1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ti_fpc202.c - FPC202 Dual Port Controller driver 4 * 5 * Copyright (C) 2024 Bootlin 6 * 7 */ 8 9 #include <linux/cleanup.h> 10 #include <linux/err.h> 11 #include <linux/i2c.h> 12 #include <linux/i2c-atr.h> 13 #include <linux/gpio/consumer.h> 14 #include <linux/gpio/driver.h> 15 #include <linux/module.h> 16 17 #define FPC202_NUM_PORTS 2 18 #define FPC202_ALIASES_PER_PORT 2 19 20 /* 21 * GPIO: port mapping 22 * 23 * 0: P0_S0_IN_A 24 * 1: P0_S1_IN_A 25 * 2: P1_S0_IN_A 26 * 3: P1_S1_IN_A 27 * 4: P0_S0_IN_B 28 * ... 29 * 8: P0_S0_IN_C 30 * ... 31 * 12: P0_S0_OUT_A 32 * ... 33 * 16: P0_S0_OUT_B 34 * ... 35 * 19: P1_S1_OUT_B 36 * 37 */ 38 39 #define FPC202_GPIO_COUNT 20 40 #define FPC202_GPIO_P0_S0_IN_B 4 41 #define FPC202_GPIO_P0_S0_OUT_A 12 42 43 #define FPC202_REG_IN_A_INT 0x6 44 #define FPC202_REG_IN_C_IN_B 0x7 45 #define FPC202_REG_OUT_A_OUT_B 0x8 46 47 #define FPC202_REG_OUT_A_OUT_B_VAL 0xa 48 49 #define FPC202_REG_MOD_DEV(port, dev) (0xb4 + ((port) * 4) + (dev)) 50 #define FPC202_REG_AUX_DEV(port, dev) (0xb6 + ((port) * 4) + (dev)) 51 52 /* 53 * The FPC202 doesn't support turning off address translation on a single port. 54 * So just set an invalid I2C address as the translation target when no client 55 * address is attached. 56 */ 57 #define FPC202_REG_DEV_INVALID 0 58 59 /* Even aliases are assigned to device 0 and odd aliases to device 1 */ 60 #define fpc202_dev_num_from_alias(alias) ((alias) % 2) 61 62 struct fpc202_priv { 63 struct i2c_client *client; 64 struct i2c_atr *atr; 65 struct gpio_desc *en_gpio; 66 struct gpio_chip gpio; 67 68 /* Lock REG_MOD/AUX_DEV and addr_caches during attach/detach */ 69 struct mutex reg_dev_lock; 70 71 /* Cached device addresses for both ports and their devices */ 72 u8 addr_caches[2][2]; 73 74 /* Keep track of which ports were probed */ 75 DECLARE_BITMAP(probed_ports, FPC202_NUM_PORTS); 76 }; 77 78 static void fpc202_fill_alias_table(struct i2c_client *client, u16 *aliases, int port_id) 79 { 80 u16 first_alias; 81 int i; 82 83 /* 84 * There is a predefined list of aliases for each FPC202 I2C 85 * self-address. This allows daisy-chained FPC202 units to 86 * automatically take on different sets of aliases. 87 * Each port of an FPC202 unit is assigned two aliases from this list. 88 */ 89 first_alias = 0x10 + 4 * port_id + 8 * ((u16)client->addr - 2); 90 91 for (i = 0; i < FPC202_ALIASES_PER_PORT; i++) 92 aliases[i] = first_alias + i; 93 } 94 95 static int fpc202_gpio_get_dir(int offset) 96 { 97 return offset < FPC202_GPIO_P0_S0_OUT_A ? GPIO_LINE_DIRECTION_IN : GPIO_LINE_DIRECTION_OUT; 98 } 99 100 static int fpc202_read(struct fpc202_priv *priv, u8 reg) 101 { 102 int val; 103 104 val = i2c_smbus_read_byte_data(priv->client, reg); 105 return val; 106 } 107 108 static int fpc202_write(struct fpc202_priv *priv, u8 reg, u8 value) 109 { 110 return i2c_smbus_write_byte_data(priv->client, reg, value); 111 } 112 113 static void fpc202_set_enable(struct fpc202_priv *priv, int enable) 114 { 115 if (!priv->en_gpio) 116 return; 117 118 gpiod_set_value(priv->en_gpio, enable); 119 } 120 121 static int fpc202_gpio_set(struct gpio_chip *chip, unsigned int offset, 122 int value) 123 { 124 struct fpc202_priv *priv = gpiochip_get_data(chip); 125 int ret; 126 u8 val; 127 128 ret = fpc202_read(priv, FPC202_REG_OUT_A_OUT_B_VAL); 129 if (ret < 0) { 130 dev_err(&priv->client->dev, "Failed to set GPIO %d value! err %d\n", offset, ret); 131 return ret; 132 } 133 134 val = (u8)ret; 135 136 if (value) 137 val |= BIT(offset - FPC202_GPIO_P0_S0_OUT_A); 138 else 139 val &= ~BIT(offset - FPC202_GPIO_P0_S0_OUT_A); 140 141 return fpc202_write(priv, FPC202_REG_OUT_A_OUT_B_VAL, val); 142 } 143 144 static int fpc202_gpio_get(struct gpio_chip *chip, unsigned int offset) 145 { 146 struct fpc202_priv *priv = gpiochip_get_data(chip); 147 u8 reg, bit; 148 int ret; 149 150 if (offset < FPC202_GPIO_P0_S0_IN_B) { 151 reg = FPC202_REG_IN_A_INT; 152 bit = BIT(4 + offset); 153 } else if (offset < FPC202_GPIO_P0_S0_OUT_A) { 154 reg = FPC202_REG_IN_C_IN_B; 155 bit = BIT(offset - FPC202_GPIO_P0_S0_IN_B); 156 } else { 157 reg = FPC202_REG_OUT_A_OUT_B_VAL; 158 bit = BIT(offset - FPC202_GPIO_P0_S0_OUT_A); 159 } 160 161 ret = fpc202_read(priv, reg); 162 if (ret < 0) 163 return ret; 164 165 return !!(((u8)ret) & bit); 166 } 167 168 static int fpc202_gpio_direction_input(struct gpio_chip *chip, unsigned int offset) 169 { 170 if (fpc202_gpio_get_dir(offset) == GPIO_LINE_DIRECTION_OUT) 171 return -EINVAL; 172 173 return 0; 174 } 175 176 static int fpc202_gpio_direction_output(struct gpio_chip *chip, unsigned int offset, 177 int value) 178 { 179 struct fpc202_priv *priv = gpiochip_get_data(chip); 180 int ret; 181 u8 val; 182 183 if (fpc202_gpio_get_dir(offset) == GPIO_LINE_DIRECTION_IN) 184 return -EINVAL; 185 186 fpc202_gpio_set(chip, offset, value); 187 188 ret = fpc202_read(priv, FPC202_REG_OUT_A_OUT_B); 189 if (ret < 0) 190 return ret; 191 192 val = (u8)ret | BIT(offset - FPC202_GPIO_P0_S0_OUT_A); 193 194 return fpc202_write(priv, FPC202_REG_OUT_A_OUT_B, val); 195 } 196 197 /* 198 * Set the translation table entry associated with a port and device number. 199 * 200 * Each downstream port of the FPC202 has two fixed aliases corresponding to 201 * device numbers 0 and 1. If one of these aliases is found in an incoming I2C 202 * transfer, it will be translated to the address given by the corresponding 203 * translation table entry. 204 */ 205 static int fpc202_write_dev_addr(struct fpc202_priv *priv, u32 port_id, int dev_num, u16 addr) 206 { 207 int ret, reg_mod, reg_aux; 208 u8 val; 209 210 guard(mutex)(&priv->reg_dev_lock); 211 212 reg_mod = FPC202_REG_MOD_DEV(port_id, dev_num); 213 reg_aux = FPC202_REG_AUX_DEV(port_id, dev_num); 214 val = addr & 0x7f; 215 216 ret = fpc202_write(priv, reg_mod, val); 217 if (ret) 218 return ret; 219 220 /* 221 * The FPC202 datasheet is unclear about the role of the AUX registers. 