drivers/rtc/rtc-rx6110.c

   1 /*
   2  * Driver for the Epson RTC module RX-6110 SA
   3  *
   4  * Copyright(C) 2015 Pengutronix, Steffen Trumtrar <kernel@pengutronix.de>
   5  * Copyright(C) SEIKO EPSON CORPORATION 2013. All rights reserved.
   6  *
   7  * This driver software is distributed as is, without any warranty of any kind,
   8  * either express or implied as further specified in the GNU Public License.
   9  * This software may be used and distributed according to the terms of the GNU
  10  * Public License, version 2 as published by the Free Software Foundation.
  11  * See the file COPYING in the main directory of this archive for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program. If not, see <http://www.gnu.org/licenses/>.
  15  */
  16
  17 #include <linux/bcd.h>
  18 #include <linux/init.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/of_gpio.h>
  22 #include <linux/regmap.h>
  23 #include <linux/rtc.h>
  24 #include <linux/spi/spi.h>
  25
  26 /* RX-6110 Register definitions */
  27 #define RX6110_REG_SEC          0x10
  28 #define RX6110_REG_MIN          0x11
  29 #define RX6110_REG_HOUR         0x12
  30 #define RX6110_REG_WDAY         0x13
  31 #define RX6110_REG_MDAY         0x14
  32 #define RX6110_REG_MONTH        0x15
  33 #define RX6110_REG_YEAR         0x16
  34 #define RX6110_REG_RES1         0x17
  35 #define RX6110_REG_ALMIN        0x18
  36 #define RX6110_REG_ALHOUR       0x19
  37 #define RX6110_REG_ALWDAY       0x1A
  38 #define RX6110_REG_TCOUNT0      0x1B
  39 #define RX6110_REG_TCOUNT1      0x1C
  40 #define RX6110_REG_EXT          0x1D
  41 #define RX6110_REG_FLAG         0x1E
  42 #define RX6110_REG_CTRL         0x1F
  43 #define RX6110_REG_USER0        0x20
  44 #define RX6110_REG_USER1        0x21
  45 #define RX6110_REG_USER2        0x22
  46 #define RX6110_REG_USER3        0x23
  47 #define RX6110_REG_USER4        0x24
  48 #define RX6110_REG_USER5        0x25
  49 #define RX6110_REG_USER6        0x26
  50 #define RX6110_REG_USER7        0x27
  51 #define RX6110_REG_USER8        0x28
  52 #define RX6110_REG_USER9        0x29
  53 #define RX6110_REG_USERA        0x2A
  54 #define RX6110_REG_USERB        0x2B
  55 #define RX6110_REG_USERC        0x2C
  56 #define RX6110_REG_USERD        0x2D
  57 #define RX6110_REG_USERE        0x2E
  58 #define RX6110_REG_USERF        0x2F
  59 #define RX6110_REG_RES2         0x30
  60 #define RX6110_REG_RES3         0x31
  61 #define RX6110_REG_IRQ          0x32
  62
  63 #define RX6110_BIT_ALARM_EN             BIT(7)
  64
  65 /* Extension Register (1Dh) bit positions */
  66 #define RX6110_BIT_EXT_TSEL0            BIT(0)
  67 #define RX6110_BIT_EXT_TSEL1            BIT(1)
  68 #define RX6110_BIT_EXT_TSEL2            BIT(2)
  69 #define RX6110_BIT_EXT_WADA             BIT(3)
  70 #define RX6110_BIT_EXT_TE               BIT(4)
  71 #define RX6110_BIT_EXT_USEL             BIT(5)
  72 #define RX6110_BIT_EXT_FSEL0            BIT(6)
  73 #define RX6110_BIT_EXT_FSEL1            BIT(7)
  74
  75 /* Flag Register (1Eh) bit positions */
