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_led { 105 struct pca955x_chipdef *chipdef; 106 struct i2c_client *client; 107 struct work_struct work; 108 spinlock_t lock; 109 enum led_brightness brightness; 110 struct led_classdev led_cdev; 111 int led_num; /* 0 .. 15 potentially */ 112 char name[32]; 113 }; 114 115 /* 8 bits per input register */ 116 static inline int pca95xx_num_input_regs(int bits) 117 { 118 return (bits + 7) / 8; 119 } 120 121 /* 4 bits per LED selector register */ 122 static inline int pca95xx_num_led_regs(int bits) 123 { 124 return (bits + 3) / 4; 125 } 126 127 /* 128 * Return an LED selector register value based on an existing one, with 129 * the appropriate 2-bit state value set for the given LED number (0-3). 130 */ 131 static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state) 132 { 133 return (oldval & (~(0x3 << (led_num << 1)))) | 134 ((state & 0x3) << (led_num << 1)); 135 } 136 137 /* 138 * Write to frequency prescaler register, used to program the 139 * period of the PWM output. period = (PSCx + 1) / 38 140 */ 141 static void pca955x_write_psc(struct i2c_client *client, int n, u8 val) 142 { 143 struct pca955x_led *pca955x = i2c_get_clientdata(client); 144 145 i2c_smbus_write_byte_data(client, 146 pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n, 147 val); 148 } 149 150 /* 151 * Write to PWM register, which determines the duty cycle of the 152 * output. LED is OFF when the count is less than the value of this 153 * register, and ON when it is greater. If PWMx == 0, LED is always OFF. 154 * 155 * Duty cycle is (256 - PWMx) / 256 156 */ 157 static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val) 158 { 159 struct pca955x_led *pca955x = i2c_get_clientdata(client); 160 161 i2c_smbus_write_byte_data(client, 162 pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n, 163 val); 164 } 165 166 /* 167 * Write to LED selector register, which determines the source that 168 * drives the LED output. 169 */ 170 static void pca955x_write_ls(struct i2c_client *client, int n, u8 val) 171 { 172 struct pca955x_led *pca955x = i2c_get_clientdata(client); 173 174 i2c_smbus_write_byte_data(client, 175 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n, 176 val); 177 } 178 179 /* 180 * Read the LED selector register, which determines the source that 181 * drives the LED output. 182 */ 183 static u8 pca955x_read_ls(struct i2c_client *client, int n) 184 { 185 struct pca955x_led *pca955x = i2c_get_clientdata(client); 186 187 return (u8) i2c_smbus_read_byte_data(client, 188 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n); 189 } 190 191 static void pca955x_led_work(struct work_struct *work) 192 { 193 struct pca955x_led *pca955x; 194 u8 ls; 195 int chip_ls; /* which LSx to use (0-3 potentially) */ 196 int ls_led; /* which set of bits within LSx to use (0-3) */ 197 198 pca955x = container_of(work, struct pca955x_led, work); 199 chip_ls = pca955x->led_num / 4; 200 ls_led = pca955x->led_num % 4; 201 202 ls = pca955x_read_ls(pca955x->client, chip_ls); 203 204 switch (pca955x->brightness) { 205 case LED_FULL: 206 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON); 207 break; 208 case LED_OFF: 209 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF); 210 break; 211 case LED_HALF: 212 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0); 213 break; 214 default: 215 /* 216 * Use PWM1 for all other values. This has the unwanted 217 * side effect of making all LEDs on the chip share the 218 * same brightness level if set to a value other than 219 * OFF, HALF, or FULL. But, this is probably better than 220 * just turning off for all other values. 