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, ret;
 103         unsigned long flags;
 104         struct bcm_kona_wdt *wdt = s->private;
 105
 106         if (!wdt)
 107                 return seq_puts(s, "No device pointer\n");
 108
 109         spin_lock_irqsave(&wdt->lock, flags);
 110         ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG);
 111         cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG);
 112         spin_unlock_irqrestore(&wdt->lock, flags);
 113
 114         if (ctl_val < 0 || cur_val < 0) {
 115                 ret = seq_puts(s, "Error accessing hardware\n");
 116         } else {
 117                 int ctl, cur, ctl_sec, cur_sec, res;
 118
 119                 ctl = ctl_val & SECWDOG_COUNT_MASK;
 120                 res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT;
 121                 cur = cur_val & SECWDOG_COUNT_MASK;
 122                 ctl_sec = TICKS_TO_SECS(ctl, wdt);
 123                 cur_sec = TICKS_TO_SECS(cur, wdt);
 124                 ret = seq_printf(s, "Resolution: %d / %d\n"
 125                                 "Control: %d s / %d (%#x) ticks\n"
 126                                 "Current: %d s / %d (%#x) ticks\n"
 127                                 "Busy count: %lu\n", res,
 128                                 wdt->resolution, ctl_sec, ctl, ctl, cur_sec,
 129                                 cur, cur, wdt->busy_count);
 130         }
 131
 132         return ret;
 133 }
 134
 135 static int bcm_kona_dbg_open(struct inode *inode, struct file *file)
 136 {
 137         return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private);
 138 }
 139
 140 static const struct file_operations bcm_kona_dbg_operations = {
 141         .open           = bcm_kona_dbg_open,
 142         .read           = seq_read,
 143         .llseek         = seq_lseek,
 144         .release        = single_release,
 145 };
 146
 147 static void bcm_kona_wdt_debug_init(struct platform_device *pdev)
 148 {
 149         struct dentry *dir;
 150         struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
 151
 152         if (!wdt)
 153                 return;
 154
 155         wdt->debugfs = NULL;
 156
 157         dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL);
 158         if (IS_ERR_OR_NULL(dir))
 159                 return;
 160
 161         if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
 162                                 &bcm_kona_dbg_operations))
 163                 wdt->debugfs = dir;
 164         else
 165                 debugfs_remove_recursive(dir);
 166 }
 167
 168 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev)
 169 {
 170         struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
 171
 172         if (wdt && wdt->debugfs) {
 173                 debugfs_remove_recursive(wdt->debugfs);
 174                 wdt->debugfs = NULL;
 175         }
 176 }
 177
 178 #else
 179
 180 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
 181 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}
 182
 183 #endif /* CONFIG_BCM_KONA_WDT_DEBUG */
 184
 185 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
 186                                         unsigned mask, unsigned newval)
 187 {
 188         int val;
 189         unsigned long flags;
 190         int ret = 0;
 191
 192         spin_lock_irqsave(&wdt->lock, flags);
 193
 194         val = secure_register_read(wdt, SECWDOG_CTRL_REG);
 195         if (val < 0) {
 196                 ret = val;
 197         } else {
 198                 val &= ~mask;
 199                 val |= newval;
 200                 writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
 201         }
 202
 203         spin_unlock_irqrestore(&wdt->lock, flags);
 204
 205         return ret;
 206 }
 207
 208 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
 209 {
 210         if (wdt->resolution > SECWDOG_MAX_RES)
 211                 return -EINVAL;
 212
 213         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
 214                                         wdt->resolution << SECWDOG_CLKS_SHIFT);
 215 }
 216
 217 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
 218                                         unsigned watchdog_flags)
 219 {
 220         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
 221
 222         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
 223                                         SECS_TO_TICKS(wdog->timeout, wdt) |
 224                                         watchdog_flags);
 225 }
 226
 227 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
 228         unsigned int t)
 229 {
 230         wdog->timeout = t;
 231         return 0;
 232 }
 233
 234 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
 235 {
 236         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
