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 wdt_config(struct watchdog_device *wdd, bool ping)
 125 {
 126         struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 127         int ret;
 128
 129         if (!ping) {
 130
 131                 ret = clk_prepare_enable(wdt->clk);
 132                 if (ret) {
 133                         dev_err(&wdt->adev->dev, "clock enable fail");
 134                         return ret;
 135                 }
 136         }
 137
 138         spin_lock(&wdt->lock);
 139
 140         writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
 141         writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
 142
 143         if (!ping) {
 144                 writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
 145                 writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
 146                                 WDTCONTROL);
 147         }
 148
 149         writel_relaxed(LOCK, wdt->base + WDTLOCK);
 150
 151         /* Flush posted writes. */
 152         readl_relaxed(wdt->base + WDTLOCK);
 153         spin_unlock(&wdt->lock);
 154
 155         return 0;
 156 }
 157
 158 static int wdt_ping(struct watchdog_device *wdd)
 159 {
 160         return wdt_config(wdd, true);
 161 }
 162
 163 /* enables watchdog timers reset */
 164 static int wdt_enable(struct watchdog_device *wdd)
 165 {
 166         return wdt_config(wdd, false);
 167 }
 168
 169 /* disables watchdog timers reset */
 170 static int wdt_disable(struct watchdog_device *wdd)
 171 {
 172         struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 173
 174         spin_lock(&wdt->lock);
 175
 176         writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
 177         writel_relaxed(0, wdt->base + WDTCONTROL);
 178         writel_relaxed(LOCK, wdt->base + WDTLOCK);
 179
 180         /* Flush posted writes. */
 181         readl_relaxed(wdt->base + WDTLOCK);
 182         spin_unlock(&wdt->lock);
 183
 184         clk_disable_unprepare(wdt->clk);
 185
 186         return 0;
 187 }
 188
 189 static const struct watchdog_info wdt_info = {
 190         .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 191         .identity = MODULE_NAME,
 192 };
 193
 194 static const struct watchdog_ops wdt_ops = {
 195         .owner          = THIS_MODULE,
 196         .start          = wdt_enable,
 197         .stop           = wdt_disable,
 198         .ping           = wdt_ping,
 199         .set_timeout    = wdt_setload,
 200         .get_timeleft   = wdt_timeleft,
 201 };
 202
 203 static int
 204 sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
 205 {
 206         struct sp805_wdt *wdt;
 207         int ret = 0;
 208
 209         wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
 210         if (!wdt) {
 211                 ret = -ENOMEM;
 212                 goto err;
 213         }
 214
 215         wdt->base = devm_ioremap_resource(&adev->dev, &adev->res);
 216         if (IS_ERR(wdt->base))
 217                 return PTR_ERR(wdt->base);
 218
 219         wdt->clk = devm_clk_get(&adev->dev, NULL);
 220         if (IS_ERR(wdt->clk)) {
 221                 dev_warn(&adev->dev, "Clock not found\n");
 222                 ret = PTR_ERR(wdt->clk);
 223                 goto err;
 224         }
 225
 226         wdt->adev = adev;
 227         wdt->wdd.info = &wdt_info;
 228         wdt->wdd.ops = &wdt_ops;
 229
 230         spin_lock_init(&wdt->lock);
 231         watchdog_set_nowayout(&wdt->wdd, nowayout);
 232         watchdog_set_drvdata(&wdt->wdd, wdt);
 233         wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);
 234
 235         ret = watchdog_register_device(&wdt->wdd);
 236         if (ret) {
 237                 dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
 238                                 ret);
 239                 goto err;
 240         }
 241         amba_set_drvdata(adev, wdt);
 242
 243         dev_info(&adev->dev, "registration successful\n");
 244         return 0;
 245
 246 err:
 247         dev_err(&adev->dev, "Probe Failed!!!\n");
 248         return ret;
 249 }
 250
 251 static int sp805_wdt_remove(struct amba_device *adev)
 252 {
 253         struct sp805_wdt *wdt = amba_get_drvdata(adev);
 254
 255         watchdog_unregister_device(&wdt->wdd);
 256         watchdog_set_drvdata(&wdt->wdd, NULL);
 257
 258         return 0;
 259 }
 260
 261 static int __maybe_unused sp805_wdt_suspend(struct device *dev)
 262 {
 263         struct sp805_wdt *wdt = dev_get_drvdata(dev);
 264
 265         if (watchdog_active(&wdt->wdd))
 266                 return wdt_disable(&wdt->wdd);
 267
 268         return 0;
 269 }
 270
 271 static int __maybe_unused sp805_wdt_resume(struct device *dev)
 272 {
 273         struct sp805_wdt *wdt = dev_get_drvdata(dev);
 274
 275         if (watchdog_active(&wdt->wdd))
 276                 return wdt_enable(&wdt->wdd);
 277
 278         return 0;
 279 }
 280
 281 static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
 282                 sp805_wdt_resume);
 283
 284 static struct amba_id sp805_wdt_ids[] = {
 285         {
 286                 .id     = 0x00141805,
 287                 .mask   = 0x00ffffff,
 288         },
 289         { 0, 0 },
 290 };
 291
 292 MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
 293
 294 static struct amba_driver sp805_wdt_driver = {
 295         .drv = {
 296                 .name   = MODULE_NAME,
 297                 .pm     = &sp805_wdt_dev_pm_ops,
 298         },
 299         .id_table       = sp805_wdt_ids,
 300         .probe          = sp805_wdt_probe,
 301         .remove = sp805_wdt_remove,
 302 };
 303
 304 module_amba_driver(sp805_wdt_driver);
 305
 306 MODULE_AUTHOR("Viresh Kumar <vireshk@kernel.org>");
 307 MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
 308 MODULE_LICENSE("GPL");