drivers/rtc/rtc-ab8500.c

   1 /*
   2  * Copyright (C) ST-Ericsson SA 2010
   3  *
   4  * License terms: GNU General Public License (GPL) version 2
   5  * Author: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
   6  *
   7  * RTC clock driver for the RTC part of the AB8500 Power management chip.
   8  * Based on RTC clock driver for the AB3100 Analog Baseband Chip by
   9  * Linus Walleij <linus.walleij@stericsson.com>
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/init.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/rtc.h>
  17 #include <linux/mfd/abx500.h>
  18 #include <linux/mfd/ab8500.h>
  19 #include <linux/delay.h>
  20
  21 #define AB8500_RTC_SOFF_STAT_REG        0x00
  22 #define AB8500_RTC_CC_CONF_REG          0x01
  23 #define AB8500_RTC_READ_REQ_REG         0x02
  24 #define AB8500_RTC_WATCH_TSECMID_REG    0x03
  25 #define AB8500_RTC_WATCH_TSECHI_REG     0x04
  26 #define AB8500_RTC_WATCH_TMIN_LOW_REG   0x05
  27 #define AB8500_RTC_WATCH_TMIN_MID_REG   0x06
  28 #define AB8500_RTC_WATCH_TMIN_HI_REG    0x07
  29 #define AB8500_RTC_ALRM_MIN_LOW_REG     0x08
  30 #define AB8500_RTC_ALRM_MIN_MID_REG     0x09
  31 #define AB8500_RTC_ALRM_MIN_HI_REG      0x0A
  32 #define AB8500_RTC_STAT_REG             0x0B
  33 #define AB8500_RTC_BKUP_CHG_REG         0x0C
  34 #define AB8500_RTC_FORCE_BKUP_REG       0x0D
  35 #define AB8500_RTC_CALIB_REG            0x0E
  36 #define AB8500_RTC_SWITCH_STAT_REG      0x0F
  37
  38 /* RtcReadRequest bits */
  39 #define RTC_READ_REQUEST                0x01
  40 #define RTC_WRITE_REQUEST               0x02
  41
  42 /* RtcCtrl bits */
  43 #define RTC_ALARM_ENA                   0x04
  44 #define RTC_STATUS_DATA                 0x01
  45
  46 #define COUNTS_PER_SEC                  (0xF000 / 60)
  47 #define AB8500_RTC_EPOCH                2000
  48
  49 static const u8 ab8500_rtc_time_regs[] = {
  50         AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
  51         AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
  52         AB8500_RTC_WATCH_TSECMID_REG
  53 };
  54
  55 static const u8 ab8500_rtc_alarm_regs[] = {
  56         AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
  57         AB8500_RTC_ALRM_MIN_LOW_REG
  58 };
  59
  60 /* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
  61 static unsigned long get_elapsed_seconds(int year)
  62 {
  63         unsigned long secs;
  64         struct rtc_time tm = {
  65                 .tm_year = year - 1900,
  66                 .tm_mday = 1,
  67         };
  68
  69         /*
  70          * This function calculates secs from 1970 and not from
  71          * 1900, even if we supply the offset from year 1900.
