drivers/rtc/rtc-brcmstb-waketimer.c

   1 /*
   2  * Copyright © 2014-2017 Broadcom
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/clk.h>
  17 #include <linux/device.h>
  18 #include <linux/err.h>
  19 #include <linux/init.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/io.h>
  22 #include <linux/irqreturn.h>
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/of.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/pm.h>
  28 #include <linux/pm_wakeup.h>
  29 #include <linux/reboot.h>
  30 #include <linux/rtc.h>
  31 #include <linux/stat.h>
  32 #include <linux/suspend.h>
  33
  34 struct brcmstb_waketmr {
  35         struct rtc_device *rtc;
  36         struct device *dev;
  37         void __iomem *base;
  38         int irq;
  39         struct notifier_block reboot_notifier;
  40         struct clk *clk;
  41         u32 rate;
  42 };
  43
  44 #define BRCMSTB_WKTMR_EVENT             0x00
  45 #define BRCMSTB_WKTMR_COUNTER           0x04
  46 #define BRCMSTB_WKTMR_ALARM             0x08
  47 #define BRCMSTB_WKTMR_PRESCALER         0x0C
  48 #define BRCMSTB_WKTMR_PRESCALER_VAL     0x10
  49
  50 #define BRCMSTB_WKTMR_DEFAULT_FREQ      27000000
  51
  52 static inline void brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr *timer)
  53 {
  54         writel_relaxed(1, timer->base + BRCMSTB_WKTMR_EVENT);
  55         (void)readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
  56 }
  57
  58 static void brcmstb_waketmr_set_alarm(struct brcmstb_waketmr *timer,
  59                                       unsigned int secs)
  60 {
  61         brcmstb_waketmr_clear_alarm(timer);
  62
  63         writel_relaxed(secs + 1, timer->base + BRCMSTB_WKTMR_ALARM);
  64 }
  65
  66 static irqreturn_t brcmstb_waketmr_irq(int irq, void *data)
  67 {
  68         struct brcmstb_waketmr *timer = data;
  69
  70         pm_wakeup_event(timer->dev, 0);
  71
  72         return IRQ_HANDLED;
  73 }
  74
  75 struct wktmr_time {
  76         u32 sec;
  77         u32 pre;
  78 };
  79
  80 static void wktmr_read(struct brcmstb_waketmr *timer,
  81                        struct wktmr_time *t)
  82 {
  83         u32 tmp;
  84
  85         do {
  86                 t->sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
  87                 tmp = readl_relaxed(timer->base + BRCMSTB_WKTMR_PRESCALER_VAL);
  88         } while (tmp >= timer->rate);
  89
  90         t->pre = timer->rate - tmp;
  91 }
  92
  93 static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
  94 {
  95         struct device *dev = timer->dev;
  96         int ret = 0;
  97
  98         if (device_may_wakeup(dev)) {
  99                 ret = enable_irq_wake(timer->irq);
 100                 if (ret) {
 101                         dev_err(dev, "failed to enable wake-up interrupt\n");
 102                         return ret;
 103                 }
 104         }
 105
 106         return ret;
 107 }
 108
 109 /* If enabled as a wakeup-source, arm the timer when powering off */
 110 static int brcmstb_waketmr_reboot(struct notifier_block *nb,
 111                 unsigned long action, void *data)
 112 {
 113         struct brcmstb_waketmr *timer;
 114
 115         timer = container_of(nb, struct brcmstb_waketmr, reboot_notifier);
 116
 117         /* Set timer for cold boot */
 118         if (action == SYS_POWER_OFF)
 119                 brcmstb_waketmr_prepare_suspend(timer);
 120
 121         return NOTIFY_DONE;
 122 }
 123
 124 static int brcmstb_waketmr_gettime(struct device *dev,
 125                                    struct rtc_time *tm)
 126 {
 127         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 128         struct wktmr_time now;
 129
 130         wktmr_read(timer, &now);
 131
 132         rtc_time_to_tm(now.sec, tm);
 133
 134         return 0;
 135 }
 136
 137 static int brcmstb_waketmr_settime(struct device *dev,
 138                                    struct rtc_time *tm)
 139 {
 140         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 141         time64_t sec;
 142
 143         sec = rtc_tm_to_time64(tm);
 144
 145         if (sec > U32_MAX || sec < 0)
 146                 return -EINVAL;
 147
 148         writel_relaxed(sec, timer->base + BRCMSTB_WKTMR_COUNTER);
 149
 150         return 0;
 151 }
 152
 153 static int brcmstb_waketmr_getalarm(struct device *dev,
 154                                     struct rtc_wkalrm *alarm)
 155 {
 156         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 157         time64_t sec;
 158         u32 reg;
 159
 160         sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_ALARM);
 161         if (sec != 0) {
 162                 /* Alarm is enabled */
 163                 alarm->enabled = 1;
 164                 rtc_time64_to_tm(sec, &alarm->time);
 165         }
 166
 167         reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
 168         alarm->pending = !!(reg & 1);
 169
 170         return 0;
 171 }
 172
 173 static int brcmstb_waketmr_setalarm(struct device *dev,
 174                                      struct rtc_wkalrm *alarm)
 175 {
 176         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 177         time64_t sec;
 178
 179         if (alarm->enabled)
 180                 sec = rtc_tm_to_time64(&alarm->time);
 181         else
 182                 sec = 0;
 183
 184         if (sec > U32_MAX || sec < 0)
 185                 return -EINVAL;
 186
 187         brcmstb_waketmr_set_alarm(timer, sec);
 188
 189         return 0;
 190 }
 191
 192 /*
 193  * Does not do much but keep the RTC class happy. We always support
 194  * alarms.
