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
  21 /* These register offsets are relative to LP (Low Power) range */
  22 #define SNVS_LPCR               0x04
  23 #define SNVS_LPSR               0x18
  24 #define SNVS_LPSRTCMR           0x1c
  25 #define SNVS_LPSRTCLR           0x20
  26 #define SNVS_LPTAR              0x24
  27 #define SNVS_LPPGDR             0x30
  28
  29 #define SNVS_LPCR_SRTC_ENV      (1 << 0)
  30 #define SNVS_LPCR_LPTA_EN       (1 << 1)
  31 #define SNVS_LPCR_LPWUI_EN      (1 << 3)
  32 #define SNVS_LPSR_LPTA          (1 << 0)
  33
  34 #define SNVS_LPPGDR_INIT        0x41736166
  35 #define CNTR_TO_SECS_SH         15
  36
  37 struct snvs_rtc_data {
  38         struct rtc_device *rtc;
  39         void __iomem *ioaddr;
  40         int irq;
  41         spinlock_t lock;
  42 };
  43
  44 static u32 rtc_read_lp_counter(void __iomem *ioaddr)
  45 {
  46         u64 read1, read2;
  47
  48         do {
  49                 read1 = readl(ioaddr + SNVS_LPSRTCMR);
  50                 read1 <<= 32;
  51                 read1 |= readl(ioaddr + SNVS_LPSRTCLR);
  52
  53                 read2 = readl(ioaddr + SNVS_LPSRTCMR);
  54                 read2 <<= 32;
  55                 read2 |= readl(ioaddr + SNVS_LPSRTCLR);
  56         } while (read1 != read2);
  57
  58         /* Convert 47-bit counter to 32-bit raw second count */
  59         return (u32) (read1 >> CNTR_TO_SECS_SH);
  60 }
  61
  62 static void rtc_write_sync_lp(void __iomem *ioaddr)
  63 {
  64         u32 count1, count2, count3;
  65         int i;
  66
  67         /* Wait for 3 CKIL cycles */
  68         for (i = 0; i < 3; i++) {
  69                 do {
  70                         count1 = readl(ioaddr + SNVS_LPSRTCLR);
  71                         count2 = readl(ioaddr + SNVS_LPSRTCLR);
  72                 } while (count1 != count2);
  73
  74                 /* Now wait until counter value changes */
  75                 do {
  76                         do {
  77                                 count2 = readl(ioaddr + SNVS_LPSRTCLR);
  78                                 count3 = readl(ioaddr + SNVS_LPSRTCLR);
  79                         } while (count2 != count3);
  80                 } while (count3 == count1);
  81         }
  82 }
  83
  84 static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable)
  85 {
  86         unsigned long flags;
  87         int timeout = 1000;
  88         u32 lpcr;
  89
  90         spin_lock_irqsave(&data->lock, flags);
  91
  92         lpcr = readl(data->ioaddr + SNVS_LPCR);
  93         if (enable)
  94                 lpcr |= SNVS_LPCR_SRTC_ENV;
  95         else
  96                 lpcr &= ~SNVS_LPCR_SRTC_ENV;
  97         writel(lpcr, data->ioaddr + SNVS_LPCR);
  98
  99         spin_unlock_irqrestore(&data->lock, flags);
 100
 101         while (--timeout) {
 102                 lpcr = readl(data->ioaddr + SNVS_LPCR);
 103
 104                 if (enable) {
 105                         if (lpcr & SNVS_LPCR_SRTC_ENV)
 106                                 break;
 107                 } else {
 108                         if (!(lpcr & SNVS_LPCR_SRTC_ENV))
 109                                 break;
 110                 }
 111         }
 112
 113         if (!timeout)
 114                 return -ETIMEDOUT;
 115
 116         return 0;
 117 }
 118
 119 static int snvs_rtc_read_time(struct device *dev, struct rtc_time *tm)
 120 {
 121         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 122         unsigned long time = rtc_read_lp_counter(data->ioaddr);
 123
