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/slab.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 { 104 struct mutex lock; 105 struct pca955x_led *leds; 106 struct pca955x_chipdef *chipdef; 107 struct i2c_client *client; 108 }; 109 110 struct pca955x_led { 111 struct pca955x *pca955x; 112 struct led_classdev led_cdev; 113 int led_num; /* 0 .. 15 potentially */ 114 char name[32]; 115 }; 116 117 /* 8 bits per input register */ 118 static inline int pca95xx_num_input_regs(int bits) 119 { 120 return (bits + 7) / 8; 121 } 122 123 /* 4 bits per LED selector register */ 124 static inline int pca95xx_num_led_regs(int bits) 125 { 126 return (bits + 3) / 4; 127 } 128 129 /* 130 * Return an LED selector register value based on an existing one, with 131 * the appropriate 2-bit state value set for the given LED number (0-3). 132 */ 133 static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state) 134 { 135 return (oldval & (~(0x3 << (led_num << 1)))) | 136 ((state & 0x3) << (led_num << 1)); 137 } 138 139 /* 140 * Write to frequency prescaler register, used to program the 141 * period of the PWM output. period = (PSCx + 1) / 38 142 */ 143 static void pca955x_write_psc(struct i2c_client *client, int n, u8 val) 144 { 145 struct pca955x *pca955x = i2c_get_clientdata(client); 146 147 i2c_smbus_write_byte_data(client, 148 pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n, 149 val); 150 } 151 152 /* 153 * Write to PWM register, which determines the duty cycle of the 154 * output. LED is OFF when the count is less than the value of this 155 * register, and ON when it is greater. If PWMx == 0, LED is always OFF. 156 * 157 * Duty cycle is (256 - PWMx) / 256 158 */ 159 static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val) 160 { 161 struct pca955x *pca955x = i2c_get_clientdata(client); 162 163 i2c_smbus_write_byte_data(client, 164 pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n, 165 val); 166 } 167 168 /* 169 * Write to LED selector register, which determines the source that 170 * drives the LED output. 171 */ 172 static void pca955x_write_ls(struct i2c_client *client, int n, u8 val) 173 { 174 struct pca955x *pca955x = i2c_get_clientdata(client); 175 176 i2c_smbus_write_byte_data(client, 177 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n, 178 val); 179 } 180 181 /* 182 * Read the LED selector register, which determines the source that 183 * drives the LED output. 184 */ 185 static u8 pca955x_read_ls(struct i2c_client *client, int n) 186 { 187 struct pca955x *pca955x = i2c_get_clientdata(client); 188 189 return (u8) i2c_smbus_read_byte_data(client, 190 pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n); 191 } 192 193 static int pca955x_led_set(struct led_classdev *led_cdev, 194 enum led_brightness value) 195 { 196 struct pca955x_led *pca955x_led; 197 struct pca955x *pca955x; 198 u8 ls; 199 int chip_ls; /* which LSx to use (0-3 potentially) */ 200 int ls_led; /* which set of bits within LSx to use (0-3) */ 201 202 pca955x_led = container_of(led_cdev, struct pca955x_led, led_cdev); 203 pca955x = pca955x_led->pca955x; 204 205 chip_ls = pca955x_led->led_num / 4; 206 ls_led = pca955x_led->led_num % 4; 207 208 mutex_lock(&pca955x->lock); 209 210 ls = pca955x_read_ls(pca955x->client, chip_ls); 211 212 switch (value) { 213 case LED_FULL: 214 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON); 215 break; 216 case LED_OFF: 217 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF); 218 break; 219 case LED_HALF: 220 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0); 221 break; 222 default: 223 /* 224 * Use PWM1 for all other values. This has the unwanted 225 * side effect of making all LEDs on the chip share the 226 * same brightness level if set to a value other than 227 * OFF, HALF, or FULL. But, this is probably better than 228 * just turning off for all other values. 