drivers/rtc/rtc-st-lpc.c

   1 /*
   2  * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer
   3  *
   4  * Copyright (C) 2014 STMicroelectronics Limited
   5  *
   6  * Author: David Paris <david.paris@st.com> for STMicroelectronics
   7  *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
   8  *
   9  * Based on the original driver written by Stuart Menefy.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public Licence
  13  * as published by the Free Software Foundation; either version
  14  * 2 of the Licence, or (at your option) any later version.
  15  */
  16
  17 #include <linux/clk.h>
  18 #include <linux/delay.h>
  19 #include <linux/init.h>
  20 #include <linux/io.h>
  21 #include <linux/irq.h>
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/of.h>
  25 #include <linux/of_irq.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/rtc.h>
  28
  29 #include <dt-bindings/mfd/st-lpc.h>
  30
  31 /* Low Power Timer */
  32 #define LPC_LPT_LSB_OFF         0x400
  33 #define LPC_LPT_MSB_OFF         0x404
  34 #define LPC_LPT_START_OFF       0x408
  35
  36 /* Low Power Alarm */
  37 #define LPC_LPA_LSB_OFF         0x410
  38 #define LPC_LPA_MSB_OFF         0x414
  39 #define LPC_LPA_START_OFF       0x418
  40
  41 /* LPC as WDT */
  42 #define LPC_WDT_OFF             0x510
  43 #define LPC_WDT_FLAG_OFF        0x514
  44
  45 struct st_rtc {
  46         struct rtc_device *rtc_dev;
  47         struct rtc_wkalrm alarm;
  48         struct resource *res;
  49         struct clk *clk;
  50         unsigned long clkrate;
  51         void __iomem *ioaddr;
  52         bool irq_enabled:1;
  53         spinlock_t lock;
  54         short irq;
  55 };
  56
  57 static void st_rtc_set_hw_alarm(struct st_rtc *rtc,
  58                                 unsigned long msb, unsigned long  lsb)
  59 {
  60         unsigned long flags;
  61
  62         spin_lock_irqsave(&rtc->lock, flags);
  63
  64         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
  65
  66         writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);
  67         writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);
  68         writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
  69
  70         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
  71
  72         spin_unlock_irqrestore(&rtc->lock, flags);
  73 }
  74
  75 static irqreturn_t st_rtc_handler(int this_irq, void *data)
  76 {
  77         struct st_rtc *rtc = (struct st_rtc *)data;
  78
  79         rtc_update_irq(rtc->rtc_dev, 1, RTC_AF);
  80
  81         return IRQ_HANDLED;
  82 }
  83
  84 static int st_rtc_read_time(struct device *dev, struct rtc_time *tm)
  85 {
  86         struct st_rtc *rtc = dev_get_drvdata(dev);
  87         unsigned long lpt_lsb, lpt_msb;
  88         unsigned long long lpt;
  89         unsigned long flags;
  90
  91         spin_lock_irqsave(&rtc->lock, flags);
  92
  93         do {
  94                 lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF);
  95                 lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF);
  96         } while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb);
  97
  98         spin_unlock_irqrestore(&rtc->lock, flags);
  99
 100         lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;
 101         do_div(lpt, rtc->clkrate);
 102         rtc_time_to_tm(lpt, tm);
 103
 104         return 0;
 105 }
 106
 107 static int st_rtc_set_time(struct device *dev, struct rtc_time *tm)
 108 {
 109         struct st_rtc *rtc = dev_get_drvdata(dev);
 110         unsigned long long lpt;
 111         unsigned long secs, flags;
 112         int ret;
 113
 114         ret = rtc_tm_to_time(tm, &secs);
 115         if (ret)
 116                 return ret;
 117
 118         lpt = (unsigned long long)secs * rtc->clkrate;
 119
 120         spin_lock_irqsave(&rtc->lock, flags);
 121
 122         writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
 123         writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
 124         writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF);
 125
 126         spin_unlock_irqrestore(&rtc->lock, flags);
 127
 128         return 0;
 129 }
 130
 131 static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 132 {
 133         struct st_rtc *rtc = dev_get_drvdata(dev);
 134         unsigned long flags;
 135
 136         spin_lock_irqsave(&rtc->lock, flags);
 137
 138         memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
 139
 140         spin_unlock_irqrestore(&rtc->lock, flags);
 141
 142         return 0;
 143 }
 144
 145 static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 146 {
 147         struct st_rtc *rtc = dev_get_drvdata(dev);
 148
 149         if (enabled && !rtc->irq_enabled) {
 150                 enable_irq(rtc->irq);
 151                 rtc->irq_enabled = true;
 152         } else if (!enabled && rtc->irq_enabled) {
 153                 disable_irq(rtc->irq);
 154                 rtc->irq_enabled = false;
 155         }
 156
 157         return 0;
 158 }
 159
 160 static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 161 {
 162         struct st_rtc *rtc = dev_get_drvdata(dev);
 163         struct rtc_time now;
 164         unsigned long now_secs;
 165         unsigned long alarm_secs;
 166         unsigned long long lpa;
 167
 168         st_rtc_read_time(dev, &now);
 169         rtc_tm_to_time(&now, &now_secs);
 170         rtc_tm_to_time(&t->time, &alarm_secs);
 171
 172         /* Invalid alarm time */
 173         if (now_secs > alarm_secs)
 174                 return -EINVAL;
 175
 176         memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
 177
 178         /* Now many secs to fire */
 179         alarm_secs -= now_secs;
 180         lpa = (unsigned long long)alarm_secs * rtc->clkrate;
 181
 182         st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
