1 /* 2 * Copyright 2007-2008 Extreme Engineering Solutions, Inc. 3 * 4 * Author: Nate Case <ncase@xes-inc.com> 5 * 6 * This file is subject to the terms and conditions of version 2 of 7 * the GNU General Public License. See the file COPYING in the main 8 * directory of this archive for more details. 9 * 10 * LED driver for various PCA955x I2C LED drivers 11 * 12 * Supported devices: 13 * 14 * Device Description 7-bit slave address 15 * ------ ----------- ------------------- 16 * PCA9550 2-bit driver 0x60 .. 0x61 17 * PCA9551 8-bit driver 0x60 .. 0x67 18 * PCA9552 16-bit driver 0x60 .. 0x67 19 * PCA9553/01 4-bit driver 0x62 20 * PCA9553/02 4-bit driver 0x63 21 * 22 * Philips PCA955x LED driver chips follow a register map as shown below: 23 * 24 * Control Register Description 25 * ---------------- ----------- 26 * 0x0 Input register 0 27 * .. 28 * NUM_INPUT_REGS - 1 Last Input register X 29 * 30 * NUM_INPUT_REGS Frequency prescaler 0 31 * NUM_INPUT_REGS + 1 PWM register 0 32 * NUM_INPUT_REGS + 2 Frequency prescaler 1 33 * NUM_INPUT_REGS + 3 PWM register 1 34 * 35 * NUM_INPUT_REGS + 4 LED selector 0 36 * NUM_INPUT_REGS + 4 37 * + NUM_LED_REGS - 1 Last LED selector 38 * 39 * where NUM_INPUT_REGS and NUM_LED_REGS vary depending on how many 40 * bits the chip supports. 41 */ 42 43 #include <linux/acpi.h> 44 #include <linux/module.h> 45 #include <linux/delay.h> 46 #include <linux/string.h> 47 #include <linux/ctype.h> 48 #include <linux/leds.h> 49 #include <linux/err.h> 50 #include <linux/i2c.h> 51 #include <linux/slab.h> 52 53 /* LED select registers determine the source that drives LED outputs */ 54 #define PCA955X_LS_LED_ON 0x0 /* Output LOW */ 55 #define PCA955X_LS_LED_OFF 0x1 /* Output HI-Z */ 56 #define PCA955X_LS_BLINK0 0x2 /* Blink at PWM0 rate */ 57 #define PCA955X_LS_BLINK1 0x3 /* Blink at PWM1 rate */ 58 59 enum pca955x_type { 60 pca9550, 61 pca9551, 62 pca9552, 63 pca9553, 64 }; 65 66 struct pca955x_chipdef { 67 int bits; 68 u8 slv_addr; /* 7-bit slave address mask */ 69 int slv_addr_shift; /* Number of bits to ignore */ 70 }; 71 72 static struct pca955x_chipdef pca955x_chipdefs[] = { 73 [pca9550] = { 74 .bits = 2, 75 .slv_addr = /* 110000x */ 0x60, 76 .slv_addr_shift = 1, 77 }, 78 [pca9551] = { 79 .bits = 8, 80 .slv_addr = /* 1100xxx */ 0x60, 81 .slv_addr_shift = 3, 82 }, 83 [pca9552] = { 84 .bits = 16, 85 .slv_addr = /* 1100xxx */ 0x60, 86 .slv_addr_shift = 3, 87 }, 88 [pca9553] = { 89 .bits = 4, 90 .slv_addr = /* 110001x */ 0x62, 91 .slv_addr_shift = 1, 92 }, 93 }; 94 95 static const struct i2c_device_id pca955x_id[] = { 96 { "pca9550", pca9550 }, 97 { "pca9551", pca9551 }, 98 { "pca9552", pca9552 }, 99 { "pca9553", pca9553 }, 100 { } 101 }; 102 MODULE_DEVICE_TABLE(i2c, pca955x_id); 103 104 static const struct acpi_device_id pca955x_acpi_ids[] = { 105 { "PCA9550", pca9550 }, 106 { "PCA9551", pca9551 }, 107 { "PCA9552", pca9552 }, 108 { "PCA9553", pca9553 }, 109 { } 110 }; 111 MODULE_DEVICE_TABLE(acpi, pca955x_acpi_ids); 112 113 struct pca955x { 114 struct mutex lock; 115 struct pca955x_led *leds; 116 struct pca955x_chipdef *chipdef; 117 struct i2c_client *client; 118 }; 119 120 struct pca955x_led { 121 struct pca955x *pca955x; 122 struct led_classdev led_cdev; 123 int led_num; /* 0 .. 15 potentially */ 124 char name[32]; 125 }; 126 127 /* 8 bits per input register */ 128 static inline int pca95xx_num_input_regs(int bits) 129 { 130 return (bits + 7) / 8; 131 } 132 133 /* 4 bits per LED selector register */ 134 static inline int pca95xx_num_led_regs(int bits) 135 { 136 return (bits + 3) / 4; 137 } 138 139 /* 140 * Return an LED selector register value based on an existing one, with 141 * the appropriate 2-bit state value set for the given LED number (0-3). 