drivers/rtc/rtc-snvs.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 //
   3 // Copyright (C) 2011-2012 Freescale Semiconductor, Inc.
   4
   5 #include <linux/init.h>
   6 #include <linux/io.h>
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/of.h>
  10 #include <linux/of_device.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/pm_wakeirq.h>
  13 #include <linux/rtc.h>
  14 #include <linux/clk.h>
  15 #include <linux/mfd/syscon.h>
  16 #include <linux/regmap.h>
  17
  18 #define SNVS_LPREGISTER_OFFSET  0x34
  19
  20 /* These register offsets are relative to LP (Low Power) range */
  21 #define SNVS_LPCR               0x04
  22 #define SNVS_LPSR               0x18
  23 #define SNVS_LPSRTCMR           0x1c
  24 #define SNVS_LPSRTCLR           0x20
  25 #define SNVS_LPTAR              0x24
  26 #define SNVS_LPPGDR             0x30
  27
  28 #define SNVS_LPCR_SRTC_ENV      (1 << 0)
  29 #define SNVS_LPCR_LPTA_EN       (1 << 1)
  30 #define SNVS_LPCR_LPWUI_EN      (1 << 3)
  31 #define SNVS_LPSR_LPTA          (1 << 0)
  32
  33 #define SNVS_LPPGDR_INIT        0x41736166
  34 #define CNTR_TO_SECS_SH         15
  35
  36 struct snvs_rtc_data {
  37         struct rtc_device *rtc;
  38         struct regmap *regmap;
  39         int offset;
  40         int irq;
  41         struct clk *clk;
  42 };
  43
  44 /* Read 64 bit timer register, which could be in inconsistent state */
  45 static u64 rtc_read_lpsrt(struct snvs_rtc_data *data)
  46 {
  47         u32 msb, lsb;
  48
  49         regmap_read(data->regmap, data->offset + SNVS_LPSRTCMR, &msb);
  50         regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &lsb);
  51         return (u64)msb << 32 | lsb;
  52 }
  53
  54 /* Read the secure real time counter, taking care to deal with the cases of the
  55  * counter updating while being read.
  56  */
  57 static u32 rtc_read_lp_counter(struct snvs_rtc_data *data)
  58 {
  59         u64 read1, read2;
  60         unsigned int timeout = 100;
  61
  62         /* As expected, the registers might update between the read of the LSB
  63          * reg and the MSB reg.  It's also possible that one register might be
  64          * in partially modified state as well.
  65          */
  66         read1 = rtc_read_lpsrt(data);
  67         do {
  68                 read2 = read1;
  69                 read1 = rtc_read_lpsrt(data);
  70         } while (read1 != read2 && --timeout);
  71         if (!timeout)
  72                 dev_err(&data->rtc->dev, "Timeout trying to get valid LPSRT Counter read\n");
  73
  74         /* Convert 47-bit counter to 32-bit raw second count */
  75         return (u32) (read1 >> CNTR_TO_SECS_SH);
  76 }
  77
  78 /* Just read the lsb from the counter, dealing with inconsistent state */
  79 static int rtc_read_lp_counter_lsb(struct snvs_rtc_data *data, u32 *lsb)
  80 {
  81         u32 count1, count2;
  82         unsigned int timeout = 100;
  83
  84         regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &count1);
  85         do {
  86                 count2 = count1;
  87                 regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &count1);
  88         } while (count1 != count2 && --timeout);
  89         if (!timeout) {
  90                 dev_err(&data->rtc->dev, "Timeout trying to get valid LPSRT Counter read\n");
  91                 return -ETIMEDOUT;
  92         }
  93
  94         *lsb = count1;
  95         return 0;
  96 }
  97
  98 static int rtc_write_sync_lp(struct snvs_rtc_data *data)
  99 {
 100         u32 count1, count2;
 101         u32 elapsed;
 102         unsigned int timeout = 1000;
 103         int ret;
 104
 105         ret = rtc_read_lp_counter_lsb(data, &count1);
 106         if (ret)
 107                 return ret;
 108
 109         /* Wait for 3 CKIL cycles, about 61.0-91.5 µs */
 110         do {
 111                 ret = rtc_read_lp_counter_lsb(data, &count2);
 112                 if (ret)
 113                         return ret;
 114                 elapsed = count2 - count1; /* wrap around _is_ handled! */
 115         } while (elapsed < 3 && --timeout);
 116         if (!timeout) {
 117                 dev_err(&data->rtc->dev, "Timeout waiting for LPSRT Counter to change\n");
 118                 return -ETIMEDOUT;
 119         }
 120         return 0;
 121 }
 122
 123 static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable)
 124 {
 125         int timeout = 1000;
 126         u32 lpcr;
 127
 128         regmap_update_bits(data->regmap, data->offset + SNVS_LPCR, SNVS_LPCR_SRTC_ENV,
 129                            enable ? SNVS_LPCR_SRTC_ENV : 0);
 130
 131         while (--timeout) {
 132                 regmap_read(data->regmap, data->offset + SNVS_LPCR, &lpcr);
 133