  76 #define RX6110_BIT_FLAG_VLF             BIT(1)
  77 #define RX6110_BIT_FLAG_AF              BIT(3)
  78 #define RX6110_BIT_FLAG_TF              BIT(4)
  79 #define RX6110_BIT_FLAG_UF              BIT(5)
  80
  81 /* Control Register (1Fh) bit positions */
  82 #define RX6110_BIT_CTRL_TBKE            BIT(0)
  83 #define RX6110_BIT_CTRL_TBKON           BIT(1)
  84 #define RX6110_BIT_CTRL_TSTP            BIT(2)
  85 #define RX6110_BIT_CTRL_AIE             BIT(3)
  86 #define RX6110_BIT_CTRL_TIE             BIT(4)
  87 #define RX6110_BIT_CTRL_UIE             BIT(5)
  88 #define RX6110_BIT_CTRL_STOP            BIT(6)
  89 #define RX6110_BIT_CTRL_TEST            BIT(7)
  90
  91 enum {
  92         RTC_SEC = 0,
  93         RTC_MIN,
  94         RTC_HOUR,
  95         RTC_WDAY,
  96         RTC_MDAY,
  97         RTC_MONTH,
  98         RTC_YEAR,
  99         RTC_NR_TIME
 100 };
 101
 102 #define RX6110_DRIVER_NAME              "rx6110"
 103
 104 struct rx6110_data {
 105         struct rtc_device *rtc;
 106         struct regmap *regmap;
 107 };
 108
 109 /**
 110  * rx6110_rtc_tm_to_data - convert rtc_time to native time encoding
 111  *
 112  * @tm: holds date and time
 113  * @data: holds the encoding in rx6110 native form
 114  */
 115 static int rx6110_rtc_tm_to_data(struct rtc_time *tm, u8 *data)
 116 {
 117         pr_debug("%s: date %ptRr\n", __func__, tm);
 118
 119         /*
 120          * The year in the RTC is a value between 0 and 99.
 121          * Assume that this represents the current century
 122          * and disregard all other values.
 123          */
 124         if (tm->tm_year < 100 || tm->tm_year >= 200)
 125                 return -EINVAL;
 126
 127         data[RTC_SEC] = bin2bcd(tm->tm_sec);
 128         data[RTC_MIN] = bin2bcd(tm->tm_min);
 129         data[RTC_HOUR] = bin2bcd(tm->tm_hour);
 130         data[RTC_WDAY] = BIT(bin2bcd(tm->tm_wday));
 131         data[RTC_MDAY] = bin2bcd(tm->tm_mday);
 132         data[RTC_MONTH] = bin2bcd(tm->tm_mon + 1);
 133         data[RTC_YEAR] = bin2bcd(tm->tm_year % 100);
 134
 135         return 0;
 136 }
 137
 138 /**
 139  * rx6110_data_to_rtc_tm - convert native time encoding to rtc_time
 140  *
 141  * @data: holds the encoding in rx6110 native form
 142  * @tm: holds date and time
 143  */
 144 static int rx6110_data_to_rtc_tm(u8 *data, struct rtc_time *tm)
 145 {
 146         tm->tm_sec = bcd2bin(data[RTC_SEC] & 0x7f);
 147         tm->tm_min = bcd2bin(data[RTC_MIN] & 0x7f);
 148         /* only 24-hour clock */
 149         tm->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3f);
 150         tm->tm_wday = ffs(data[RTC_WDAY] & 0x7f);
 151         tm->tm_mday = bcd2bin(data[RTC_MDAY] & 0x3f);
 152         tm->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1f) - 1;
 153         tm->tm_year = bcd2bin(data[RTC_YEAR]) + 100;
 154
 155         pr_debug("%s: date %ptRr\n", __func__, tm);
 156
 157         /*
 158          * The year in the RTC is a value between 0 and 99.
 159          * Assume that this represents the current century
 160          * and disregard all other values.
