1 /* 2 * leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip 3 * 4 * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it> 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 version 2 as 8 * published by the Free Software Foundation. 9 * 10 */ 11 12 /* 13 * I2C driver for National Semiconductor LP3944 Funlight Chip 14 * http://www.national.com/pf/LP/LP3944.html 15 * 16 * This helper chip can drive up to 8 leds, with two programmable DIM modes; 17 * it could even be used as a gpio expander but this driver assumes it is used 18 * as a led controller. 19 * 20 * The DIM modes are used to set _blink_ patterns for leds, the pattern is 21 * specified supplying two parameters: 22 * - period: from 0s to 1.6s 23 * - duty cycle: percentage of the period the led is on, from 0 to 100 24 * 25 * LP3944 can be found on Motorola A910 smartphone, where it drives the rgb 26 * leds, the camera flash light and the displays backlights. 27 */ 28 29 #include <linux/module.h> 30 #include <linux/i2c.h> 31 #include <linux/leds.h> 32 #include <linux/mutex.h> 33 #include <linux/workqueue.h> 34 #include <linux/leds-lp3944.h> 35 36 /* Read Only Registers */ 37 #define LP3944_REG_INPUT1 0x00 /* LEDs 0-7 InputRegister (Read Only) */ 38 #define LP3944_REG_REGISTER1 0x01 /* None (Read Only) */ 39 40 #define LP3944_REG_PSC0 0x02 /* Frequency Prescaler 0 (R/W) */ 41 #define LP3944_REG_PWM0 0x03 /* PWM Register 0 (R/W) */ 42 #define LP3944_REG_PSC1 0x04 /* Frequency Prescaler 1 (R/W) */ 43 #define LP3944_REG_PWM1 0x05 /* PWM Register 1 (R/W) */ 44 #define LP3944_REG_LS0 0x06 /* LEDs 0-3 Selector (R/W) */ 45 #define LP3944_REG_LS1 0x07 /* LEDs 4-7 Selector (R/W) */ 46 47 /* These registers are not used to control leds in LP3944, they can store 48 * arbitrary values which the chip will ignore. 49 */ 50 #define LP3944_REG_REGISTER8 0x08 51 #define LP3944_REG_REGISTER9 0x09 52 53 #define LP3944_DIM0 0 54 #define LP3944_DIM1 1 55 56 /* period in ms */ 57 #define LP3944_PERIOD_MIN 0 58 #define LP3944_PERIOD_MAX 1600 59 60 /* duty cycle is a percentage */ 61 #define LP3944_DUTY_CYCLE_MIN 0 62 #define LP3944_DUTY_CYCLE_MAX 100 63 64 #define ldev_to_led(c) container_of(c, struct lp3944_led_data, ldev) 65 66 /* Saved data */ 67 struct lp3944_led_data { 68 u8 id; 69 enum lp3944_type type; 70 enum lp3944_status status; 71 struct led_classdev ldev; 72 struct i2c_client *client; 73 struct work_struct work; 74 }; 75 76 struct lp3944_data { 77 struct mutex lock; 78 struct i2c_client *client; 79 struct lp3944_led_data leds[LP3944_LEDS_MAX]; 80 }; 81 82 static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value) 83 { 84 int tmp; 85 86 tmp = i2c_smbus_read_byte_data(client, reg); 87 if (tmp < 0) 88 return -EINVAL; 89 90 *value = tmp; 91 92 return 0; 93 } 94 95 static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value) 96 { 97 return i2c_smbus_write_byte_data(client, reg, value); 98 } 99 100 /** 101 * Set the period for DIM status 102 * 103 * @client: the i2c client 104 * @dim: either LP3944_DIM0 or LP3944_DIM1 105 * @period: period of a blink, that is a on/off cycle, expressed in ms. 106 */ 107 static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period) 108 { 109 u8 psc_reg; 110 u8 psc_value; 111 int err; 112 113 if (dim == LP3944_DIM0) 114 psc_reg = LP3944_REG_PSC0; 115 else if (dim == LP3944_DIM1) 116 psc_reg = LP3944_REG_PSC1; 117 else 118 return -EINVAL; 119 120 /* Convert period to Prescaler value */ 121 if (period > LP3944_PERIOD_MAX) 122 return -EINVAL; 123 124 psc_value = (period * 255) / LP3944_PERIOD_MAX; 125 126 err = lp3944_reg_write(client, psc_reg, psc_value); 127 128 return err; 129 } 130 131 /** 132 * Set the duty cycle for DIM status 133 * 134 * @client: the i2c client 135 * @dim: either LP3944_DIM0 or LP3944_DIM1 136 * @duty_cycle: percentage of a period during which a led is ON 137 */ 138 static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim, 139 u8 duty_cycle) 140 { 141 u8 pwm_reg; 142 u8 pwm_value; 143 int err; 144 145 if (dim == LP3944_DIM0) 146 pwm_reg = LP3944_REG_PWM0; 147 else if (dim == LP3944_DIM1) 148 pwm_reg = LP3944_REG_PWM1; 149 else 150 return -EINVAL; 151 152 /* Convert duty cycle to PWM value */ 153 if (duty_cycle > LP3944_DUTY_CYCLE_MAX) 154 return -EINVAL; 155 156 pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX; 157 158 err = lp3944_reg_write(client, pwm_reg, pwm_value); 159 160 return err; 161 } 162 163 /** 164 * Set the led status 165 * 166 * @led: a lp3944_led_data structure 167 * @status: one of LP3944_LED_STATUS_OFF 168 * LP3944_LED_STATUS_ON 169 * LP3944_LED_STATUS_DIM0 170 * LP3944_LED_STATUS_DIM1 171 */ 172 static int lp3944_led_set(struct lp3944_led_data *led, u8 status) 173 { 174 struct lp3944_data *data = i2c_get_clientdata(led->client); 175 u8 id = led->id; 176 u8 reg; 177 u8 val = 0; 178 int err; 179 180 dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n", 181 __func__, led->ldev.name, status); 182 183 switch (id) { 184 case LP3944_LED0: 185 case LP3944_LED1: 186 case LP3944_LED2: 187 case LP3944_LED3: 188 reg = LP3944_REG_LS0; 189 break; 190 case LP3944_LED4: 191 case LP3944_LED5: 192 case LP3944_LED6: 193 case LP3944_LED7: 194 id -= LP3944_LED4; 195 reg = LP3944_REG_LS1; 196 break; 197 default: 198 return -EINVAL; 199 } 200 201 if (status > LP3944_LED_STATUS_DIM1) 202 return -EINVAL; 203 204 /* invert only 0 and 1, leave unchanged the other values, 205 * remember we are abusing status to set blink patterns 206 */ 207 if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2) 208 status = 1 - status; 209 210 mutex_lock(&data->lock); 211 lp3944_reg_read(led->client, reg, &val); 212 213 val &= ~(LP3944_LED_STATUS_MASK << (id << 1)); 214 val |= (status << (id << 1)); 215 216 dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n", 217 __func__, led->ldev.name, reg, id, status, val); 218 219 /* set led status */ 220 err = lp3944_reg_write(led->client, reg, val); 221 mutex_unlock(&data->lock); 222 223 return err; 224 } 225 226 static int lp3944_led_set_blink(struct led_classdev *led_cdev, 227 unsigned long *delay_on, 228 unsigned long *delay_off) 229 { 230 struct lp3944_led_data *led = ldev_to_led(led_cdev); 231 u16 period; 232 u8 duty_cycle; 233 int err; 234 235 /* units are in ms */ 236 if (*delay_on + *delay_off > LP3944_PERIOD_MAX) 237 return -EINVAL; 238 239 if (*delay_on == 0 && *delay_off == 0) { 240 /* Special case: the leds subsystem requires a default user 241 * friendly blink pattern for the LED. Let's blink the led 242 * slowly (1Hz). 243 */ 244 *delay_on = 500; 245 *delay_off = 500; 246 } 247 248 period = (*delay_on) + (*delay_off); 249 250 /* duty_cycle is the percentage of period during which the led is ON */ 251 duty_cycle = 100 * (*delay_on) / period; 252 253 /* invert duty cycle for inverted leds, this has the same effect of 254 * swapping delay_on and delay_off 255 */ 256 if (led->type == LP3944_LED_TYPE_LED_INVERTED) 257 duty_cycle = 100 - duty_cycle; 258 259 /* NOTE: using always the first DIM mode, this means that all leds 260 * will have the same blinking pattern. 261 * 262 * We could find a way later to have two leds blinking in hardware 263 * with different patterns at the same time, falling back to software 264 * control for the other ones. 265 */ 266 err = lp3944_dim_set_period(led->client, LP3944_DIM0, period); 267 if (err) 268 return err; 269 270 err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle); 271 if (err) 272 return err; 273 274 dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n", 275 __func__); 276 277 led->status = LP3944_LED_STATUS_DIM0; 278 schedule_work(&led->work); 279 280 return 0; 281 } 282 283 static void lp3944_led_set_brightness(struct led_classdev *led_cdev, 284 enum led_brightness brightness) 285 { 286 struct lp3944_led_data *led = ldev_to_led(led_cdev); 287 288 dev_dbg(&led->client->dev, "%s: %s, %d\n", 289 __func__, led_cdev->name, brightness); 290 291 led->status = brightness; 292 schedule_work(&led->work); 293 } 294 295 static void lp3944_led_work(struct work_struct *work) 296 { 297 struct lp3944_led_data *led; 298 299 led = container_of(work, struct lp3944_led_data, work); 300 