142 */ 143 static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state) 144 { 145 return (oldval & (~(0x3 << (led_num << 1)))) | 146 ((state & 0x3) << (led_num << 1)); 147 } 148 149 /* 150 * Write to frequency prescaler register, used to program the 151 * period of the PWM output. period = (PSCx + 1) / 38 152 */ 153 static void pca955x_write_psc(struct i2c_client *client, int n, u8 val) 154 { 155 struct pca955x *pca955x = i2c_get_clientdata(client); 156 157 i2c_smbus_write_byte_data(client, 158 pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n, 159 val); 160 } 161 162 /* 163 * Write to PWM register, which determines the duty cycle of the 164 * output. LED is OFF when the count is less than the value of this 165 * register, and ON when it is greater. If PWMx == 0, LED is always OFF. 166 * 167 * Duty cycle is (256 - PWMx) / 256 168 */ 169 static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val) 170 { 171 struct pca955x *pca955x = i2c_get_clientdata(client); 172 173 i2c_smbus_write_byte_data(client, 174 pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n, 175 val); 176 } 177 178 /* 179 * Write to LED selector register, which determines the source that 180 * drives the LED output. 181 */ 182 static void pca955x_write_ls(struct i2c_client *client, int n, u8 val) 183 { 184 struct pca955x *pca955x = i2c_get_clientdata(client); 185 186 i2c_smbus_write_byte_data(client, 187 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n, 188 val); 189 } 190 191 /* 192 * Read the LED selector register, which determines the source that 193 * drives the LED output. 194 */ 195 static u8 pca955x_read_ls(struct i2c_client *client, int n) 196 { 197 struct pca955x *pca955x = i2c_get_clientdata(client); 198 199 return (u8) i2c_smbus_read_byte_data(client, 200 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n); 201 } 202 203 static int pca955x_led_set(struct led_classdev *led_cdev, 204 enum led_brightness value) 205 { 206 struct pca955x_led *pca955x_led; 207 struct pca955x *pca955x; 208 u8 ls; 209 int chip_ls; /* which LSx to use (0-3 potentially) */ 210 int ls_led; /* which set of bits within LSx to use (0-3) */ 211 212 pca955x_led = container_of(led_cdev, struct pca955x_led, led_cdev); 213 pca955x = pca955x_led->pca955x; 214 215 chip_ls = pca955x_led->led_num / 4; 216 ls_led = pca955x_led->led_num % 4; 217 218 mutex_lock(&pca955x->lock); 219 220 ls = pca955x_read_ls(pca955x->client, chip_ls); 221 222 switch (value) { 223 case LED_FULL: 224 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON); 225 break; 226 case LED_OFF: 227 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF); 228 break; 229 case LED_HALF: 230 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0); 231 break; 232 default: 233 /* 234 * Use PWM1 for all other values. This has the unwanted 235 * side effect of making all LEDs on the chip share the 236 * same brightness level if set to a value other than 237 * OFF, HALF, or FULL. But, this is probably better than 238 * just turning off for all other values. 