  72          */
  73         rtc_tm_to_time(&tm, &secs);
  74         return secs;
  75 }
  76
  77 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
  78 {
  79         unsigned long timeout = jiffies + HZ;
  80         int retval, i;
  81         unsigned long mins, secs;
  82         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
  83         u8 value;
  84
  85         /* Request a data read */
  86         retval = abx500_set_register_interruptible(dev,
  87                 AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
  88         if (retval < 0)
  89                 return retval;
  90
  91         /* Early AB8500 chips will not clear the rtc read request bit */
  92         if (abx500_get_chip_id(dev) == 0) {
  93                 msleep(1);
  94         } else {
  95                 /* Wait for some cycles after enabling the rtc read in ab8500 */
  96                 while (time_before(jiffies, timeout)) {
  97                         retval = abx500_get_register_interruptible(dev,
  98                                 AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
  99                         if (retval < 0)
 100                                 return retval;
 101
 102                         if (!(value & RTC_READ_REQUEST))
 103                                 break;
 104
 105                         msleep(1);
 106                 }
 107         }
 108
 109         /* Read the Watchtime registers */
 110         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 111                 retval = abx500_get_register_interruptible(dev,
 112                         AB8500_RTC, ab8500_rtc_time_regs[i], &value);
 113                 if (retval < 0)
 114                         return retval;
 115                 buf[i] = value;
 116         }
 117
 118         mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
 119
 120         secs =  (buf[3] << 8) | buf[4];
 121         secs =  secs / COUNTS_PER_SEC;
 122         secs =  secs + (mins * 60);
 123
 124         /* Add back the initially subtracted number of seconds */
 125         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 126
 127         rtc_time_to_tm(secs, tm);
 128         return rtc_valid_tm(tm);
 129 }
 130
 131 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 132 {
 133         int retval, i;
 134         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 135         unsigned long no_secs, no_mins, secs = 0;
 136
 137         if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
 138                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 139                                 AB8500_RTC_EPOCH);
 140                 return -EINVAL;
 141         }
 142
 143         /* Get the number of seconds since 1970 */
 144         rtc_tm_to_time(tm, &secs);
 145
 146         /*
 147          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 148          * we only have a small counter in the RTC.
 149          */
 150         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 151
 152         no_mins = secs / 60;
 153
 154         no_secs = secs % 60;
 155         /* Make the seconds count as per the RTC resolution */
 156         no_secs = no_secs * COUNTS_PER_SEC;
 157
 158         buf[4] = no_secs & 0xFF;
 159         buf[3] = (no_secs >> 8) & 0xFF;
 160
 161         buf[2] = no_mins & 0xFF;
 162         buf[1] = (no_mins >> 8) & 0xFF;
 163         buf[0] = (no_mins >> 16) & 0xFF;
 164
 165         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 166                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 167                         ab8500_rtc_time_regs[i], buf[i]);
 168                 if (retval < 0)
 169                         return retval;
 170         }
 171
 172         /* Request a data write */
 173         return abx500_set_register_interruptible(dev, AB8500_RTC,
 174                 AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 175 }
 176
 177 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 178 {
 179         int retval, i;
 180         u8 rtc_ctrl, value;
 181         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 182         unsigned long secs, mins;
 183
 184         /* Check if the alarm is enabled or not */
 185         retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 186                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 187         if (retval < 0)
 188                 return retval;
 189
 190         if (rtc_ctrl & RTC_ALARM_ENA)
 191                 alarm->enabled = 1;
 192         else
 193                 alarm->enabled = 0;
 194
 195         alarm->pending = 0;
 196
 197         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 198                 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 199                         ab8500_rtc_alarm_regs[i], &value);
 200                 if (retval < 0)
 201                         return retval;
 202                 buf[i] = value;
 203         }
 204
 205         mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 206         secs = mins * 60;
 207
 208         /* Add back the initially subtracted number of seconds */
 209         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 210
 211         rtc_time_to_tm(secs, &alarm->time);
 212
 213         return rtc_valid_tm(&alarm->time);
 214 }
 215
 216 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 217 {
 218         return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
 219                 AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 220                 enabled ? RTC_ALARM_ENA : 0);
 221 }
 222
 223 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 224 {
 225         int retval, i;
 226         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 227         unsigned long mins, secs = 0;
 228
 229         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 230                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 231                                 AB8500_RTC_EPOCH);
 232                 return -EINVAL;
 233         }
 234
 235         /* Get the number of seconds since 1970 */
 236         rtc_tm_to_time(&alarm->time, &secs);
 237
 238         /*
 239          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 240          * we only have a small counter in the RTC.