lp3944_led_set(led, led->status); 301 } 302 303 static int lp3944_configure(struct i2c_client *client, 304 struct lp3944_data *data, 305 struct lp3944_platform_data *pdata) 306 { 307 int i, err = 0; 308 309 for (i = 0; i < pdata->leds_size; i++) { 310 struct lp3944_led *pled = &pdata->leds[i]; 311 struct lp3944_led_data *led = &data->leds[i]; 312 led->client = client; 313 led->id = i; 314 315 switch (pled->type) { 316 317 case LP3944_LED_TYPE_LED: 318 case LP3944_LED_TYPE_LED_INVERTED: 319 led->type = pled->type; 320 led->status = pled->status; 321 led->ldev.name = pled->name; 322 led->ldev.max_brightness = 1; 323 led->ldev.brightness_set = lp3944_led_set_brightness; 324 led->ldev.blink_set = lp3944_led_set_blink; 325 led->ldev.flags = LED_CORE_SUSPENDRESUME; 326 327 INIT_WORK(&led->work, lp3944_led_work); 328 err = led_classdev_register(&client->dev, &led->ldev); 329 if (err < 0) { 330 dev_err(&client->dev, 331 "couldn't register LED %s\n", 332 led->ldev.name); 333 goto exit; 334 } 335 336 /* to expose the default value to userspace */ 337 led->ldev.brightness = led->status; 338 339 /* Set the default led status */ 340 err = lp3944_led_set(led, led->status); 341 if (err < 0) { 342 dev_err(&client->dev, 343 "%s couldn't set STATUS %d\n", 344 led->ldev.name, led->status); 345 goto exit; 346 } 347 break; 348 349 case LP3944_LED_TYPE_NONE: 350 default: 351 break; 352 353 } 354 } 355 return 0; 356 357 exit: 358 if (i > 0) 359 for (i = i - 1; i >= 0; i--) 360 switch (pdata->leds[i].type) { 361 362 case LP3944_LED_TYPE_LED: 363 case LP3944_LED_TYPE_LED_INVERTED: 364 led_classdev_unregister(&data->leds[i].ldev); 365 cancel_work_sync(&data->leds[i].work); 366 break; 367 368 case LP3944_LED_TYPE_NONE: 369 default: 370 break; 371 } 372 373 return err; 374 } 375 376 static int __devinit lp3944_probe(struct i2c_client *client, 377 const struct i2c_device_id *id) 378 { 379 struct lp3944_platform_data *lp3944_pdata = client->dev.platform_data; 380 struct lp3944_data *data; 381 382 if (lp3944_pdata == NULL) { 383 dev_err(&client->dev, "no platform data\n"); 384 return -EINVAL; 385 } 386 387 /* Let's see whether this adapter can support what we need. */ 388 if (!i2c_check_functionality(client->adapter, 389 I2C_FUNC_SMBUS_BYTE_DATA)) { 390 dev_err(&client->dev, "insufficient functionality!\n"); 391 return -ENODEV; 392 } 393 394 data = kzalloc(sizeof(struct lp3944_data), GFP_KERNEL); 395 if (!data) 396 return -ENOMEM; 397 398 data->client = client; 399 i2c_set_clientdata(client, data); 400 401 mutex_init(&data->lock); 402 403 dev_info(&client->dev, "lp3944 enabled\n"); 404 405 lp3944_configure(client, data, lp3944_pdata); 406 return 0; 407 } 408 409 static int __devexit lp3944_remove(struct i2c_client *client) 410 { 411 struct lp3944_platform_data *pdata = client->dev.platform_data; 412 struct lp3944_data *data = i2c_get_clientdata(client); 413 int i; 414 415 for (i = 0; i < pdata->leds_size; i++) 416 switch (data->leds[i].type) { 417 case LP3944_LED_TYPE_LED: 418 case LP3944_LED_TYPE_LED_INVERTED: 419 led_classdev_unregister(&data->leds[i].ldev); 420 cancel_work_sync(&data->leds[i].work); 421 break; 422 423 case LP3944_LED_TYPE_NONE: 424 default: 425 break; 426 } 427 428 kfree(data); 429 i2c_set_clientdata(client, NULL); 430 431 return 0; 432 } 433 434 /* lp3944 i2c driver struct */ 435 static const struct i2c_device_id lp3944_id[] = { 436 {"lp3944", 0}, 437 {} 438 }; 439 440 MODULE_DEVICE_TABLE(i2c, lp3944_id); 441 442 static struct i2c_driver lp3944_driver = { 443 .driver = { 444 .name = "lp3944", 445 }, 446 .probe = lp3944_probe, 447 .remove = __devexit_p(lp3944_remove), 448 .id_table = lp3944_id, 449 }; 450 451 static int __init lp3944_module_init(void) 452 { 453 return i2c_add_driver(&lp3944_driver); 454 } 455 456 static void __exit lp3944_module_exit(void) 457 { 458 i2c_del_driver(&lp3944_driver); 459 } 460 461 module_init(lp3944_module_init); 462 module_exit(lp3944_module_exit); 463 464 MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>"); 465 MODULE_DESCRIPTION("LP3944 Fun Light Chip"); 466 MODULE_LICENSE("GPL"); 467