drivers/rtc/rtc-snvs.c

   1 /*
   2  * Copyright (C) 2011-2012 Freescale Semiconductor, Inc.
   3  *
   4  * The code contained herein is licensed under the GNU General Public
   5  * License. You may obtain a copy of the GNU General Public License
   6  * Version 2 or later at the following locations:
   7  *
   8  * http://www.opensource.org/licenses/gpl-license.html
   9  * http://www.gnu.org/copyleft/gpl.html
  10  */
  11
  12 #include <linux/init.h>
  13 #include <linux/io.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/of.h>
  17 #include <linux/of_device.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/rtc.h>
  20 #include <linux/clk.h>
  21 #include <linux/mfd/syscon.h>
  22 #include <linux/regmap.h>
  23
  24 #define SNVS_LPREGISTER_OFFSET  0x34
  25
  26 /* These register offsets are relative to LP (Low Power) range */
  27 #define SNVS_LPCR               0x04
  28 #define SNVS_LPSR               0x18
  29 #define SNVS_LPSRTCMR           0x1c
  30 #define SNVS_LPSRTCLR           0x20
  31 #define SNVS_LPTAR              0x24
  32 #define SNVS_LPPGDR             0x30
  33
  34 #define SNVS_LPCR_SRTC_ENV      (1 << 0)
  35 #define SNVS_LPCR_LPTA_EN       (1 << 1)
  36 #define SNVS_LPCR_LPWUI_EN      (1 << 3)
  37 #define SNVS_LPSR_LPTA          (1 << 0)
  38
  39 #define SNVS_LPPGDR_INIT        0x41736166
  40 #define CNTR_TO_SECS_SH         15
  41
  42 struct snvs_rtc_data {
  43         struct rtc_device *rtc;
  44         struct regmap *regmap;
  45         int offset;
  46         int irq;
  47         struct clk *clk;
  48 };
  49
  50 static u32 rtc_read_lp_counter(struct snvs_rtc_data *data)
  51 {
  52         u64 read1, read2;
  53         u32 val;
  54
  55         do {
  56                 regmap_read(data->regmap, data->offset + SNVS_LPSRTCMR, &val);
  57                 read1 = val;
  58                 read1 <<= 32;
  59                 regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &val);
  60                 read1 |= val;
  61
  62                 regmap_read(data->regmap, data->offset + SNVS_LPSRTCMR, &val);
  63                 read2 = val;
  64                 read2 <<= 32;
  65                 regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &val);
  66                 read2 |= val;
  67         } while (read1 != read2);
  68
  69         /* Convert 47-bit counter to 32-bit raw second count */
  70         return (u32) (read1 >> CNTR_TO_SECS_SH);
  71 }
  72
  73 static void rtc_write_sync_lp(struct snvs_rtc_data *data)
  74 {
  75         u32 count1, count2, count3;
  76         int i;
  77
  78         /* Wait for 3 CKIL cycles */
  79         for (i = 0; i < 3; i++) {
  80                 do {
  81                         regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &count1);
  82                         regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &count2);
  83                 } while (count1 != count2);
  84
  85                 /* Now wait until counter value changes */
  86                 do {
  87                         do {
  88                                 regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &count2);
  89                                 regmap_read(data->regmap, data->offset + SNVS_LPSRTCLR, &count3);
  90                         } while (count2 != count3);
  91                 } while (count3 == count1);
  92         }
  93 }
  94
  95 static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable)
  96 {
  97         int timeout = 1000;
  98         u32 lpcr;
  99
 100         regmap_update_bits(data->regmap, data->offset + SNVS_LPCR, SNVS_LPCR_SRTC_ENV,
 101                            enable ? SNVS_LPCR_SRTC_ENV : 0);
 102
 103         while (--timeout) {
 104                 regmap_read(data->regmap, data->offset + SNVS_LPCR, &lpcr);
 105
 106                 if (enable) {
 107                         if (lpcr & SNVS_LPCR_SRTC_ENV)
 108                                 break;
 109                 } else {
 110                         if (!(lpcr & SNVS_LPCR_SRTC_ENV))
 111                                 break;
 112                 }
 113         }
 114
 115         if (!timeout)
 116                 return -ETIMEDOUT;
 117
 118         return 0;
 119 }
 120
 121 static int snvs_rtc_read_time(struct device *dev, struct rtc_time *tm)
 122 {
 123         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 124         unsigned long time = rtc_read_lp_counter(data);
 125
 126         rtc_time_to_tm(time, tm);
 127
 128         return 0;
