1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip 4 * 5 * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it> 6 */ 7 8 /* 9 * I2C driver for National Semiconductor LP3944 Funlight Chip 10 * http://www.national.com/pf/LP/LP3944.html 11 * 12 * This helper chip can drive up to 8 leds, with two programmable DIM modes; 13 * it could even be used as a gpio expander but this driver assumes it is used 14 * as a led controller. 15 * 16 * The DIM modes are used to set _blink_ patterns for leds, the pattern is 17 * specified supplying two parameters: 18 * - period: from 0s to 1.6s 19 * - duty cycle: percentage of the period the led is on, from 0 to 100 20 * 21 * LP3944 can be found on Motorola A910 smartphone, where it drives the rgb 22 * leds, the camera flash light and the displays backlights. 23 */ 24 25 #include <linux/module.h> 26 #include <linux/i2c.h> 27 #include <linux/slab.h> 28 #include <linux/leds.h> 29 #include <linux/mutex.h> 30 #include <linux/leds-lp3944.h> 31 32 /* Read Only Registers */ 33 #define LP3944_REG_INPUT1 0x00 /* LEDs 0-7 InputRegister (Read Only) */ 34 #define LP3944_REG_REGISTER1 0x01 /* None (Read Only) */ 35 36 #define LP3944_REG_PSC0 0x02 /* Frequency Prescaler 0 (R/W) */ 37 #define LP3944_REG_PWM0 0x03 /* PWM Register 0 (R/W) */ 38 #define LP3944_REG_PSC1 0x04 /* Frequency Prescaler 1 (R/W) */ 39 #define LP3944_REG_PWM1 0x05 /* PWM Register 1 (R/W) */ 40 #define LP3944_REG_LS0 0x06 /* LEDs 0-3 Selector (R/W) */ 41 #define LP3944_REG_LS1 0x07 /* LEDs 4-7 Selector (R/W) */ 42 43 /* These registers are not used to control leds in LP3944, they can store 44 * arbitrary values which the chip will ignore. 45 */ 46 #define LP3944_REG_REGISTER8 0x08 47 #define LP3944_REG_REGISTER9 0x09 48 49 #define LP3944_DIM0 0 50 #define LP3944_DIM1 1 51 52 /* period in ms */ 53 #define LP3944_PERIOD_MIN 0 54 #define LP3944_PERIOD_MAX 1600 55 56 /* duty cycle is a percentage */ 57 #define LP3944_DUTY_CYCLE_MIN 0 58 #define LP3944_DUTY_CYCLE_MAX 100 59 60 #define ldev_to_led(c) container_of(c, struct lp3944_led_data, ldev) 61 62 /* Saved data */ 63 struct lp3944_led_data { 64 u8 id; 65 enum lp3944_type type; 66 struct led_classdev ldev; 67 struct i2c_client *client; 68 }; 69 70 struct lp3944_data { 71 struct mutex lock; 72 struct i2c_client *client; 73 struct lp3944_led_data leds[LP3944_LEDS_MAX]; 74 }; 75 76 static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value) 77 { 78 int tmp; 79 80 tmp = i2c_smbus_read_byte_data(client, reg); 81 if (tmp < 0) 82 return tmp; 83 84 *value = tmp; 85 86 return 0; 87 } 88 89 static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value) 90 { 91 return i2c_smbus_write_byte_data(client, reg, value); 92 } 93 94 /** 95 * lp3944_dim_set_period() - Set the period for DIM status 96 * 97 * @client: the i2c client 98 * @dim: either LP3944_DIM0 or LP3944_DIM1 99 * @period: period of a blink, that is a on/off cycle, expressed in ms. 100 */ 101 static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period) 102 { 103 u8 psc_reg; 104 u8 psc_value; 105 int err; 106 107 if (dim == LP3944_DIM0) 108 psc_reg = LP3944_REG_PSC0; 109 else if (dim == LP3944_DIM1) 110 psc_reg = LP3944_REG_PSC1; 111 else 112 return -EINVAL; 113 114 /* Convert period to Prescaler value */ 115 if (period > LP3944_PERIOD_MAX) 116 return -EINVAL; 117 118 psc_value = (period * 255) / LP3944_PERIOD_MAX; 119 120 err = lp3944_reg_write(client, psc_reg, psc_value); 121 122 return err; 123 } 124 125 /** 126 * lp3944_dim_set_dutycycle - Set the duty cycle for DIM status 127 * 128 * @client: the i2c client 129 * @dim: either LP3944_DIM0 or LP3944_DIM1 130 * @duty_cycle: percentage of a period during which a led is ON 131 */ 132 static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim, 133 u8 duty_cycle) 134 { 135 u8 pwm_reg; 136 u8 pwm_value; 137 int err; 138 139 if (dim == LP3944_DIM0) 140 pwm_reg = LP3944_REG_PWM0; 141 else if (dim == LP3944_DIM1) 142 pwm_reg = LP3944_REG_PWM1; 143 else 144 return -EINVAL; 145 146 /* Convert duty cycle to PWM value */ 147 if (duty_cycle > LP3944_DUTY_CYCLE_MAX) 148 return -EINVAL; 149 150 pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX; 151 152 err = lp3944_reg_write(client, pwm_reg, pwm_value); 153 154 return err; 155 } 156 157 /** 158 * lp3944_led_set() - Set the led status 159 * 160 * @led: a lp3944_led_data structure 161 * @status: one of LP3944_LED_STATUS_OFF 162 * LP3944_LED_STATUS_ON 163 * LP3944_LED_STATUS_DIM0 164 * LP3944_LED_STATUS_DIM1 165 */ 166 static int lp3944_led_set(struct lp3944_led_data *led, u8 status) 167 { 168 struct lp3944_data *data = i2c_get_clientdata(led->client); 169 u8 id = led->id; 170 u8 reg; 171 u8 val = 0; 172 int err; 173 174 dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n", 175 __func__, led->ldev.name, status); 176 177 switch (id) { 178 case LP3944_LED0: 179 case LP3944_LED1: 180 case LP3944_LED2: 181 case LP3944_LED3: 182 reg = LP3944_REG_LS0; 183 break; 184 case LP3944_LED4: 185 case LP3944_LED5: 186 case LP3944_LED6: 187 case LP3944_LED7: 188 id -= LP3944_LED4; 189 reg = LP3944_REG_LS1; 190 break; 191 default: 192 return -EINVAL; 193 } 194 195 if (status > LP3944_LED_STATUS_DIM1) 196 return -EINVAL; 197 198 /* 199 * Invert status only when it's < 2 (i.e. 0 or 1) which means it's 200 * controlling the on/off state directly. 201 * When, instead, status is >= 2 don't invert it because it would mean 202 * to mess with the hardware blinking mode. 203 */ 204 if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2) 205 status = 1 - status; 206 207 mutex_lock(&data->lock); 208 lp3944_reg_read(led->client, reg, &val); 209 210 val &= ~(LP3944_LED_STATUS_MASK << (id << 1)); 211 val |= (status << (id << 1)); 212 213 dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n", 214 __func__, led->ldev.name, reg, id, status, val); 215 216 /* set led status */ 217 err = lp3944_reg_write(led->client, reg, val); 218 mutex_unlock(&data->lock); 219 220 return err; 221 } 222 223 static int lp3944_led_set_blink(struct led_classdev *led_cdev, 224 unsigned long *delay_on, 225 unsigned long *delay_off) 226 { 227 struct lp3944_led_data *led = ldev_to_led(led_cdev); 228 u16 period; 229 u8 duty_cycle; 230 int err; 231 232 /* units are in ms */ 233 if (*delay_on + *delay_off > LP3944_PERIOD_MAX) 234 return -EINVAL; 235 236 if (*delay_on == 0 && *delay_off == 0) { 237 /* Special case: the leds subsystem requires a default user 238 * friendly blink pattern for the LED. Let's blink the led 239 * slowly (1Hz). 240 */ 241 *delay_on = 500; 242 *delay_off = 500; 243 } 244 245 period = (*delay_on) + (*delay_off); 246 247 /* duty_cycle is the percentage of period during which the led is ON */ 248 duty_cycle = 100 * (*delay_on) / period; 249 250 /* invert duty cycle for inverted leds, this has the same effect of 251 * swapping delay_on and delay_off 252 */ 253 if (led->type == LP3944_LED_TYPE_LED_INVERTED) 254 duty_cycle = 100 - duty_cycle; 255 256 /* NOTE: using always the first DIM mode, this means that all leds 257 * will have the same blinking pattern. 258 * 259 * We could find a way later to have two leds blinking in hardware 260 * with different patterns at the same time, falling back to software 261 * control for the other ones. 262 */ 263 err = lp3944_dim_set_period(led->client, LP3944_DIM0, period); 264 if (err) 265 return err; 266 267 err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle); 268 if (err) 269 return err; 270 271 dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n", 272 __func__); 273 274 lp3944_led_set(led, LP3944_LED_STATUS_DIM0); 275 276 return 0; 277 } 278 279 static int lp3944_led_set_brightness(struct led_classdev *led_cdev, 280 enum led_brightness brightness) 