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/slab.h> 32 #include <linux/leds.h> 33 #include <linux/mutex.h> 34 #include <linux/workqueue.h> 35 #include <linux/leds-lp3944.h> 36 37 /* Read Only Registers */ 38 #define LP3944_REG_INPUT1 0x00 /* LEDs 0-7 InputRegister (Read Only) */ 39 #define LP3944_REG_REGISTER1 0x01 /* None (Read Only) */ 40 41 #define LP3944_REG_PSC0 0x02 /* Frequency Prescaler 0 (R/W) */ 42 #define LP3944_REG_PWM0 0x03 /* PWM Register 0 (R/W) */ 43 #define LP3944_REG_PSC1 0x04 /* Frequency Prescaler 1 (R/W) */ 44 #define LP3944_REG_PWM1 0x05 /* PWM Register 1 (R/W) */ 45 #define LP3944_REG_LS0 0x06 /* LEDs 0-3 Selector (R/W) */ 46 #define LP3944_REG_LS1 0x07 /* LEDs 4-7 Selector (R/W) */ 47 48 /* These registers are not used to control leds in LP3944, they can store 49 * arbitrary values which the chip will ignore. 50 */ 51 #define LP3944_REG_REGISTER8 0x08 52 #define LP3944_REG_REGISTER9 0x09 53 54 #define LP3944_DIM0 0 55 #define LP3944_DIM1 1 56 57 /* period in ms */ 58 #define LP3944_PERIOD_MIN 0 59 #define LP3944_PERIOD_MAX 1600 60 61 /* duty cycle is a percentage */ 62 #define LP3944_DUTY_CYCLE_MIN 0 63 #define LP3944_DUTY_CYCLE_MAX 100 64 65 #define ldev_to_led(c) container_of(c, struct lp3944_led_data, ldev) 66 67 /* Saved data */ 68 struct lp3944_led_data { 69 u8 id; 70 enum lp3944_type type; 71 enum lp3944_status status; 72 struct led_classdev ldev; 73 struct i2c_client *client; 74 struct work_struct work; 75 }; 76 77 struct lp3944_data { 78 struct mutex lock; 79 struct i2c_client *client; 80 struct lp3944_led_data leds[LP3944_LEDS_MAX]; 81 }; 82 83 static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value) 84 { 85 int tmp; 86 87 tmp = i2c_smbus_read_byte_data(client, reg); 88 if (tmp < 0) 89 return tmp; 90 91 *value = tmp; 92 93 return 0; 94 } 95 96 static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value) 97 { 98 return i2c_smbus_write_byte_data(client, reg, value); 99 } 100 101 /** 102 * Set the period for DIM status 103 * 104 * @client: the i2c client 105 * @dim: either LP3944_DIM0 or LP3944_DIM1 106 * @period: period of a blink, that is a on/off cycle, expressed in ms. 107 */ 108 static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period) 109 { 110 u8 psc_reg; 111 u8 psc_value; 112 int err; 113 114 if (dim == LP3944_DIM0) 115 psc_reg = LP3944_REG_PSC0; 116 else if (dim == LP3944_DIM1) 117 psc_reg = LP3944_REG_PSC1; 118 else 119 return -EINVAL; 120 121 /* Convert period to Prescaler value */ 122 if (period > LP3944_PERIOD_MAX) 123 return -EINVAL; 124 125 psc_value = (period * 255) / LP3944_PERIOD_MAX; 126 127 err = lp3944_reg_write(client, psc_reg, psc_value); 128 129 return err; 130 } 131 132 /** 133 * Set the duty cycle for DIM status 134 * 135 * @client: the i2c client 136 * @dim: either LP3944_DIM0 or LP3944_DIM1 137 * @duty_cycle: percentage of a period during which a led is ON 138 */ 139 static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim, 140 u8 duty_cycle) 141 { 142 u8 pwm_reg; 143 u8 pwm_value; 144 int err; 145 146 if (dim == LP3944_DIM0) 147 pwm_reg = LP3944_REG_PWM0; 148 else if (dim == LP3944_DIM1) 149 pwm_reg = LP3944_REG_PWM1; 150 else 151 return -EINVAL; 152 153 /* Convert duty cycle to PWM value */ 154 if (duty_cycle > LP3944_DUTY_CYCLE_MAX) 155 return -EINVAL; 156 157 pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX; 158 159 err = lp3944_reg_write(client, pwm_reg, pwm_value); 160 161 return err; 162 } 163 164 /** 165 * Set the led status 166 * 167 * @led: a lp3944_led_data structure 168 * @status: one of LP3944_LED_STATUS_OFF 169 * LP3944_LED_STATUS_ON 170 * LP3944_LED_STATUS_DIM0 171 * LP3944_LED_STATUS_DIM1 172 */ 