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 #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 struct pca955x { 105 struct mutex lock; 106 struct pca955x_led *leds; 107 struct pca955x_chipdef *chipdef; 108 struct i2c_client *client; 109 }; 110 111 struct pca955x_led { 112 struct pca955x *pca955x; 113 struct work_struct work; 114 enum led_brightness brightness; 115 struct led_classdev led_cdev; 116 int led_num; /* 0 .. 15 potentially */ 117 char name[32]; 118 }; 119 120 /* 8 bits per input register */ 121 static inline int pca95xx_num_input_regs(int bits) 122 { 123 return (bits + 7) / 8; 124 } 125 126 /* 4 bits per LED selector register */ 127 static inline int pca95xx_num_led_regs(int bits) 128 { 129 return (bits + 3) / 4; 130 } 131 132 /* 133 * Return an LED selector register value based on an existing one, with 134 * the appropriate 2-bit state value set for the given LED number (0-3). 135 */ 136 static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state) 137 { 138 return (oldval & (~(0x3 << (led_num << 1)))) | 139 ((state & 0x3) << (led_num << 1)); 140 } 141 142 /* 143 * Write to frequency prescaler register, used to program the 144 * period of the PWM output. period = (PSCx + 1) / 38 145 */ 146 static void pca955x_write_psc(struct i2c_client *client, int n, u8 val) 147 { 148 struct pca955x *pca955x = i2c_get_clientdata(client); 149 150 i2c_smbus_write_byte_data(client, 151 pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n, 152 val); 153 } 154 155 /* 156 * Write to PWM register, which determines the duty cycle of the 157 * output. LED is OFF when the count is less than the value of this 158 * register, and ON when it is greater. If PWMx == 0, LED is always OFF. 159 * 160 * Duty cycle is (256 - PWMx) / 256 161 */ 162 static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val) 163 { 164 struct pca955x *pca955x = i2c_get_clientdata(client); 165 166 i2c_smbus_write_byte_data(client, 167 pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n, 168 val); 169 } 170 171 /* 172 * Write to LED selector register, which determines the source that 173 * drives the LED output. 174 */ 175 static void pca955x_write_ls(struct i2c_client *client, int n, u8 val) 176 { 177 struct pca955x *pca955x = i2c_get_clientdata(client); 178 179 i2c_smbus_write_byte_data(client, 180 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n, 181 val); 182 } 183 184 /* 185 * Read the LED selector register, which determines the source that 186 * drives the LED output. 187 */ 188 static u8 pca955x_read_ls(struct i2c_client *client, int n) 189 { 190 struct pca955x *pca955x = i2c_get_clientdata(client); 191 192 return (u8) i2c_smbus_read_byte_data(client, 193 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n); 194 } 195 196 static void pca955x_led_work(struct work_struct *work) 197 { 198 struct pca955x_led *pca955x_led; 199 struct pca955x *pca955x; 200 u8 ls; 201 int chip_ls; /* which LSx to use (0-3 potentially) */ 202 int ls_led; /* which set of bits within LSx to use (0-3) */ 203 204 pca955x_led = container_of(work, struct pca955x_led, work); 205 pca955x = pca955x_led->pca955x; 206 207 chip_ls = pca955x_led->led_num / 4; 208 ls_led = pca955x_led->led_num % 4; 209 210 mutex_lock(&pca955x->lock); 211 212 ls = pca955x_read_ls(pca955x->client, chip_ls); 213 214 switch (pca955x_led->brightness) { 215 case LED_FULL: 216 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON); 217 break; 218 case LED_OFF: 219 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF); 220 break; 221 case LED_HALF: 222 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0); 223 break; 224 default: 225 /* 226 * Use PWM1 for all other values. This has the unwanted 227 * side effect of making all LEDs on the chip share the 228 * same brightness level if set to a value other than 229 * OFF, HALF, or FULL. But, this is probably better than 230 * just turning off for all other values. 