221 */ 222 pca955x_write_pwm(pca955x->client, 1, 255-pca955x->brightness); 223 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1); 224 break; 225 } 226 227 pca955x_write_ls(pca955x->client, chip_ls, ls); 228 } 229 230 static void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness value) 231 { 232 struct pca955x_led *pca955x; 233 234 pca955x = container_of(led_cdev, struct pca955x_led, led_cdev); 235 236 spin_lock(&pca955x->lock); 237 pca955x->brightness = value; 238 239 /* 240 * Must use workqueue for the actual I/O since I2C operations 241 * can sleep. 242 */ 243 schedule_work(&pca955x->work); 244 245 spin_unlock(&pca955x->lock); 246 } 247 248 static int __devinit pca955x_probe(struct i2c_client *client, 249 const struct i2c_device_id *id) 250 { 251 struct pca955x_led *pca955x; 252 struct pca955x_chipdef *chip; 253 struct i2c_adapter *adapter; 254 struct led_platform_data *pdata; 255 int i, err; 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 pca955x = kzalloc(sizeof(*pca955x) * chip->bits, GFP_KERNEL); 286 if (!pca955x) 287 return -ENOMEM; 288 289 i2c_set_clientdata(client, pca955x); 290 291 for (i = 0; i < chip->bits; i++) { 292 pca955x[i].chipdef = chip; 293 pca955x[i].client = client; 294 pca955x[i].led_num = i; 295 296 /* Platform data can specify LED names and default triggers */ 297 if (pdata) { 298 if (pdata->leds[i].name) 299 snprintf(pca955x[i].name, 300 sizeof(pca955x[i].name), "pca955x:%s", 301 pdata->leds[i].name); 302 if (pdata->leds[i].default_trigger) 303 pca955x[i].led_cdev.default_trigger = 304 pdata->leds[i].default_trigger; 305 } else { 306 snprintf(pca955x[i].name, sizeof(pca955x[i].name), 307 "pca955x:%d", i); 308 } 309 310 spin_lock_init(&pca955x[i].lock); 311 312 pca955x[i].led_cdev.name = pca955x[i].name; 313 pca955x[i].led_cdev.brightness_set = pca955x_led_set; 314 315 INIT_WORK(&pca955x[i].work, pca955x_led_work); 316 317 err = led_classdev_register(&client->dev, &pca955x[i].led_cdev); 318 if (err < 0) 319 goto exit; 320 } 321 322 /* Turn off LEDs */ 323 for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++) 324 pca955x_write_ls(client, i, 0x55); 325 326 /* PWM0 is used for half brightness or 50% duty cycle */ 327 pca955x_write_pwm(client, 0, 255-LED_HALF); 328 329 /* PWM1 is used for variable brightness, default to OFF */ 330 pca955x_write_pwm(client, 1, 0); 331 332 /* Set to fast frequency so we do not see flashing */ 333 pca955x_write_psc(client, 0, 0); 334 pca955x_write_psc(client, 1, 0); 335 336 return 0; 337 338 exit: 339 while (i--) { 340 led_classdev_unregister(&pca955x[i].led_cdev); 341 cancel_work_sync(&pca955x[i].work); 342 } 343 344 kfree(pca955x); 345 346 return err; 347 } 348 349 static int __devexit pca955x_remove(struct i2c_client *client) 350 { 351 struct pca955x_led *pca955x = i2c_get_clientdata(client); 352 int i; 353 354 for (i = 0; i < pca955x->chipdef->bits; i++) { 355 led_classdev_unregister(&pca955x[i].led_cdev); 356 cancel_work_sync(&pca955x[i].work); 357 } 358 359 kfree(pca955x); 360 361 return 0; 362 } 363 364 static struct i2c_driver pca955x_driver = { 365 .driver = { 366 .name = "leds-pca955x", 367 .owner = THIS_MODULE, 368 }, 369 .probe = pca955x_probe, 370 .remove = __devexit_p(pca955x_remove), 371 .id_table = pca955x_id, 372 }; 373 374 static int __init pca955x_leds_init(void) 375 { 376 return i2c_add_driver(&pca955x_driver); 377 } 378 379 static void __exit pca955x_leds_exit(void) 380 { 381 i2c_del_driver(&pca955x_driver); 382 } 383 384 module_init(pca955x_leds_init); 385 module_exit(pca955x_leds_exit); 386 387 MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>"); 388 MODULE_DESCRIPTION("PCA955x LED driver"); 389 MODULE_LICENSE("GPL v2"); 390