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