drivers/rtc/rtc-zynqmp.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Xilinx Zynq Ultrascale+ MPSoC Real Time Clock Driver
   4  *
   5  * Copyright (C) 2015 Xilinx, Inc.
   6  *
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/delay.h>
  11 #include <linux/init.h>
  12 #include <linux/io.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/rtc.h>
  17
  18 /* RTC Registers */
  19 #define RTC_SET_TM_WR           0x00
  20 #define RTC_SET_TM_RD           0x04
  21 #define RTC_CALIB_WR            0x08
  22 #define RTC_CALIB_RD            0x0C
  23 #define RTC_CUR_TM              0x10
  24 #define RTC_CUR_TICK            0x14
  25 #define RTC_ALRM                0x18
  26 #define RTC_INT_STS             0x20
  27 #define RTC_INT_MASK            0x24
  28 #define RTC_INT_EN              0x28
  29 #define RTC_INT_DIS             0x2C
  30 #define RTC_CTRL                0x40
  31
  32 #define RTC_FR_EN               BIT(20)
  33 #define RTC_FR_DATSHIFT         16
  34 #define RTC_TICK_MASK           0xFFFF
  35 #define RTC_INT_SEC             BIT(0)
  36 #define RTC_INT_ALRM            BIT(1)
  37 #define RTC_OSC_EN              BIT(24)
  38 #define RTC_BATT_EN             BIT(31)
  39
  40 #define RTC_CALIB_DEF           0x7FFF
  41 #define RTC_CALIB_MASK          0x1FFFFF
  42 #define RTC_ALRM_MASK          BIT(1)
  43 #define RTC_MSEC               1000
  44 #define RTC_FR_MASK             0xF0000
  45 #define RTC_FR_MAX_TICKS        16
  46 #define RTC_PPB                 1000000000LL
  47 #define RTC_MIN_OFFSET          -32768000
  48 #define RTC_MAX_OFFSET          32767000
  49
  50 struct xlnx_rtc_dev {
  51         struct rtc_device       *rtc;
  52         void __iomem            *reg_base;
  53         int                     alarm_irq;
  54         int                     sec_irq;
  55         struct clk              *rtc_clk;
  56         unsigned int            freq;
  57 };
  58
  59 static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
  60 {
  61         struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
  62         unsigned long new_time;
  63
  64         /*
  65          * The value written will be updated after 1 sec into the
  66          * seconds read register, so we need to program time +1 sec
  67          * to get the correct time on read.
  68          */
  69         new_time = rtc_tm_to_time64(tm) + 1;
  70
  71         writel(new_time, xrtcdev->reg_base + RTC_SET_TM_WR);
  72
  73         /*
  74          * Clear the rtc interrupt status register after setting the
  75          * time. During a read_time function, the code should read the
  76          * RTC_INT_STATUS register and if bit 0 is still 0, it means
  77          * that one second has not elapsed yet since RTC was set and
  78          * the current time should be read from SET_TIME_READ register;
  79          * otherwise, CURRENT_TIME register is read to report the time
  80          */
  81         writel(RTC_INT_SEC, xrtcdev->reg_base + RTC_INT_STS);
  82
  83         return 0;
  84 }
  85
  86 static int xlnx_rtc_read_time(struct device *dev, struct rtc_time *tm)
  87 {
  88         u32 status;
  89         unsigned long read_time;
  90         struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
  91
  92         status = readl(xrtcdev->reg_base + RTC_INT_STS);
  93
  94         if (status & RTC_INT_SEC) {
  95                 /*
  96                  * RTC has updated the CURRENT_TIME with the time written into
  97                  * SET_TIME_WRITE register.
  98                  */
  99                 read_time = readl(xrtcdev->reg_base + RTC_CUR_TM);
 100         } else {
 101                 /*
 102                  * Time written in SET_TIME_WRITE has not yet updated into
 103                  * the seconds read register, so read the time from the
 104                  * SET_TIME_WRITE instead of CURRENT_TIME register.
 105                  * Since we add +1 sec while writing, we need to -1 sec while
 106                  * reading.
