drivers/watchdog/bcm_kona_wdt.c

   1 /*
   2  * Copyright (C) 2013 Broadcom Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation version 2.
   7  *
   8  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
   9  * kind, whether express or implied; without even the implied warranty
  10  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <linux/debugfs.h>
  15 #include <linux/delay.h>
  16 #include <linux/err.h>
  17 #include <linux/io.h>
  18 #include <linux/module.h>
  19 #include <linux/of_address.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/watchdog.h>
  22
  23 #define SECWDOG_CTRL_REG                0x00000000
  24 #define SECWDOG_COUNT_REG               0x00000004
  25
  26 #define SECWDOG_RESERVED_MASK           0x1dffffff
  27 #define SECWDOG_WD_LOAD_FLAG            0x10000000
  28 #define SECWDOG_EN_MASK                 0x08000000
  29 #define SECWDOG_SRSTEN_MASK             0x04000000
  30 #define SECWDOG_RES_MASK                0x00f00000
  31 #define SECWDOG_COUNT_MASK              0x000fffff
  32
  33 #define SECWDOG_MAX_COUNT               SECWDOG_COUNT_MASK
  34 #define SECWDOG_CLKS_SHIFT              20
  35 #define SECWDOG_MAX_RES                 15
  36 #define SECWDOG_DEFAULT_RESOLUTION      4
  37 #define SECWDOG_MAX_TRY                 1000
  38
  39 #define SECS_TO_TICKS(x, w)             ((x) << (w)->resolution)
  40 #define TICKS_TO_SECS(x, w)             ((x) >> (w)->resolution)
  41
  42 #define BCM_KONA_WDT_NAME               "bcm_kona_wdt"
  43
  44 struct bcm_kona_wdt {
  45         void __iomem *base;
  46         /*
  47          * One watchdog tick is 1/(2^resolution) seconds. Resolution can take
  48          * the values 0-15, meaning one tick can be 1s to 30.52us. Our default
  49          * resolution of 4 means one tick is 62.5ms.
  50          *
  51          * The watchdog counter is 20 bits. Depending on resolution, the maximum
  52          * counter value of 0xfffff expires after about 12 days (resolution 0)
  53          * down to only 32s (resolution 15). The default resolution of 4 gives
  54          * us a maximum of about 18 hours and 12 minutes before the watchdog
  55          * times out.
  56          */
  57         int resolution;
  58         spinlock_t lock;
  59 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
  60         unsigned long busy_count;
  61         struct dentry *debugfs;
  62 #endif
  63 };
  64
  65 static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset)
  66 {
  67         uint32_t val;
  68         unsigned count = 0;
  69
  70         /*
  71          * If the WD_LOAD_FLAG is set, the watchdog counter field is being
  72          * updated in hardware. Once the WD timer is updated in hardware, it
  73          * gets cleared.
  74          */
  75         do {
  76                 if (unlikely(count > 1))
  77                         udelay(5);
  78                 val = readl_relaxed(wdt->base + offset);
  79                 count++;
  80         } while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY);
  81
  82 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
  83         /* Remember the maximum number iterations due to WD_LOAD_FLAG */
  84         if (count > wdt->busy_count)
  85                 wdt->busy_count = count;
  86 #endif
  87
  88         /* This is the only place we return a negative value. */
  89         if (val & SECWDOG_WD_LOAD_FLAG)
  90                 return -ETIMEDOUT;
  91
  92         /* We always mask out reserved bits. */
  93         val &= SECWDOG_RESERVED_MASK;
  94
  95         return val;
  96 }
  97
  98 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
  99
 100 static int bcm_kona_wdt_dbg_show(struct seq_file *s, void *data)
 101 {
 102         int ctl_val, cur_val;
 103         unsigned long flags;
 104         struct bcm_kona_wdt *wdt = s->private;
 105
 106         if (!wdt) {
 107                 seq_puts(s, "No device pointer\n");
 108                 return 0;
 109         }
 110
 111         spin_lock_irqsave(&wdt->lock, flags);
 112         ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG);
 113         cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG);
 114         spin_unlock_irqrestore(&wdt->lock, flags);
 115
 116         if (ctl_val < 0 || cur_val < 0) {
 117                 seq_puts(s, "Error accessing hardware\n");
 118         } else {
 119                 int ctl, cur, ctl_sec, cur_sec, res;
 120
