linux/drivers/leds/leds-pca955x.c
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   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
  59enum pca955x_type {
  60        pca9550,
  61        pca9551,
  62        pca9552,
  63        pca9553,
  64};
  65
  66struct 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
  72static 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
  95static const struct i2c_device_id pca955x_id[] = {
  96        { "pca9550", pca9550 },
  97        { "pca9551", pca9551 },
  98        { "pca9552", pca9552 },
  99        { "pca9553", pca9553 },
 100        { }
 101};
 102MODULE_DEVICE_TABLE(i2c, pca955x_id);
 103
 104struct pca955x {
 105        struct mutex lock;
 106        struct pca955x_led *leds;
 107        struct pca955x_chipdef  *chipdef;
 108        struct i2c_client       *client;
 109};
 110
 111struct 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 */
 121static inline int pca95xx_num_input_regs(int bits)
 122{
 123        return (bits + 7) / 8;
 124}
 125
 126/* 4 bits per LED selector register */
 127static 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 */
 136static 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 */
 146static 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 */
 162static 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 */
 175static 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 */
 188static 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
 196static 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
 243static 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
 258static int 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        dev_info(&client->dev, "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
 357exit:
 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
 366static int 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
 379static struct i2c_driver pca955x_driver = {
 380        .driver = {
 381                .name   = "leds-pca955x",
 382                .owner  = THIS_MODULE,
 383        },
 384        .probe  = pca955x_probe,
 385        .remove = pca955x_remove,
 386        .id_table = pca955x_id,
 387};
 388
 389module_i2c_driver(pca955x_driver);
 390
 391MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
 392MODULE_DESCRIPTION("PCA955x LED driver");
 393MODULE_LICENSE("GPL v2");
 394
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