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/ab8500.h>
  18 #include <linux/delay.h>
  19
  20 #define AB8500_RTC_SOFF_STAT_REG        0x0F00
  21 #define AB8500_RTC_CC_CONF_REG          0x0F01
  22 #define AB8500_RTC_READ_REQ_REG         0x0F02
  23 #define AB8500_RTC_WATCH_TSECMID_REG    0x0F03
  24 #define AB8500_RTC_WATCH_TSECHI_REG     0x0F04
  25 #define AB8500_RTC_WATCH_TMIN_LOW_REG   0x0F05
  26 #define AB8500_RTC_WATCH_TMIN_MID_REG   0x0F06
  27 #define AB8500_RTC_WATCH_TMIN_HI_REG    0x0F07
  28 #define AB8500_RTC_ALRM_MIN_LOW_REG     0x0F08
  29 #define AB8500_RTC_ALRM_MIN_MID_REG     0x0F09
  30 #define AB8500_RTC_ALRM_MIN_HI_REG      0x0F0A
  31 #define AB8500_RTC_STAT_REG             0x0F0B
  32 #define AB8500_RTC_BKUP_CHG_REG         0x0F0C
  33 #define AB8500_RTC_FORCE_BKUP_REG       0x0F0D
  34 #define AB8500_RTC_CALIB_REG            0x0F0E
  35 #define AB8500_RTC_SWITCH_STAT_REG      0x0F0F
  36 #define AB8500_REV_REG                  0x1080
  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 unsigned long 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 unsigned long 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         struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
  80         unsigned long timeout = jiffies + HZ;
  81         int retval, i;
  82         unsigned long mins, secs;
  83         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
  84
  85         /* Request a data read */
  86         retval = ab8500_write(ab8500, AB8500_RTC_READ_REQ_REG,
  87                               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 (ab8500->revision == 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 = ab8500_read(ab8500, AB8500_RTC_READ_REQ_REG);
  98                         if (retval < 0)
  99                                 return retval;
 100
 101                         if (!(retval & RTC_READ_REQUEST))
 102                                 break;
 103
 104                         msleep(1);
 105                 }
 106         }
 107
 108         /* Read the Watchtime registers */
 109         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 110                 retval = ab8500_read(ab8500, ab8500_rtc_time_regs[i]);
 111                 if (retval < 0)
 112                         return retval;
 113                 buf[i] = retval;
 114         }
 115
 116         mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
 117
 118         secs =  (buf[3] << 8) | buf[4];
 119         secs =  secs / COUNTS_PER_SEC;
 120         secs =  secs + (mins * 60);
 121
 122         /* Add back the initially subtracted number of seconds */
 123         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 124
 125         rtc_time_to_tm(secs, tm);
 126         return rtc_valid_tm(tm);
 127 }
 128
 129 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 130 {
 131         struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
 132         int retval, i;
 133         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 134         unsigned long no_secs, no_mins, secs = 0;
 135
 136         if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
 137                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 138                                 AB8500_RTC_EPOCH);
 139                 return -EINVAL;
 140         }
 141
 142         /* Get the number of seconds since 1970 */
 143         rtc_tm_to_time(tm, &secs);
 144
 145         /*
 146          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 147          * we only have a small counter in the RTC.
 148          */
 149         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 150
 151         no_mins = secs / 60;
 152
 153         no_secs = secs % 60;
 154         /* Make the seconds count as per the RTC resolution */
 155         no_secs = no_secs * COUNTS_PER_SEC;
 156
 157         buf[4] = no_secs & 0xFF;
 158         buf[3] = (no_secs >> 8) & 0xFF;
 159
 160         buf[2] = no_mins & 0xFF;
 161         buf[1] = (no_mins >> 8) & 0xFF;
 162         buf[0] = (no_mins >> 16) & 0xFF;
 163
 164         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 165                 retval = ab8500_write(ab8500, ab8500_rtc_time_regs[i], buf[i]);
 166                 if (retval < 0)
 167                         return retval;
 168         }
 169
 170         /* Request a data write */
 171         return ab8500_write(ab8500, AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 172 }
 173
 174 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 175 {
 176         struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
 177         int retval, i;
 178         int rtc_ctrl;
 179         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 180         unsigned long secs, mins;
 181
 182         /* Check if the alarm is enabled or not */
 183         rtc_ctrl = ab8500_read(ab8500, AB8500_RTC_STAT_REG);
 184         if (rtc_ctrl < 0)
 185                 return rtc_ctrl;
 186
 187         if (rtc_ctrl & RTC_ALARM_ENA)
 188                 alarm->enabled = 1;
 189         else
 190                 alarm->enabled = 0;
 191
 192         alarm->pending = 0;
 193
 194         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 195                 retval = ab8500_read(ab8500, ab8500_rtc_alarm_regs[i]);
 196                 if (retval < 0)
 197                         return retval;
 198                 buf[i] = retval;
 199         }
 200
 201         mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 202         secs = mins * 60;
 203
 204         /* Add back the initially subtracted number of seconds */
 205         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 206
 207         rtc_time_to_tm(secs, &alarm->time);
 208
 209         return rtc_valid_tm(&alarm->time);
 210 }
 211
 212 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 213 {
 214         struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
 215
 216         return ab8500_set_bits(ab8500, AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 217                                enabled ? RTC_ALARM_ENA : 0);
 218 }
 219
 220 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 221 {
 222         struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
 223         int retval, i;
 224         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 225         unsigned long mins, secs = 0;
 226
 227         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 228                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 229                                 AB8500_RTC_EPOCH);
 230                 return -EINVAL;
 231         }
 232
 233         /* Get the number of seconds since 1970 */
 234         rtc_tm_to_time(&alarm->time, &secs);
 235
 236         /*
 237          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 238          * we only have a small counter in the RTC.