 124         rtc_time_to_tm(time, tm);
 125
 126         return 0;
 127 }
 128
 129 static int snvs_rtc_set_time(struct device *dev, struct rtc_time *tm)
 130 {
 131         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 132         unsigned long time;
 133
 134         rtc_tm_to_time(tm, &time);
 135
 136         /* Disable RTC first */
 137         snvs_rtc_enable(data, false);
 138
 139         /* Write 32-bit time to 47-bit timer, leaving 15 LSBs blank */
 140         writel(time << CNTR_TO_SECS_SH, data->ioaddr + SNVS_LPSRTCLR);
 141         writel(time >> (32 - CNTR_TO_SECS_SH), data->ioaddr + SNVS_LPSRTCMR);
 142
 143         /* Enable RTC again */
 144         snvs_rtc_enable(data, true);
 145
 146         return 0;
 147 }
 148
 149 static int snvs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 150 {
 151         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 152         u32 lptar, lpsr;
 153
 154         lptar = readl(data->ioaddr + SNVS_LPTAR);
 155         rtc_time_to_tm(lptar, &alrm->time);
 156
 157         lpsr = readl(data->ioaddr + SNVS_LPSR);
 158         alrm->pending = (lpsr & SNVS_LPSR_LPTA) ? 1 : 0;
 159
 160         return 0;
 161 }
 162
 163 static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
 164 {
 165         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 166         u32 lpcr;
 167         unsigned long flags;
 168
 169         spin_lock_irqsave(&data->lock, flags);
 170
 171         lpcr = readl(data->ioaddr + SNVS_LPCR);
 172         if (enable)
 173                 lpcr |= (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
 174         else
 175                 lpcr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
 176         writel(lpcr, data->ioaddr + SNVS_LPCR);
 177
 178         spin_unlock_irqrestore(&data->lock, flags);
 179
 180         rtc_write_sync_lp(data->ioaddr);
 181
 182         return 0;
 183 }
 184
 185 static int snvs_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 186 {
 187         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 188         struct rtc_time *alrm_tm = &alrm->time;
 189         unsigned long time;
 190         unsigned long flags;
 191         u32 lpcr;
 192
 193         rtc_tm_to_time(alrm_tm, &time);
 194
 195         spin_lock_irqsave(&data->lock, flags);
 196
 197         /* Have to clear LPTA_EN before programming new alarm time in LPTAR */
 198         lpcr = readl(data->ioaddr + SNVS_LPCR);
 199         lpcr &= ~SNVS_LPCR_LPTA_EN;
 200         writel(lpcr, data->ioaddr + SNVS_LPCR);
 201
 202         spin_unlock_irqrestore(&data->lock, flags);
 203
 204         writel(time, data->ioaddr + SNVS_LPTAR);
 205
 206         /* Clear alarm interrupt status bit */
 207         writel(SNVS_LPSR_LPTA, data->ioaddr + SNVS_LPSR);
 208
 209         return snvs_rtc_alarm_irq_enable(dev, alrm->enabled);
 210 }
 211
 212 static const struct rtc_class_ops snvs_rtc_ops = {
 213         .read_time = snvs_rtc_read_time,
 214         .set_time = snvs_rtc_set_time,
 215         .read_alarm = snvs_rtc_read_alarm,
 216         .set_alarm = snvs_rtc_set_alarm,
 217         .alarm_irq_enable = snvs_rtc_alarm_irq_enable,
 218 };
 219
 220 static irqreturn_t snvs_rtc_irq_handler(int irq, void *dev_id)
 221 {
 222         struct device *dev = dev_id;
 223         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 224         u32 lpsr;
 225         u32 events = 0;
 226
 227         lpsr = readl(data->ioaddr + SNVS_LPSR);
 228
 229         if (lpsr & SNVS_LPSR_LPTA) {
 230                 events |= (RTC_AF | RTC_IRQF);
 231
