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/module.h> 44 #include <linux/delay.h> 45 #include <linux/string.h> 46 #include <linux/ctype.h> 47 #include <linux/leds.h> 48 #include <linux/err.h> 49 #include <linux/i2c.h> 50 #include <linux/workqueue.h> 51 52 /* LED select registers determine the source that drives LED outputs */ 53 #define PCA955X_LS_LED_ON 0x0 /* Output LOW */ 54 #define PCA955X_LS_LED_OFF 0x1 /* Output HI-Z */ 55 #define PCA955X_LS_BLINK0 0x2 /* Blink at PWM0 rate */ 56 #define PCA955X_LS_BLINK1 0x3 /* Blink at PWM1 rate */ 57 58 enum pca955x_type { 59 pca9550, 60 pca9551, 61 pca9552, 62 pca9553, 63 }; 64 65 struct pca955x_chipdef { 66 int bits; 67 u8 slv_addr; /* 7-bit slave address mask */ 68 int slv_addr_shift; /* Number of bits to ignore */ 69 }; 70 71 static struct pca955x_chipdef pca955x_chipdefs[] = { 72 [pca9550] = { 73 .bits = 2, 74 .slv_addr = /* 110000x */ 0x60, 75 .slv_addr_shift = 1, 76 }, 77 [pca9551] = { 78 .bits = 8, 79 .slv_addr = /* 1100xxx */ 0x60, 80 .slv_addr_shift = 3, 81 }, 82 [pca9552] = { 83 .bits = 16, 84 .slv_addr = /* 1100xxx */ 0x60, 85 .slv_addr_shift = 3, 86 }, 87 [pca9553] = { 88 .bits = 4, 89 .slv_addr = /* 110001x */ 0x62, 90 .slv_addr_shift = 1, 91 }, 92 }; 93 94 static const struct i2c_device_id pca955x_id[] = { 95 { "pca9550", pca9550 }, 96 { "pca9551", pca9551 }, 97 { "pca9552", pca9552 }, 98 { "pca9553", pca9553 }, 99 { } 100 }; 101 MODULE_DEVICE_TABLE(i2c, pca955x_id); 102 103 struct pca955x_led { 104 struct pca955x_chipdef *chipdef; 105 struct i2c_client *client; 106 struct work_struct work; 107 spinlock_t lock; 108 enum led_brightness brightness; 109 struct led_classdev led_cdev; 110 int led_num; /* 0 .. 15 potentially */ 111 char name[32]; 112 }; 113 114 /* 8 bits per input register */ 115 static inline int pca95xx_num_input_regs(int bits) 116 { 117 return (bits + 7) / 8; 118 } 119 120 /* 4 bits per LED selector register */ 121 static inline int pca95xx_num_led_regs(int bits) 122 { 123 return (bits + 3) / 4; 124 } 125 126 /* 127 * Return an LED selector register value based on an existing one, with 128 * the appropriate 2-bit state value set for the given LED number (0-3). 129 */ 130 static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state) 131 { 132 return (oldval & (~(0x3 << (led_num << 1)))) | 133 ((state & 0x3) << (led_num << 1)); 134 } 135 136 /* 137 * Write to frequency prescaler register, used to program the 138 * period of the PWM output. period = (PSCx + 1) / 38 139 */ 140 static void pca955x_write_psc(struct i2c_client *client, int n, u8 val) 141 { 142 struct pca955x_led *pca955x = i2c_get_clientdata(client); 143 144 i2c_smbus_write_byte_data(client, 145 pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n, 146 val); 147 } 148 149 /* 150 * Write to PWM register, which determines the duty cycle of the 151 * output. LED is OFF when the count is less than the value of this 152 * register, and ON when it is greater. If PWMx == 0, LED is always OFF. 153 * 154 * Duty cycle is (256 - PWMx) / 256 155 */ 156 static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val) 157 { 158 struct pca955x_led *pca955x = i2c_get_clientdata(client); 159 160 i2c_smbus_write_byte_data(client, 161 pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n, 162 val); 163 } 164 165 /* 166 * Write to LED selector register, which determines the source that 167 * drives the LED output. 168 */ 169 static void pca955x_write_ls(struct i2c_client *client, int n, u8 val) 170 { 171 struct pca955x_led *pca955x = i2c_get_clientdata(client); 172 173 i2c_smbus_write_byte_data(client, 174 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n, 175 val); 176 } 177 178 /* 179 * Read the LED selector register, which determines the source that 180 * drives the LED output. 181 */ 182 static u8 pca955x_read_ls(struct i2c_client *client, int n) 183 { 184 struct pca955x_led *pca955x = i2c_get_clientdata(client); 185 186 return (u8) i2c_smbus_read_byte_data(client, 187 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n); 188 } 189 190 static void pca955x_led_work(struct work_struct *work) 191 { 192 struct pca955x_led *pca955x; 193 u8 ls; 194 int chip_ls; /* which LSx to use (0-3 potentially) */ 195 int ls_led; /* which set of bits within LSx to use (0-3) */ 196 197 pca955x = container_of(work, struct pca955x_led, work); 198 chip_ls = pca955x->led_num / 4; 199 ls_led = pca955x->led_num % 4; 200 201 ls = pca955x_read_ls(pca955x->client, chip_ls); 202 203 switch (pca955x->brightness) { 204 case LED_FULL: 205 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON); 206 break; 207 case LED_OFF: 208 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF); 209 break; 210 case LED_HALF: 211 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0); 212 break; 213 default: 214 /* 215 * Use PWM1 for all other values. This has the unwanted 216 * side effect of making all LEDs on the chip share the 217 * same brightness level if set to a value other than 218 * OFF, HALF, or FULL. But, this is probably better than 219 * just turning off for all other values. 