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_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 module_i2c_driver(pca955x_driver);
 375
 376 MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
 377 MODULE_DESCRIPTION("PCA955x LED driver");
 378 MODULE_LICENSE("GPL v2");