 107                  */
 108                 read_time = readl(xrtcdev->reg_base + RTC_SET_TM_RD) - 1;
 109         }
 110         rtc_time64_to_tm(read_time, tm);
 111
 112         return 0;
 113 }
 114
 115 static int xlnx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 116 {
 117         struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
 118
 119         rtc_time64_to_tm(readl(xrtcdev->reg_base + RTC_ALRM), &alrm->time);
 120         alrm->enabled = readl(xrtcdev->reg_base + RTC_INT_MASK) & RTC_INT_ALRM;
 121
 122         return 0;
 123 }
 124
 125 static int xlnx_rtc_alarm_irq_enable(struct device *dev, u32 enabled)
 126 {
 127         struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
 128         unsigned int status;
 129         ulong timeout;
 130
 131         timeout = jiffies + msecs_to_jiffies(RTC_MSEC);
 132
 133         if (enabled) {
 134                 while (1) {
 135                         status = readl(xrtcdev->reg_base + RTC_INT_STS);
 136                         if (!((status & RTC_ALRM_MASK) == RTC_ALRM_MASK))
 137                                 break;
 138
 139                         if (time_after_eq(jiffies, timeout)) {
 140                                 dev_err(dev, "Time out occur, while clearing alarm status bit\n");
 141                                 return -ETIMEDOUT;
 142                         }
 143                         writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_STS);
 144                 }
 145
 146                 writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_EN);
 147         } else {
 148                 writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_DIS);
 149         }
 150
 151         return 0;
 152 }
 153
 154 static int xlnx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 155 {
 156         struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
 157         unsigned long alarm_time;
 158
 159         alarm_time = rtc_tm_to_time64(&alrm->time);
 160
 161         writel((u32)alarm_time, (xrtcdev->reg_base + RTC_ALRM));
 162
 163         xlnx_rtc_alarm_irq_enable(dev, alrm->enabled);
 164
 165         return 0;
 166 }
 167
 168 static void xlnx_init_rtc(struct xlnx_rtc_dev *xrtcdev)
 169 {
 170         u32 rtc_ctrl;
 171
 172         /* Enable RTC switch to battery when VCC_PSAUX is not available */
 173         rtc_ctrl = readl(xrtcdev->reg_base + RTC_CTRL);
 174         rtc_ctrl |= RTC_BATT_EN;
 175         writel(rtc_ctrl, xrtcdev->reg_base + RTC_CTRL);
 176 }
 177
 178 static int xlnx_rtc_read_offset(struct device *dev, long *offset)
 179 {
 180         struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
 181         unsigned long long rtc_ppb = RTC_PPB;
 182         unsigned int tick_mult = do_div(rtc_ppb, xrtcdev->freq);
 183         unsigned int calibval;
 184         long offset_val;
 185
 186         calibval = readl(xrtcdev->reg_base + RTC_CALIB_RD);
 187         /* Offset with seconds ticks */
 188         offset_val = calibval & RTC_TICK_MASK;
 189         offset_val = offset_val - RTC_CALIB_DEF;
 190         offset_val = offset_val * tick_mult;
 191
 192         /* Offset with fractional ticks */
 193         if (calibval & RTC_FR_EN)
 194                 offset_val += ((calibval & RTC_FR_MASK) >> RTC_FR_DATSHIFT)
 195                         * (tick_mult / RTC_FR_MAX_TICKS);
 196         *offset = offset_val;
 197
 198         return 0;
 199 }
 200
 201 static int xlnx_rtc_set_offset(struct device *dev, long offset)
 202 {
 203         struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
 204         unsigned long long rtc_ppb = RTC_PPB;