 121                 ctl = ctl_val & SECWDOG_COUNT_MASK;
 122                 res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT;
 123                 cur = cur_val & SECWDOG_COUNT_MASK;
 124                 ctl_sec = TICKS_TO_SECS(ctl, wdt);
 125                 cur_sec = TICKS_TO_SECS(cur, wdt);
 126                 seq_printf(s,
 127                            "Resolution: %d / %d\n"
 128                            "Control: %d s / %d (%#x) ticks\n"
 129                            "Current: %d s / %d (%#x) ticks\n"
 130                            "Busy count: %lu\n",
 131                            res, wdt->resolution,
 132                            ctl_sec, ctl, ctl,
 133                            cur_sec, cur, cur,
 134                            wdt->busy_count);
 135         }
 136
 137         return 0;
 138 }
 139
 140 static int bcm_kona_dbg_open(struct inode *inode, struct file *file)
 141 {
 142         return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private);
 143 }
 144
 145 static const struct file_operations bcm_kona_dbg_operations = {
 146         .open           = bcm_kona_dbg_open,
 147         .read           = seq_read,
 148         .llseek         = seq_lseek,
 149         .release        = single_release,
 150 };
 151
 152 static void bcm_kona_wdt_debug_init(struct platform_device *pdev)
 153 {
 154         struct dentry *dir;
 155         struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
 156
 157         if (!wdt)
 158                 return;
 159
 160         wdt->debugfs = NULL;
 161
 162         dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL);
 163         if (IS_ERR_OR_NULL(dir))
 164                 return;
 165
 166         if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
 167                                 &bcm_kona_dbg_operations))
 168                 wdt->debugfs = dir;
 169         else
 170                 debugfs_remove_recursive(dir);
 171 }
 172
 173 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev)
 174 {
 175         struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
 176
 177         if (wdt && wdt->debugfs) {
 178                 debugfs_remove_recursive(wdt->debugfs);
 179                 wdt->debugfs = NULL;
 180         }
 181 }
 182
 183 #else
 184
 185 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
 186 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}
 187
 188 #endif /* CONFIG_BCM_KONA_WDT_DEBUG */
 189
 190 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
 191                                         unsigned mask, unsigned newval)
 192 {
 193         int val;
 194         unsigned long flags;
 195         int ret = 0;
 196
 197         spin_lock_irqsave(&wdt->lock, flags);
 198
 199         val = secure_register_read(wdt, SECWDOG_CTRL_REG);
 200         if (val < 0) {
 201                 ret = val;
 202         } else {
 203                 val &= ~mask;
 204                 val |= newval;
 205                 writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
 206         }
 207
 208         spin_unlock_irqrestore(&wdt->lock, flags);
 209
 210         return ret;
 211 }
 212
 213 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
 214 {
 215         if (wdt->resolution > SECWDOG_MAX_RES)
 216                 return -EINVAL;
 217
 218         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
 219                                         wdt->resolution << SECWDOG_CLKS_SHIFT);
 220 }
 221
 222 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
 223                                         unsigned watchdog_flags)
 224 {
 225         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
 226
 227         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
 228                                         SECS_TO_TICKS(wdog->timeout, wdt) |
 229                                         watchdog_flags);
 230 }
 231
 232 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
 233         unsigned int t)
 234 {
 235         wdog->timeout = t;
 236         return 0;
 237 }
 238
 239 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
 240 {
 241         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
 242         int val;
 243         unsigned long flags;
 244
 245         spin_lock_irqsave(&wdt->lock, flags);
 246         val = secure_register_read(wdt, SECWDOG_COUNT_REG);
 247         spin_unlock_irqrestore(&wdt->lock, flags);
 248
 249         if (val < 0)
 250                 return val;
 251
