drivers/rtc/rtc-sirfsoc.c

   1 /*
   2  * SiRFSoC Real Time Clock interface for Linux
   3  *
   4  * Copyright (c) 2013 Cambridge Silicon Radio Limited, a CSR plc group company.
   5  *
   6  * Licensed under GPLv2 or later.
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/err.h>
  11 #include <linux/rtc.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/slab.h>
  14 #include <linux/io.h>
  15 #include <linux/of.h>
  16 #include <linux/regmap.h>
  17 #include <linux/rtc/sirfsoc_rtciobrg.h>
  18
  19
  20 #define RTC_CN                  0x00
  21 #define RTC_ALARM0              0x04
  22 #define RTC_ALARM1              0x18
  23 #define RTC_STATUS              0x08
  24 #define RTC_SW_VALUE            0x40
  25 #define SIRFSOC_RTC_AL1E        (1<<6)
  26 #define SIRFSOC_RTC_AL1         (1<<4)
  27 #define SIRFSOC_RTC_HZE         (1<<3)
  28 #define SIRFSOC_RTC_AL0E        (1<<2)
  29 #define SIRFSOC_RTC_HZ          (1<<1)
  30 #define SIRFSOC_RTC_AL0         (1<<0)
  31 #define RTC_DIV                 0x0c
  32 #define RTC_DEEP_CTRL           0x14
  33 #define RTC_CLOCK_SWITCH        0x1c
  34 #define SIRFSOC_RTC_CLK         0x03    /* others are reserved */
  35
  36 /* Refer to RTC DIV switch */
  37 #define RTC_HZ                  16
  38
  39 /* This macro is also defined in arch/arm/plat-sirfsoc/cpu.c */
  40 #define RTC_SHIFT               4
  41
  42 #define INTR_SYSRTC_CN          0x48
  43
  44 struct sirfsoc_rtc_drv {
  45         struct rtc_device       *rtc;
  46         u32                     rtc_base;
  47         u32                     irq;
  48         unsigned                irq_wake;
  49         /* Overflow for every 8 years extra time */
  50         u32                     overflow_rtc;
  51         spinlock_t              lock;
  52         struct regmap *regmap;
  53 #ifdef CONFIG_PM
  54         u32             saved_counter;
  55         u32             saved_overflow_rtc;
  56 #endif
  57 };
  58
  59 static u32 sirfsoc_rtc_readl(struct sirfsoc_rtc_drv *rtcdrv, u32 offset)
  60 {
  61         u32 val;
  62
  63         regmap_read(rtcdrv->regmap, rtcdrv->rtc_base + offset, &val);
  64         return val;
  65 }
  66
  67 static void sirfsoc_rtc_writel(struct sirfsoc_rtc_drv *rtcdrv,
  68                                u32 offset, u32 val)
  69 {
  70         regmap_write(rtcdrv->regmap, rtcdrv->rtc_base + offset, val);
  71 }
  72
  73 static int sirfsoc_rtc_read_alarm(struct device *dev,
  74                 struct rtc_wkalrm *alrm)
  75 {
  76         unsigned long rtc_alarm, rtc_count;
  77         struct sirfsoc_rtc_drv *rtcdrv;
  78
  79         rtcdrv = dev_get_drvdata(dev);
  80
  81         spin_lock_irq(&rtcdrv->lock);
  82
  83         rtc_count = sirfsoc_rtc_readl(rtcdrv, RTC_CN);
  84
  85         rtc_alarm = sirfsoc_rtc_readl(rtcdrv, RTC_ALARM0);
  86         memset(alrm, 0, sizeof(struct rtc_wkalrm));
  87
  88         /*
  89          * assume alarm interval not beyond one round counter overflow_rtc:
  90          * 0->0xffffffff
  91          */
  92         /* if alarm is in next overflow cycle */
  93         if (rtc_count > rtc_alarm)
  94                 rtc_time_to_tm((rtcdrv->overflow_rtc + 1)
  95                                 << (BITS_PER_LONG - RTC_SHIFT)
  96                                 | rtc_alarm >> RTC_SHIFT, &(alrm->time));
  97         else
  98                 rtc_time_to_tm(rtcdrv->overflow_rtc
  99                                 << (BITS_PER_LONG - RTC_SHIFT)
