drivers/rtc/rtc-isl12026.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * An I2C driver for the Intersil ISL 12026
   4  *
   5  * Copyright (c) 2018 Cavium, Inc.
   6  */
   7 #include <linux/bcd.h>
   8 #include <linux/delay.h>
   9 #include <linux/i2c.h>
  10 #include <linux/module.h>
  11 #include <linux/mutex.h>
  12 #include <linux/nvmem-provider.h>
  13 #include <linux/of.h>
  14 #include <linux/of_device.h>
  15 #include <linux/rtc.h>
  16 #include <linux/slab.h>
  17
  18 /* register offsets */
  19 #define ISL12026_REG_PWR        0x14
  20 # define ISL12026_REG_PWR_BSW   BIT(6)
  21 # define ISL12026_REG_PWR_SBIB  BIT(7)
  22 #define ISL12026_REG_SC         0x30
  23 #define ISL12026_REG_HR         0x32
  24 # define ISL12026_REG_HR_MIL    BIT(7)  /* military or 24 hour time */
  25 #define ISL12026_REG_SR         0x3f
  26 # define ISL12026_REG_SR_RTCF   BIT(0)
  27 # define ISL12026_REG_SR_WEL    BIT(1)
  28 # define ISL12026_REG_SR_RWEL   BIT(2)
  29 # define ISL12026_REG_SR_MBZ    BIT(3)
  30 # define ISL12026_REG_SR_OSCF   BIT(4)
  31
  32 /* The EEPROM array responds at i2c address 0x57 */
  33 #define ISL12026_EEPROM_ADDR    0x57
  34
  35 #define ISL12026_PAGESIZE 16
  36 #define ISL12026_NVMEM_WRITE_TIME 20
  37
  38 struct isl12026 {
  39         struct rtc_device *rtc;
  40         struct i2c_client *nvm_client;
  41 };
  42
  43 static int isl12026_read_reg(struct i2c_client *client, int reg)
  44 {
  45         u8 addr[] = {0, reg};
  46         u8 val;
  47         int ret;
  48
  49         struct i2c_msg msgs[] = {
  50                 {
  51                         .addr   = client->addr,
  52                         .flags  = 0,
  53                         .len    = sizeof(addr),
  54                         .buf    = addr
  55                 }, {
  56                         .addr   = client->addr,
  57                         .flags  = I2C_M_RD,
  58                         .len    = 1,
  59                         .buf    = &val
  60                 }
  61         };
  62
  63         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
  64         if (ret != ARRAY_SIZE(msgs)) {
  65                 dev_err(&client->dev, "read reg error, ret=%d\n", ret);
  66                 ret = ret < 0 ? ret : -EIO;
  67         } else {
  68                 ret = val;
  69         }
  70
  71         return ret;
  72 }
  73
  74 static int isl12026_arm_write(struct i2c_client *client)
  75 {
  76         int ret;
  77         u8 op[3];
  78         struct i2c_msg msg = {
  79                 .addr   = client->addr,
  80                 .flags  = 0,
  81                 .len    = 1,
  82                 .buf    = op
  83         };
  84
  85         /* Set SR.WEL */
  86         op[0] = 0;
  87         op[1] = ISL12026_REG_SR;
  88         op[2] = ISL12026_REG_SR_WEL;
  89         msg.len = 3;
  90         ret = i2c_transfer(client->adapter, &msg, 1);
  91         if (ret != 1) {
  92                 dev_err(&client->dev, "write error SR.WEL, ret=%d\n", ret);
  93                 ret = ret < 0 ? ret : -EIO;
  94                 goto out;
  95         }
  96
  97         /* Set SR.WEL and SR.RWEL */
  98         op[2] = ISL12026_REG_SR_WEL | ISL12026_REG_SR_RWEL;
  99         msg.len = 3;
 100         ret = i2c_transfer(client->adapter, &msg, 1);
 101         if (ret != 1) {
 102                 dev_err(&client->dev,
 103                         "write error SR.WEL|SR.RWEL, ret=%d\n", ret);
 104                 ret = ret < 0 ? ret : -EIO;
 105                 goto out;
 106         } else {
 107                 ret = 0;
 108         }
 109 out:
 110         return ret;
 111 }
 112
 113 static int isl12026_disarm_write(struct i2c_client *client)
 114 {
 115         int ret;
 116         u8 op[3] = {0, ISL12026_REG_SR, 0};
 117         struct i2c_msg msg = {
 118                 .addr   = client->addr,
 119                 .flags  = 0,
 120                 .len    = sizeof(op),
 121                 .buf    = op
 122         };
 123
 124         ret = i2c_transfer(client->adapter, &msg, 1);
 125         if (ret != 1) {
 126                 dev_err(&client->dev,
 127                         "write error SR, ret=%d\n", ret);
 128                 ret = ret < 0 ? ret : -EIO;
 129         } else {
 130                 ret = 0;
 131         }
 132
 133         return ret;
 134 }
 135
 136 static int isl12026_write_reg(struct i2c_client *client, int reg, u8 val)
 137 {
 138         int ret;
 139         u8 op[3] = {0, reg, val};