 232                 /* RTC alarm should be one-shot */
 233                 snvs_rtc_alarm_irq_enable(dev, 0);
 234
 235                 rtc_update_irq(data->rtc, 1, events);
 236         }
 237
 238         /* clear interrupt status */
 239         writel(lpsr, data->ioaddr + SNVS_LPSR);
 240
 241         return events ? IRQ_HANDLED : IRQ_NONE;
 242 }
 243
 244 static int snvs_rtc_probe(struct platform_device *pdev)
 245 {
 246         struct snvs_rtc_data *data;
 247         struct resource *res;
 248         int ret;
 249
 250         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 251         if (!data)
 252                 return -ENOMEM;
 253
 254         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 255         data->ioaddr = devm_ioremap_resource(&pdev->dev, res);
 256         if (IS_ERR(data->ioaddr))
 257                 return PTR_ERR(data->ioaddr);
 258
 259         data->irq = platform_get_irq(pdev, 0);
 260         if (data->irq < 0)
 261                 return data->irq;
 262
 263         platform_set_drvdata(pdev, data);
 264
 265         spin_lock_init(&data->lock);
 266
 267         /* Initialize glitch detect */
 268         writel(SNVS_LPPGDR_INIT, data->ioaddr + SNVS_LPPGDR);
 269
 270         /* Clear interrupt status */
 271         writel(0xffffffff, data->ioaddr + SNVS_LPSR);
 272
 273         /* Enable RTC */
 274         snvs_rtc_enable(data, true);
 275
 276         device_init_wakeup(&pdev->dev, true);
 277
 278         ret = devm_request_irq(&pdev->dev, data->irq, snvs_rtc_irq_handler,
 279                                IRQF_SHARED, "rtc alarm", &pdev->dev);
 280         if (ret) {
 281                 dev_err(&pdev->dev, "failed to request irq %d: %d\n",
 282                         data->irq, ret);
 283                 return ret;
 284         }
 285
 286         data->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 287                                         &snvs_rtc_ops, THIS_MODULE);
 288         if (IS_ERR(data->rtc)) {
 289                 ret = PTR_ERR(data->rtc);
 290                 dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
 291                 return ret;
 292         }
 293
 294         return 0;
 295 }
 296
 297 #ifdef CONFIG_PM_SLEEP
 298 static int snvs_rtc_suspend(struct device *dev)
 299 {
 300         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 301
 302         if (device_may_wakeup(dev))
 303                 enable_irq_wake(data->irq);
 304
 305         return 0;
 306 }
 307
 308 static int snvs_rtc_resume(struct device *dev)
 309 {
 310         struct snvs_rtc_data *data = dev_get_drvdata(dev);
 311
 312         if (device_may_wakeup(dev))
 313                 disable_irq_wake(data->irq);
 314
 315         return 0;
 316 }
 317 #endif
 318
 319 static SIMPLE_DEV_PM_OPS(snvs_rtc_pm_ops, snvs_rtc_suspend, snvs_rtc_resume);
 320
 321 static const struct of_device_id snvs_dt_ids[] = {
 322         { .compatible = "fsl,sec-v4.0-mon-rtc-lp", },
 323         { /* sentinel */ }
 324 };
 325 MODULE_DEVICE_TABLE(of, snvs_dt_ids);
 326
 327 static struct platform_driver snvs_rtc_driver = {
 328         .driver = {
 329                 .name   = "snvs_rtc",
 330                 .owner  = THIS_MODULE,
 331                 .pm     = &snvs_rtc_pm_ops,
 332                 .of_match_table = snvs_dt_ids,
 333         },
 334         .probe          = snvs_rtc_probe,
 335 };
 336 module_platform_driver(snvs_rtc_driver);
 337
 338 MODULE_AUTHOR("Freescale Semiconductor, Inc.");
 339 MODULE_DESCRIPTION("Freescale SNVS RTC Driver");
 340 MODULE_LICENSE("GPL");