drivers/rtc/rtc-st-lpc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer
   4  *
   5  * Copyright (C) 2014 STMicroelectronics Limited
   6  *
   7  * Author: David Paris <david.paris@st.com> for STMicroelectronics
   8  *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
   9  *
  10  * Based on the original driver written by Stuart Menefy.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/delay.h>
  15 #include <linux/init.h>
  16 #include <linux/io.h>
  17 #include <linux/irq.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/of.h>
  21 #include <linux/of_irq.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/rtc.h>
  24
  25 #include <dt-bindings/mfd/st-lpc.h>
  26
  27 /* Low Power Timer */
  28 #define LPC_LPT_LSB_OFF         0x400
  29 #define LPC_LPT_MSB_OFF         0x404
  30 #define LPC_LPT_START_OFF       0x408
  31
  32 /* Low Power Alarm */
  33 #define LPC_LPA_LSB_OFF         0x410
  34 #define LPC_LPA_MSB_OFF         0x414
  35 #define LPC_LPA_START_OFF       0x418
  36
  37 /* LPC as WDT */
  38 #define LPC_WDT_OFF             0x510
  39 #define LPC_WDT_FLAG_OFF        0x514
  40
  41 struct st_rtc {
  42         struct rtc_device *rtc_dev;
  43         struct rtc_wkalrm alarm;
  44         struct resource *res;
  45         struct clk *clk;
  46         unsigned long clkrate;
  47         void __iomem *ioaddr;
  48         bool irq_enabled:1;
  49         spinlock_t lock;
  50         short irq;
  51 };
  52
  53 static void st_rtc_set_hw_alarm(struct st_rtc *rtc,
  54                                 unsigned long msb, unsigned long  lsb)
  55 {
  56         unsigned long flags;
  57
  58         spin_lock_irqsave(&rtc->lock, flags);
  59
  60         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
  61
  62         writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);
  63         writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);
  64         writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
  65
  66         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
  67
  68         spin_unlock_irqrestore(&rtc->lock, flags);
  69 }
  70
  71 static irqreturn_t st_rtc_handler(int this_irq, void *data)
  72 {
  73         struct st_rtc *rtc = (struct st_rtc *)data;
  74
  75         rtc_update_irq(rtc->rtc_dev, 1, RTC_AF);
  76
  77         return IRQ_HANDLED;
  78 }
  79
  80 static int st_rtc_read_time(struct device *dev, struct rtc_time *tm)
  81 {
  82         struct st_rtc *rtc = dev_get_drvdata(dev);
  83         unsigned long lpt_lsb, lpt_msb;
  84         unsigned long long lpt;
  85         unsigned long flags;
  86
  87         spin_lock_irqsave(&rtc->lock, flags);
  88
  89         do {
  90                 lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF);
  91                 lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF);
  92         } while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb);
  93
  94         spin_unlock_irqrestore(&rtc->lock, flags);
  95
  96         lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;
  97         do_div(lpt, rtc->clkrate);
  98         rtc_time64_to_tm(lpt, tm);
  99
 100         return 0;
 101 }
 102
 103 static int st_rtc_set_time(struct device *dev, struct rtc_time *tm)
 104 {
 105         struct st_rtc *rtc = dev_get_drvdata(dev);
 106         unsigned long long lpt, secs;
 107         unsigned long flags;
 108
 109         secs = rtc_tm_to_time64(tm);
 110
 111         lpt = (unsigned long long)secs * rtc->clkrate;
 112
 113         spin_lock_irqsave(&rtc->lock, flags);
 114
 115         writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
 116         writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
 117         writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF);
 118
 119         spin_unlock_irqrestore(&rtc->lock, flags);
 120
 121         return 0;
 122 }
 123
 124 static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 125 {
 126         struct st_rtc *rtc = dev_get_drvdata(dev);
 127         unsigned long flags;
 128
 129         spin_lock_irqsave(&rtc->lock, flags);
 130
 131         memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
 132
 133         spin_unlock_irqrestore(&rtc->lock, flags);
 134
 135         return 0;
 136 }
 137
 138 static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 139 {
 140         struct st_rtc *rtc = dev_get_drvdata(dev);
 141
 142         if (enabled && !rtc->irq_enabled) {
 143                 enable_irq(rtc->irq);
 144                 rtc->irq_enabled = true;
 145         } else if (!enabled && rtc->irq_enabled) {
 146                 disable_irq(rtc->irq);
 147                 rtc->irq_enabled = false;
 148         }
 149
 150         return 0;
 151 }
 152
 153 static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 154 {
 155         struct st_rtc *rtc = dev_get_drvdata(dev);
 156         struct rtc_time now;
 157         unsigned long long now_secs;
 158         unsigned long long alarm_secs;
 159         unsigned long long lpa;
 160
 161         st_rtc_read_time(dev, &now);
 162         now_secs = rtc_tm_to_time64(&now);
 163         alarm_secs = rtc_tm_to_time64(&t->time);
 164
 165         /* Invalid alarm time */
 166         if (now_secs > alarm_secs)
 167                 return -EINVAL;
 168
 169         memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
 170
 171         /* Now many secs to fire */
