drivers/leds/leds-pca955x.c

   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");