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_time64_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, secs;
 111         unsigned long flags;
 112
 113         secs = rtc_tm_to_time64(tm);
 114
 115         lpt = (unsigned long long)secs * rtc->clkrate;
 116
 117         spin_lock_irqsave(&rtc->lock, flags);
 118
 119         writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
 120         writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
 121         writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF);
 122
 123         spin_unlock_irqrestore(&rtc->lock, flags);
 124
 125         return 0;
 126 }
 127
 128 static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 129 {
 130         struct st_rtc *rtc = dev_get_drvdata(dev);
 131         unsigned long flags;
 132
 133         spin_lock_irqsave(&rtc->lock, flags);
 134
 135         memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
 136
 137         spin_unlock_irqrestore(&rtc->lock, flags);
 138
 139         return 0;
 140 }
 141
 142 static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 143 {
 144         struct st_rtc *rtc = dev_get_drvdata(dev);
 145
 146         if (enabled && !rtc->irq_enabled) {
 147                 enable_irq(rtc->irq);
 148                 rtc->irq_enabled = true;
 149         } else if (!enabled && rtc->irq_enabled) {
 150                 disable_irq(rtc->irq);
 151                 rtc->irq_enabled = false;
 152         }
 153
 154         return 0;
 155 }
 156
 157 static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 158 {
 159         struct st_rtc *rtc = dev_get_drvdata(dev);
 160         struct rtc_time now;
 161         unsigned long long now_secs;
 162         unsigned long long alarm_secs;
 163         unsigned long long lpa;
 164
 165         st_rtc_read_time(dev, &now);
 166         now_secs = rtc_tm_to_time64(&now);
 167         alarm_secs = rtc_tm_to_time64(&t->time);
 168
 169         /* Invalid alarm time */
 170         if (now_secs > alarm_secs)
 171                 return -EINVAL;
 172
 173         memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
 174
 175         /* Now many secs to fire */
 176         alarm_secs -= now_secs;
 177         lpa = (unsigned long long)alarm_secs * rtc->clkrate;
 178
 179         st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
 180         st_rtc_alarm_irq_enable(dev, t->enabled);
 181
 182         return 0;
 183 }
 184
 185 static struct rtc_class_ops st_rtc_ops = {
 186         .read_time              = st_rtc_read_time,
 187         .set_time               = st_rtc_set_time,
 188         .read_alarm             = st_rtc_read_alarm,
 189         .set_alarm              = st_rtc_set_alarm,
 190         .alarm_irq_enable       = st_rtc_alarm_irq_enable,
 191 };
 192
 193 static int st_rtc_probe(struct platform_device *pdev)
 194 {
 195         struct device_node *np = pdev->dev.of_node;
 196         struct st_rtc *rtc;
 197         struct resource *res;
 198         struct rtc_time tm_check;
 199         uint32_t mode;
 200         int ret = 0;
 201
 202         ret = of_property_read_u32(np, "st,lpc-mode", &mode);
 203         if (ret) {
 204                 dev_err(&pdev->dev, "An LPC mode must be provided\n");
 205                 return -EINVAL;
 206         }
 207
 208         /* LPC can either run as a Clocksource or in RTC or WDT mode */
 209         if (mode != ST_LPC_MODE_RTC)
 210                 return -ENODEV;
 211
 212         rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
 213         if (!rtc)
 214                 return -ENOMEM;
 215
 216         spin_lock_init(&rtc->lock);
 217
 218         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 219         rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res);
 220         if (IS_ERR(rtc->ioaddr))
 221                 return PTR_ERR(rtc->ioaddr);
 222
 223         rtc->irq = irq_of_parse_and_map(np, 0);
 224         if (!rtc->irq) {
 225                 dev_err(&pdev->dev, "IRQ missing or invalid\n");
 226                 return -EINVAL;
 227         }
 228
 229         ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0,
 230                                pdev->name, rtc);
 231         if (ret) {
 232                 dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq);
 233                 return ret;
 234         }
 235
 236         enable_irq_wake(rtc->irq);
 237         disable_irq(rtc->irq);
 238
 239         rtc->clk = clk_get(&pdev->dev, NULL);
 240         if (IS_ERR(rtc->clk)) {
 241                 dev_err(&pdev->dev, "Unable to request clock\n");
 242                 return PTR_ERR(rtc->clk);
 243         }
 244
 245         clk_prepare_enable(rtc->clk);
 246
 247         rtc->clkrate = clk_get_rate(rtc->clk);
 248         if (!rtc->clkrate) {
 249                 dev_err(&pdev->dev, "Unable to fetch clock rate\n");
 250                 return -EINVAL;
 251         }
 252
 253         device_set_wakeup_capable(&pdev->dev, 1);
 254
 255         platform_set_drvdata(pdev, rtc);
 256
 257         /*
 258          * The RTC-LPC is able to manage date.year > 2038
 259          * but currently the kernel can not manage this date!