222 * Empirically, writing to them as well seems to be necessary for 223 * address translation to function properly. 224 */ 225 ret = fpc202_write(priv, reg_aux, val); 226 227 priv->addr_caches[port_id][dev_num] = val; 228 229 return ret; 230 } 231 232 static int fpc202_attach_addr(struct i2c_atr *atr, u32 chan_id, 233 u16 addr, u16 alias) 234 { 235 struct fpc202_priv *priv = i2c_atr_get_driver_data(atr); 236 237 dev_dbg(&priv->client->dev, "attaching address 0x%02x to alias 0x%02x\n", addr, alias); 238 239 return fpc202_write_dev_addr(priv, chan_id, fpc202_dev_num_from_alias(alias), addr); 240 } 241 242 static void fpc202_detach_addr(struct i2c_atr *atr, u32 chan_id, 243 u16 addr) 244 { 245 struct fpc202_priv *priv = i2c_atr_get_driver_data(atr); 246 int dev_num, reg_mod, val; 247 248 for (dev_num = 0; dev_num < 2; dev_num++) { 249 reg_mod = FPC202_REG_MOD_DEV(chan_id, dev_num); 250 251 mutex_lock(&priv->reg_dev_lock); 252 253 val = priv->addr_caches[chan_id][dev_num]; 254 255 mutex_unlock(&priv->reg_dev_lock); 256 257 if (val < 0) { 258 dev_err(&priv->client->dev, "failed to read register 0x%x while detaching address 0x%02x\n", 259 reg_mod, addr); 260 return; 261 } 262 263 if (val == (addr & 0x7f)) { 264 fpc202_write_dev_addr(priv, chan_id, dev_num, FPC202_REG_DEV_INVALID); 265 return; 266 } 267 } 268 } 269 270 static const struct i2c_atr_ops fpc202_atr_ops = { 271 .attach_addr = fpc202_attach_addr, 272 .detach_addr = fpc202_detach_addr, 273 }; 274 275 static int fpc202_probe_port(struct fpc202_priv *priv, struct device_node *i2c_handle, int port_id) 276 { 277 u16 aliases[FPC202_ALIASES_PER_PORT] = { }; 278 struct device *dev = &priv->client->dev; 279 struct i2c_atr_adap_desc desc = { }; 280 int ret = 0; 281 282 desc.chan_id = port_id; 283 desc.parent = dev; 284 desc.bus_handle = of_fwnode_handle(i2c_handle); 285 desc.num_aliases = FPC202_ALIASES_PER_PORT; 286 287 fpc202_fill_alias_table(priv->client, aliases, port_id); 288 desc.aliases = aliases; 289 290 ret = i2c_atr_add_adapter(priv->atr, &desc); 291 if (ret) 292 return ret; 293 294 set_bit(port_id, priv->probed_ports); 295 296 ret = fpc202_write_dev_addr(priv, port_id, 0, FPC202_REG_DEV_INVALID); 297 if (ret) 298 return ret; 299 300 return fpc202_write_dev_addr(priv, port_id, 1, FPC202_REG_DEV_INVALID); 301 } 302 303 static void fpc202_remove_port(struct fpc202_priv *priv, int port_id) 304 { 305 i2c_atr_del_adapter(priv->atr, port_id); 306 clear_bit(port_id, priv->probed_ports); 307 } 308 309 static int fpc202_probe(struct i2c_client *client) 310 { 311 struct device *dev = &client->dev; 312 struct device_node *i2c_handle; 313 struct fpc202_priv *priv; 314 int ret, port_id; 315 316 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 317 if (!priv) 318 return -ENOMEM; 319 320 mutex_init(&priv->reg_dev_lock); 321 322 priv->client = client; 323 i2c_set_clientdata(client, priv); 324 325 priv->en_gpio = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_HIGH); 326 if (IS_ERR(priv->en_gpio)) { 327 ret = PTR_ERR(priv->en_gpio); 