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/delay.h>
  15 #include <linux/err.h>
  16 #include <linux/io.h>
  17 #include <linux/module.h>
  18 #include <linux/of_address.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/watchdog.h>
  21
  22 #define SECWDOG_CTRL_REG                0x00000000
  23 #define SECWDOG_COUNT_REG               0x00000004
  24
  25 #define SECWDOG_RESERVED_MASK           0x1dffffff
  26 #define SECWDOG_WD_LOAD_FLAG            0x10000000
  27 #define SECWDOG_EN_MASK                 0x08000000
  28 #define SECWDOG_SRSTEN_MASK             0x04000000
  29 #define SECWDOG_RES_MASK                0x00f00000
  30 #define SECWDOG_COUNT_MASK              0x000fffff
  31
  32 #define SECWDOG_MAX_COUNT               SECWDOG_COUNT_MASK
  33 #define SECWDOG_CLKS_SHIFT              20
  34 #define SECWDOG_MAX_RES                 15
  35 #define SECWDOG_DEFAULT_RESOLUTION      4
  36 #define SECWDOG_MAX_TRY                 1000
  37
  38 #define SECS_TO_TICKS(x, w)             ((x) << (w)->resolution)
  39 #define TICKS_TO_SECS(x, w)             ((x) >> (w)->resolution)
  40
  41 #define BCM_KONA_WDT_NAME               "bcm_kona_wdt"
  42
  43 struct bcm_kona_wdt {
  44         void __iomem *base;
  45         /*
  46          * One watchdog tick is 1/(2^resolution) seconds. Resolution can take
  47          * the values 0-15, meaning one tick can be 1s to 30.52us. Our default
  48          * resolution of 4 means one tick is 62.5ms.
  49          *
  50          * The watchdog counter is 20 bits. Depending on resolution, the maximum
  51          * counter value of 0xfffff expires after about 12 days (resolution 0)
  52          * down to only 32s (resolution 15). The default resolution of 4 gives
  53          * us a maximum of about 18 hours and 12 minutes before the watchdog
  54          * times out.
  55          */
  56         int resolution;
  57         spinlock_t lock;
  58 };
  59
  60 static int secure_register_read(void __iomem *addr)
  61 {
  62         uint32_t val;
  63         unsigned count = 0;
  64
  65         /*
  66          * If the WD_LOAD_FLAG is set, the watchdog counter field is being
  67          * updated in hardware. Once the WD timer is updated in hardware, it
  68          * gets cleared.
  69          */
  70         do {
  71                 if (unlikely(count > 1))
  72                         udelay(5);
  73                 val = readl_relaxed(addr);
  74                 count++;
  75         } while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY);
  76
  77         /* This is the only place we return a negative value. */
  78         if (val & SECWDOG_WD_LOAD_FLAG)
  79                 return -ETIMEDOUT;
  80
  81         /* We always mask out reserved bits. */
  82         val &= SECWDOG_RESERVED_MASK;
  83
  84         return val;
  85 }
  86
  87 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
  88                                         unsigned mask, unsigned newval)
  89 {
  90         int val;
  91         unsigned long flags;
  92         int ret = 0;
  93
  94         spin_lock_irqsave(&wdt->lock, flags);
  95
  96         val = secure_register_read(wdt->base + SECWDOG_CTRL_REG);
  97         if (val < 0) {
  98                 ret = val;
  99         } else {
 100                 val &= ~mask;
 101                 val |= newval;
 102                 writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
 103         }
 104
 105         spin_unlock_irqrestore(&wdt->lock, flags);
 106
 107         return ret;
 108 }
 109
 110 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
 111 {
 112         if (wdt->resolution > SECWDOG_MAX_RES)
 113                 return -EINVAL;
 114
 115         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
 116                                         wdt->resolution << SECWDOG_CLKS_SHIFT);
 117 }
 118
 119 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
 120                                         unsigned watchdog_flags)
 121 {
 122         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
 123
 124         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
 125                                         SECS_TO_TICKS(wdog->timeout, wdt) |
 126                                         watchdog_flags);
 127 }
 128
 129 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
 130         unsigned int t)
 131 {
 132         wdog->timeout = t;
 133         return 0;
 134 }
 135
 136 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
 137 {
 138         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
 139         int val;
 140         unsigned long flags;
