drivers/rtc/s35392a.c

   1 /*
   2  * SII Semiconductor Corporation S35392A RTC driver.
   3  *
   4  * Copyright (c) 2017, General Electric Company
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  *
  18  * SPDX-License-Identifier:     GPL-2.0
  19  */
  20
  21 #include <command.h>
  22 #include <common.h>
  23 #include <dm.h>
  24 #include <i2c.h>
  25 #include <linux/bitrev.h>
  26 #include <rtc.h>
  27
  28 #define S35390A_CMD_STATUS1             0x30
  29 #define S35390A_CMD_STATUS2             0x31
  30 #define S35390A_CMD_TIME1               0x32
  31 #define S35390A_CMD_TIME2               0x33
  32 #define S35390A_CMD_INT2_REG1   0x35
  33
  34 #define S35390A_BYTE_YEAR       0
  35 #define S35390A_BYTE_MONTH      1
  36 #define S35390A_BYTE_DAY        2
  37 #define S35390A_BYTE_WDAY       3
  38 #define S35390A_BYTE_HOURS      4
  39 #define S35390A_BYTE_MINS       5
  40 #define S35390A_BYTE_SECS       6
  41
  42 /* flags for STATUS1 */
  43 #define S35390A_FLAG_POC        0x01
  44 #define S35390A_FLAG_BLD        0x02
  45 #define S35390A_FLAG_INT2       0x04
  46 #define S35390A_FLAG_24H        0x40
  47 #define S35390A_FLAG_RESET      0x80
  48
  49 /*
  50  * If either BLD or POC is set, then the chip has lost power long enough for
  51  * the time value to become invalid.
  52  */
  53 #define S35390A_LOW_VOLTAGE (S35390A_FLAG_POC | S35390A_FLAG_BLD)
  54
  55 /*---------------------------------------------------------------------*/
  56 #undef DEBUG_RTC
  57
  58 #ifdef DEBUG_RTC
  59 #define DEBUGR(fmt, args...) printf(fmt, ##args)
  60 #else
  61 #define DEBUGR(fmt, args...)
  62 #endif
  63 /*---------------------------------------------------------------------*/
  64
  65 #ifdef CONFIG_DM_RTC
  66 #define DEV_TYPE struct udevice
  67 #else
  68 /* Local udevice */
  69 struct ludevice {
  70         u8 chip;
  71 };
  72
  73 #define DEV_TYPE struct ludevice
  74 struct ludevice dev;
  75
  76 #endif
  77
  78 #define msleep(a) udelay(a * 1000)
  79
  80 int lowvoltage;
  81
  82 static int s35392a_rtc_reset(DEV_TYPE *dev);
  83
  84 static int s35392a_rtc_read(DEV_TYPE *dev, u8 reg, u8 *buf, int len)
  85 {
  86         int ret;
  87
  88 #ifdef CONFIG_DM_RTC
  89         /* TODO: we need to tweak the chip address to reg */
  90         ret = dm_i2c_read(dev, 0, buf, len);
  91 #else
  92         (void)dev;
  93         ret = i2c_read(reg, 0, -1, buf, len);
  94 #endif
  95
  96         return ret;
  97 }
  98
  99 static int s35392a_rtc_write(DEV_TYPE *dev, u8 reg, u8 *buf, int len)
 100 {
 101         int ret;
 102
 103 #ifdef CONFIG_DM_RTC
 104         /* TODO: we need to tweak the chip address to reg */
 105         ret = dm_i2c_write(dev, 0, buf, 1);
 106 #else
 107         (void)dev;
 108         ret = i2c_write(reg, 0, 0, buf, len);
 109 #endif
 110
 111         return ret;
 112 }
 113
 114 static int s35392a_rtc_read8(DEV_TYPE *dev, unsigned int reg)
 115 {
 116         u8 val;
 117         int ret;
 118
 119         ret = s35392a_rtc_read(dev, reg, &val, sizeof(val));
 120         return ret < 0 ? ret : val;
 121 }
 122
 123 static int s35392a_rtc_write8(DEV_TYPE *dev, unsigned int reg, int val)
 124 {
 125         int ret;
 126         u8 lval = val;
 127
 128         ret = s35392a_rtc_write(dev, reg, &lval, sizeof(lval));
 129         return ret < 0 ? ret : 0;
 130 }
 131
 132 static int validate_time(const struct rtc_time *tm)
 133 {
 134         if ((tm->tm_year < 2000) || (tm->tm_year > 2099))
 135                 return -EINVAL;
 136
 137         if ((tm->tm_mon < 1) || (tm->tm_mon > 12))
