135 | } |
| 136 | |
| 137 | static int pcf857x_input16(struct gpio_chip *chip, unsigned offset) |
| 138 | { |
| 139 | struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); |
| 140 | int status; |
| 141 | |
| 142 | mutex_lock(&gpio->lock); |
| 143 | gpio->out |= (1 << offset); |
| 144 | status = i2c_write_le16(gpio->client, gpio->out); |
| 145 | mutex_unlock(&gpio->lock); |
| 146 | |
| 147 | return status; |
| 148 | } |
| 149 | |
| 150 | static int pcf857x_get16(struct gpio_chip *chip, unsigned offset) |
| 151 | { |
| 152 | struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); |
| 153 | int value; |
| 154 | |
| 155 | value = i2c_read_le16(gpio->client); |
| 156 | return (value < 0) ? 0 : (value & (1 << offset)); |
| 157 | } |
| 158 | |
| 159 | static int pcf857x_output16(struct gpio_chip *chip, unsigned offset, int value) |
| 160 | { |
| 161 | struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); |
| 162 | unsigned bit = 1 << offset; |
| 163 | int status; |
| 164 | |
| 165 | mutex_lock(&gpio->lock); |
| 166 | if (value) |
| 167 | gpio->out |= bit; |
| 168 | else |
| 169 | gpio->out &= ~bit; |
| 170 | status = i2c_write_le16(gpio->client, gpio->out); |
| 171 | mutex_unlock(&gpio->lock); |
| 172 | |
| 173 | return status; |
| 174 | } |
| 175 | |
| 176 | static void pcf857x_set16(struct gpio_chip *chip, unsigned offset, int value) |
| 177 | { |
| 178 | pcf857x_output16(chip, offset, value); |
| 179 | } |
| 180 | |
| 181 | /*-------------------------------------------------------------------------*/ |
| 182 | |
| 183 | static int pcf857x_probe(struct i2c_client *client, |
| 184 | const struct i2c_device_id *id) |
| 185 | { |
| 186 | struct pcf857x_platform_data *pdata; |
| 187 | struct pcf857x *gpio; |
| 188 | int status; |
| 189 | |
| 190 | pdata = client->dev.platform_data; |
| 191 | if (!pdata) |
| 192 | return -ENODEV; |
| 193 | |
| 194 | /* Allocate, initialize, and register this gpio_chip. */ |
| 195 | gpio = kzalloc(sizeof *gpio, GFP_KERNEL); |
| 196 | if (!gpio) |
| 197 | return -ENOMEM; |
| 198 | |
| 199 | mutex_init(&gpio->lock); |
| 200 | |
| 201 | gpio->chip.base = pdata->gpio_base; |
| 202 | gpio->chip.can_sleep = 1; |
| 203 | gpio->chip.dev = &client->dev; |
| 204 | gpio->chip.owner = THIS_MODULE; |
| 205 | |
| 206 | /* NOTE: the OnSemi jlc1562b is also largely compatible with |
| 207 | * these parts, notably for output. It has a low-resolution |
| 208 | * DAC instead of pin change IRQs; and its inputs can be the |
| 209 | * result of comparators. |
| 210 | */ |
| 211 | |
| 212 | /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f; |
| 213 | * 9670, 9672, 9764, and 9764a use quite a variety. |
| 214 | * |
| 215 | * NOTE: we don't distinguish here between *4 and *4a parts. |
| 216 | */ |
| 217 | gpio->chip.ngpio = id->driver_data; |
| 218 | if (gpio->chip.ngpio == 8) { |
| 219 | gpio->chip.direction_input = pcf857x_input8; |
| 220 | gpio->chip.get = pcf857x_get8; |
| 221 | gpio->chip.direction_output = pcf857x_output8; |
| 222 | gpio->chip.set = pcf857x_set8; |
| 223 | |
| 224 | if (!i2c_check_functionality(client->adapter, |
| 225 | I2C_FUNC_SMBUS_BYTE)) |
| 226 | status = -EIO; |
| 227 | |
| 228 | /* fail if there's no chip present */ |
| 229 | else |
| 230 | status = i2c_smbus_read_byte(client); |
| 231 | |
| 232 | /* '75/'75c addresses are 0x20..0x27, just like the '74; |
| 233 | * the '75c doesn't have a current source pulling high. |
| 234 | * 9671, 9673, and 9765 use quite a variety of addresses. |
| 235 | * |
| 236 | * NOTE: we don't distinguish here between '75 and '75c parts. |
| 237 | */ |
| 238 | } else if (gpio->chip.ngpio == 16) { |
| 239 | gpio->chip.direction_input = pcf857x_input16; |
| 240 | gpio->chip.get = pcf857x_get16; |
| 241 | gpio->chip.direction_output = pcf857x_output16; |
| 242 | gpio->chip.set = pcf857x_set16; |
| 243 | |
| 244 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) |
| 245 | status = -EIO; |
| 246 | |
| 247 | /* fail if there's no chip present */ |