 100                                 | rtc_alarm >> RTC_SHIFT, &(alrm->time));
 101         if (sirfsoc_rtc_readl(rtcdrv, RTC_STATUS) & SIRFSOC_RTC_AL0E)
 102                 alrm->enabled = 1;
 103
 104         spin_unlock_irq(&rtcdrv->lock);
 105
 106         return 0;
 107 }
 108
 109 static int sirfsoc_rtc_set_alarm(struct device *dev,
 110                 struct rtc_wkalrm *alrm)
 111 {
 112         unsigned long rtc_status_reg, rtc_alarm;
 113         struct sirfsoc_rtc_drv *rtcdrv;
 114         rtcdrv = dev_get_drvdata(dev);
 115
 116         if (alrm->enabled) {
 117                 rtc_tm_to_time(&(alrm->time), &rtc_alarm);
 118
 119                 spin_lock_irq(&rtcdrv->lock);
 120
 121                 rtc_status_reg = sirfsoc_rtc_readl(rtcdrv, RTC_STATUS);
 122                 if (rtc_status_reg & SIRFSOC_RTC_AL0E) {
 123                         /*
 124                          * An ongoing alarm in progress - ingore it and not
 125                          * to return EBUSY
 126                          */
 127                         dev_info(dev, "An old alarm was set, will be replaced by a new one\n");
 128                 }
 129
 130                 sirfsoc_rtc_writel(rtcdrv, RTC_ALARM0, rtc_alarm << RTC_SHIFT);
 131                 rtc_status_reg &= ~0x07; /* mask out the lower status bits */
 132                 /*
 133                  * This bit RTC_AL sets it as a wake-up source for Sleep Mode
 134                  * Writing 1 into this bit will clear it
 135                  */
 136                 rtc_status_reg |= SIRFSOC_RTC_AL0;
 137                 /* enable the RTC alarm interrupt */
 138                 rtc_status_reg |= SIRFSOC_RTC_AL0E;
 139                 sirfsoc_rtc_writel(rtcdrv, RTC_STATUS, rtc_status_reg);
 140
 141                 spin_unlock_irq(&rtcdrv->lock);
 142         } else {
 143                 /*
 144                  * if this function was called with enabled=0
 145                  * then it could mean that the application is
 146                  * trying to cancel an ongoing alarm
 147                  */
 148                 spin_lock_irq(&rtcdrv->lock);
 149
 150                 rtc_status_reg = sirfsoc_rtc_readl(rtcdrv, RTC_STATUS);
 151                 if (rtc_status_reg & SIRFSOC_RTC_AL0E) {
 152                         /* clear the RTC status register's alarm bit */
 153                         rtc_status_reg &= ~0x07;
 154                         /* write 1 into SIRFSOC_RTC_AL0 to force a clear */
 155                         rtc_status_reg |= (SIRFSOC_RTC_AL0);
 156                         /* Clear the Alarm enable bit */
 157                         rtc_status_reg &= ~(SIRFSOC_RTC_AL0E);
 158
 159                         sirfsoc_rtc_writel(rtcdrv, RTC_STATUS,
 160                                            rtc_status_reg);
 161                 }
 162
 163                 spin_unlock_irq(&rtcdrv->lock);
 164         }
 165
 166         return 0;
 167 }
 168
 169 static int sirfsoc_rtc_read_time(struct device *dev,
 170                 struct rtc_time *tm)
 171 {
 172         unsigned long tmp_rtc = 0;
 173         struct sirfsoc_rtc_drv *rtcdrv;
 174         rtcdrv = dev_get_drvdata(dev);
 175         /*
 176          * This patch is taken from WinCE - Need to validate this for
 177          * correctness. To work around sirfsoc RTC counter double sync logic
 178          * fail, read several times to make sure get stable value.