 205         unsigned int tick_mult = do_div(rtc_ppb, xrtcdev->freq);
 206         unsigned char fract_tick = 0;
 207         unsigned int calibval;
 208         short int  max_tick;
 209         int fract_offset;
 210
 211         if (offset < RTC_MIN_OFFSET || offset > RTC_MAX_OFFSET)
 212                 return -ERANGE;
 213
 214         /* Number ticks for given offset */
 215         max_tick = div_s64_rem(offset, tick_mult, &fract_offset);
 216
 217         /* Number fractional ticks for given offset */
 218         if (fract_offset) {
 219                 if (fract_offset < 0) {
 220                         fract_offset = fract_offset + tick_mult;
 221                         max_tick--;
 222                 }
 223                 if (fract_offset > (tick_mult / RTC_FR_MAX_TICKS)) {
 224                         for (fract_tick = 1; fract_tick < 16; fract_tick++) {
 225                                 if (fract_offset <=
 226                                     (fract_tick *
 227                                      (tick_mult / RTC_FR_MAX_TICKS)))
 228                                         break;
 229                         }
 230                 }
 231         }
 232
 233         /* Zynqmp RTC uses second and fractional tick
 234          * counters for compensation
 235          */
 236         calibval = max_tick + RTC_CALIB_DEF;
 237
 238         if (fract_tick)
 239                 calibval |= RTC_FR_EN;
 240
 241         calibval |= (fract_tick << RTC_FR_DATSHIFT);
 242
 243         writel(calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
 244
 245         return 0;
 246 }
 247
 248 static const struct rtc_class_ops xlnx_rtc_ops = {
 249         .set_time         = xlnx_rtc_set_time,
 250         .read_time        = xlnx_rtc_read_time,
 251         .read_alarm       = xlnx_rtc_read_alarm,
 252         .set_alarm        = xlnx_rtc_set_alarm,
 253         .alarm_irq_enable = xlnx_rtc_alarm_irq_enable,
 254         .read_offset      = xlnx_rtc_read_offset,
 255         .set_offset       = xlnx_rtc_set_offset,
 256 };
 257
 258 static irqreturn_t xlnx_rtc_interrupt(int irq, void *id)
 259 {
 260         struct xlnx_rtc_dev *xrtcdev = (struct xlnx_rtc_dev *)id;
 261         unsigned int status;
 262
 263         status = readl(xrtcdev->reg_base + RTC_INT_STS);
 264         /* Check if interrupt asserted */
 265         if (!(status & (RTC_INT_SEC | RTC_INT_ALRM)))
 266                 return IRQ_NONE;
 267
 268         /* Disable RTC_INT_ALRM interrupt only */
 269         writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_DIS);
 270
 271         if (status & RTC_INT_ALRM)
 272                 rtc_update_irq(xrtcdev->rtc, 1, RTC_IRQF | RTC_AF);
 273
 274         return IRQ_HANDLED;
 275 }
 276
 277 static int xlnx_rtc_probe(struct platform_device *pdev)
 278 {
 279         struct xlnx_rtc_dev *xrtcdev;
 280         int ret;
 281
 282         xrtcdev = devm_kzalloc(&pdev->dev, sizeof(*xrtcdev), GFP_KERNEL);
 283         if (!xrtcdev)
 284                 return -ENOMEM;
 285
 286         platform_set_drvdata(pdev, xrtcdev);
 287
 288         xrtcdev->rtc = devm_rtc_allocate_device(&pdev->dev);
 289         if (IS_ERR(xrtcdev->rtc))
 290                 return PTR_ERR(xrtcdev->rtc);
 291
 292         xrtcdev->rtc->ops = &xlnx_rtc_ops;
 293         xrtcdev->rtc->range_max = U32_MAX;
 294
 295         xrtcdev->reg_base = devm_platform_ioremap_resource(pdev, 0);
 296         if (IS_ERR(xrtcdev->reg_base))
 297                 return PTR_ERR(xrtcdev->reg_base);
 298
 299         xrtcdev->alarm_irq = platform_get_irq_byname(pdev, "alarm");
 300         if (xrtcdev->alarm_irq < 0)