 161          */
 162         if (tm->tm_year < 100 || tm->tm_year >= 200)
 163                 return -EINVAL;
 164
 165         return 0;
 166 }
 167
 168 /**
 169  * rx6110_set_time - set the current time in the rx6110 registers
 170  *
 171  * @dev: the rtc device in use
 172  * @tm: holds date and time
 173  *
 174  * BUG: The HW assumes every year that is a multiple of 4 to be a leap
 175  * year. Next time this is wrong is 2100, which will not be a leap year
 176  *
 177  * Note: If STOP is not set/cleared, the clock will start when the seconds
 178  *       register is written
 179  *
 180  */
 181 static int rx6110_set_time(struct device *dev, struct rtc_time *tm)
 182 {
 183         struct rx6110_data *rx6110 = dev_get_drvdata(dev);
 184         u8 data[RTC_NR_TIME];
 185         int ret;
 186
 187         ret = rx6110_rtc_tm_to_data(tm, data);
 188         if (ret < 0)
 189                 return ret;
 190
 191         /* set STOP bit before changing clock/calendar */
 192         ret = regmap_update_bits(rx6110->regmap, RX6110_REG_CTRL,
 193                                  RX6110_BIT_CTRL_STOP, RX6110_BIT_CTRL_STOP);
 194         if (ret)
 195                 return ret;
 196
 197         ret = regmap_bulk_write(rx6110->regmap, RX6110_REG_SEC, data,
 198                                 RTC_NR_TIME);
 199         if (ret)
 200                 return ret;
 201
 202         /* The time in the RTC is valid. Be sure to have VLF cleared. */
 203         ret = regmap_update_bits(rx6110->regmap, RX6110_REG_FLAG,
 204                                  RX6110_BIT_FLAG_VLF, 0);
 205         if (ret)
 206                 return ret;
 207
 208         /* clear STOP bit after changing clock/calendar */
 209         ret = regmap_update_bits(rx6110->regmap, RX6110_REG_CTRL,
 210                                  RX6110_BIT_CTRL_STOP, 0);
 211
 212         return ret;
 213 }
 214
 215 /**
 216  * rx6110_get_time - get the current time from the rx6110 registers
 217  * @dev: the rtc device in use
 218  * @tm: holds date and time
 219  */
 220 static int rx6110_get_time(struct device *dev, struct rtc_time *tm)
 221 {
 222         struct rx6110_data *rx6110 = dev_get_drvdata(dev);
 223         u8 data[RTC_NR_TIME];
 224         int flags;
 225         int ret;
 226
 227         ret = regmap_read(rx6110->regmap, RX6110_REG_FLAG, &flags);
 228         if (ret)
 229                 return -EINVAL;
 230
 231         /* check for VLF Flag (set at power-on) */
 232         if ((flags & RX6110_BIT_FLAG_VLF)) {
 233                 dev_warn(dev, "Voltage low, data is invalid.\n");
 234                 return -EINVAL;
 235         }
 236
 237         /* read registers to date */
 238         ret = regmap_bulk_read(rx6110->regmap, RX6110_REG_SEC, data,
 239                                RTC_NR_TIME);
 240         if (ret)
 241                 return ret;
 242
 243         ret = rx6110_data_to_rtc_tm(data, tm);
 244         if (ret)
 245                 return ret;
 246
 247         dev_dbg(dev, "%s: date %ptRr\n", __func__, tm);
 248
 249         return 0;
 250 }
 251
 252 static const struct reg_sequence rx6110_default_regs[] = {
 253         { RX6110_REG_RES1,   0xB8 },
 254         { RX6110_REG_RES2,   0x00 },
 255         { RX6110_REG_RES3,   0x10 },
 256         { RX6110_REG_IRQ,    0x00 },
 257         { RX6110_REG_ALMIN,  0x00 },
 258         { RX6110_REG_ALHOUR, 0x00 },
 259         { RX6110_REG_ALWDAY, 0x00 },
 260 };
 261
 262 /**
 263  * rx6110_init - initialize the rx6110 registers
 264  *
 265  * @rx6110: pointer to the rx6110 struct in use
 266  *
 267  */
 268 static int rx6110_init(struct rx6110_data *rx6110)
 269 {
 270         struct rtc_device *rtc = rx6110->rtc;
 271         int flags;
 272         int ret;
 273
 274         ret = regmap_update_bits(rx6110->regmap, RX6110_REG_EXT,
 275                                  RX6110_BIT_EXT_TE, 0);
 276         if (ret)
 277                 return ret;
 278
 279         ret = regmap_register_patch(rx6110->regmap, rx6110_default_regs,
