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