 140         struct i2c_msg msg = {
 141                 .addr   = client->addr,
 142                 .flags  = 0,
 143                 .len    = sizeof(op),
 144                 .buf    = op
 145         };
 146
 147         ret = isl12026_arm_write(client);
 148         if (ret)
 149                 return ret;
 150
 151         ret = i2c_transfer(client->adapter, &msg, 1);
 152         if (ret != 1) {
 153                 dev_err(&client->dev, "write error CCR, ret=%d\n", ret);
 154                 ret = ret < 0 ? ret : -EIO;
 155                 goto out;
 156         }
 157
 158         msleep(ISL12026_NVMEM_WRITE_TIME);
 159
 160         ret = isl12026_disarm_write(client);
 161 out:
 162         return ret;
 163 }
 164
 165 static int isl12026_rtc_set_time(struct device *dev, struct rtc_time *tm)
 166 {
 167         struct i2c_client *client = to_i2c_client(dev);
 168         int ret;
 169         u8 op[10];
 170         struct i2c_msg msg = {
 171                 .addr   = client->addr,
 172                 .flags  = 0,
 173                 .len    = sizeof(op),
 174                 .buf    = op
 175         };
 176
 177         ret = isl12026_arm_write(client);
 178         if (ret)
 179                 return ret;
 180
 181         /* Set the CCR registers */
 182         op[0] = 0;
 183         op[1] = ISL12026_REG_SC;
 184         op[2] = bin2bcd(tm->tm_sec); /* SC */
 185         op[3] = bin2bcd(tm->tm_min); /* MN */
 186         op[4] = bin2bcd(tm->tm_hour) | ISL12026_REG_HR_MIL; /* HR */
 187         op[5] = bin2bcd(tm->tm_mday); /* DT */
 188         op[6] = bin2bcd(tm->tm_mon + 1); /* MO */
 189         op[7] = bin2bcd(tm->tm_year % 100); /* YR */
 190         op[8] = bin2bcd(tm->tm_wday & 7); /* DW */
 191         op[9] = bin2bcd(tm->tm_year >= 100 ? 20 : 19); /* Y2K */
 192         ret = i2c_transfer(client->adapter, &msg, 1);
 193         if (ret != 1) {
 194                 dev_err(&client->dev, "write error CCR, ret=%d\n", ret);
 195                 ret = ret < 0 ? ret : -EIO;
 196                 goto out;
 197         }
 198
 199         ret = isl12026_disarm_write(client);
 200 out:
 201         return ret;
 202 }
 203
 204 static int isl12026_rtc_read_time(struct device *dev, struct rtc_time *tm)
 205 {
 206         struct i2c_client *client = to_i2c_client(dev);
 207         u8 ccr[8];
 208         u8 addr[2];
 209         u8 sr;
 210         int ret;
 211         struct i2c_msg msgs[] = {
 212                 {
 213                         .addr   = client->addr,
 214                         .flags  = 0,
 215                         .len    = sizeof(addr),
 216                         .buf    = addr
 217                 }, {
 218                         .addr   = client->addr,
 219                         .flags  = I2C_M_RD,
 220                 }
 221         };
 222
 223         /* First, read SR */
 224         addr[0] = 0;
 225         addr[1] = ISL12026_REG_SR;
 226         msgs[1].len = 1;
 227         msgs[1].buf = &sr;
 228
 229         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 230         if (ret != ARRAY_SIZE(msgs)) {
 231                 dev_err(&client->dev, "read error, ret=%d\n", ret);
 232                 ret = ret < 0 ? ret : -EIO;
 233                 goto out;
 234         }
 235
 236         if (sr & ISL12026_REG_SR_RTCF)
 237                 dev_warn(&client->dev, "Real-Time Clock Failure on read\n");
 238         if (sr & ISL12026_REG_SR_OSCF)
 239                 dev_warn(&client->dev, "Oscillator Failure on read\n");
 240
 241         /* Second, CCR regs */
 242         addr[0] = 0;
 243         addr[1] = ISL12026_REG_SC;
 244         msgs[1].len = sizeof(ccr);
 245         msgs[1].buf = ccr;
 246
 247         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 248         if (ret != ARRAY_SIZE(msgs)) {
 249                 dev_err(&client->dev, "read error, ret=%d\n", ret);
 250                 ret = ret < 0 ? ret : -EIO;
 251                 goto out;
 252         }
 253
 254         tm->tm_sec = bcd2bin(ccr[0] & 0x7F);
 255         tm->tm_min = bcd2bin(ccr[1] & 0x7F);
 256         if (ccr[2] & ISL12026_REG_HR_MIL)
 257                 tm->tm_hour = bcd2bin(ccr[2] & 0x3F);
 258         else
 259                 tm->tm_hour = bcd2bin(ccr[2] & 0x1F) +
 260                         ((ccr[2] & 0x20) ? 12 : 0);
 261         tm->tm_mday = bcd2bin(ccr[3] & 0x3F);
 262         tm->tm_mon = bcd2bin(ccr[4] & 0x1F) - 1;
 263         tm->tm_year = bcd2bin(ccr[5]);