 280                                     ARRAY_SIZE(rx6110_default_regs));
 281         if (ret)
 282                 return ret;
 283
 284         ret = regmap_read(rx6110->regmap, RX6110_REG_FLAG, &flags);
 285         if (ret)
 286                 return ret;
 287
 288         /* check for VLF Flag (set at power-on) */
 289         if ((flags & RX6110_BIT_FLAG_VLF))
 290                 dev_warn(&rtc->dev, "Voltage low, data loss detected.\n");
 291
 292         /* check for Alarm Flag */
 293         if (flags & RX6110_BIT_FLAG_AF)
 294                 dev_warn(&rtc->dev, "An alarm may have been missed.\n");
 295
 296         /* check for Periodic Timer Flag */
 297         if (flags & RX6110_BIT_FLAG_TF)
 298                 dev_warn(&rtc->dev, "Periodic timer was detected\n");
 299
 300         /* check for Update Timer Flag */
 301         if (flags & RX6110_BIT_FLAG_UF)
 302                 dev_warn(&rtc->dev, "Update timer was detected\n");
 303
 304         /* clear all flags BUT VLF */
 305         ret = regmap_update_bits(rx6110->regmap, RX6110_REG_FLAG,
 306                                  RX6110_BIT_FLAG_AF |
 307                                  RX6110_BIT_FLAG_UF |
 308                                  RX6110_BIT_FLAG_TF,
 309                                  0);
 310
 311         return ret;
 312 }
 313
 314 static const struct rtc_class_ops rx6110_rtc_ops = {
 315         .read_time = rx6110_get_time,
 316         .set_time = rx6110_set_time,
 317 };
 318
 319 static struct regmap_config regmap_spi_config = {
 320         .reg_bits = 8,
 321         .val_bits = 8,
 322         .max_register = RX6110_REG_IRQ,
 323         .read_flag_mask = 0x80,
 324 };
 325
 326 /**
 327  * rx6110_probe - initialize rtc driver
 328  * @spi: pointer to spi device
 329  */
 330 static int rx6110_probe(struct spi_device *spi)
 331 {
 332         struct rx6110_data *rx6110;
 333         int err;
 334
 335         if ((spi->bits_per_word && spi->bits_per_word != 8) ||
 336             (spi->max_speed_hz > 2000000) ||
 337             (spi->mode != (SPI_CS_HIGH | SPI_CPOL | SPI_CPHA))) {
 338                 dev_warn(&spi->dev, "SPI settings: bits_per_word: %d, max_speed_hz: %d, mode: %xh\n",
 339                          spi->bits_per_word, spi->max_speed_hz, spi->mode);
 340                 dev_warn(&spi->dev, "driving device in an unsupported mode");
 341         }
 342
 343         rx6110 = devm_kzalloc(&spi->dev, sizeof(*rx6110), GFP_KERNEL);
 344         if (!rx6110)
 345                 return -ENOMEM;
 346
 347         rx6110->regmap = devm_regmap_init_spi(spi, &regmap_spi_config);
 348         if (IS_ERR(rx6110->regmap)) {
 349                 dev_err(&spi->dev, "regmap init failed for rtc rx6110\n");
 350                 return PTR_ERR(rx6110->regmap);
 351         }
 352
 353         spi_set_drvdata(spi, rx6110);
 354
 355         rx6110->rtc = devm_rtc_device_register(&spi->dev,
 356                                                RX6110_DRIVER_NAME,
 357                                                &rx6110_rtc_ops, THIS_MODULE);
 358
 359         if (IS_ERR(rx6110->rtc))
 360                 return PTR_ERR(rx6110->rtc);
 361
 362         err = rx6110_init(rx6110);
 363         if (err)
 364                 return err;
 365
 366         rx6110->rtc->max_user_freq = 1;
 367
 368         return 0;
 369 }
 370
 371 static int rx6110_remove(struct spi_device *spi)
 372 {
 373         return 0;
 374 }
 375
 376 static const struct spi_device_id rx6110_id[] = {
 377         { "rx6110", 0 },
 378         { }
 379 };
 380 MODULE_DEVICE_TABLE(spi, rx6110_id);
 381
 382 static struct spi_driver rx6110_driver = {
 383         .driver = {
 384                 .name = RX6110_DRIVER_NAME,
 385         },
 386         .probe          = rx6110_probe,
 387         .remove         = rx6110_remove,
 388         .id_table       = rx6110_id,
 389 };
 390
 391 module_spi_driver(rx6110_driver);
 392
 393 MODULE_AUTHOR("Val Krutov <val.krutov@erd.epson.com>");
 394 MODULE_DESCRIPTION("RX-6110 SA RTC driver");
 395 MODULE_LICENSE("GPL");