328 dev_err(dev, "failed to fetch enable GPIO! err %d\n", ret); 329 goto destroy_mutex; 330 } 331 332 priv->gpio.label = "gpio-fpc202"; 333 priv->gpio.base = -1; 334 priv->gpio.direction_input = fpc202_gpio_direction_input; 335 priv->gpio.direction_output = fpc202_gpio_direction_output; 336 priv->gpio.set_rv = fpc202_gpio_set; 337 priv->gpio.get = fpc202_gpio_get; 338 priv->gpio.ngpio = FPC202_GPIO_COUNT; 339 priv->gpio.parent = dev; 340 priv->gpio.owner = THIS_MODULE; 341 342 ret = gpiochip_add_data(&priv->gpio, priv); 343 if (ret) { 344 priv->gpio.parent = NULL; 345 dev_err(dev, "failed to add gpiochip err %d\n", ret); 346 goto disable_gpio; 347 } 348 349 priv->atr = i2c_atr_new(client->adapter, dev, &fpc202_atr_ops, 2, 0); 350 if (IS_ERR(priv->atr)) { 351 ret = PTR_ERR(priv->atr); 352 dev_err(dev, "failed to create i2c atr err %d\n", ret); 353 goto disable_gpio; 354 } 355 356 i2c_atr_set_driver_data(priv->atr, priv); 357 358 bitmap_zero(priv->probed_ports, FPC202_NUM_PORTS); 359 360 for_each_child_of_node(dev->of_node, i2c_handle) { 361 ret = of_property_read_u32(i2c_handle, "reg", &port_id); 362 if (ret) { 363 if (ret == -EINVAL) 364 continue; 365 366 dev_err(dev, "failed to read 'reg' property of child node, err %d\n", ret); 367 goto unregister_chans; 368 } 369 370 if (port_id > FPC202_NUM_PORTS) { 371 dev_err(dev, "port ID %d is out of range!\n", port_id); 372 ret = -EINVAL; 373 goto unregister_chans; 374 } 375 376 ret = fpc202_probe_port(priv, i2c_handle, port_id); 377 if (ret) { 378 dev_err(dev, "Failed to probe port %d, err %d\n", port_id, ret); 379 goto unregister_chans; 380 } 381 } 382 383 goto out; 384 385 unregister_chans: 386 for_each_set_bit(port_id, priv->probed_ports, FPC202_NUM_PORTS) 387 fpc202_remove_port(priv, port_id); 388 389 i2c_atr_delete(priv->atr); 390 disable_gpio: 391 fpc202_set_enable(priv, 0); 392 gpiochip_remove(&priv->gpio); 393 destroy_mutex: 394 mutex_destroy(&priv->reg_dev_lock); 395 out: 396 return ret; 397 } 398 399 static void fpc202_remove(struct i2c_client *client) 400 { 401 struct fpc202_priv *priv = i2c_get_clientdata(client); 402 int port_id; 403 404 for_each_set_bit(port_id, priv->probed_ports, FPC202_NUM_PORTS) 405 fpc202_remove_port(priv, port_id); 406 407 mutex_destroy(&priv->reg_dev_lock); 408 409 i2c_atr_delete(priv->atr); 410 411 fpc202_set_enable(priv, 0); 412 gpiochip_remove(&priv->gpio); 413 } 414 415 static const struct of_device_id fpc202_of_match[] = { 416 { .compatible = "ti,fpc202" }, 417 {} 418 }; 419 MODULE_DEVICE_TABLE(of, fpc202_of_match); 420 421 static struct i2c_driver fpc202_driver = { 422 .driver = { 423 .name = "fpc202", 424 .of_match_table = fpc202_of_match, 425 }, 426 .probe = fpc202_probe, 427 .remove = fpc202_remove, 428 }; 429 430 module_i2c_driver(fpc202_driver); 431 432 MODULE_AUTHOR("Romain Gantois <romain.gantois@bootlin.com>"); 433 MODULE_DESCRIPTION("TI FPC202 Dual Port Controller driver"); 434 MODULE_LICENSE("GPL"); 435 MODULE_IMPORT_NS("I2C_ATR"); 436