220 */ 221 pca955x_write_pwm(pca955x->client, 1, 255-pca955x->brightness); 222 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1); 223 break; 224 } 225 226 pca955x_write_ls(pca955x->client, chip_ls, ls); 227 } 228 229 void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness value) 230 { 231 struct pca955x_led *pca955x; 232 233 pca955x = container_of(led_cdev, struct pca955x_led, led_cdev); 234 235 spin_lock(&pca955x->lock); 236 pca955x->brightness = value; 237 238 /* 239 * Must use workqueue for the actual I/O since I2C operations 240 * can sleep. 241 */ 242 schedule_work(&pca955x->work); 243 244 spin_unlock(&pca955x->lock); 245 } 246 247 static int __devinit pca955x_probe(struct i2c_client *client, 248 const struct i2c_device_id *id) 249 { 250 struct pca955x_led *pca955x; 251 int i; 252 int err = -ENODEV; 253 struct pca955x_chipdef *chip; 254 struct i2c_adapter *adapter; 255 struct led_platform_data *pdata; 256 257 chip = &pca955x_chipdefs[id->driver_data]; 258 adapter = to_i2c_adapter(client->dev.parent); 259 pdata = client->dev.platform_data; 260 261 /* Make sure the slave address / chip type combo given is possible */ 262 if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) != 263 chip->slv_addr) { 264 dev_err(&client->dev, "invalid slave address %02x\n", 265 client->addr); 266 return -ENODEV; 267 } 268 269 printk(KERN_INFO "leds-pca955x: Using %s %d-bit LED driver at " 270 "slave address 0x%02x\n", 271 id->name, chip->bits, client->addr); 272 273 if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) 274 return -EIO; 275 276 if (pdata) { 277 if (pdata->num_leds != chip->bits) { 278 dev_err(&client->dev, "board info claims %d LEDs" 279 " on a %d-bit chip\n", 280 pdata->num_leds, chip->bits); 281 return -ENODEV; 282 } 283 } 284 285 for (i = 0; i < chip->bits; i++) { 286 pca955x = kzalloc(sizeof(struct pca955x_led), GFP_KERNEL); 287 if (!pca955x) { 288 err = -ENOMEM; 289 goto exit; 290 } 291 292 pca955x->chipdef = chip; 293 pca955x->client = client; 294 pca955x->led_num = i; 295 /* Platform data can specify LED names and default triggers */ 296 if (pdata) { 297 if (pdata->leds[i].name) 298 snprintf(pca955x->name, 32, "pca955x:%s", 299 pdata->leds[i].name); 300 if (pdata->leds[i].default_trigger) 301 pca955x->led_cdev.default_trigger = 302 pdata->leds[i].default_trigger; 303 } else { 304 snprintf(pca955x->name, 32, "pca955x:%d", i); 305 } 306 spin_lock_init(&pca955x->lock); 307 308 pca955x->led_cdev.name = pca955x->name; 309 pca955x->led_cdev.brightness_set = 310 pca955x_led_set; 311 312 /* 313 * Client data is a pointer to the _first_ pca955x_led 314 * struct 315 */ 316 if (i == 0) 317 i2c_set_clientdata(client, pca955x); 318 319 INIT_WORK(&(pca955x->work), pca955x_led_work); 320 321 led_classdev_register(&client->dev, &(pca955x->led_cdev)); 322 } 323 324 /* Turn off LEDs */ 325 for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++) 326 pca955x_write_ls(client, i, 0x55); 327 328 /* PWM0 is used for half brightness or 50% duty cycle */ 329 pca955x_write_pwm(client, 0, 255-LED_HALF); 330 331 /* PWM1 is used for variable brightness, default to OFF */ 332 pca955x_write_pwm(client, 1, 0); 333 334 /* Set to fast frequency so we do not see flashing */ 335 pca955x_write_psc(client, 0, 0); 336 pca955x_write_psc(client, 1, 0); 337 338 return 0; 339 exit: 340 return err; 341 } 342 343 static int __devexit pca955x_remove(struct i2c_client *client) 344 { 345 struct pca955x_led *pca955x = i2c_get_clientdata(client); 346 int leds = pca955x->chipdef->bits; 347 int i; 348 349 for (i = 0; i < leds; i++) { 350 led_classdev_unregister(&(pca955x->led_cdev)); 351 cancel_work_sync(&(pca955x->work)); 352 kfree(pca955x); 353 pca955x = pca955x + 1; 354 } 355 356 return 0; 357 } 358 359 static struct i2c_driver pca955x_driver = { 360 .driver = { 361 .name = "leds-pca955x", 362 .owner = THIS_MODULE, 363 }, 364 .probe = pca955x_probe, 365 .remove = __devexit_p(pca955x_remove), 366 .id_table = pca955x_id, 367 }; 368 369 static int __init pca955x_leds_init(void) 370 { 371 return i2c_add_driver(&pca955x_driver); 372 } 373 374 static void __exit pca955x_leds_exit(void) 375 { 376 i2c_del_driver(&pca955x_driver); 377 } 378 379 module_init(pca955x_leds_init); 380 module_exit(pca955x_leds_exit); 381 382 MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>"); 383 MODULE_DESCRIPTION("PCA955x LED driver"); 384 MODULE_LICENSE("GPL v2"); 385