drivers/watchdog/sp805_wdt.c

   1 /*
   2  * drivers/char/watchdog/sp805-wdt.c
   3  *
   4  * Watchdog driver for ARM SP805 watchdog module
   5  *
   6  * Copyright (C) 2010 ST Microelectronics
   7  * Viresh Kumar <viresh.linux@gmail.com>
   8  *
   9  * This file is licensed under the terms of the GNU General Public
  10  * License version 2 or later. This program is licensed "as is" without any
  11  * warranty of any kind, whether express or implied.
  12  */
  13
  14 #include <linux/device.h>
  15 #include <linux/resource.h>
  16 #include <linux/amba/bus.h>
  17 #include <linux/bitops.h>
  18 #include <linux/clk.h>
  19 #include <linux/init.h>
  20 #include <linux/io.h>
  21 #include <linux/ioport.h>
  22 #include <linux/kernel.h>
  23 #include <linux/math64.h>
  24 #include <linux/module.h>
  25 #include <linux/moduleparam.h>
  26 #include <linux/pm.h>
  27 #include <linux/slab.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/types.h>
  30 #include <linux/watchdog.h>
  31
  32 /* default timeout in seconds */
  33 #define DEFAULT_TIMEOUT         60
  34
  35 #define MODULE_NAME             "sp805-wdt"
  36
  37 /* watchdog register offsets and masks */
  38 #define WDTLOAD                 0x000
  39         #define LOAD_MIN        0x00000001
  40         #define LOAD_MAX        0xFFFFFFFF
  41 #define WDTVALUE                0x004
  42 #define WDTCONTROL              0x008
  43         /* control register masks */
  44         #define INT_ENABLE      (1 << 0)
  45         #define RESET_ENABLE    (1 << 1)
  46 #define WDTINTCLR               0x00C
  47 #define WDTRIS                  0x010
  48 #define WDTMIS                  0x014
  49         #define INT_MASK        (1 << 0)
  50 #define WDTLOCK                 0xC00
  51         #define UNLOCK          0x1ACCE551
  52         #define LOCK            0x00000001
  53
  54 /**
  55  * struct sp805_wdt: sp805 wdt device structure
  56  * @wdd: instance of struct watchdog_device
  57  * @lock: spin lock protecting dev structure and io access
  58  * @base: base address of wdt
  59  * @clk: clock structure of wdt
  60  * @adev: amba device structure of wdt
  61  * @status: current status of wdt
  62  * @load_val: load value to be set for current timeout
  63  * @timeout: current programmed timeout
  64  */
  65 struct sp805_wdt {
  66         struct watchdog_device          wdd;
  67         spinlock_t                      lock;
  68         void __iomem                    *base;
  69         struct clk                      *clk;
  70         struct amba_device              *adev;
  71         unsigned int                    load_val;
  72         unsigned int                    timeout;
  73 };
  74
  75 static bool nowayout = WATCHDOG_NOWAYOUT;
  76 module_param(nowayout, bool, 0);
  77 MODULE_PARM_DESC(nowayout,
  78                 "Set to 1 to keep watchdog running after device release");
  79
  80 /* This routine finds load value that will reset system in required timout */
  81 static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
  82 {
  83         struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
  84         u64 load, rate;
  85
  86         rate = clk_get_rate(wdt->clk);
  87
  88         /*
  89          * sp805 runs counter with given value twice, after the end of first
  90          * counter it gives an interrupt and then starts counter again. If
  91          * interrupt already occurred then it resets the system. This is why
  92          * load is half of what should be required.
  93          */
  94         load = div_u64(rate, 2) * timeout - 1;
  95
  96         load = (load > LOAD_MAX) ? LOAD_MAX : load;
  97         load = (load < LOAD_MIN) ? LOAD_MIN : load;
  98
  99         spin_lock(&wdt->lock);
 100         wdt->load_val = load;
 101         /* roundup timeout to closest positive integer value */
 102         wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
 103         spin_unlock(&wdt->lock);
 104
 105         return 0;
 106 }
 107
 108 /* returns number of seconds left for reset to occur */
 109 static unsigned int wdt_timeleft(struct watchdog_device *wdd)
 110 {
 111         struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 112         u64 load, rate;
 113
 114         rate = clk_get_rate(wdt->clk);
 115
 116         spin_lock(&wdt->lock);
 117         load = readl_relaxed(wdt->base + WDTVALUE);
 118
 119         /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
 120         if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
 121                 load += wdt->load_val + 1;
 122         spin_unlock(&wdt->lock);
 123
 124         return div_u64(load, rate);
 125 }
 126
 127 static int wdt_config(struct watchdog_device *wdd, bool ping)
 128 {
 129         struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 130         int ret;
 131
 132         if (!ping) {
 133
 134                 ret = clk_prepare_enable(wdt->clk);
 135                 if (ret) {
 136                         dev_err(&wdt->adev->dev, "clock enable fail");
 137                         return ret;
 138                 }
 139         }
 140
 141         spin_lock(&wdt->lock);
 142
 143         writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
 144         writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
 145
 146         if (!ping) {
 147                 writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
 148                 writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
 149                                 WDTCONTROL);
 150         }
 151
