linux/drivers/rtc/rtc-snvs.c
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   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
  42struct snvs_rtc_data {
  43        struct rtc_device *rtc;
  44        struct regmap *regmap;
  45        int offset;
  46        int irq;
  47        struct clk *clk;
  48};
  49
  50static 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
  73static 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
  95static 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
 121static 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
 131static 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
 151static 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
 165static 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
 178static 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        regmap_write(data->regmap, data->offset + SNVS_LPTAR, time);
 188
 189        /* Clear alarm interrupt status bit */
 190        regmap_write(data->regmap, data->offset + SNVS_LPSR, SNVS_LPSR_LPTA);
 191
 192        return snvs_rtc_alarm_irq_enable(dev, alrm->enabled);
 193}
 194
 195static const struct rtc_class_ops snvs_rtc_ops = {
 196        .read_time = snvs_rtc_read_time,
 197        .set_time = snvs_rtc_set_time,
 198        .read_alarm = snvs_rtc_read_alarm,
 199        .set_alarm = snvs_rtc_set_alarm,
 200        .alarm_irq_enable = snvs_rtc_alarm_irq_enable,
 201};
 202
 203static irqreturn_t snvs_rtc_irq_handler(int irq, void *dev_id)
 204{
 205        struct device *dev = dev_id;
 206        struct snvs_rtc_data *data = dev_get_drvdata(dev);
 207        u32 lpsr;
 208        u32 events = 0;
 209
 210        regmap_read(data->regmap, data->offset + SNVS_LPSR, &lpsr);
 211
 212        if (lpsr & SNVS_LPSR_LPTA) {
 213                events |= (RTC_AF | RTC_IRQF);
 214
 215                /* RTC alarm should be one-shot */
 216                snvs_rtc_alarm_irq_enable(dev, 0);
 217
 218                rtc_update_irq(data->rtc, 1, events);
 219        }
 220
 221        /* clear interrupt status */
 222        regmap_write(data->regmap, data->offset + SNVS_LPSR, lpsr);
 223
 224        return events ? IRQ_HANDLED : IRQ_NONE;
 225}
 226
 227static const struct regmap_config snvs_rtc_config = {
 228        .reg_bits = 32,
 229        .val_bits = 32,
 230        .reg_stride = 4,
 231};
 232
 233static int snvs_rtc_probe(struct platform_device *pdev)
 234{
 235        struct snvs_rtc_data *data;
 236        struct resource *res;
 237        int ret;
 238        void __iomem *mmio;
 239
 240        data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 241        if (!data)
 242                return -ENOMEM;
 243
 244        data->regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
 245
 246        if (IS_ERR(data->regmap)) {
 247                dev_warn(&pdev->dev, "snvs rtc: you use old dts file, please update it\n");
 248                res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 249
 250                mmio = devm_ioremap_resource(&pdev->dev, res);
 251                if (IS_ERR(mmio))
 252                        return PTR_ERR(mmio);
 253
 254                data->regmap = devm_regmap_init_mmio(&pdev->dev, mmio, &snvs_rtc_config);
 255        } else {
 256                data->offset = SNVS_LPREGISTER_OFFSET;
 257                of_property_read_u32(pdev->dev.of_node, "offset", &data->offset);
 258        }
 259
 260        if (!data->regmap) {
 261                dev_err(&pdev->dev, "Can't find snvs syscon\n");
 262                return -ENODEV;
 263        }
 264
 265        data->irq = platform_get_irq(pdev, 0);
 266        if (data->irq < 0)
 267                return data->irq;
 268
 269        data->clk = devm_clk_get(&pdev->dev, "snvs-rtc");
 270        if (IS_ERR(data->clk)) {