| 248 | else |
| 249 | status = i2c_read_le16(client); |
| 250 | |
| 251 | } else |
| 252 | status = -ENODEV; |
| 253 | |
| 254 | if (status < 0) |
| 255 | goto fail; |
| 256 | |
| 257 | gpio->chip.label = client->name; |
| 258 | |
| 259 | gpio->client = client; |
| 260 | i2c_set_clientdata(client, gpio); |
| 261 | |
| 262 | /* NOTE: these chips have strange "quasi-bidirectional" I/O pins. |
| 263 | * We can't actually know whether a pin is configured (a) as output |
| 264 | * and driving the signal low, or (b) as input and reporting a low |
| 265 | * value ... without knowing the last value written since the chip |
| 266 | * came out of reset (if any). We can't read the latched output. |
| 267 | * |
| 268 | * In short, the only reliable solution for setting up pin direction |
| 269 | * is to do it explicitly. The setup() method can do that, but it |
| 270 | * may cause transient glitching since it can't know the last value |
| 271 | * written (some pins may need to be driven low). |
| 272 | * |
| 273 | * Using pdata->n_latch avoids that trouble. When left initialized |
| 274 | * to zero, our software copy of the "latch" then matches the chip's |
| 275 | * all-ones reset state. Otherwise it flags pins to be driven low. |
| 276 | */ |
| 277 | gpio->out = ~pdata->n_latch; |
| 278 | |
| 279 | status = gpiochip_add(&gpio->chip); |
| 280 | if (status < 0) |
| 281 | goto fail; |
| 282 | |
| 283 | /* NOTE: these chips can issue "some pin-changed" IRQs, which we |
| 284 | * don't yet even try to use. Among other issues, the relevant |
| 285 | * genirq state isn't available to modular drivers; and most irq |
| 286 | * methods can't be called from sleeping contexts. |
| 287 | */ |
| 288 | |
| 289 | dev_info(&client->dev, "gpios %d..%d on a %s%s\n", |
| 290 | gpio->chip.base, |
| 291 | gpio->chip.base + gpio->chip.ngpio - 1, |
| 292 | client->name, |
| 293 | client->irq ? " (irq ignored)" : ""); |
| 294 | |
| 295 | /* Let platform code set up the GPIOs and their users. |
| 296 | * Now is the first time anyone could use them. |
| 297 | */ |
| 298 | if (pdata->setup) { |
| 299 | status = pdata->setup(client, |
| 300 | gpio->chip.base, gpio->chip.ngpio, |
| 301 | pdata->context); |
| 302 | if (status < 0) |
| 303 | dev_warn(&client->dev, "setup --> %d\n", status); |
| 304 | } |
| 305 | |
| 306 | return 0; |
| 307 | |
| 308 | fail: |
| 309 | dev_dbg(&client->dev, "probe error %d for '%s'\n", |
| 310 | status, client->name); |
| 311 | kfree(gpio); |
| 312 | return status; |
| 313 | } |
| 314 | |
| 315 | static int pcf857x_remove(struct i2c_client *client) |
| 316 | { |
| 317 | struct pcf857x_platform_data *pdata = client->dev.platform_data; |
| 318 | struct pcf857x *gpio = i2c_get_clientdata(client); |
| 319 | int status = 0; |
| 320 | |
| 321 | if (pdata->teardown) { |
| 322 | status = pdata->teardown(client, |
| 323 | gpio->chip.base, gpio->chip.ngpio, |
| 324 | pdata->context); |
| 325 | if (status < 0) { |
| 326 | dev_err(&client->dev, "%s --> %d\n", |
| 327 | "teardown", status); |
| 328 | return status; |
| 329 | } |
| 330 | } |
| 331 | |
| 332 | status = gpiochip_remove(&gpio->chip); |
| 333 | if (status == 0) |
| 334 | kfree(gpio); |
| 335 | else |
| 336 | dev_err(&client->dev, "%s --> %d\n", "remove", status); |
| 337 | return status; |
| 338 | } |
| 339 | |
| 340 | static struct i2c_driver pcf857x_driver = { |
| 341 | .driver = { |
| 342 | .name = "pcf857x", |
| 343 | .owner = THIS_MODULE, |
| 344 | }, |
| 345 | .probe = pcf857x_probe, |
| 346 | .remove = pcf857x_remove, |
| 347 | .id_table = pcf857x_id, |
| 348 | }; |
| 349 | |
| 350 | static int __init pcf857x_init(void) |
| 351 | { |
| 352 | return i2c_add_driver(&pcf857x_driver); |
| 353 | } |
| 354 | module_init(pcf857x_init); |
| 355 | |
| 356 | static void __exit pcf857x_exit(void) |
| 357 | { |
| 358 | i2c_del_driver(&pcf857x_driver); |
| 359 | } |
| 360 | module_exit(pcf857x_exit); |
| 361 | |
| 362 | MODULE_LICENSE("GPL"); |
| 363 | MODULE_AUTHOR("David Brownell"); |