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_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 */
 116static inline int pca95xx_num_input_regs(int bits)
 117{
 118        return (bits + 7) / 8;
 119}
 120
 121/* 4 bits per LED selector register */
 122static 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 */
 131static 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 */
 141static 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 */
 157static 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 */
 170static 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 */
 183static 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
 191static 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
 230static 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
 248static 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
 338exit:
 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
 349static 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
 364static 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
 374module_i2c_driver(pca955x_driver);
 375
 376MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
 377MODULE_DESCRIPTION("PCA955x LED driver");
 378MODULE_LICENSE("GPL v2");
 379