 271                data->clk = NULL;
 272        } else {
 273                ret = clk_prepare_enable(data->clk);
 274                if (ret) {
 275                        dev_err(&pdev->dev,
 276                                "Could not prepare or enable the snvs clock\n");
 277                        return ret;
 278                }
 279        }
 280
 281        platform_set_drvdata(pdev, data);
 282
 283        /* Initialize glitch detect */
 284        regmap_write(data->regmap, data->offset + SNVS_LPPGDR, SNVS_LPPGDR_INIT);
 285
 286        /* Clear interrupt status */
 287        regmap_write(data->regmap, data->offset + SNVS_LPSR, 0xffffffff);
 288
 289        /* Enable RTC */
 290        snvs_rtc_enable(data, true);
 291
 292        device_init_wakeup(&pdev->dev, true);
 293
 294        ret = devm_request_irq(&pdev->dev, data->irq, snvs_rtc_irq_handler,
 295                               IRQF_SHARED, "rtc alarm", &pdev->dev);
 296        if (ret) {
 297                dev_err(&pdev->dev, "failed to request irq %d: %d\n",
 298                        data->irq, ret);
 299                goto error_rtc_device_register;
 300        }
 301
 302        data->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 303                                        &snvs_rtc_ops, THIS_MODULE);
 304        if (IS_ERR(data->rtc)) {
 305                ret = PTR_ERR(data->rtc);
 306                dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
 307                goto error_rtc_device_register;
 308        }
 309
 310        return 0;
 311
 312error_rtc_device_register:
 313        if (data->clk)
 314                clk_disable_unprepare(data->clk);
 315
 316        return ret;
 317}
 318
 319#ifdef CONFIG_PM_SLEEP
 320static int snvs_rtc_suspend(struct device *dev)
 321{
 322        struct snvs_rtc_data *data = dev_get_drvdata(dev);
 323
 324        if (device_may_wakeup(dev))
 325                return enable_irq_wake(data->irq);
 326
 327        return 0;
 328}
 329
 330static int snvs_rtc_suspend_noirq(struct device *dev)
 331{
 332        struct snvs_rtc_data *data = dev_get_drvdata(dev);
 333
 334        if (data->clk)
 335                clk_disable_unprepare(data->clk);
 336
 337        return 0;
 338}
 339
 340static int snvs_rtc_resume(struct device *dev)
 341{
 342        struct snvs_rtc_data *data = dev_get_drvdata(dev);
 343
 344        if (device_may_wakeup(dev))
 345                return disable_irq_wake(data->irq);
 346
 347        return 0;
 348}
 349
 350static int snvs_rtc_resume_noirq(struct device *dev)
 351{
 352        struct snvs_rtc_data *data = dev_get_drvdata(dev);
 353
 354        if (data->clk)
 355                return clk_prepare_enable(data->clk);
 356
 357        return 0;
 358}
 359
 360static const struct dev_pm_ops snvs_rtc_pm_ops = {
 361        .suspend = snvs_rtc_suspend,
 362        .suspend_noirq = snvs_rtc_suspend_noirq,
 363        .resume = snvs_rtc_resume,
 364        .resume_noirq = snvs_rtc_resume_noirq,
 365};
 366
 367#define SNVS_RTC_PM_OPS (&snvs_rtc_pm_ops)
 368
 369#else
 370
 371#define SNVS_RTC_PM_OPS NULL
 372
 373#endif
 374
 375static const struct of_device_id snvs_dt_ids[] = {
 376        { .compatible = "fsl,sec-v4.0-mon-rtc-lp", },
 377        { /* sentinel */ }
 378};
 379MODULE_DEVICE_TABLE(of, snvs_dt_ids);
 380
 381static struct platform_driver snvs_rtc_driver = {
 382        .driver = {
 383                .name   = "snvs_rtc",
 384                .pm     = SNVS_RTC_PM_OPS,
 385                .of_match_table = snvs_dt_ids,
 386        },
 387        .probe          = snvs_rtc_probe,
 388};
 389module_platform_driver(snvs_rtc_driver);
 390
 391MODULE_AUTHOR("Freescale Semiconductor, Inc.");
 392MODULE_DESCRIPTION("Freescale SNVS RTC Driver");
 393MODULE_LICENSE("GPL");
 394