173 static int lp3944_led_set(struct lp3944_led_data *led, u8 status) 174 { 175 struct lp3944_data *data = i2c_get_clientdata(led->client); 176 u8 id = led->id; 177 u8 reg; 178 u8 val = 0; 179 int err; 180 181 dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n", 182 __func__, led->ldev.name, status); 183 184 switch (id) { 185 case LP3944_LED0: 186 case LP3944_LED1: 187 case LP3944_LED2: 188 case LP3944_LED3: 189 reg = LP3944_REG_LS0; 190 break; 191 case LP3944_LED4: 192 case LP3944_LED5: 193 case LP3944_LED6: 194 case LP3944_LED7: 195 id -= LP3944_LED4; 196 reg = LP3944_REG_LS1; 197 break; 198 default: 199 return -EINVAL; 200 } 201 202 if (status > LP3944_LED_STATUS_DIM1) 203 return -EINVAL; 204 205 /* invert only 0 and 1, leave unchanged the other values, 206 * remember we are abusing status to set blink patterns 207 */ 208 if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2) 209 status = 1 - status; 210 211 mutex_lock(&data->lock); 212 lp3944_reg_read(led->client, reg, &val); 213 214 val &= ~(LP3944_LED_STATUS_MASK << (id << 1)); 215 val |= (status << (id << 1)); 216 217 dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n", 218 __func__, led->ldev.name, reg, id, status, val); 219 220 /* set led status */ 221 err = lp3944_reg_write(led->client, reg, val); 222 mutex_unlock(&data->lock); 223 224 return err; 225 } 226 227 static int lp3944_led_set_blink(struct led_classdev *led_cdev, 228 unsigned long *delay_on, 229 unsigned long *delay_off) 230 { 231 struct lp3944_led_data *led = ldev_to_led(led_cdev); 232 u16 period; 233 u8 duty_cycle; 234 int err; 235 236 /* units are in ms */ 237 if (*delay_on + *delay_off > LP3944_PERIOD_MAX) 238 return -EINVAL; 239 240 if (*delay_on == 0 && *delay_off == 0) { 241 /* Special case: the leds subsystem requires a default user 242 * friendly blink pattern for the LED. Let's blink the led 243 * slowly (1Hz). 244 */ 245 *delay_on = 500; 246 *delay_off = 500; 247 } 248 249 period = (*delay_on) + (*delay_off); 250 251 /* duty_cycle is the percentage of period during which the led is ON */ 252 duty_cycle = 100 * (*delay_on) / period; 253 254 /* invert duty cycle for inverted leds, this has the same effect of 255 * swapping delay_on and delay_off 256 */ 257 if (led->type == LP3944_LED_TYPE_LED_INVERTED) 258 duty_cycle = 100 - duty_cycle; 259 260 /* NOTE: using always the first DIM mode, this means that all leds 261 * will have the same blinking pattern. 262 * 263 * We could find a way later to have two leds blinking in hardware 264 * with different patterns at the same time, falling back to software 265 * control for the other ones. 266 */ 267 err = lp3944_dim_set_period(led->client, LP3944_DIM0, period); 268 if (err) 269 return err; 270 271 err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle); 272 if (err) 273 return err; 274 275 dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n", 276 __func__); 277 278 led->status = LP3944_LED_STATUS_DIM0; 279 schedule_work(&led->work); 280 281 return 0; 282 } 283 284 static void lp3944_led_set_brightness(struct led_classdev *led_cdev, 285 enum led_brightness brightness) 286 { 287 struct lp3944_led_data *led = ldev_to_led(led_cdev); 288 289 dev_dbg(&led->client->dev, "%s: %s, %d\n", 290 __func__, led_cdev->name, brightness); 291 292 led->status = !!brightness; 293 schedule_work(&led->work); 294 } 295 296 static void lp3944_led_work(struct work_struct *work) 297 { 298 struct lp3944_led_data *led; 299 300 led = container_of(work, struct lp3944_led_data, work); 301 lp3944_led_set(led, led->status); 302 } 303 304 static int lp3944_configure(struct i2c_client *client, 305 struct lp3944_data *data, 306 struct lp3944_platform_data *pdata) 307 { 308 int i, err = 0; 309 310 for (i = 0; i < pdata->leds_size; i++) { 311 struct lp3944_led *pled = &pdata->leds[i]; 312 struct lp3944_led_data *led = &data->leds[i]; 313 led->client = client; 314 led->id = i; 315 316 switch (pled->type) { 317 318 case LP3944_LED_TYPE_LED: 319 case LP3944_LED_TYPE_LED_INVERTED: 320 led->type = pled->type; 321 led->status = pled->status; 322 led->ldev.name = pled->name; 323 led->ldev.max_brightness = 1; 324 led->ldev.brightness_set = lp3944_led_set_brightness; 325 led->ldev.blink_set = lp3944_led_set_blink; 326 led->ldev.flags = LED_CORE_SUSPENDRESUME; 327 328 INIT_WORK(&led->work, lp3944_led_work); 329 err = led_classdev_register(&client->dev, &led->ldev); 330 if (err < 0) { 331 dev_err(&client->dev, 332 "couldn't register LED %s\n", 333 led->ldev.name); 334 goto exit; 335 } 336 337 /* to expose the default value to userspace */ 338 led->ldev.brightness = led->status; 339 340 /* Set the default led status */ 341 err = lp3944_led_set(led, led->status); 342 if (err < 0) { 343 dev_err(&client->dev, 344 "%s couldn't set STATUS %d\n", 345 led->ldev.name, led->status); 346 goto exit; 347 } 348 break; 349 350 case LP3944_LED_TYPE_NONE: 351 default: 352 break; 353 354 } 355 } 356 return 0; 357 358 exit: 359 if (i > 0) 360 for (i = i - 1; i >= 0; i--) 361 switch (pdata->leds[i].type) { 362 363 case LP3944_LED_TYPE_LED: 364 case LP3944_LED_TYPE_LED_INVERTED: 365 led_classdev_unregister(&data->leds[i].ldev); 366 cancel_work_sync(&data->leds[i].work); 367 break; 368 369 case LP3944_LED_TYPE_NONE: 370 default: 371 break; 372 } 373 374 return err; 375 } 376 377 static int lp3944_probe(struct i2c_client *client, 378 const struct i2c_device_id *id) 379 { 380 struct lp3944_platform_data *lp3944_pdata = 381 dev_get_platdata(&client->dev); 382 struct lp3944_data *data; 383 int err; 384 385 if (lp3944_pdata == NULL) { 386 dev_err(&client->dev, "no platform data\n"); 387 return -EINVAL; 388 } 389 390 /* Let's see whether this adapter can support what we need. */ 391 if (!i2c_check_functionality(client->adapter, 392 I2C_FUNC_SMBUS_BYTE_DATA)) { 393 dev_err(&client->dev, "insufficient functionality!\n"); 394 return -ENODEV; 395 } 396 397 data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data), 398 GFP_KERNEL); 399 if (!data) 400 return -ENOMEM; 401 402 data->client = client; 403 i2c_set_clientdata(client, data); 404 405 mutex_init(&data->lock); 406 407 err = lp3944_configure(client, data, lp3944_pdata); 408 if (err < 0) 409 return err; 410 411 dev_info(&client->dev, "lp3944 enabled\n"); 412 return 0; 413 } 414 415 static int lp3944_remove(struct i2c_client *client) 416 { 417 struct lp3944_platform_data *pdata = dev_get_platdata(&client->dev); 418 struct lp3944_data *data = i2c_get_clientdata(client); 419 int i; 420 421 for (i = 0; i < pdata->leds_size; i++) 422 switch (data->leds[i].type) { 423 case LP3944_LED_TYPE_LED: 424 case LP3944_LED_TYPE_LED_INVERTED: 425 led_classdev_unregister(&data->leds[i].ldev); 426 cancel_work_sync(&data->leds[i].work); 427 break; 428 429 case LP3944_LED_TYPE_NONE: 430 default: 431 break; 432 } 433 434 return 0; 435 } 436 437 /* lp3944 i2c driver struct */ 438 static const struct i2c_device_id lp3944_id[] = { 439 {"lp3944", 0}, 440 {} 441 }; 442 443 MODULE_DEVICE_TABLE(i2c, lp3944_id); 444 445 static struct i2c_driver lp3944_driver = { 446 .driver = { 447 .name = "lp3944", 448 }, 449 .probe = lp3944_probe, 450 .remove = lp3944_remove, 451 .id_table = lp3944_id, 452 }; 453 454 module_i2c_driver(lp3944_driver); 455 456 MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>"); 457 MODULE_DESCRIPTION("LP3944 Fun Light Chip"); 458 MODULE_LICENSE("GPL"); 459