 172         alarm_secs -= now_secs;
 173         lpa = (unsigned long long)alarm_secs * rtc->clkrate;
 174
 175         st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
 176         st_rtc_alarm_irq_enable(dev, t->enabled);
 177
 178         return 0;
 179 }
 180
 181 static struct rtc_class_ops st_rtc_ops = {
 182         .read_time              = st_rtc_read_time,
 183         .set_time               = st_rtc_set_time,
 184         .read_alarm             = st_rtc_read_alarm,
 185         .set_alarm              = st_rtc_set_alarm,
 186         .alarm_irq_enable       = st_rtc_alarm_irq_enable,
 187 };
 188
 189 static int st_rtc_probe(struct platform_device *pdev)
 190 {
 191         struct device_node *np = pdev->dev.of_node;
 192         struct st_rtc *rtc;
 193         struct resource *res;
 194         uint32_t mode;
 195         int ret = 0;
 196
 197         ret = of_property_read_u32(np, "st,lpc-mode", &mode);
 198         if (ret) {
 199                 dev_err(&pdev->dev, "An LPC mode must be provided\n");
 200                 return -EINVAL;
 201         }
 202
 203         /* LPC can either run as a Clocksource or in RTC or WDT mode */
 204         if (mode != ST_LPC_MODE_RTC)
 205                 return -ENODEV;
 206
 207         rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
 208         if (!rtc)
 209                 return -ENOMEM;
 210
 211         rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
 212         if (IS_ERR(rtc->rtc_dev))
 213                 return PTR_ERR(rtc->rtc_dev);
 214
 215         spin_lock_init(&rtc->lock);
 216
 217         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 218         rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res);
 219         if (IS_ERR(rtc->ioaddr))
 220                 return PTR_ERR(rtc->ioaddr);
 221
 222         rtc->irq = irq_of_parse_and_map(np, 0);
 223         if (!rtc->irq) {
 224                 dev_err(&pdev->dev, "IRQ missing or invalid\n");
 225                 return -EINVAL;
 226         }
 227
 228         ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0,
 229                                pdev->name, rtc);
 230         if (ret) {
 231                 dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq);
 232                 return ret;
 233         }
 234
 235         enable_irq_wake(rtc->irq);
 236         disable_irq(rtc->irq);
 237
 238         rtc->clk = clk_get(&pdev->dev, NULL);
 239         if (IS_ERR(rtc->clk)) {
 240                 dev_err(&pdev->dev, "Unable to request clock\n");
 241                 return PTR_ERR(rtc->clk);
 242         }
 243
 244         clk_prepare_enable(rtc->clk);
 245
 246         rtc->clkrate = clk_get_rate(rtc->clk);
 247         if (!rtc->clkrate) {
 248                 dev_err(&pdev->dev, "Unable to fetch clock rate\n");
 249                 return -EINVAL;
 250         }
 251
 252         device_set_wakeup_capable(&pdev->dev, 1);
 253
 254         platform_set_drvdata(pdev, rtc);
 255
 256         rtc->rtc_dev->ops = &st_rtc_ops;
 257         rtc->rtc_dev->range_max = U64_MAX;
 258         do_div(rtc->rtc_dev->range_max, rtc->clkrate);
 259
 260         ret = rtc_register_device(rtc->rtc_dev);
 261         if (ret) {
 262                 clk_disable_unprepare(rtc->clk);
 263                 return ret;
 264         }
 265
 266         return 0;
 267 }
 268
 269 #ifdef CONFIG_PM_SLEEP
 270 static int st_rtc_suspend(struct device *dev)
 271 {
 272         struct st_rtc *rtc = dev_get_drvdata(dev);
 273
 274         if (device_may_wakeup(dev))
 275                 return 0;
 276
 277         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
 278         writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF);
 279         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
 280
 281         return 0;
 282 }
 283
 284 static int st_rtc_resume(struct device *dev)
 285 {
 286         struct st_rtc *rtc = dev_get_drvdata(dev);
 287
 288         rtc_alarm_irq_enable(rtc->rtc_dev, 0);
 289
 290         /*
 291          * clean 'rtc->alarm' to allow a new
 292          * .set_alarm to the upper RTC layer
 293          */
 294         memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));
 295
 296         writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
 297         writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
 298         writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);
 299         writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);
 300         writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);
 301
 302         return 0;
 303 }
 304 #endif
 305
 306 static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
 307
 308 static const struct of_device_id st_rtc_match[] = {
 309         { .compatible = "st,stih407-lpc" },
 310         {}
 311 };
 312 MODULE_DEVICE_TABLE(of, st_rtc_match);
 313
 314 static struct platform_driver st_rtc_platform_driver = {
 315         .driver = {
 316                 .name = "st-lpc-rtc",
 317                 .pm = &st_rtc_pm_ops,
 318                 .of_match_table = st_rtc_match,
 319         },
 320         .probe = st_rtc_probe,
 321 };
 322
 323 module_platform_driver(st_rtc_platform_driver);
 324
 325 MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
 326 MODULE_AUTHOR("David Paris <david.paris@st.com>");
 327 MODULE_LICENSE("GPL");