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