 195  */
 196 static int brcmstb_waketmr_alarm_enable(struct device *dev,
 197                                         unsigned int enabled)
 198 {
 199         return 0;
 200 }
 201
 202 static const struct rtc_class_ops brcmstb_waketmr_ops = {
 203         .read_time      = brcmstb_waketmr_gettime,
 204         .set_time       = brcmstb_waketmr_settime,
 205         .read_alarm     = brcmstb_waketmr_getalarm,
 206         .set_alarm      = brcmstb_waketmr_setalarm,
 207         .alarm_irq_enable = brcmstb_waketmr_alarm_enable,
 208 };
 209
 210 static int brcmstb_waketmr_probe(struct platform_device *pdev)
 211 {
 212         struct device *dev = &pdev->dev;
 213         struct brcmstb_waketmr *timer;
 214         struct resource *res;
 215         int ret;
 216
 217         timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
 218         if (!timer)
 219                 return -ENOMEM;
 220
 221         platform_set_drvdata(pdev, timer);
 222         timer->dev = dev;
 223
 224         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 225         timer->base = devm_ioremap_resource(dev, res);
 226         if (IS_ERR(timer->base))
 227                 return PTR_ERR(timer->base);
 228
 229         /*
 230          * Set wakeup capability before requesting wakeup interrupt, so we can
 231          * process boot-time "wakeups" (e.g., from S5 soft-off)
 232          */
 233         device_set_wakeup_capable(dev, true);
 234         device_wakeup_enable(dev);
 235
 236         timer->irq = platform_get_irq(pdev, 0);
 237         if (timer->irq < 0)
 238                 return -ENODEV;
 239
 240         timer->clk = devm_clk_get(dev, NULL);
 241         if (!IS_ERR(timer->clk)) {
 242                 ret = clk_prepare_enable(timer->clk);
 243                 if (ret)
 244                         return ret;
 245                 timer->rate = clk_get_rate(timer->clk);
 246                 if (!timer->rate)
 247                         timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
 248         } else {
 249                 timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
 250                 timer->clk = NULL;
 251         }
 252
 253         ret = devm_request_irq(dev, timer->irq, brcmstb_waketmr_irq, 0,
 254                                "brcmstb-waketimer", timer);
 255         if (ret < 0)
 256                 return ret;
 257
 258         timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
 259         register_reboot_notifier(&timer->reboot_notifier);
 260
 261         timer->rtc = rtc_device_register("brcmstb-waketmr", dev,
 262                                          &brcmstb_waketmr_ops, THIS_MODULE);
 263         if (IS_ERR(timer->rtc)) {
 264                 dev_err(dev, "unable to register device\n");
 265                 unregister_reboot_notifier(&timer->reboot_notifier);
 266                 return PTR_ERR(timer->rtc);
 267         }
 268
 269         dev_info(dev, "registered, with irq %d\n", timer->irq);
 270
 271         return ret;
 272 }
 273
 274 static int brcmstb_waketmr_remove(struct platform_device *pdev)
 275 {
 276         struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);
 277
 278         unregister_reboot_notifier(&timer->reboot_notifier);
 279         rtc_device_unregister(timer->rtc);
 280
 281         return 0;
 282 }
 283
 284 #ifdef CONFIG_PM_SLEEP
 285 static int brcmstb_waketmr_suspend(struct device *dev)
 286 {
 287         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 288
 289         return brcmstb_waketmr_prepare_suspend(timer);
 290 }
 291
 292 static int brcmstb_waketmr_resume(struct device *dev)
 293 {
 294         struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
 295         int ret;
 296
 297         if (!device_may_wakeup(dev))
 298                 return 0;
 299
 300         ret = disable_irq_wake(timer->irq);
 301
 302         brcmstb_waketmr_clear_alarm(timer);
 303
 304         return ret;
 305 }
 306 #endif /* CONFIG_PM_SLEEP */
 307
 308 static SIMPLE_DEV_PM_OPS(brcmstb_waketmr_pm_ops,
 309                          brcmstb_waketmr_suspend, brcmstb_waketmr_resume);
 310
 311 static const struct of_device_id brcmstb_waketmr_of_match[] = {
 312         { .compatible = "brcm,brcmstb-waketimer" },
 313         { /* sentinel */ },
 314 };
 315
 316 static struct platform_driver brcmstb_waketmr_driver = {
 317         .probe                  = brcmstb_waketmr_probe,
 318         .remove                 = brcmstb_waketmr_remove,
 319         .driver = {
 320                 .name           = "brcmstb-waketimer",
 321                 .pm             = &brcmstb_waketmr_pm_ops,
 322                 .of_match_table = of_match_ptr(brcmstb_waketmr_of_match),
 323         }
 324 };
 325 module_platform_driver(brcmstb_waketmr_driver);
 326
 327 MODULE_LICENSE("GPL v2");
 328 MODULE_AUTHOR("Brian Norris");
 329 MODULE_AUTHOR("Markus Mayer");
 330 MODULE_DESCRIPTION("Wake-up timer driver for STB chips");