 134                 if (enable) {
 135                         if (lpcr & SNVS_LPCR_SRTC_ENV)
 136                                 break;
 137                 } else {
 138                         if (!(lpcr & SNVS_LPCR_SRTC_ENV))
 139                                 break;
 140                 }
 141         }
 142
 143         if (!timeout)
 144                 return -ETIMEDOUT;
 145
 146         return 0;
 147 }
 148
 149 static int snvs_rtc_read_time(struct device *dev, struct rtc_time *tm)
 150 {
 151         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 152         unsigned long time = rtc_read_lp_counter(data);
 153
 154         rtc_time64_to_tm(time, tm);
 155
 156         return 0;
 157 }
 158
 159 static int snvs_rtc_set_time(struct device *dev, struct rtc_time *tm)
 160 {
 161         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 162         unsigned long time = rtc_tm_to_time64(tm);
 163         int ret;
 164
 165         /* Disable RTC first */
 166         ret = snvs_rtc_enable(data, false);
 167         if (ret)
 168                 return ret;
 169
 170         /* Write 32-bit time to 47-bit timer, leaving 15 LSBs blank */
 171         regmap_write(data->regmap, data->offset + SNVS_LPSRTCLR, time << CNTR_TO_SECS_SH);
 172         regmap_write(data->regmap, data->offset + SNVS_LPSRTCMR, time >> (32 - CNTR_TO_SECS_SH));
 173
 174         /* Enable RTC again */
 175         ret = snvs_rtc_enable(data, true);
 176
 177         return ret;
 178 }
 179
 180 static int snvs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 181 {
 182         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 183         u32 lptar, lpsr;
 184
 185         regmap_read(data->regmap, data->offset + SNVS_LPTAR, &lptar);
 186         rtc_time64_to_tm(lptar, &alrm->time);
 187
 188         regmap_read(data->regmap, data->offset + SNVS_LPSR, &lpsr);
 189         alrm->pending = (lpsr & SNVS_LPSR_LPTA) ? 1 : 0;
 190
 191         return 0;
 192 }
 193
 194 static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
 195 {
 196         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 197
 198         regmap_update_bits(data->regmap, data->offset + SNVS_LPCR,
 199                            (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN),
 200                            enable ? (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN) : 0);
 201
 202         return rtc_write_sync_lp(data);
 203 }
 204
 205 static int snvs_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 206 {
 207         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 208         unsigned long time = rtc_tm_to_time64(&alrm->time);
 209         int ret;
 210
 211         regmap_update_bits(data->regmap, data->offset + SNVS_LPCR, SNVS_LPCR_LPTA_EN, 0);
 212         ret = rtc_write_sync_lp(data);
 213         if (ret)
 214                 return ret;
 215         regmap_write(data->regmap, data->offset + SNVS_LPTAR, time);
 216
 217         /* Clear alarm interrupt status bit */
 218         regmap_write(data->regmap, data->offset + SNVS_LPSR, SNVS_LPSR_LPTA);
 219
 220         return snvs_rtc_alarm_irq_enable(dev, alrm->enabled);
 221 }
 222
 223 static const struct rtc_class_ops snvs_rtc_ops = {
 224         .read_time = snvs_rtc_read_time,
 225         .set_time = snvs_rtc_set_time,
 226         .read_alarm = snvs_rtc_read_alarm,
 227         .set_alarm = snvs_rtc_set_alarm,
 228         .alarm_irq_enable = snvs_rtc_alarm_irq_enable,
 229 };
 230
 231 static irqreturn_t snvs_rtc_irq_handler(int irq, void *dev_id)
 232 {
 233         struct device *dev = dev_id;
 234         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 235         u32 lpsr;
 236         u32 events = 0;
 237
 238         if (data->clk)
 239                 clk_enable(data->clk);
 240
 241         regmap_read(data->regmap, data->offset + SNVS_LPSR, &lpsr);
 242
 243         if (lpsr & SNVS_LPSR_LPTA) {
 244                 events |= (RTC_AF | RTC_IRQF);
 245
 246                 /* RTC alarm should be one-shot */
 247                 snvs_rtc_alarm_irq_enable(dev, 0);
 248
 249                 rtc_update_irq(data->rtc, 1, events);
 250         }
 251
 252         /* clear interrupt status */
 253         regmap_write(data->regmap, data->offset + SNVS_LPSR, lpsr);
 254
 255         if (data->clk)
 256                 clk_disable(data->clk);
 257
 258         return events ? IRQ_HANDLED : IRQ_NONE;
 259 }
 260
 261 static const struct regmap_config snvs_rtc_config = {
 262         .reg_bits = 32,
 263         .val_bits = 32,
 264         .reg_stride = 4,
 265 };
 266
 267 static int snvs_rtc_probe(struct platform_device *pdev)
 268 {
 269         struct snvs_rtc_data *data;
 270         int ret;
 271         void __iomem *mmio;
 272