 129 }
 130
 131 static int snvs_rtc_set_time(struct device *dev, struct rtc_time *tm)
 132 {
 133         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 134         unsigned long time;
 135
 136         rtc_tm_to_time(tm, &time);
 137
 138         /* Disable RTC first */
 139         snvs_rtc_enable(data, false);
 140
 141         /* Write 32-bit time to 47-bit timer, leaving 15 LSBs blank */
 142         regmap_write(data->regmap, data->offset + SNVS_LPSRTCLR, time << CNTR_TO_SECS_SH);
 143         regmap_write(data->regmap, data->offset + SNVS_LPSRTCMR, time >> (32 - CNTR_TO_SECS_SH));
 144
 145         /* Enable RTC again */
 146         snvs_rtc_enable(data, true);
 147
 148         return 0;
 149 }
 150
 151 static int snvs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 152 {
 153         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 154         u32 lptar, lpsr;
 155
 156         regmap_read(data->regmap, data->offset + SNVS_LPTAR, &lptar);
 157         rtc_time_to_tm(lptar, &alrm->time);
 158
 159         regmap_read(data->regmap, data->offset + SNVS_LPSR, &lpsr);
 160         alrm->pending = (lpsr & SNVS_LPSR_LPTA) ? 1 : 0;
 161
 162         return 0;
 163 }
 164
 165 static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
 166 {
 167         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 168
 169         regmap_update_bits(data->regmap, data->offset + SNVS_LPCR,
 170                            (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN),
 171                            enable ? (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN) : 0);
 172
 173         rtc_write_sync_lp(data);
 174
 175         return 0;
 176 }
 177
 178 static int snvs_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 179 {
 180         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 181         struct rtc_time *alrm_tm = &alrm->time;
 182         unsigned long time;
 183
 184         rtc_tm_to_time(alrm_tm, &time);
 185
 186         regmap_update_bits(data->regmap, data->offset + SNVS_LPCR, SNVS_LPCR_LPTA_EN, 0);
 187         rtc_write_sync_lp(data);
 188         regmap_write(data->regmap, data->offset + SNVS_LPTAR, time);
 189
 190         /* Clear alarm interrupt status bit */
 191         regmap_write(data->regmap, data->offset + SNVS_LPSR, SNVS_LPSR_LPTA);
 192
 193         return snvs_rtc_alarm_irq_enable(dev, alrm->enabled);
 194 }
 195
 196 static const struct rtc_class_ops snvs_rtc_ops = {
 197         .read_time = snvs_rtc_read_time,
 198         .set_time = snvs_rtc_set_time,
 199         .read_alarm = snvs_rtc_read_alarm,
 200         .set_alarm = snvs_rtc_set_alarm,
 201         .alarm_irq_enable = snvs_rtc_alarm_irq_enable,
 202 };
 203
 204 static irqreturn_t snvs_rtc_irq_handler(int irq, void *dev_id)
 205 {
 206         struct device *dev = dev_id;
 207         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 208         u32 lpsr;
 209         u32 events = 0;
 210
 211         regmap_read(data->regmap, data->offset + SNVS_LPSR, &lpsr);
 212
 213         if (lpsr & SNVS_LPSR_LPTA) {
 214                 events |= (RTC_AF | RTC_IRQF);
 215
 216                 /* RTC alarm should be one-shot */
 217                 snvs_rtc_alarm_irq_enable(dev, 0);
 218
 219                 rtc_update_irq(data->rtc, 1, events);
 220         }
 221
 222         /* clear interrupt status */
 223         regmap_write(data->regmap, data->offset + SNVS_LPSR, lpsr);
 224
 225         return events ? IRQ_HANDLED : IRQ_NONE;
 226 }
 227
 228 static const struct regmap_config snvs_rtc_config = {
 229         .reg_bits = 32,
 230         .val_bits = 32,
 231         .reg_stride = 4,
 232 };
 233
 234 static int snvs_rtc_probe(struct platform_device *pdev)
 235 {
 236         struct snvs_rtc_data *data;
 237         struct resource *res;
 238         int ret;
 239         void __iomem *mmio;
 240
 241         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 242         if (!data)
 243                 return -ENOMEM;
 244
 245         data->regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
 246
 247         if (IS_ERR(data->regmap)) {
 248                 dev_warn(&pdev->dev, "snvs rtc: you use old dts file, please update it\n");
 249                 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 250
 251                 mmio = devm_ioremap_resource(&pdev->dev, res);
 252                 if (IS_ERR(mmio))
 253                         return PTR_ERR(mmio);
 254
 255                 data->regmap = devm_regmap_init_mmio(&pdev->dev, mmio, &snvs_rtc_config);