 138                 return -EINVAL;
 139
 140         if ((tm->tm_mday < 1) || (tm->tm_mday > 31))
 141                 return -EINVAL;
 142
 143         if ((tm->tm_wday < 0) || (tm->tm_wday > 6))
 144                 return -EINVAL;
 145
 146         if ((tm->tm_hour < 0) || (tm->tm_hour > 23))
 147                 return -EINVAL;
 148
 149         if ((tm->tm_min < 0) || (tm->tm_min > 59))
 150                 return -EINVAL;
 151
 152         if ((tm->tm_sec < 0) || (tm->tm_sec > 59))
 153                 return -EINVAL;
 154
 155         return 0;
 156 }
 157
 158 void s35392a_rtc_init(DEV_TYPE *dev)
 159 {
 160         int status;
 161
 162         status = s35392a_rtc_read8(dev, S35390A_CMD_STATUS1);
 163         if (status < 0)
 164                 goto error;
 165
 166         DEBUGR("init: S35390A_CMD_STATUS1: 0x%x\n", status);
 167
 168         lowvoltage = status & S35390A_LOW_VOLTAGE ? 1 : 0;
 169
 170         if (status & S35390A_FLAG_POC)
 171                 /*
 172                  * Do not communicate for 0.5 seconds since the power-on
 173                  * detection circuit is in operation.
 174                  */
 175                 msleep(500);
 176
 177         else if (!lowvoltage)
 178                 /*
 179                  * If both POC and BLD are unset everything is fine.
 180                  */
 181                 return;
 182
 183         if (lowvoltage)
 184                 printf("RTC low voltage detected\n");
 185
 186         if (!s35392a_rtc_reset(dev))
 187                 return;
 188
 189 error:
 190         printf("Error RTC init.\n");
 191 }
 192
 193 /* Get the current time from the RTC */
 194 static int s35392a_rtc_get(DEV_TYPE *dev, struct rtc_time *tm)
 195 {
 196         u8 date[7];
 197         int ret, i;
 198
 199         if (lowvoltage) {
 200                 DEBUGR("RTC low voltage detected\n");
 201                 return -EINVAL;
 202         }
 203
 204         ret = s35392a_rtc_read(dev, S35390A_CMD_TIME1, date, sizeof(date));
 205         if (ret < 0) {
 206                 DEBUGR("Error reading date from RTC\n");
 207                 return -EIO;
 208         }
 209
 210         /* This chip returns the bits of each byte in reverse order */
 211         for (i = 0; i < 7; ++i)
 212                 date[i] = bitrev8(date[i]);
 213
 214         tm->tm_sec  = bcd2bin(date[S35390A_BYTE_SECS]);
 215         tm->tm_min  = bcd2bin(date[S35390A_BYTE_MINS]);
 216         tm->tm_hour = bcd2bin(date[S35390A_BYTE_HOURS] & ~S35390A_FLAG_24H);
 217         tm->tm_wday = bcd2bin(date[S35390A_BYTE_WDAY]);
 218         tm->tm_mday = bcd2bin(date[S35390A_BYTE_DAY]);
 219         tm->tm_mon  = bcd2bin(date[S35390A_BYTE_MONTH]);
 220         tm->tm_year = bcd2bin(date[S35390A_BYTE_YEAR]) + 2000;
 221
 222         DEBUGR("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 223                tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday,
 224                tm->tm_hour, tm->tm_min, tm->tm_sec);
 225
 226         return 0;
 227 }
 228
 229 /* Set the RTC */
 230 static int s35392a_rtc_set(DEV_TYPE *dev, const struct rtc_time *tm)
 231 {
 232         int i, ret;
 233         int status;
 234         u8 date[7];
 235
 236         DEBUGR("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 237                tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday,
 238                tm->tm_hour, tm->tm_min, tm->tm_sec);
 239
 240         ret = validate_time(tm);
 241         if (ret < 0)
 242                 return -EINVAL;
 243
 244         /* We support only 24h mode */
