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
  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");