 141
 142         spin_lock_irqsave(&wdt->lock, flags);
 143         val = secure_register_read(wdt->base + SECWDOG_COUNT_REG);
 144         spin_unlock_irqrestore(&wdt->lock, flags);
 145
 146         if (val < 0)
 147                 return val;
 148
 149         return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
 150 }
 151
 152 static int bcm_kona_wdt_start(struct watchdog_device *wdog)
 153 {
 154         return bcm_kona_wdt_set_timeout_reg(wdog,
 155                                         SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
 156 }
 157
 158 static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
 159 {
 160         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
 161
 162         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
 163                                             SECWDOG_SRSTEN_MASK, 0);
 164 }
 165
 166 static struct watchdog_ops bcm_kona_wdt_ops = {
 167         .owner =        THIS_MODULE,
 168         .start =        bcm_kona_wdt_start,
 169         .stop =         bcm_kona_wdt_stop,
 170         .set_timeout =  bcm_kona_wdt_set_timeout,
 171         .get_timeleft = bcm_kona_wdt_get_timeleft,
 172 };
 173
 174 static struct watchdog_info bcm_kona_wdt_info = {
 175         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 176                         WDIOF_KEEPALIVEPING,
 177         .identity =     "Broadcom Kona Watchdog Timer",
 178 };
 179
 180 static struct watchdog_device bcm_kona_wdt_wdd = {
 181         .info =         &bcm_kona_wdt_info,
 182         .ops =          &bcm_kona_wdt_ops,
 183         .min_timeout =  1,
 184         .max_timeout =  SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
 185         .timeout =      SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
 186 };
 187
 188 static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
 189 {
 190         bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
 191 }
 192
 193 static int bcm_kona_wdt_probe(struct platform_device *pdev)
 194 {
 195         struct device *dev = &pdev->dev;
 196         struct bcm_kona_wdt *wdt;
 197         struct resource *res;
 198         int ret;
 199
 200         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 201         if (!wdt)
 202                 return -ENOMEM;
 203
 204         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 205         wdt->base = devm_ioremap_resource(dev, res);
 206         if (IS_ERR(wdt->base))
 207                 return -ENODEV;
 208
 209         wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
 210         ret = bcm_kona_wdt_set_resolution_reg(wdt);
 211         if (ret) {
 212                 dev_err(dev, "Failed to set resolution (error: %d)", ret);
 213                 return ret;
 214         }
 215
 216         spin_lock_init(&wdt->lock);
 217         platform_set_drvdata(pdev, wdt);
 218         watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
 219
 220         ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
 221         if (ret) {
 222                 dev_err(dev, "Failed set watchdog timeout");
 223                 return ret;
 224         }
 225
 226         ret = watchdog_register_device(&bcm_kona_wdt_wdd);
 227         if (ret) {
 228                 dev_err(dev, "Failed to register watchdog device");
 229                 return ret;
 230         }
 231
 232         dev_dbg(dev, "Broadcom Kona Watchdog Timer");
 233
 234         return 0;
 235 }
 236
 237 static int bcm_kona_wdt_remove(struct platform_device *pdev)
 238 {
 239         bcm_kona_wdt_shutdown(pdev);
 240         watchdog_unregister_device(&bcm_kona_wdt_wdd);
 241         dev_dbg(&pdev->dev, "Watchdog driver disabled");
 242
 243         return 0;
 244 }
 245
 246 static const struct of_device_id bcm_kona_wdt_of_match[] = {
 247         { .compatible = "brcm,kona-wdt", },
 248         {},
 249 };
 250 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
 251
 252 static struct platform_driver bcm_kona_wdt_driver = {
 253         .driver = {
 254                         .name = BCM_KONA_WDT_NAME,
 255                         .owner = THIS_MODULE,
 256                         .of_match_table = bcm_kona_wdt_of_match,
 257                   },
 258         .probe = bcm_kona_wdt_probe,
 259         .remove = bcm_kona_wdt_remove,
 260         .shutdown = bcm_kona_wdt_shutdown,
 261 };
 262
 263 module_platform_driver(bcm_kona_wdt_driver);
 264
 265 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
 266 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
 267 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
 268 MODULE_LICENSE("GPL v2");