 301                 return xrtcdev->alarm_irq;
 302         ret = devm_request_irq(&pdev->dev, xrtcdev->alarm_irq,
 303                                xlnx_rtc_interrupt, 0,
 304                                dev_name(&pdev->dev), xrtcdev);
 305         if (ret) {
 306                 dev_err(&pdev->dev, "request irq failed\n");
 307                 return ret;
 308         }
 309
 310         xrtcdev->sec_irq = platform_get_irq_byname(pdev, "sec");
 311         if (xrtcdev->sec_irq < 0)
 312                 return xrtcdev->sec_irq;
 313         ret = devm_request_irq(&pdev->dev, xrtcdev->sec_irq,
 314                                xlnx_rtc_interrupt, 0,
 315                                dev_name(&pdev->dev), xrtcdev);
 316         if (ret) {
 317                 dev_err(&pdev->dev, "request irq failed\n");
 318                 return ret;
 319         }
 320
 321         /* Getting the rtc_clk info */
 322         xrtcdev->rtc_clk = devm_clk_get_optional(&pdev->dev, "rtc_clk");
 323         if (IS_ERR(xrtcdev->rtc_clk)) {
 324                 if (PTR_ERR(xrtcdev->rtc_clk) != -EPROBE_DEFER)
 325                         dev_warn(&pdev->dev, "Device clock not found.\n");
 326         }
 327         xrtcdev->freq = clk_get_rate(xrtcdev->rtc_clk);
 328         if (!xrtcdev->freq) {
 329                 ret = of_property_read_u32(pdev->dev.of_node, "calibration",
 330                                            &xrtcdev->freq);
 331                 if (ret)
 332                         xrtcdev->freq = RTC_CALIB_DEF;
 333         }
 334         ret = readl(xrtcdev->reg_base + RTC_CALIB_RD);
 335         if (!ret)
 336                 writel(xrtcdev->freq, (xrtcdev->reg_base + RTC_CALIB_WR));
 337
 338         xlnx_init_rtc(xrtcdev);
 339
 340         device_init_wakeup(&pdev->dev, 1);
 341
 342         return devm_rtc_register_device(xrtcdev->rtc);
 343 }
 344
 345 static int xlnx_rtc_remove(struct platform_device *pdev)
 346 {
 347         xlnx_rtc_alarm_irq_enable(&pdev->dev, 0);
 348         device_init_wakeup(&pdev->dev, 0);
 349
 350         return 0;
 351 }
 352
 353 static int __maybe_unused xlnx_rtc_suspend(struct device *dev)
 354 {
 355         struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
 356
 357         if (device_may_wakeup(dev))
 358                 enable_irq_wake(xrtcdev->alarm_irq);
 359         else
 360                 xlnx_rtc_alarm_irq_enable(dev, 0);
 361
 362         return 0;
 363 }
 364
 365 static int __maybe_unused xlnx_rtc_resume(struct device *dev)
 366 {
 367         struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
 368
 369         if (device_may_wakeup(dev))
 370                 disable_irq_wake(xrtcdev->alarm_irq);
 371         else
 372                 xlnx_rtc_alarm_irq_enable(dev, 1);
 373
 374         return 0;
 375 }
 376
 377 static SIMPLE_DEV_PM_OPS(xlnx_rtc_pm_ops, xlnx_rtc_suspend, xlnx_rtc_resume);
 378
 379 static const struct of_device_id xlnx_rtc_of_match[] = {
 380         {.compatible = "xlnx,zynqmp-rtc" },
 381         { }
 382 };
 383 MODULE_DEVICE_TABLE(of, xlnx_rtc_of_match);
 384
 385 static struct platform_driver xlnx_rtc_driver = {
 386         .probe          = xlnx_rtc_probe,
 387         .remove         = xlnx_rtc_remove,
 388         .driver         = {
 389                 .name   = KBUILD_MODNAME,
 390                 .pm     = &xlnx_rtc_pm_ops,
 391                 .of_match_table = xlnx_rtc_of_match,
 392         },
 393 };
 394
 395 module_platform_driver(xlnx_rtc_driver);
 396
 397 MODULE_DESCRIPTION("Xilinx Zynq MPSoC RTC driver");
 398 MODULE_AUTHOR("Xilinx Inc.");
 399 MODULE_LICENSE("GPL v2");