 179          */
 180         do {
 181                 tmp_rtc = sirfsoc_rtc_readl(rtcdrv, RTC_CN);
 182                 cpu_relax();
 183         } while (tmp_rtc != sirfsoc_rtc_readl(rtcdrv, RTC_CN));
 184
 185         rtc_time_to_tm(rtcdrv->overflow_rtc << (BITS_PER_LONG - RTC_SHIFT) |
 186                                         tmp_rtc >> RTC_SHIFT, tm);
 187         return 0;
 188 }
 189
 190 static int sirfsoc_rtc_set_time(struct device *dev,
 191                 struct rtc_time *tm)
 192 {
 193         unsigned long rtc_time;
 194         struct sirfsoc_rtc_drv *rtcdrv;
 195         rtcdrv = dev_get_drvdata(dev);
 196
 197         rtc_tm_to_time(tm, &rtc_time);
 198
 199         rtcdrv->overflow_rtc = rtc_time >> (BITS_PER_LONG - RTC_SHIFT);
 200
 201         sirfsoc_rtc_writel(rtcdrv, RTC_SW_VALUE, rtcdrv->overflow_rtc);
 202         sirfsoc_rtc_writel(rtcdrv, RTC_CN, rtc_time << RTC_SHIFT);
 203
 204         return 0;
 205 }
 206
 207 static int sirfsoc_rtc_alarm_irq_enable(struct device *dev,
 208                 unsigned int enabled)
 209 {
 210         unsigned long rtc_status_reg = 0x0;
 211         struct sirfsoc_rtc_drv *rtcdrv;
 212
 213         rtcdrv = dev_get_drvdata(dev);
 214
 215         spin_lock_irq(&rtcdrv->lock);
 216
 217         rtc_status_reg = sirfsoc_rtc_readl(rtcdrv, RTC_STATUS);
 218         if (enabled)
 219                 rtc_status_reg |= SIRFSOC_RTC_AL0E;
 220         else
 221                 rtc_status_reg &= ~SIRFSOC_RTC_AL0E;
 222
 223         sirfsoc_rtc_writel(rtcdrv, RTC_STATUS, rtc_status_reg);
 224
 225         spin_unlock_irq(&rtcdrv->lock);
 226
 227         return 0;
 228
 229 }
 230
 231 static const struct rtc_class_ops sirfsoc_rtc_ops = {
 232         .read_time = sirfsoc_rtc_read_time,
 233         .set_time = sirfsoc_rtc_set_time,
 234         .read_alarm = sirfsoc_rtc_read_alarm,
 235         .set_alarm = sirfsoc_rtc_set_alarm,
 236         .alarm_irq_enable = sirfsoc_rtc_alarm_irq_enable
 237 };
 238
 239 static irqreturn_t sirfsoc_rtc_irq_handler(int irq, void *pdata)
 240 {
 241         struct sirfsoc_rtc_drv *rtcdrv = pdata;
 242         unsigned long rtc_status_reg = 0x0;
 243         unsigned long events = 0x0;
 244
 245         spin_lock(&rtcdrv->lock);
 246
 247         rtc_status_reg = sirfsoc_rtc_readl(rtcdrv, RTC_STATUS);
 248         /* this bit will be set ONLY if an alarm was active
 249          * and it expired NOW
 250          * So this is being used as an ASSERT
 251          */
 252         if (rtc_status_reg & SIRFSOC_RTC_AL0) {
 253                 /*
 254                  * clear the RTC status register's alarm bit
 255                  * mask out the lower status bits
 256                  */
 257                 rtc_status_reg &= ~0x07;
 258                 /* write 1 into SIRFSOC_RTC_AL0 to ACK the alarm interrupt */
 259                 rtc_status_reg |= (SIRFSOC_RTC_AL0);
 260                 /* Clear the Alarm enable bit */
 261                 rtc_status_reg &= ~(SIRFSOC_RTC_AL0E);
 262         }
 263
 264         sirfsoc_rtc_writel(rtcdrv, RTC_STATUS, rtc_status_reg);
 265
 266         spin_unlock(&rtcdrv->lock);
 267
 268         /* this should wake up any apps polling/waiting on the read
 269          * after setting the alarm
 270          */
 271         events |= RTC_IRQF | RTC_AF;
 272         rtc_update_irq(rtcdrv->rtc, 1, events);
 273