239 */ 240 pca955x_write_pwm(pca955x->client, 1, 241 255 - value); 242 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1); 243 break; 244 } 245 246 pca955x_write_ls(pca955x->client, chip_ls, ls); 247 248 mutex_unlock(&pca955x->lock); 249 250 return 0; 251 } 252 253 static int pca955x_probe(struct i2c_client *client, 254 const struct i2c_device_id *id) 255 { 256 struct pca955x *pca955x; 257 struct pca955x_led *pca955x_led; 258 struct pca955x_chipdef *chip; 259 struct i2c_adapter *adapter; 260 struct led_platform_data *pdata; 261 int i, err; 262 263 if (id) { 264 chip = &pca955x_chipdefs[id->driver_data]; 265 } else { 266 const struct acpi_device_id *acpi_id; 267 268 acpi_id = acpi_match_device(pca955x_acpi_ids, &client->dev); 269 if (!acpi_id) 270 return -ENODEV; 271 chip = &pca955x_chipdefs[acpi_id->driver_data]; 272 } 273 adapter = to_i2c_adapter(client->dev.parent); 274 pdata = dev_get_platdata(&client->dev); 275 276 /* Make sure the slave address / chip type combo given is possible */ 277 if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) != 278 chip->slv_addr) { 279 dev_err(&client->dev, "invalid slave address %02x\n", 280 client->addr); 281 return -ENODEV; 282 } 283 284 dev_info(&client->dev, "leds-pca955x: Using %s %d-bit LED driver at " 285 "slave address 0x%02x\n", 286 client->name, chip->bits, client->addr); 287 288 if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) 289 return -EIO; 290 291 if (pdata) { 292 if (pdata->num_leds != chip->bits) { 293 dev_err(&client->dev, "board info claims %d LEDs" 294 " on a %d-bit chip\n", 295 pdata->num_leds, chip->bits); 296 return -ENODEV; 297 } 298 } 299 300 pca955x = devm_kzalloc(&client->dev, sizeof(*pca955x), GFP_KERNEL); 301 if (!pca955x) 302 return -ENOMEM; 303 304 pca955x->leds = devm_kzalloc(&client->dev, 305 sizeof(*pca955x_led) * chip->bits, GFP_KERNEL); 306 if (!pca955x->leds) 307 return -ENOMEM; 308 309 i2c_set_clientdata(client, pca955x); 310 311 mutex_init(&pca955x->lock); 312 pca955x->client = client; 313 pca955x->chipdef = chip; 314 315 for (i = 0; i < chip->bits; i++) { 316 pca955x_led = &pca955x->leds[i]; 317 pca955x_led->led_num = i; 318 pca955x_led->pca955x = pca955x; 319 320 /* Platform data can specify LED names and default triggers */ 321 if (pdata) { 322 if (pdata->leds[i].name) 323 snprintf(pca955x_led->name, 324 sizeof(pca955x_led->name), "pca955x:%s", 325 pdata->leds[i].name); 326 if (pdata->leds[i].default_trigger) 327 pca955x_led->led_cdev.default_trigger = 328 pdata->leds[i].default_trigger; 329 } else { 330 snprintf(pca955x_led->name, sizeof(pca955x_led->name), 331 "pca955x:%d", i); 332 } 333 334 pca955x_led->led_cdev.name = pca955x_led->name; 335 pca955x_led->led_cdev.brightness_set_blocking = pca955x_led_set; 336 337 err = led_classdev_register(&client->dev, 338 &pca955x_led->led_cdev); 339 if (err < 0) 340 goto exit; 341 } 342 343 /* Turn off LEDs */ 344 for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++) 345 pca955x_write_ls(client, i, 0x55); 346 347 /* PWM0 is used for half brightness or 50% duty cycle */ 348 pca955x_write_pwm(client, 0, 255-LED_HALF); 349 350 /* PWM1 is used for variable brightness, default to OFF */ 351 pca955x_write_pwm(client, 1, 0); 352 353 /* Set to fast frequency so we do not see flashing */ 354 pca955x_write_psc(client, 0, 0); 355 pca955x_write_psc(client, 1, 0); 356 357 return 0; 358 359 exit: 360 while (i--) 361 led_classdev_unregister(&pca955x->leds[i].led_cdev); 362 363 return err; 364 } 365 366 static int pca955x_remove(struct i2c_client *client) 367 { 368 struct pca955x *pca955x = i2c_get_clientdata(client); 369 int i; 370 371 for (i = 0; i < pca955x->chipdef->bits; i++) 372 led_classdev_unregister(&pca955x->leds[i].led_cdev); 373 374 return 0; 375 } 376 377 static struct i2c_driver pca955x_driver = { 378 .driver = { 379 .name = "leds-pca955x", 380 .acpi_match_table = ACPI_PTR(pca955x_acpi_ids), 381 }, 382 .probe = pca955x_probe, 383 .remove = pca955x_remove, 384 .id_table = pca955x_id, 385 }; 386 387 module_i2c_driver(pca955x_driver); 388 389 MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>"); 390 MODULE_DESCRIPTION("PCA955x LED driver"); 391 MODULE_LICENSE("GPL v2"); 392