 256         } else {
 257                 data->offset = SNVS_LPREGISTER_OFFSET;
 258                 of_property_read_u32(pdev->dev.of_node, "offset", &data->offset);
 259         }
 260
 261         if (IS_ERR(data->regmap)) {
 262                 dev_err(&pdev->dev, "Can't find snvs syscon\n");
 263                 return -ENODEV;
 264         }
 265
 266         data->irq = platform_get_irq(pdev, 0);
 267         if (data->irq < 0)
 268                 return data->irq;
 269
 270         data->clk = devm_clk_get(&pdev->dev, "snvs-rtc");
 271         if (IS_ERR(data->clk)) {
 272                 data->clk = NULL;
 273         } else {
 274                 ret = clk_prepare_enable(data->clk);
 275                 if (ret) {
 276                         dev_err(&pdev->dev,
 277                                 "Could not prepare or enable the snvs clock\n");
 278                         return ret;
 279                 }
 280         }
 281
 282         platform_set_drvdata(pdev, data);
 283
 284         /* Initialize glitch detect */
 285         regmap_write(data->regmap, data->offset + SNVS_LPPGDR, SNVS_LPPGDR_INIT);
 286
 287         /* Clear interrupt status */
 288         regmap_write(data->regmap, data->offset + SNVS_LPSR, 0xffffffff);
 289
 290         /* Enable RTC */
 291         snvs_rtc_enable(data, true);
 292
 293         device_init_wakeup(&pdev->dev, true);
 294
 295         ret = devm_request_irq(&pdev->dev, data->irq, snvs_rtc_irq_handler,
 296                                IRQF_SHARED, "rtc alarm", &pdev->dev);
 297         if (ret) {
 298                 dev_err(&pdev->dev, "failed to request irq %d: %d\n",
 299                         data->irq, ret);
 300                 goto error_rtc_device_register;
 301         }
 302
 303         data->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 304                                         &snvs_rtc_ops, THIS_MODULE);
 305         if (IS_ERR(data->rtc)) {
 306                 ret = PTR_ERR(data->rtc);
 307                 dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
 308                 goto error_rtc_device_register;
 309         }
 310
 311         return 0;
 312
 313 error_rtc_device_register:
 314         if (data->clk)
 315                 clk_disable_unprepare(data->clk);
 316
 317         return ret;
 318 }
 319
 320 #ifdef CONFIG_PM_SLEEP
 321 static int snvs_rtc_suspend(struct device *dev)
 322 {
 323         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 324
 325         if (device_may_wakeup(dev))
 326                 return enable_irq_wake(data->irq);
 327
 328         return 0;
 329 }
 330
 331 static int snvs_rtc_suspend_noirq(struct device *dev)
 332 {
 333         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 334
 335         if (data->clk)
 336                 clk_disable_unprepare(data->clk);
 337
 338         return 0;
 339 }
 340
 341 static int snvs_rtc_resume(struct device *dev)
 342 {
 343         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 344
 345         if (device_may_wakeup(dev))
 346                 return disable_irq_wake(data->irq);
 347
 348         return 0;
 349 }
 350
 351 static int snvs_rtc_resume_noirq(struct device *dev)
 352 {
 353         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 354
 355         if (data->clk)
 356                 return clk_prepare_enable(data->clk);
 357
 358         return 0;
 359 }
 360
 361 static const struct dev_pm_ops snvs_rtc_pm_ops = {
 362         .suspend = snvs_rtc_suspend,
 363         .suspend_noirq = snvs_rtc_suspend_noirq,
 364         .resume = snvs_rtc_resume,
 365         .resume_noirq = snvs_rtc_resume_noirq,
 366 };
 367
 368 #define SNVS_RTC_PM_OPS (&snvs_rtc_pm_ops)
 369
 370 #else
 371
 372 #define SNVS_RTC_PM_OPS NULL
 373
 374 #endif
 375
 376 static const struct of_device_id snvs_dt_ids[] = {
 377         { .compatible = "fsl,sec-v4.0-mon-rtc-lp", },
 378         { /* sentinel */ }
 379 };
 380 MODULE_DEVICE_TABLE(of, snvs_dt_ids);
 381
 382 static struct platform_driver snvs_rtc_driver = {
 383         .driver = {
 384                 .name   = "snvs_rtc",
 385                 .pm     = SNVS_RTC_PM_OPS,
 386                 .of_match_table = snvs_dt_ids,
 387         },
 388         .probe          = snvs_rtc_probe,
 389 };
 390 module_platform_driver(snvs_rtc_driver);
 391
 392 MODULE_AUTHOR("Freescale Semiconductor, Inc.");
 393 MODULE_DESCRIPTION("Freescale SNVS RTC Driver");
 394 MODULE_LICENSE("GPL");