drivers/watchdog/mtk_wdt.c

   1 /*
   2  * Mediatek Watchdog Driver
   3  *
   4  * Copyright (C) 2014 Matthias Brugger
   5  *
   6  * Matthias Brugger <matthias.bgg@gmail.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * Based on sunxi_wdt.c
  19  */
  20
  21 #include <linux/err.h>
  22 #include <linux/init.h>
  23 #include <linux/io.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/moduleparam.h>
  27 #include <linux/of.h>
  28 #include <linux/platform_device.h>
  29 #include <linux/types.h>
  30 #include <linux/watchdog.h>
  31 #include <linux/notifier.h>
  32 #include <linux/reboot.h>
  33 #include <linux/delay.h>
  34
  35 #define WDT_MAX_TIMEOUT         31
  36 #define WDT_MIN_TIMEOUT         1
  37 #define WDT_LENGTH_TIMEOUT(n)   ((n) << 5)
  38
  39 #define WDT_LENGTH              0x04
  40 #define WDT_LENGTH_KEY          0x8
  41
  42 #define WDT_RST                 0x08
  43 #define WDT_RST_RELOAD          0x1971
  44
  45 #define WDT_MODE                0x00
  46 #define WDT_MODE_EN             (1 << 0)
  47 #define WDT_MODE_EXT_POL_LOW    (0 << 1)
  48 #define WDT_MODE_EXT_POL_HIGH   (1 << 1)
  49 #define WDT_MODE_EXRST_EN       (1 << 2)
  50 #define WDT_MODE_IRQ_EN         (1 << 3)
  51 #define WDT_MODE_AUTO_START     (1 << 4)
  52 #define WDT_MODE_DUAL_EN        (1 << 6)
  53 #define WDT_MODE_KEY            0x22000000
  54
  55 #define WDT_SWRST               0x14
  56 #define WDT_SWRST_KEY           0x1209
  57
  58 #define DRV_NAME                "mtk-wdt"
  59 #define DRV_VERSION             "1.0"
  60
  61 static bool nowayout = WATCHDOG_NOWAYOUT;
  62 static unsigned int timeout = WDT_MAX_TIMEOUT;
  63
  64 struct mtk_wdt_dev {
  65         struct watchdog_device wdt_dev;
  66         void __iomem *wdt_base;
  67         struct notifier_block restart_handler;
  68 };
  69
  70 static int mtk_reset_handler(struct notifier_block *this, unsigned long mode,
  71                                 void *cmd)
  72 {
  73         struct mtk_wdt_dev *mtk_wdt;
  74         void __iomem *wdt_base;
  75
  76         mtk_wdt = container_of(this, struct mtk_wdt_dev, restart_handler);
  77         wdt_base = mtk_wdt->wdt_base;
  78
  79         while (1) {
  80                 writel(WDT_SWRST_KEY, wdt_base + WDT_SWRST);
  81                 mdelay(5);
  82         }
  83
  84         return NOTIFY_DONE;
  85 }
  86
  87 static int mtk_wdt_ping(struct watchdog_device *wdt_dev)
  88 {
  89         struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
  90         void __iomem *wdt_base = mtk_wdt->wdt_base;
  91
  92         iowrite32(WDT_RST_RELOAD, wdt_base + WDT_RST);
  93
  94         return 0;
  95 }
  96
  97 static int mtk_wdt_set_timeout(struct watchdog_device *wdt_dev,
  98                                 unsigned int timeout)
  99 {
 100         struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
 101         void __iomem *wdt_base = mtk_wdt->wdt_base;
 102         u32 reg;
 103
 104         wdt_dev->timeout = timeout;
 105
 106         /*
 107          * One bit is the value of 512 ticks
 108          * The clock has 32 KHz
 109          */
 110         reg = WDT_LENGTH_TIMEOUT(timeout << 6) | WDT_LENGTH_KEY;
 111         iowrite32(reg, wdt_base + WDT_LENGTH);
 112
 113         mtk_wdt_ping(wdt_dev);
 114
 115         return 0;
 116 }
 117
 118 static int mtk_wdt_stop(struct watchdog_device *wdt_dev)
 119 {
 120         struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
 121         void __iomem *wdt_base = mtk_wdt->wdt_base;
 122         u32 reg;
 123
 124         reg = readl(wdt_base + WDT_MODE);
 125         reg &= ~WDT_MODE_EN;
 126         iowrite32(reg, wdt_base + WDT_MODE);
 127
 128         return 0;
 129 }
 130
 131 static int mtk_wdt_start(struct watchdog_device *wdt_dev)
 132 {
 133         u32 reg;
 134         struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
 135         void __iomem *wdt_base = mtk_wdt->wdt_base;
 136         int ret;
 137
 138         ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
 139         if (ret < 0)