 264         if (bcd2bin(ccr[7]) == 20)
 265                 tm->tm_year += 100;
 266         tm->tm_wday = ccr[6] & 0x07;
 267
 268         ret = 0;
 269 out:
 270         return ret;
 271 }
 272
 273 static const struct rtc_class_ops isl12026_rtc_ops = {
 274         .read_time      = isl12026_rtc_read_time,
 275         .set_time       = isl12026_rtc_set_time,
 276 };
 277
 278 static int isl12026_nvm_read(void *p, unsigned int offset,
 279                              void *val, size_t bytes)
 280 {
 281         struct isl12026 *priv = p;
 282         int ret;
 283         u8 addr[2];
 284         struct i2c_msg msgs[] = {
 285                 {
 286                         .addr   = priv->nvm_client->addr,
 287                         .flags  = 0,
 288                         .len    = sizeof(addr),
 289                         .buf    = addr
 290                 }, {
 291                         .addr   = priv->nvm_client->addr,
 292                         .flags  = I2C_M_RD,
 293                         .buf    = val
 294                 }
 295         };
 296
 297         /*
 298          * offset and bytes checked and limited by nvmem core, so
 299          * proceed without further checks.
 300          */
 301         ret = mutex_lock_interruptible(&priv->rtc->ops_lock);
 302         if (ret)
 303                 return ret;
 304
 305         /* 2 bytes of address, most significant first */
 306         addr[0] = offset >> 8;
 307         addr[1] = offset;
 308         msgs[1].len = bytes;
 309         ret = i2c_transfer(priv->nvm_client->adapter, msgs, ARRAY_SIZE(msgs));
 310
 311         mutex_unlock(&priv->rtc->ops_lock);
 312
 313         if (ret != ARRAY_SIZE(msgs)) {
 314                 dev_err(&priv->nvm_client->dev,
 315                         "nvmem read error, ret=%d\n", ret);
 316                 return ret < 0 ? ret : -EIO;
 317         }
 318
 319         return 0;
 320 }
 321
 322 static int isl12026_nvm_write(void *p, unsigned int offset,
 323                               void *val, size_t bytes)
 324 {
 325         struct isl12026 *priv = p;
 326         int ret;
 327         u8 *v = val;
 328         size_t chunk_size, num_written;
 329         u8 payload[ISL12026_PAGESIZE + 2]; /* page + 2 address bytes */
 330         struct i2c_msg msgs[] = {
 331                 {
 332                         .addr   = priv->nvm_client->addr,
 333                         .flags  = 0,
 334                         .buf    = payload
 335                 }
 336         };
 337
 338         /*
 339          * offset and bytes checked and limited by nvmem core, so
 340          * proceed without further checks.
 341          */
 342         ret = mutex_lock_interruptible(&priv->rtc->ops_lock);
 343         if (ret)
 344                 return ret;
 345
 346         num_written = 0;
 347         while (bytes) {
 348                 chunk_size = round_down(offset, ISL12026_PAGESIZE) +
 349                         ISL12026_PAGESIZE - offset;
 350                 chunk_size = min(bytes, chunk_size);
 351                 /*
 352                  * 2 bytes of address, most significant first, followed
 353                  * by page data bytes
 354                  */
 355                 memcpy(payload + 2, v + num_written, chunk_size);
 356                 payload[0] = offset >> 8;
 357                 payload[1] = offset;
 358                 msgs[0].len = chunk_size + 2;
 359                 ret = i2c_transfer(priv->nvm_client->adapter,
 360                                    msgs, ARRAY_SIZE(msgs));
 361                 if (ret != ARRAY_SIZE(msgs)) {
 362                         dev_err(&priv->nvm_client->dev,
 363                                 "nvmem write error, ret=%d\n", ret);
 364                         ret = ret < 0 ? ret : -EIO;
 365                         break;
 366                 }
 367                 ret = 0;
 368                 bytes -= chunk_size;
 369                 offset += chunk_size;
 370                 num_written += chunk_size;
 371                 msleep(ISL12026_NVMEM_WRITE_TIME);
 372         }
 373
 374         mutex_unlock(&priv->rtc->ops_lock);
 375
 376         return ret;
 377 }
 378
 379 static void isl12026_force_power_modes(struct i2c_client *client)
 380 {
 381         int ret;
 382         int pwr, requested_pwr;
 383         u32 bsw_val, sbib_val;
 384         bool set_bsw, set_sbib;
 385
 386         /*
 387          * If we can read the of_property, set the specified value.