 260          * If the RTC-LPC has a date.year > 2038 then
 261          * it's set to the epoch "Jan 1st 2000"
 262          */
 263         st_rtc_read_time(&pdev->dev, &tm_check);
 264
 265         if (tm_check.tm_year >=  (2038 - 1900)) {
 266                 memset(&tm_check, 0, sizeof(tm_check));
 267                 tm_check.tm_year = 100;
 268                 tm_check.tm_mday = 1;
 269                 st_rtc_set_time(&pdev->dev, &tm_check);
 270         }
 271
 272         rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev,
 273                                            &st_rtc_ops, THIS_MODULE);
 274         if (IS_ERR(rtc->rtc_dev)) {
 275                 clk_disable_unprepare(rtc->clk);
 276                 return PTR_ERR(rtc->rtc_dev);
 277         }
 278
 279         return 0;
 280 }
 281
 282 static int st_rtc_remove(struct platform_device *pdev)
 283 {
 284         struct st_rtc *rtc = platform_get_drvdata(pdev);
 285
 286         if (likely(rtc->rtc_dev))
 287                 rtc_device_unregister(rtc->rtc_dev);
 288
 289         return 0;
 290 }
 291
 292 #ifdef CONFIG_PM_SLEEP
 293 static int st_rtc_suspend(struct device *dev)
 294 {
 295         struct st_rtc *rtc = dev_get_drvdata(dev);
 296
 297         if (device_may_wakeup(dev))
 298                 return 0;
 299
 300         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
 301         writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF);
 302         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
 303
 304         return 0;
 305 }
 306
 307 static int st_rtc_resume(struct device *dev)
 308 {
 309         struct st_rtc *rtc = dev_get_drvdata(dev);
 310
 311         rtc_alarm_irq_enable(rtc->rtc_dev, 0);
 312
 313         /*
 314          * clean 'rtc->alarm' to allow a new
 315          * .set_alarm to the upper RTC layer
 316          */
 317         memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));
 318
 319         writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
 320         writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
 321         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
 322         writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
 323         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
 324
 325         return 0;
 326 }
 327 #endif
 328
 329 static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
 330
 331 static const struct of_device_id st_rtc_match[] = {
 332         { .compatible = "st,stih407-lpc" },
 333         {}
 334 };
 335 MODULE_DEVICE_TABLE(of, st_rtc_match);
 336
 337 static struct platform_driver st_rtc_platform_driver = {
 338         .driver = {
 339                 .name = "st-lpc-rtc",
 340                 .pm = &st_rtc_pm_ops,
 341                 .of_match_table = st_rtc_match,
 342         },
 343         .probe = st_rtc_probe,
 344         .remove = st_rtc_remove,
 345 };
 346
 347 module_platform_driver(st_rtc_platform_driver);
 348
 349 MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
 350 MODULE_AUTHOR("David Paris <david.paris@st.com>");
 351 MODULE_LICENSE("GPL");