 274         return IRQ_HANDLED;
 275 }
 276
 277 static const struct of_device_id sirfsoc_rtc_of_match[] = {
 278         { .compatible = "sirf,prima2-sysrtc"},
 279         {},
 280 };
 281
 282 const struct regmap_config sysrtc_regmap_config = {
 283         .reg_bits = 32,
 284         .val_bits = 32,
 285         .fast_io = true,
 286 };
 287
 288 MODULE_DEVICE_TABLE(of, sirfsoc_rtc_of_match);
 289
 290 static int sirfsoc_rtc_probe(struct platform_device *pdev)
 291 {
 292         int err;
 293         unsigned long rtc_div;
 294         struct sirfsoc_rtc_drv *rtcdrv;
 295         struct device_node *np = pdev->dev.of_node;
 296
 297         rtcdrv = devm_kzalloc(&pdev->dev,
 298                 sizeof(struct sirfsoc_rtc_drv), GFP_KERNEL);
 299         if (rtcdrv == NULL)
 300                 return -ENOMEM;
 301
 302         spin_lock_init(&rtcdrv->lock);
 303
 304         err = of_property_read_u32(np, "reg", &rtcdrv->rtc_base);
 305         if (err) {
 306                 dev_err(&pdev->dev, "unable to find base address of rtc node in dtb\n");
 307                 return err;
 308         }
 309
 310         platform_set_drvdata(pdev, rtcdrv);
 311
 312         /* Register rtc alarm as a wakeup source */
 313         device_init_wakeup(&pdev->dev, 1);
 314
 315         rtcdrv->regmap = devm_regmap_init_iobg(&pdev->dev,
 316                         &sysrtc_regmap_config);
 317         if (IS_ERR(rtcdrv->regmap)) {
 318                 err = PTR_ERR(rtcdrv->regmap);
 319                 dev_err(&pdev->dev, "Failed to allocate register map: %d\n",
 320                         err);
 321                 return err;
 322         }
 323
 324         /*
 325          * Set SYS_RTC counter in RTC_HZ HZ Units
 326          * We are using 32K RTC crystal (32768 / RTC_HZ / 2) -1
 327          * If 16HZ, therefore RTC_DIV = 1023;
 328          */
 329         rtc_div = ((32768 / RTC_HZ) / 2) - 1;
 330         sirfsoc_rtc_writel(rtcdrv, RTC_DIV, rtc_div);
 331
 332         /* 0x3 -> RTC_CLK */
 333         sirfsoc_rtc_writel(rtcdrv, RTC_CLOCK_SWITCH, SIRFSOC_RTC_CLK);
 334
 335         /* reset SYS RTC ALARM0 */
 336         sirfsoc_rtc_writel(rtcdrv, RTC_ALARM0, 0x0);
 337
 338         /* reset SYS RTC ALARM1 */
 339         sirfsoc_rtc_writel(rtcdrv, RTC_ALARM1, 0x0);
 340
 341         /* Restore RTC Overflow From Register After Command Reboot */
 342         rtcdrv->overflow_rtc =
 343                 sirfsoc_rtc_readl(rtcdrv, RTC_SW_VALUE);
 344
 345         rtcdrv->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 346                         &sirfsoc_rtc_ops, THIS_MODULE);
 347         if (IS_ERR(rtcdrv->rtc)) {
 348                 err = PTR_ERR(rtcdrv->rtc);
 349                 dev_err(&pdev->dev, "can't register RTC device\n");
 350                 return err;
 351         }
 352
 353         rtcdrv->irq = platform_get_irq(pdev, 0);
 354         err = devm_request_irq(
 355                         &pdev->dev,
 356                         rtcdrv->irq,
 357                         sirfsoc_rtc_irq_handler,
 358                         IRQF_SHARED,
 359                         pdev->name,
 360                         rtcdrv);
 361         if (err) {
 362                 dev_err(&pdev->dev, "Unable to register for the SiRF SOC RTC IRQ\n");
 363                 return err;
 364         }
 365
 366         return 0;
 367 }
 368