 140                 return ret;
 141
 142         reg = ioread32(wdt_base + WDT_MODE);
 143         reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
 144         reg |= (WDT_MODE_EN | WDT_MODE_KEY);
 145         iowrite32(reg, wdt_base + WDT_MODE);
 146
 147         return 0;
 148 }
 149
 150 static const struct watchdog_info mtk_wdt_info = {
 151         .identity       = DRV_NAME,
 152         .options        = WDIOF_SETTIMEOUT |
 153                           WDIOF_KEEPALIVEPING |
 154                           WDIOF_MAGICCLOSE,
 155 };
 156
 157 static const struct watchdog_ops mtk_wdt_ops = {
 158         .owner          = THIS_MODULE,
 159         .start          = mtk_wdt_start,
 160         .stop           = mtk_wdt_stop,
 161         .ping           = mtk_wdt_ping,
 162         .set_timeout    = mtk_wdt_set_timeout,
 163 };
 164
 165 static int mtk_wdt_probe(struct platform_device *pdev)
 166 {
 167         struct mtk_wdt_dev *mtk_wdt;
 168         struct resource *res;
 169         int err;
 170
 171         mtk_wdt = devm_kzalloc(&pdev->dev, sizeof(*mtk_wdt), GFP_KERNEL);
 172         if (!mtk_wdt)
 173                 return -ENOMEM;
 174
 175         platform_set_drvdata(pdev, mtk_wdt);
 176
 177         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 178         mtk_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
 179         if (IS_ERR(mtk_wdt->wdt_base))
 180                 return PTR_ERR(mtk_wdt->wdt_base);
 181
 182         mtk_wdt->wdt_dev.info = &mtk_wdt_info;
 183         mtk_wdt->wdt_dev.ops = &mtk_wdt_ops;
 184         mtk_wdt->wdt_dev.timeout = WDT_MAX_TIMEOUT;
 185         mtk_wdt->wdt_dev.max_timeout = WDT_MAX_TIMEOUT;
 186         mtk_wdt->wdt_dev.min_timeout = WDT_MIN_TIMEOUT;
 187         mtk_wdt->wdt_dev.parent = &pdev->dev;
 188
 189         watchdog_init_timeout(&mtk_wdt->wdt_dev, timeout, &pdev->dev);
 190         watchdog_set_nowayout(&mtk_wdt->wdt_dev, nowayout);
 191
 192         watchdog_set_drvdata(&mtk_wdt->wdt_dev, mtk_wdt);
 193
 194         mtk_wdt_stop(&mtk_wdt->wdt_dev);
 195
 196         err = watchdog_register_device(&mtk_wdt->wdt_dev);
 197         if (unlikely(err))
 198                 return err;
 199
 200         mtk_wdt->restart_handler.notifier_call = mtk_reset_handler;
 201         mtk_wdt->restart_handler.priority = 128;
 202         err = register_restart_handler(&mtk_wdt->restart_handler);
 203         if (err)
 204                 dev_warn(&pdev->dev,
 205                         "cannot register restart handler (err=%d)\n", err);
 206
 207         dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)\n",
 208                         mtk_wdt->wdt_dev.timeout, nowayout);
 209
 210         return 0;
 211 }
 212
 213 static int mtk_wdt_remove(struct platform_device *pdev)
 214 {
 215         struct mtk_wdt_dev *mtk_wdt = platform_get_drvdata(pdev);
 216
 217         unregister_restart_handler(&mtk_wdt->restart_handler);
 218
 219         watchdog_unregister_device(&mtk_wdt->wdt_dev);
 220
 221         return 0;
 222 }
 223
 224 static const struct of_device_id mtk_wdt_dt_ids[] = {
 225         { .compatible = "mediatek,mt6589-wdt" },
 226         { /* sentinel */ }
 227 };
 228 MODULE_DEVICE_TABLE(of, mtk_wdt_dt_ids);
 229
 230 static struct platform_driver mtk_wdt_driver = {
 231         .probe          = mtk_wdt_probe,
 232         .remove         = mtk_wdt_remove,
 233         .driver         = {
 234                 .name           = DRV_NAME,
 235                 .of_match_table = mtk_wdt_dt_ids,
 236         },
 237 };
 238
 239 module_platform_driver(mtk_wdt_driver);
 240
 241 module_param(timeout, uint, 0);
 242 MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
 243
 244 module_param(nowayout, bool, 0);
 245 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 246                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 247
 248 MODULE_LICENSE("GPL");
 249 MODULE_AUTHOR("Matthias Brugger <matthias.bgg@gmail.com>");
 250 MODULE_DESCRIPTION("Mediatek WatchDog Timer Driver");
 251 MODULE_VERSION(DRV_VERSION);