 152         writel_relaxed(LOCK, wdt->base + WDTLOCK);
 153
 154         /* Flush posted writes. */
 155         readl_relaxed(wdt->base + WDTLOCK);
 156         spin_unlock(&wdt->lock);
 157
 158         return 0;
 159 }
 160
 161 static int wdt_ping(struct watchdog_device *wdd)
 162 {
 163         return wdt_config(wdd, true);
 164 }
 165
 166 /* enables watchdog timers reset */
 167 static int wdt_enable(struct watchdog_device *wdd)
 168 {
 169         return wdt_config(wdd, false);
 170 }
 171
 172 /* disables watchdog timers reset */
 173 static int wdt_disable(struct watchdog_device *wdd)
 174 {
 175         struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 176
 177         spin_lock(&wdt->lock);
 178
 179         writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
 180         writel_relaxed(0, wdt->base + WDTCONTROL);
 181         writel_relaxed(LOCK, wdt->base + WDTLOCK);
 182
 183         /* Flush posted writes. */
 184         readl_relaxed(wdt->base + WDTLOCK);
 185         spin_unlock(&wdt->lock);
 186
 187         clk_disable_unprepare(wdt->clk);
 188
 189         return 0;
 190 }
 191
 192 static const struct watchdog_info wdt_info = {
 193         .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 194         .identity = MODULE_NAME,
 195 };
 196
 197 static const struct watchdog_ops wdt_ops = {
 198         .owner          = THIS_MODULE,
 199         .start          = wdt_enable,
 200         .stop           = wdt_disable,
 201         .ping           = wdt_ping,
 202         .set_timeout    = wdt_setload,
 203         .get_timeleft   = wdt_timeleft,
 204 };
 205
 206 static int
 207 sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
 208 {
 209         struct sp805_wdt *wdt;
 210         int ret = 0;
 211
 212         if (!devm_request_mem_region(&adev->dev, adev->res.start,
 213                                 resource_size(&adev->res), "sp805_wdt")) {
 214                 dev_warn(&adev->dev, "Failed to get memory region resource\n");
 215                 ret = -ENOENT;
 216                 goto err;
 217         }
 218
 219         wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
 220         if (!wdt) {
 221                 dev_warn(&adev->dev, "Kzalloc failed\n");
 222                 ret = -ENOMEM;
 223                 goto err;
 224         }
 225
 226         wdt->base = devm_ioremap(&adev->dev, adev->res.start,
 227                         resource_size(&adev->res));
 228         if (!wdt->base) {
 229                 ret = -ENOMEM;
 230                 dev_warn(&adev->dev, "ioremap fail\n");
 231                 goto err;
 232         }
 233
 234         wdt->clk = clk_get(&adev->dev, NULL);
 235         if (IS_ERR(wdt->clk)) {
 236                 dev_warn(&adev->dev, "Clock not found\n");
 237                 ret = PTR_ERR(wdt->clk);
 238                 goto err;
 239         }
 240
 241         wdt->adev = adev;
 242         wdt->wdd.info = &wdt_info;
 243         wdt->wdd.ops = &wdt_ops;
 244
 245         spin_lock_init(&wdt->lock);
 246         watchdog_set_nowayout(&wdt->wdd, nowayout);
 247         watchdog_set_drvdata(&wdt->wdd, wdt);
 248         wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);
 249
 250         ret = watchdog_register_device(&wdt->wdd);
 251         if (ret) {
 252                 dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
 253                                 ret);
 254                 goto err_register;
 255         }
 256         amba_set_drvdata(adev, wdt);
 257
 258         dev_info(&adev->dev, "registration successful\n");
 259         return 0;
 260
 261 err_register:
 262         clk_put(wdt->clk);
 263 err:
 264         dev_err(&adev->dev, "Probe Failed!!!\n");
 265         return ret;
 266 }
 267
 268 static int sp805_wdt_remove(struct amba_device *adev)
 269 {
 270         struct sp805_wdt *wdt = amba_get_drvdata(adev);
 271
 272         watchdog_unregister_device(&wdt->wdd);
 273         amba_set_drvdata(adev, NULL);
 274         watchdog_set_drvdata(&wdt->wdd, NULL);
 275         clk_put(wdt->clk);
 276
 277         return 0;
 278 }
 279
 280 static int __maybe_unused sp805_wdt_suspend(struct device *dev)
 281 {
 282         struct sp805_wdt *wdt = dev_get_drvdata(dev);
 283
 284         if (watchdog_active(&wdt->wdd))
 285                 return wdt_disable(&wdt->wdd);
 286
 287         return 0;
 288 }
 289
 290 static int __maybe_unused sp805_wdt_resume(struct device *dev)
 291 {
 292         struct sp805_wdt *wdt = dev_get_drvdata(dev);
 293
 294         if (watchdog_active(&wdt->wdd))
 295                 return wdt_enable(&wdt->wdd);
 296
 297         return 0;
 298 }
 299
 300 static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
 301                 sp805_wdt_resume);
 302
 303 static struct amba_id sp805_wdt_ids[] = {
 304         {
 305                 .id     = 0x00141805,
 306                 .mask   = 0x00ffffff,
 307         },
 308         { 0, 0 },
 309 };
 310
 311 MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
 312
 313 static struct amba_driver sp805_wdt_driver = {
 314         .drv = {
 315                 .name   = MODULE_NAME,
 316                 .pm     = &sp805_wdt_dev_pm_ops,
 317         },
 318         .id_table       = sp805_wdt_ids,
 319         .probe          = sp805_wdt_probe,
 320         .remove = sp805_wdt_remove,
 321 };
 322
 323 module_amba_driver(sp805_wdt_driver);
 324
 325 MODULE_AUTHOR("Viresh Kumar <viresh.linux@gmail.com>");
 326 MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
 327 MODULE_LICENSE("GPL");