 183         st_rtc_alarm_irq_enable(dev, t->enabled);
 184
 185         return 0;
 186 }
 187
 188 static struct rtc_class_ops st_rtc_ops = {
 189         .read_time              = st_rtc_read_time,
 190         .set_time               = st_rtc_set_time,
 191         .read_alarm             = st_rtc_read_alarm,
 192         .set_alarm              = st_rtc_set_alarm,
 193         .alarm_irq_enable       = st_rtc_alarm_irq_enable,
 194 };
 195
 196 static int st_rtc_probe(struct platform_device *pdev)
 197 {
 198         struct device_node *np = pdev->dev.of_node;
 199         struct st_rtc *rtc;
 200         struct resource *res;
 201         struct rtc_time tm_check;
 202         uint32_t mode;
 203         int ret = 0;
 204
 205         ret = of_property_read_u32(np, "st,lpc-mode", &mode);
 206         if (ret) {
 207                 dev_err(&pdev->dev, "An LPC mode must be provided\n");
 208                 return -EINVAL;
 209         }
 210
 211         /* LPC can either run in RTC or WDT mode */
 212         if (mode != ST_LPC_MODE_RTC)
 213                 return -ENODEV;
 214
 215         rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
 216         if (!rtc)
 217                 return -ENOMEM;
 218
 219         spin_lock_init(&rtc->lock);
 220
 221         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 222         rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res);
 223         if (IS_ERR(rtc->ioaddr))
 224                 return PTR_ERR(rtc->ioaddr);
 225
 226         rtc->irq = irq_of_parse_and_map(np, 0);
 227         if (!rtc->irq) {
 228                 dev_err(&pdev->dev, "IRQ missing or invalid\n");
 229                 return -EINVAL;
 230         }
 231
 232         ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0,
 233                                pdev->name, rtc);
 234         if (ret) {
 235                 dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq);
 236                 return ret;
 237         }
 238
 239         enable_irq_wake(rtc->irq);
 240         disable_irq(rtc->irq);
 241
 242         rtc->clk = clk_get(&pdev->dev, NULL);
 243         if (IS_ERR(rtc->clk)) {
 244                 dev_err(&pdev->dev, "Unable to request clock\n");
 245                 return PTR_ERR(rtc->clk);
 246         }
 247
 248         clk_prepare_enable(rtc->clk);
 249
 250         rtc->clkrate = clk_get_rate(rtc->clk);
 251         if (!rtc->clkrate) {
 252                 dev_err(&pdev->dev, "Unable to fetch clock rate\n");
 253                 return -EINVAL;
 254         }
 255
 256         device_set_wakeup_capable(&pdev->dev, 1);
 257
 258         platform_set_drvdata(pdev, rtc);
 259
 260         /*
 261          * The RTC-LPC is able to manage date.year > 2038
 262          * but currently the kernel can not manage this date!
 263          * If the RTC-LPC has a date.year > 2038 then
 264          * it's set to the epoch "Jan 1st 2000"
 265          */
 266         st_rtc_read_time(&pdev->dev, &tm_check);
 267
 268         if (tm_check.tm_year >=  (2038 - 1900)) {
 269                 memset(&tm_check, 0, sizeof(tm_check));
 270                 tm_check.tm_year = 100;
 271                 tm_check.tm_mday = 1;
 272                 st_rtc_set_time(&pdev->dev, &tm_check);
 273         }
 274
 275         rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev,
 276                                            &st_rtc_ops, THIS_MODULE);
 277         if (IS_ERR(rtc->rtc_dev)) {
 278                 clk_disable_unprepare(rtc->clk);
 279                 return PTR_ERR(rtc->rtc_dev);
 280         }
 281
 282         return 0;
 283 }
 284
 285 static int st_rtc_remove(struct platform_device *pdev)
 286 {
 287         struct st_rtc *rtc = platform_get_drvdata(pdev);
 288
 289         if (likely(rtc->rtc_dev))
 290                 rtc_device_unregister(rtc->rtc_dev);
 291
 292         return 0;
 293 }
 294
 295 #ifdef CONFIG_PM_SLEEP
 296 static int st_rtc_suspend(struct device *dev)
 297 {
 298         struct st_rtc *rtc = dev_get_drvdata(dev);
 299
 300         if (device_may_wakeup(dev))
 301                 return 0;
 302
 303         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
 304         writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF);
 305         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
 306
 307         return 0;
 308 }
 309
 310 static int st_rtc_resume(struct device *dev)
 311 {
 312         struct st_rtc *rtc = dev_get_drvdata(dev);
 313
 314         rtc_alarm_irq_enable(rtc->rtc_dev, 0);
 315
 316         /*
 317          * clean 'rtc->alarm' to allow a new
 318          * .set_alarm to the upper RTC layer
 319          */
 320         memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));
 321
 322         writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
 323         writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
 324         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
 325         writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
 326         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
 327
 328         return 0;
 329 }
 330 #endif
 331
 332 static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
 333
 334 static const struct of_device_id st_rtc_match[] = {
 335         { .compatible = "st,stih407-lpc" },
 336         {}
 337 };
 338 MODULE_DEVICE_TABLE(of, st_rtc_match);
 339
 340 static struct platform_driver st_rtc_platform_driver = {
 341         .driver = {
 342                 .name = "st-lpc-rtc",
 343                 .pm = &st_rtc_pm_ops,
 344                 .of_match_table = st_rtc_match,
 345         },
 346         .probe = st_rtc_probe,
 347         .remove = st_rtc_remove,
 348 };
 349
 350 module_platform_driver(st_rtc_platform_driver);
 351
 352 MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
 353 MODULE_AUTHOR("David Paris <david.paris@st.com>");
 354 MODULE_LICENSE("GPL");