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