 273         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 274         if (!data)
 275                 return -ENOMEM;
 276
 277         data->rtc = devm_rtc_allocate_device(&pdev->dev);
 278         if (IS_ERR(data->rtc))
 279                 return PTR_ERR(data->rtc);
 280
 281         data->regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
 282
 283         if (IS_ERR(data->regmap)) {
 284                 dev_warn(&pdev->dev, "snvs rtc: you use old dts file, please update it\n");
 285
 286                 mmio = devm_platform_ioremap_resource(pdev, 0);
 287                 if (IS_ERR(mmio))
 288                         return PTR_ERR(mmio);
 289
 290                 data->regmap = devm_regmap_init_mmio(&pdev->dev, mmio, &snvs_rtc_config);
 291         } else {
 292                 data->offset = SNVS_LPREGISTER_OFFSET;
 293                 of_property_read_u32(pdev->dev.of_node, "offset", &data->offset);
 294         }
 295
 296         if (IS_ERR(data->regmap)) {
 297                 dev_err(&pdev->dev, "Can't find snvs syscon\n");
 298                 return -ENODEV;
 299         }
 300
 301         data->irq = platform_get_irq(pdev, 0);
 302         if (data->irq < 0)
 303                 return data->irq;
 304
 305         data->clk = devm_clk_get(&pdev->dev, "snvs-rtc");
 306         if (IS_ERR(data->clk)) {
 307                 data->clk = NULL;
 308         } else {
 309                 ret = clk_prepare_enable(data->clk);
 310                 if (ret) {
 311                         dev_err(&pdev->dev,
 312                                 "Could not prepare or enable the snvs clock\n");
 313                         return ret;
 314                 }
 315         }
 316
 317         platform_set_drvdata(pdev, data);
 318
 319         /* Initialize glitch detect */
 320         regmap_write(data->regmap, data->offset + SNVS_LPPGDR, SNVS_LPPGDR_INIT);
 321
 322         /* Clear interrupt status */
 323         regmap_write(data->regmap, data->offset + SNVS_LPSR, 0xffffffff);
 324
 325         /* Enable RTC */
 326         ret = snvs_rtc_enable(data, true);
 327         if (ret) {
 328                 dev_err(&pdev->dev, "failed to enable rtc %d\n", ret);
 329                 goto error_rtc_device_register;
 330         }
 331
 332         device_init_wakeup(&pdev->dev, true);
 333         ret = dev_pm_set_wake_irq(&pdev->dev, data->irq);
 334         if (ret)
 335                 dev_err(&pdev->dev, "failed to enable irq wake\n");
 336
 337         ret = devm_request_irq(&pdev->dev, data->irq, snvs_rtc_irq_handler,
 338                                IRQF_SHARED, "rtc alarm", &pdev->dev);
 339         if (ret) {
 340                 dev_err(&pdev->dev, "failed to request irq %d: %d\n",
 341                         data->irq, ret);
 342                 goto error_rtc_device_register;
 343         }
 344
 345         data->rtc->ops = &snvs_rtc_ops;
 346         data->rtc->range_max = U32_MAX;
 347         ret = rtc_register_device(data->rtc);
 348         if (ret) {
 349                 dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
 350                 goto error_rtc_device_register;
 351         }
 352
 353         return 0;
 354
 355 error_rtc_device_register:
 356         if (data->clk)
 357                 clk_disable_unprepare(data->clk);
 358
 359         return ret;
 360 }
 361
 362 static int __maybe_unused snvs_rtc_suspend_noirq(struct device *dev)
 363 {
 364         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 365
 366         if (data->clk)
 367                 clk_disable_unprepare(data->clk);
 368
 369         return 0;
 370 }
 371
 372 static int __maybe_unused snvs_rtc_resume_noirq(struct device *dev)
 373 {
 374         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 375
 376         if (data->clk)
 377                 return clk_prepare_enable(data->clk);
 378
 379         return 0;
 380 }
 381
 382 static const struct dev_pm_ops snvs_rtc_pm_ops = {
 383         SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(snvs_rtc_suspend_noirq, snvs_rtc_resume_noirq)
 384 };
 385
 386 static const struct of_device_id snvs_dt_ids[] = {
 387         { .compatible = "fsl,sec-v4.0-mon-rtc-lp", },
 388         { /* sentinel */ }
 389 };
 390 MODULE_DEVICE_TABLE(of, snvs_dt_ids);
 391
 392 static struct platform_driver snvs_rtc_driver = {
 393         .driver = {
 394                 .name   = "snvs_rtc",
 395                 .pm     = &snvs_rtc_pm_ops,
 396                 .of_match_table = snvs_dt_ids,
 397         },
 398         .probe          = snvs_rtc_probe,
 399 };
 400 module_platform_driver(snvs_rtc_driver);
 401
 402 MODULE_AUTHOR("Freescale Semiconductor, Inc.");
 403 MODULE_DESCRIPTION("Freescale SNVS RTC Driver");
 404 MODULE_LICENSE("GPL");