 252         return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
 253 }
 254
 255 static int bcm_kona_wdt_start(struct watchdog_device *wdog)
 256 {
 257         return bcm_kona_wdt_set_timeout_reg(wdog,
 258                                         SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
 259 }
 260
 261 static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
 262 {
 263         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
 264
 265         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
 266                                             SECWDOG_SRSTEN_MASK, 0);
 267 }
 268
 269 static const struct watchdog_ops bcm_kona_wdt_ops = {
 270         .owner =        THIS_MODULE,
 271         .start =        bcm_kona_wdt_start,
 272         .stop =         bcm_kona_wdt_stop,
 273         .set_timeout =  bcm_kona_wdt_set_timeout,
 274         .get_timeleft = bcm_kona_wdt_get_timeleft,
 275 };
 276
 277 static const struct watchdog_info bcm_kona_wdt_info = {
 278         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 279                         WDIOF_KEEPALIVEPING,
 280         .identity =     "Broadcom Kona Watchdog Timer",
 281 };
 282
 283 static struct watchdog_device bcm_kona_wdt_wdd = {
 284         .info =         &bcm_kona_wdt_info,
 285         .ops =          &bcm_kona_wdt_ops,
 286         .min_timeout =  1,
 287         .max_timeout =  SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
 288         .timeout =      SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
 289 };
 290
 291 static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
 292 {
 293         bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
 294 }
 295
 296 static int bcm_kona_wdt_probe(struct platform_device *pdev)
 297 {
 298         struct device *dev = &pdev->dev;
 299         struct bcm_kona_wdt *wdt;
 300         struct resource *res;
 301         int ret;
 302
 303         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 304         if (!wdt)
 305                 return -ENOMEM;
 306
 307         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 308         wdt->base = devm_ioremap_resource(dev, res);
 309         if (IS_ERR(wdt->base))
 310                 return -ENODEV;
 311
 312         wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
 313         ret = bcm_kona_wdt_set_resolution_reg(wdt);
 314         if (ret) {
 315                 dev_err(dev, "Failed to set resolution (error: %d)", ret);
 316                 return ret;
 317         }
 318
 319         spin_lock_init(&wdt->lock);
 320         platform_set_drvdata(pdev, wdt);
 321         watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
 322         bcm_kona_wdt_wdd.parent = &pdev->dev;
 323
 324         ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
 325         if (ret) {
 326                 dev_err(dev, "Failed set watchdog timeout");
 327                 return ret;
 328         }
 329
 330         ret = watchdog_register_device(&bcm_kona_wdt_wdd);
 331         if (ret) {
 332                 dev_err(dev, "Failed to register watchdog device");
 333                 return ret;
 334         }
 335
 336         bcm_kona_wdt_debug_init(pdev);
 337         dev_dbg(dev, "Broadcom Kona Watchdog Timer");
 338
 339         return 0;
 340 }
 341
 342 static int bcm_kona_wdt_remove(struct platform_device *pdev)
 343 {
 344         bcm_kona_wdt_debug_exit(pdev);
 345         bcm_kona_wdt_shutdown(pdev);
 346         watchdog_unregister_device(&bcm_kona_wdt_wdd);
 347         dev_dbg(&pdev->dev, "Watchdog driver disabled");
 348
 349         return 0;
 350 }
 351
 352 static const struct of_device_id bcm_kona_wdt_of_match[] = {
 353         { .compatible = "brcm,kona-wdt", },
 354         {},
 355 };
 356 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
 357
 358 static struct platform_driver bcm_kona_wdt_driver = {
 359         .driver = {
 360                         .name = BCM_KONA_WDT_NAME,
 361                         .of_match_table = bcm_kona_wdt_of_match,
 362                   },
 363         .probe = bcm_kona_wdt_probe,
 364         .remove = bcm_kona_wdt_remove,
 365         .shutdown = bcm_kona_wdt_shutdown,
 366 };
 367
 368 module_platform_driver(bcm_kona_wdt_driver);
 369
 370 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
 371 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
 372 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
 373 MODULE_LICENSE("GPL v2");