 245         ret = s35392a_rtc_read8(dev, S35390A_CMD_STATUS1);
 246         if (ret < 0)
 247                 return -EIO;
 248         status = ret;
 249
 250         ret = s35392a_rtc_write8(dev, S35390A_CMD_STATUS1,
 251                                  status | S35390A_FLAG_24H);
 252         if (ret < 0)
 253                 return -EIO;
 254
 255         date[S35390A_BYTE_YEAR]  = bin2bcd(tm->tm_year - 2000);
 256         date[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon);
 257         date[S35390A_BYTE_DAY]   = bin2bcd(tm->tm_mday);
 258         date[S35390A_BYTE_WDAY]  = bin2bcd(tm->tm_wday);
 259         date[S35390A_BYTE_HOURS] = bin2bcd(tm->tm_hour);
 260         date[S35390A_BYTE_MINS]  = bin2bcd(tm->tm_min);
 261         date[S35390A_BYTE_SECS]  = bin2bcd(tm->tm_sec);
 262
 263         /* This chip expects the bits of each byte to be in reverse order */
 264         for (i = 0; i < 7; ++i)
 265                 date[i] = bitrev8(date[i]);
 266
 267         ret = s35392a_rtc_write(dev, S35390A_CMD_TIME1, date, sizeof(date));
 268         if (ret < 0) {
 269                 DEBUGR("Error writing date to RTC\n");
 270                 return -EIO;
 271         }
 272
 273         /* Now we have time. Reset the low voltage status */
 274         lowvoltage = 0;
 275
 276         return 0;
 277 }
 278
 279 /* Reset the RTC. */
 280 static int s35392a_rtc_reset(DEV_TYPE *dev)
 281 {
 282         int buf;
 283         int ret;
 284         unsigned int initcount = 0;
 285
 286         buf = S35390A_FLAG_RESET;
 287
 288 initialize:
 289         ret = s35392a_rtc_write8(dev, S35390A_CMD_STATUS1, buf);
 290         if (ret < 0)
 291                 return -EIO;
 292
 293         ret = s35392a_rtc_read8(dev, S35390A_CMD_STATUS1);
 294         if (ret < 0)
 295                 return -EIO;
 296         buf = ret;
 297
 298         if (!lowvoltage)
 299                 lowvoltage = buf & S35390A_LOW_VOLTAGE ? 1 : 0;
 300
 301         if (buf & S35390A_LOW_VOLTAGE) {
 302                 /* Try up to five times to reset the chip */
 303                 if (initcount < 5) {
 304                         ++initcount;
 305                         goto initialize;
 306                 } else {
 307                         return -EIO;
 308                 }
 309         }
 310
 311         return 0;
 312 }
 313
 314 #ifndef CONFIG_DM_RTC
 315
 316 int rtc_get(struct rtc_time *tm)
 317 {
 318         return s35392a_rtc_get(&dev, tm);
 319 }
 320
 321 int rtc_set(struct rtc_time *tm)
 322 {
 323         return s35392a_rtc_set(&dev, tm);
 324 }
 325
 326 void rtc_reset(void)
 327 {
 328         s35392a_rtc_reset(&dev);
 329 }
 330
 331 void rtc_init(void)
 332 {
 333         s35392a_rtc_init(&dev);
 334 }
 335
 336 #else
 337
 338 static int s35392a_probe(struct udevice *dev)
 339 {
 340         s35392a_rtc_init(dev);
 341         return 0;
 342 }
 343
 344 static const struct rtc_ops s35392a_rtc_ops = {
 345         .get = s35392a_rtc_get,
 346         .set = s35392a_rtc_set,
 347         .read8 = s35392a_rtc_read8,
 348         .write8 = s35392a_rtc_write8,
 349         .reset = s35392a_rtc_reset,
 350 };
 351
 352 static const struct udevice_id s35392a_rtc_ids[] = {
 353         { .compatible = "sii,s35392a-rtc" },
 354         { }
 355 };
 356
 357 U_BOOT_DRIVER(s35392a_rtc) = {
 358         .name     = "s35392a_rtc",
 359         .id           = UCLASS_RTC,
 360         .probe    = s35392a_probe,
 361         .of_match = s35392a_rtc_ids,
 362         .ops      = &s35392a_rtc_ops,
 363 };
 364
 365 #endif