231 */ 232 pca955x_write_pwm(pca955x->client, 1, 233 255 - pca955x_led->brightness); 234 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1); 235 break; 236 } 237 238 pca955x_write_ls(pca955x->client, chip_ls, ls); 239 240 mutex_unlock(&pca955x->lock); 241 } 242 243 static void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness value) 244 { 245 struct pca955x_led *pca955x; 246 247 pca955x = container_of(led_cdev, struct pca955x_led, led_cdev); 248 249 pca955x->brightness = value; 250 251 /* 252 * Must use workqueue for the actual I/O since I2C operations 253 * can sleep. 254 */ 255 schedule_work(&pca955x->work); 256 } 257 258 static int __devinit pca955x_probe(struct i2c_client *client, 259 const struct i2c_device_id *id) 260 { 261 struct pca955x *pca955x; 262 struct pca955x_led *pca955x_led; 263 struct pca955x_chipdef *chip; 264 struct i2c_adapter *adapter; 265 struct led_platform_data *pdata; 266 int i, err; 267 268 chip = &pca955x_chipdefs[id->driver_data]; 269 adapter = to_i2c_adapter(client->dev.parent); 270 pdata = client->dev.platform_data; 271 272 /* Make sure the slave address / chip type combo given is possible */ 273 if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) != 274 chip->slv_addr) { 275 dev_err(&client->dev, "invalid slave address %02x\n", 276 client->addr); 277 return -ENODEV; 278 } 279 280 printk(KERN_INFO "leds-pca955x: Using %s %d-bit LED driver at " 281 "slave address 0x%02x\n", 282 id->name, chip->bits, client->addr); 283 284 if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) 285 return -EIO; 286 287 if (pdata) { 288 if (pdata->num_leds != chip->bits) { 289 dev_err(&client->dev, "board info claims %d LEDs" 290 " on a %d-bit chip\n", 291 pdata->num_leds, chip->bits); 292 return -ENODEV; 293 } 294 } 295 296 pca955x = devm_kzalloc(&client->dev, sizeof(*pca955x), GFP_KERNEL); 297 if (!pca955x) 298 return -ENOMEM; 299 300 pca955x->leds = devm_kzalloc(&client->dev, 301 sizeof(*pca955x_led) * chip->bits, GFP_KERNEL); 302 if (!pca955x->leds) 303 return -ENOMEM; 304 305 i2c_set_clientdata(client, pca955x); 306 307 mutex_init(&pca955x->lock); 308 pca955x->client = client; 309 pca955x->chipdef = chip; 310 311 for (i = 0; i < chip->bits; i++) { 312 pca955x_led = &pca955x->leds[i]; 313 pca955x_led->led_num = i; 314 pca955x_led->pca955x = pca955x; 315 316 /* Platform data can specify LED names and default triggers */ 317 if (pdata) { 318 if (pdata->leds[i].name) 319 snprintf(pca955x_led->name, 320 sizeof(pca955x_led->name), "pca955x:%s", 321 pdata->leds[i].name); 322 if (pdata->leds[i].default_trigger) 323 pca955x_led->led_cdev.default_trigger = 324 pdata->leds[i].default_trigger; 325 } else { 326 snprintf(pca955x_led->name, sizeof(pca955x_led->name), 327 "pca955x:%d", i); 328 } 329 330 pca955x_led->led_cdev.name = pca955x_led->name; 331 pca955x_led->led_cdev.brightness_set = pca955x_led_set; 332 333 INIT_WORK(&pca955x_led->work, pca955x_led_work); 334 335 err = led_classdev_register(&client->dev, 336 &pca955x_led->led_cdev); 337 if (err < 0) 338 goto exit; 339 } 340 341 /* Turn off LEDs */ 342 for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++) 343 pca955x_write_ls(client, i, 0x55); 344 345 /* PWM0 is used for half brightness or 50% duty cycle */ 346 pca955x_write_pwm(client, 0, 255-LED_HALF); 347 348 /* PWM1 is used for variable brightness, default to OFF */ 349 pca955x_write_pwm(client, 1, 0); 350 351 /* Set to fast frequency so we do not see flashing */ 352 pca955x_write_psc(client, 0, 0); 353 pca955x_write_psc(client, 1, 0); 354 355 return 0; 356 357 exit: 358 while (i--) { 359 led_classdev_unregister(&pca955x->leds[i].led_cdev); 360 cancel_work_sync(&pca955x->leds[i].work); 361 } 362 363 return err; 364 } 365 366 static int __devexit 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 cancel_work_sync(&pca955x->leds[i].work); 374 } 375 376 return 0; 377 } 378 379 static struct i2c_driver pca955x_driver = { 380 .driver = { 381 .name = "leds-pca955x", 382 .owner = THIS_MODULE, 383 }, 384 .probe = pca955x_probe, 385 .remove = __devexit_p(pca955x_remove), 386 .id_table = pca955x_id, 387 }; 388 389 module_i2c_driver(pca955x_driver); 390 391 MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>"); 392 MODULE_DESCRIPTION("PCA955x LED driver"); 393 MODULE_LICENSE("GPL v2"); 394