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/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");