 237         int val;
 238         unsigned long flags;
 239
 240         spin_lock_irqsave(&wdt->lock, flags);
 241         val = secure_register_read(wdt, SECWDOG_COUNT_REG);
 242         spin_unlock_irqrestore(&wdt->lock, flags);
 243
 244         if (val < 0)
 245                 return val;
 246
 247         return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
 248 }
 249
 250 static int bcm_kona_wdt_start(struct watchdog_device *wdog)
 251 {
 252         return bcm_kona_wdt_set_timeout_reg(wdog,
 253                                         SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
 254 }
 255
 256 static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
 257 {
 258         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
 259
 260         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
 261                                             SECWDOG_SRSTEN_MASK, 0);
 262 }
 263
 264 static struct watchdog_ops bcm_kona_wdt_ops = {
 265         .owner =        THIS_MODULE,
 266         .start =        bcm_kona_wdt_start,
 267         .stop =         bcm_kona_wdt_stop,
 268         .set_timeout =  bcm_kona_wdt_set_timeout,
 269         .get_timeleft = bcm_kona_wdt_get_timeleft,
 270 };
 271
 272 static struct watchdog_info bcm_kona_wdt_info = {
 273         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 274                         WDIOF_KEEPALIVEPING,
 275         .identity =     "Broadcom Kona Watchdog Timer",
 276 };
 277
 278 static struct watchdog_device bcm_kona_wdt_wdd = {
 279         .info =         &bcm_kona_wdt_info,
 280         .ops =          &bcm_kona_wdt_ops,
 281         .min_timeout =  1,
 282         .max_timeout =  SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
 283         .timeout =      SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
 284 };
 285
 286 static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
 287 {
 288         bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
 289 }
 290
 291 static int bcm_kona_wdt_probe(struct platform_device *pdev)
 292 {
 293         struct device *dev = &pdev->dev;
 294         struct bcm_kona_wdt *wdt;
 295         struct resource *res;
 296         int ret;
 297
 298         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 299         if (!wdt)
 300                 return -ENOMEM;
 301
 302         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 303         wdt->base = devm_ioremap_resource(dev, res);
 304         if (IS_ERR(wdt->base))
 305                 return -ENODEV;
 306
 307         wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
 308         ret = bcm_kona_wdt_set_resolution_reg(wdt);
 309         if (ret) {
 310                 dev_err(dev, "Failed to set resolution (error: %d)", ret);
 311                 return ret;
 312         }
 313
 314         spin_lock_init(&wdt->lock);
 315         platform_set_drvdata(pdev, wdt);
 316         watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
 317
 318         ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
 319         if (ret) {
 320                 dev_err(dev, "Failed set watchdog timeout");
 321                 return ret;
 322         }
 323
 324         ret = watchdog_register_device(&bcm_kona_wdt_wdd);
 325         if (ret) {
 326                 dev_err(dev, "Failed to register watchdog device");
 327                 return ret;
 328         }
 329
 330         bcm_kona_wdt_debug_init(pdev);
 331         dev_dbg(dev, "Broadcom Kona Watchdog Timer");
 332
 333         return 0;
 334 }
 335
 336 static int bcm_kona_wdt_remove(struct platform_device *pdev)
 337 {
 338         bcm_kona_wdt_debug_exit(pdev);
 339         bcm_kona_wdt_shutdown(pdev);
 340         watchdog_unregister_device(&bcm_kona_wdt_wdd);
 341         dev_dbg(&pdev->dev, "Watchdog driver disabled");
 342
 343         return 0;
 344 }
 345
 346 static const struct of_device_id bcm_kona_wdt_of_match[] = {
 347         { .compatible = "brcm,kona-wdt", },
 348         {},
 349 };
 350 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
 351
 352 static struct platform_driver bcm_kona_wdt_driver = {
 353         .driver = {
 354                         .name = BCM_KONA_WDT_NAME,
 355                         .owner = THIS_MODULE,
 356                         .of_match_table = bcm_kona_wdt_of_match,
 357                   },
 358         .probe = bcm_kona_wdt_probe,
 359         .remove = bcm_kona_wdt_remove,
 360         .shutdown = bcm_kona_wdt_shutdown,
 361 };
 362
 363 module_platform_driver(bcm_kona_wdt_driver);
 364
 365 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
 366 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
 367 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
 368 MODULE_LICENSE("GPL v2");