 239          */
 240         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 241
 242         mins = secs / 60;
 243
 244         buf[2] = mins & 0xFF;
 245         buf[1] = (mins >> 8) & 0xFF;
 246         buf[0] = (mins >> 16) & 0xFF;
 247
 248         /* Set the alarm time */
 249         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 250                 retval = ab8500_write(ab8500, ab8500_rtc_alarm_regs[i], buf[i]);
 251                 if (retval < 0)
 252                         return retval;
 253         }
 254
 255         return ab8500_rtc_irq_enable(dev, alarm->enabled);
 256 }
 257
 258 static irqreturn_t rtc_alarm_handler(int irq, void *data)
 259 {
 260         struct rtc_device *rtc = data;
 261         unsigned long events = RTC_IRQF | RTC_AF;
 262
 263         dev_dbg(&rtc->dev, "%s\n", __func__);
 264         rtc_update_irq(rtc, 1, events);
 265
 266         return IRQ_HANDLED;
 267 }
 268
 269 static const struct rtc_class_ops ab8500_rtc_ops = {
 270         .read_time              = ab8500_rtc_read_time,
 271         .set_time               = ab8500_rtc_set_time,
 272         .read_alarm             = ab8500_rtc_read_alarm,
 273         .set_alarm              = ab8500_rtc_set_alarm,
 274         .alarm_irq_enable       = ab8500_rtc_irq_enable,
 275 };
 276
 277 static int __devinit ab8500_rtc_probe(struct platform_device *pdev)
 278 {
 279         struct ab8500 *ab8500 = dev_get_drvdata(pdev->dev.parent);
 280         int err;
 281         struct rtc_device *rtc;
 282         int rtc_ctrl;
 283         int irq;
 284
 285         irq = platform_get_irq_byname(pdev, "ALARM");
 286         if (irq < 0)
 287                 return irq;
 288
 289         /* For RTC supply test */
 290         err = ab8500_set_bits(ab8500, AB8500_RTC_STAT_REG, RTC_STATUS_DATA,
 291                         RTC_STATUS_DATA);
 292         if (err < 0)
 293                 return err;
 294
 295         /* Wait for reset by the PorRtc */
 296         msleep(1);
 297
 298         rtc_ctrl = ab8500_read(ab8500, AB8500_RTC_STAT_REG);
 299         if (rtc_ctrl < 0)
 300                 return rtc_ctrl;
 301
 302         /* Check if the RTC Supply fails */
 303         if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 304                 dev_err(&pdev->dev, "RTC supply failure\n");
 305                 return -ENODEV;
 306         }
 307
 308         rtc = rtc_device_register("ab8500-rtc", &pdev->dev, &ab8500_rtc_ops,
 309                         THIS_MODULE);
 310         if (IS_ERR(rtc)) {
 311                 dev_err(&pdev->dev, "Registration failed\n");
 312                 err = PTR_ERR(rtc);
 313                 return err;
 314         }
 315
 316         err = request_threaded_irq(irq, NULL, rtc_alarm_handler, 0,
 317                                    "ab8500-rtc", rtc);
 318         if (err < 0) {
 319                 rtc_device_unregister(rtc);
 320                 return err;
 321         }
 322
 323         platform_set_drvdata(pdev, rtc);
 324
 325         return 0;
 326 }
 327
 328 static int __devexit ab8500_rtc_remove(struct platform_device *pdev)
 329 {
 330         struct rtc_device *rtc = platform_get_drvdata(pdev);
 331         int irq = platform_get_irq_byname(pdev, "ALARM");
 332
 333         free_irq(irq, rtc);
 334         rtc_device_unregister(rtc);
 335         platform_set_drvdata(pdev, NULL);
 336
 337         return 0;
 338 }
 339
 340 static struct platform_driver ab8500_rtc_driver = {
 341         .driver = {
 342                 .name = "ab8500-rtc",
 343                 .owner = THIS_MODULE,
 344         },
 345         .probe  = ab8500_rtc_probe,
 346         .remove = __devexit_p(ab8500_rtc_remove),
 347 };
 348
 349 static int __init ab8500_rtc_init(void)
 350 {
 351         return platform_driver_register(&ab8500_rtc_driver);
 352 }
 353
 354 static void __exit ab8500_rtc_exit(void)
 355 {
 356         platform_driver_unregister(&ab8500_rtc_driver);
 357 }
 358
 359 module_init(ab8500_rtc_init);
 360 module_exit(ab8500_rtc_exit);
 361 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 362 MODULE_DESCRIPTION("AB8500 RTC Driver");
 363 MODULE_LICENSE("GPL v2");