 388          * If there is an error reading the of_property (likely
 389          * because it does not exist), keep the current value.
 390          */
 391         ret = of_property_read_u32(client->dev.of_node,
 392                                    "isil,pwr-bsw", &bsw_val);
 393         set_bsw = (ret == 0);
 394
 395         ret = of_property_read_u32(client->dev.of_node,
 396                                    "isil,pwr-sbib", &sbib_val);
 397         set_sbib = (ret == 0);
 398
 399         /* Check if PWR.BSW and/or PWR.SBIB need specified values */
 400         if (!set_bsw && !set_sbib)
 401                 return;
 402
 403         pwr = isl12026_read_reg(client, ISL12026_REG_PWR);
 404         if (pwr < 0) {
 405                 dev_warn(&client->dev, "Error: Failed to read PWR %d\n", pwr);
 406                 return;
 407         }
 408
 409         requested_pwr = pwr;
 410
 411         if (set_bsw) {
 412                 if (bsw_val)
 413                         requested_pwr |= ISL12026_REG_PWR_BSW;
 414                 else
 415                         requested_pwr &= ~ISL12026_REG_PWR_BSW;
 416         } /* else keep current BSW */
 417
 418         if (set_sbib) {
 419                 if (sbib_val)
 420                         requested_pwr |= ISL12026_REG_PWR_SBIB;
 421                 else
 422                         requested_pwr &= ~ISL12026_REG_PWR_SBIB;
 423         } /* else keep current SBIB */
 424
 425         if (pwr >= 0 && pwr != requested_pwr) {
 426                 dev_dbg(&client->dev, "PWR: %02x\n", pwr);
 427                 dev_dbg(&client->dev, "Updating PWR to: %02x\n", requested_pwr);
 428                 isl12026_write_reg(client, ISL12026_REG_PWR, requested_pwr);
 429         }
 430 }
 431
 432 static int isl12026_probe_new(struct i2c_client *client)
 433 {
 434         struct isl12026 *priv;
 435         int ret;
 436         struct nvmem_config nvm_cfg = {
 437                 .name = "isl12026-",
 438                 .base_dev = &client->dev,
 439                 .stride = 1,
 440                 .word_size = 1,
 441                 .size = 512,
 442                 .reg_read = isl12026_nvm_read,
 443                 .reg_write = isl12026_nvm_write,
 444         };
 445
 446         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 447                 return -ENODEV;
 448
 449         priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
 450         if (!priv)
 451                 return -ENOMEM;
 452
 453         i2c_set_clientdata(client, priv);
 454
 455         isl12026_force_power_modes(client);
 456
 457         priv->nvm_client = i2c_new_dummy_device(client->adapter, ISL12026_EEPROM_ADDR);
 458         if (IS_ERR(priv->nvm_client))
 459                 return PTR_ERR(priv->nvm_client);
 460
 461         priv->rtc = devm_rtc_allocate_device(&client->dev);
 462         ret = PTR_ERR_OR_ZERO(priv->rtc);
 463         if (ret)
 464                 return ret;
 465
 466         priv->rtc->ops = &isl12026_rtc_ops;
 467         nvm_cfg.priv = priv;
 468         ret = rtc_nvmem_register(priv->rtc, &nvm_cfg);
 469         if (ret)
 470                 return ret;
 471
 472         return rtc_register_device(priv->rtc);
 473 }
 474
 475 static int isl12026_remove(struct i2c_client *client)
 476 {
 477         struct isl12026 *priv = i2c_get_clientdata(client);
 478
 479         i2c_unregister_device(priv->nvm_client);
 480         return 0;
 481 }
 482
 483 static const struct of_device_id isl12026_dt_match[] = {
 484         { .compatible = "isil,isl12026" },
 485         { }
 486 };
 487 MODULE_DEVICE_TABLE(of, isl12026_dt_match);
 488
 489 static struct i2c_driver isl12026_driver = {
 490         .driver         = {
 491                 .name   = "rtc-isl12026",
 492                 .of_match_table = isl12026_dt_match,
 493         },
 494         .probe_new      = isl12026_probe_new,
 495         .remove         = isl12026_remove,
 496 };
 497
 498 module_i2c_driver(isl12026_driver);
 499
 500 MODULE_DESCRIPTION("ISL 12026 RTC driver");
 501 MODULE_LICENSE("GPL");