 241          */
 242         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 243
 244         mins = secs / 60;
 245
 246         buf[2] = mins & 0xFF;
 247         buf[1] = (mins >> 8) & 0xFF;
 248         buf[0] = (mins >> 16) & 0xFF;
 249
 250         /* Set the alarm time */
 251         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 252                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 253                         ab8500_rtc_alarm_regs[i], buf[i]);
 254                 if (retval < 0)
 255                         return retval;
 256         }
 257
 258         return ab8500_rtc_irq_enable(dev, alarm->enabled);
 259 }
 260
 261 static irqreturn_t rtc_alarm_handler(int irq, void *data)
 262 {
 263         struct rtc_device *rtc = data;
 264         unsigned long events = RTC_IRQF | RTC_AF;
 265
 266         dev_dbg(&rtc->dev, "%s\n", __func__);
 267         rtc_update_irq(rtc, 1, events);
 268
 269         return IRQ_HANDLED;
 270 }
 271
 272 static const struct rtc_class_ops ab8500_rtc_ops = {
 273         .read_time              = ab8500_rtc_read_time,
 274         .set_time               = ab8500_rtc_set_time,
 275         .read_alarm             = ab8500_rtc_read_alarm,
 276         .set_alarm              = ab8500_rtc_set_alarm,
 277         .alarm_irq_enable       = ab8500_rtc_irq_enable,
 278 };
 279
 280 static int __devinit ab8500_rtc_probe(struct platform_device *pdev)
 281 {
 282         int err;
 283         struct rtc_device *rtc;
 284         u8 rtc_ctrl;
 285         int irq;
 286
 287         irq = platform_get_irq_byname(pdev, "ALARM");
 288         if (irq < 0)
 289                 return irq;
 290
 291         /* For RTC supply test */
 292         err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
 293                 AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
 294         if (err < 0)
 295                 return err;
 296
 297         /* Wait for reset by the PorRtc */
 298         msleep(1);
 299
 300         err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
 301                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 302         if (err < 0)
 303                 return err;
 304
 305         /* Check if the RTC Supply fails */
 306         if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 307                 dev_err(&pdev->dev, "RTC supply failure\n");
 308                 return -ENODEV;
 309         }
 310
 311         rtc = rtc_device_register("ab8500-rtc", &pdev->dev, &ab8500_rtc_ops,
 312                         THIS_MODULE);
 313         if (IS_ERR(rtc)) {
 314                 dev_err(&pdev->dev, "Registration failed\n");
 315                 err = PTR_ERR(rtc);
 316                 return err;
 317         }
 318
 319         err = request_threaded_irq(irq, NULL, rtc_alarm_handler, 0,
 320                                    "ab8500-rtc", rtc);
 321         if (err < 0) {
 322                 rtc_device_unregister(rtc);
 323                 return err;
 324         }
 325
 326         platform_set_drvdata(pdev, rtc);
 327
 328         return 0;
 329 }
 330
 331 static int __devexit ab8500_rtc_remove(struct platform_device *pdev)
 332 {
 333         struct rtc_device *rtc = platform_get_drvdata(pdev);
 334         int irq = platform_get_irq_byname(pdev, "ALARM");
 335
 336         free_irq(irq, rtc);
 337         rtc_device_unregister(rtc);
 338         platform_set_drvdata(pdev, NULL);
 339
 340         return 0;
 341 }
 342
 343 static struct platform_driver ab8500_rtc_driver = {
 344         .driver = {
 345                 .name = "ab8500-rtc",
 346                 .owner = THIS_MODULE,
 347         },
 348         .probe  = ab8500_rtc_probe,
 349         .remove = __devexit_p(ab8500_rtc_remove),
 350 };
 351
 352 static int __init ab8500_rtc_init(void)
 353 {
 354         return platform_driver_register(&ab8500_rtc_driver);
 355 }
 356
 357 static void __exit ab8500_rtc_exit(void)
 358 {
 359         platform_driver_unregister(&ab8500_rtc_driver);
 360 }
 361
 362 module_init(ab8500_rtc_init);
 363 module_exit(ab8500_rtc_exit);
 364 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 365 MODULE_DESCRIPTION("AB8500 RTC Driver");
 366 MODULE_LICENSE("GPL v2");