 369 static int sirfsoc_rtc_remove(struct platform_device *pdev)
 370 {
 371         device_init_wakeup(&pdev->dev, 0);
 372
 373         return 0;
 374 }
 375
 376 #ifdef CONFIG_PM_SLEEP
 377 static int sirfsoc_rtc_suspend(struct device *dev)
 378 {
 379         struct sirfsoc_rtc_drv *rtcdrv = dev_get_drvdata(dev);
 380         rtcdrv->overflow_rtc =
 381                 sirfsoc_rtc_readl(rtcdrv, RTC_SW_VALUE);
 382
 383         rtcdrv->saved_counter =
 384                 sirfsoc_rtc_readl(rtcdrv, RTC_CN);
 385         rtcdrv->saved_overflow_rtc = rtcdrv->overflow_rtc;
 386         if (device_may_wakeup(dev) && !enable_irq_wake(rtcdrv->irq))
 387                 rtcdrv->irq_wake = 1;
 388
 389         return 0;
 390 }
 391
 392 static int sirfsoc_rtc_resume(struct device *dev)
 393 {
 394         u32 tmp;
 395         struct sirfsoc_rtc_drv *rtcdrv = dev_get_drvdata(dev);
 396
 397         /*
 398          * if resume from snapshot and the rtc power is lost,
 399          * restroe the rtc settings
 400          */
 401         if (SIRFSOC_RTC_CLK != sirfsoc_rtc_readl(rtcdrv, RTC_CLOCK_SWITCH)) {
 402                 u32 rtc_div;
 403                 /* 0x3 -> RTC_CLK */
 404                 sirfsoc_rtc_writel(rtcdrv, RTC_CLOCK_SWITCH, SIRFSOC_RTC_CLK);
 405                 /*
 406                  * Set SYS_RTC counter in RTC_HZ HZ Units
 407                  * We are using 32K RTC crystal (32768 / RTC_HZ / 2) -1
 408                  * If 16HZ, therefore RTC_DIV = 1023;
 409                  */
 410                 rtc_div = ((32768 / RTC_HZ) / 2) - 1;
 411
 412                 sirfsoc_rtc_writel(rtcdrv, RTC_DIV, rtc_div);
 413
 414                 /* reset SYS RTC ALARM0 */
 415                 sirfsoc_rtc_writel(rtcdrv, RTC_ALARM0, 0x0);
 416
 417                 /* reset SYS RTC ALARM1 */
 418                 sirfsoc_rtc_writel(rtcdrv, RTC_ALARM1, 0x0);
 419         }
 420         rtcdrv->overflow_rtc = rtcdrv->saved_overflow_rtc;
 421
 422         /*
 423          * if current counter is small than previous,
 424          * it means overflow in sleep
 425          */
 426         tmp = sirfsoc_rtc_readl(rtcdrv, RTC_CN);
 427         if (tmp <= rtcdrv->saved_counter)
 428                 rtcdrv->overflow_rtc++;
 429         /*
 430          *PWRC Value Be Changed When Suspend, Restore Overflow
 431          * In Memory To Register
 432          */
 433         sirfsoc_rtc_writel(rtcdrv, RTC_SW_VALUE, rtcdrv->overflow_rtc);
 434
 435         if (device_may_wakeup(dev) && rtcdrv->irq_wake) {
 436                 disable_irq_wake(rtcdrv->irq);
 437                 rtcdrv->irq_wake = 0;
 438         }
 439
 440         return 0;
 441 }
 442 #endif
 443
 444 static SIMPLE_DEV_PM_OPS(sirfsoc_rtc_pm_ops,
 445                 sirfsoc_rtc_suspend, sirfsoc_rtc_resume);
 446
 447 static struct platform_driver sirfsoc_rtc_driver = {
 448         .driver = {
 449                 .name = "sirfsoc-rtc",
 450                 .pm = &sirfsoc_rtc_pm_ops,
 451                 .of_match_table = sirfsoc_rtc_of_match,
 452         },
 453         .probe = sirfsoc_rtc_probe,
 454         .remove = sirfsoc_rtc_remove,
 455 };
 456 module_platform_driver(sirfsoc_rtc_driver);
 457
 458 MODULE_DESCRIPTION("SiRF SoC rtc driver");
 459 MODULE_AUTHOR("Xianglong Du <Xianglong.Du@csr.com>");
 460 MODULE_LICENSE("GPL v2");
 461 MODULE_ALIAS("platform:sirfsoc-rtc");