linux/drivers/watchdog/bcm_kona_wdt.c
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   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
  44struct 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
  65static 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
 100static 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
 135static 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
 140static 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
 147static 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
 168static 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
 180static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
 181static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}
 182
 183#endif /* CONFIG_BCM_KONA_WDT_DEBUG */
 184
 185static 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
 208static 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
 217static 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
 227static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
 228        unsigned int t)
 229{
 230        wdog->timeout = t;
 231        return 0;
 232}
 233
 234static 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
 250static 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
 256static 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
 264static 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
 272static struct watchdog_info bcm_kona_wdt_info = {
 273        .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 274                        WDIOF_KEEPALIVEPING,
 275        .identity =     "Broadcom Kona Watchdog Timer",
 276};
 277
 278static 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
 286static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
 287{
 288        bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
 289}
 290
 291static 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
 336static 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
 346static const struct of_device_id bcm_kona_wdt_of_match[] = {
 347        { .compatible = "brcm,kona-wdt", },
 348        {},
 349};
 350MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
 351
 352static struct platform_driver bcm_kona_wdt_driver = {
 353        .driver = {
 354                        .name = BCM_KONA_WDT_NAME,
 355                        .of_match_table = bcm_kona_wdt_of_match,
 356                  },
 357        .probe = bcm_kona_wdt_probe,
 358        .remove = bcm_kona_wdt_remove,
 359        .shutdown = bcm_kona_wdt_shutdown,
 360};
 361
 362module_platform_driver(bcm_kona_wdt_driver);
 363
 364MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
 365MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
 366MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
 367MODULE_LICENSE("GPL v2");
 368
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