229 */ 230 pca955x_write_pwm(pca955x->client, 1, 231 255 - value); 232 ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1); 233 break; 234 } 235 236 pca955x_write_ls(pca955x->client, chip_ls, ls); 237 238 mutex_unlock(&pca955x->lock); 239 240 return 0; 241 } 242 243 static int pca955x_probe(struct i2c_client *client, 244 const struct i2c_device_id *id) 245 { 246 struct pca955x *pca955x; 247 struct pca955x_led *pca955x_led; 248 struct pca955x_chipdef *chip; 249 struct i2c_adapter *adapter; 250 struct led_platform_data *pdata; 251 int i, err; 252 253 chip = &pca955x_chipdefs[id->driver_data]; 254 adapter = to_i2c_adapter(client->dev.parent); 255 pdata = dev_get_platdata(&client->dev); 256 257 /* Make sure the slave address / chip type combo given is possible */ 258 if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) != 259 chip->slv_addr) { 260 dev_err(&client->dev, "invalid slave address %02x\n", 261 client->addr); 262 return -ENODEV; 263 } 264 265 dev_info(&client->dev, "leds-pca955x: Using %s %d-bit LED driver at " 266 "slave address 0x%02x\n", 267 id->name, chip->bits, client->addr); 268 269 if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) 270 return -EIO; 271 272 if (pdata) { 273 if (pdata->num_leds != chip->bits) { 274 dev_err(&client->dev, "board info claims %d LEDs" 275 " on a %d-bit chip\n", 276 pdata->num_leds, chip->bits); 277 return -ENODEV; 278 } 279 } 280 281 pca955x = devm_kzalloc(&client->dev, sizeof(*pca955x), GFP_KERNEL); 282 if (!pca955x) 283 return -ENOMEM; 284 285 pca955x->leds = devm_kzalloc(&client->dev, 286 sizeof(*pca955x_led) * chip->bits, GFP_KERNEL); 287 if (!pca955x->leds) 288 return -ENOMEM; 289 290 i2c_set_clientdata(client, pca955x); 291 292 mutex_init(&pca955x->lock); 293 pca955x->client = client; 294 pca955x->chipdef = chip; 295 296 for (i = 0; i < chip->bits; i++) { 297 pca955x_led = &pca955x->leds[i]; 298 pca955x_led->led_num = i; 299 pca955x_led->pca955x = pca955x; 300 301 /* Platform data can specify LED names and default triggers */ 302 if (pdata) { 303 if (pdata->leds[i].name) 304 snprintf(pca955x_led->name, 305 sizeof(pca955x_led->name), "pca955x:%s", 306 pdata->leds[i].name); 307 if (pdata->leds[i].default_trigger) 308 pca955x_led->led_cdev.default_trigger = 309 pdata->leds[i].default_trigger; 310 } else { 311 snprintf(pca955x_led->name, sizeof(pca955x_led->name), 312 "pca955x:%d", i); 313 } 314 315 pca955x_led->led_cdev.name = pca955x_led->name; 316 pca955x_led->led_cdev.brightness_set_blocking = pca955x_led_set; 317 318 err = led_classdev_register(&client->dev, 319 &pca955x_led->led_cdev); 320 if (err < 0) 321 goto exit; 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; 339 340 exit: 341 while (i--) 342 led_classdev_unregister(&pca955x->leds[i].led_cdev); 343 344 return err; 345 } 346 347 static int pca955x_remove(struct i2c_client *client) 348 { 349 struct pca955x *pca955x = i2c_get_clientdata(client); 350 int i; 351 352 for (i = 0; i < pca955x->chipdef->bits; i++) 353 led_classdev_unregister(&pca955x->leds[i].led_cdev); 354 355 return 0; 356 } 357 358 static struct i2c_driver pca955x_driver = { 359 .driver = { 360 .name = "leds-pca955x", 361 }, 362 .probe = pca955x_probe, 363 .remove = pca955x_remove, 364 .id_table = pca955x_id, 365 }; 366 367 module_i2c_driver(pca955x_driver); 368 369 MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>"); 370 MODULE_DESCRIPTION("PCA955x LED driver"); 371 MODULE_LICENSE("GPL v2"); 372