281 { 282 struct lp3944_led_data *led = ldev_to_led(led_cdev); 283 284 dev_dbg(&led->client->dev, "%s: %s, %d\n", 285 __func__, led_cdev->name, brightness); 286 287 return lp3944_led_set(led, !!brightness); 288 } 289 290 static int lp3944_configure(struct i2c_client *client, 291 struct lp3944_data *data, 292 struct lp3944_platform_data *pdata) 293 { 294 int i, err = 0; 295 296 for (i = 0; i < pdata->leds_size; i++) { 297 struct lp3944_led *pled = &pdata->leds[i]; 298 struct lp3944_led_data *led = &data->leds[i]; 299 led->client = client; 300 led->id = i; 301 302 switch (pled->type) { 303 304 case LP3944_LED_TYPE_LED: 305 case LP3944_LED_TYPE_LED_INVERTED: 306 led->type = pled->type; 307 led->ldev.name = pled->name; 308 led->ldev.max_brightness = 1; 309 led->ldev.brightness_set_blocking = 310 lp3944_led_set_brightness; 311 led->ldev.blink_set = lp3944_led_set_blink; 312 led->ldev.flags = LED_CORE_SUSPENDRESUME; 313 314 err = led_classdev_register(&client->dev, &led->ldev); 315 if (err < 0) { 316 dev_err(&client->dev, 317 "couldn't register LED %s\n", 318 led->ldev.name); 319 goto exit; 320 } 321 322 /* to expose the default value to userspace */ 323 led->ldev.brightness = 324 (enum led_brightness) pled->status; 325 326 /* Set the default led status */ 327 err = lp3944_led_set(led, pled->status); 328 if (err < 0) { 329 dev_err(&client->dev, 330 "%s couldn't set STATUS %d\n", 331 led->ldev.name, pled->status); 332 goto exit; 333 } 334 break; 335 336 case LP3944_LED_TYPE_NONE: 337 default: 338 break; 339 340 } 341 } 342 return 0; 343 344 exit: 345 if (i > 0) 346 for (i = i - 1; i >= 0; i--) 347 switch (pdata->leds[i].type) { 348 349 case LP3944_LED_TYPE_LED: 350 case LP3944_LED_TYPE_LED_INVERTED: 351 led_classdev_unregister(&data->leds[i].ldev); 352 break; 353 354 case LP3944_LED_TYPE_NONE: 355 default: 356 break; 357 } 358 359 return err; 360 } 361 362 static int lp3944_probe(struct i2c_client *client) 363 { 364 struct lp3944_platform_data *lp3944_pdata = 365 dev_get_platdata(&client->dev); 366 struct lp3944_data *data; 367 int err; 368 369 if (lp3944_pdata == NULL) { 370 dev_err(&client->dev, "no platform data\n"); 371 return -EINVAL; 372 } 373 374 /* Let's see whether this adapter can support what we need. */ 375 if (!i2c_check_functionality(client->adapter, 376 I2C_FUNC_SMBUS_BYTE_DATA)) { 377 dev_err(&client->dev, "insufficient functionality!\n"); 378 return -ENODEV; 379 } 380 381 data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data), 382 GFP_KERNEL); 383 if (!data) 384 return -ENOMEM; 385 386 data->client = client; 387 i2c_set_clientdata(client, data); 388 389 mutex_init(&data->lock); 390 391 err = lp3944_configure(client, data, lp3944_pdata); 392 if (err < 0) 393 return err; 394 395 dev_info(&client->dev, "lp3944 enabled\n"); 396 return 0; 397 } 398 399 static void lp3944_remove(struct i2c_client *client) 400 { 401 struct lp3944_platform_data *pdata = dev_get_platdata(&client->dev); 402 struct lp3944_data *data = i2c_get_clientdata(client); 403 int i; 404 405 for (i = 0; i < pdata->leds_size; i++) 406 switch (data->leds[i].type) { 407 case LP3944_LED_TYPE_LED: 408 case LP3944_LED_TYPE_LED_INVERTED: 409 led_classdev_unregister(&data->leds[i].ldev); 410 break; 411 412 case LP3944_LED_TYPE_NONE: 413 default: 414 break; 415 } 416 } 417 418 /* lp3944 i2c driver struct */ 419 static const struct i2c_device_id lp3944_id[] = { 420 {"lp3944", 0}, 421 {} 422 }; 423 424 MODULE_DEVICE_TABLE(i2c, lp3944_id); 425 426 static struct i2c_driver lp3944_driver = { 427 .driver = { 428 .name = "lp3944", 429 }, 430 .probe = lp3944_probe, 431 .remove = lp3944_remove, 432 .id_table = lp3944_id, 433 }; 434 435 module_i2c_driver(lp3944_driver); 436 437 MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>"); 438 MODULE_DESCRIPTION("LP3944 Fun Light Chip"); 439 MODULE_LICENSE("GPL"); 440