drivers/watchdog/ep93xx_wdt.c

   1 /*
   2  * Watchdog driver for Cirrus Logic EP93xx family of devices.
   3  *
   4  * Copyright (c) 2004 Ray Lehtiniemi
   5  * Copyright (c) 2006 Tower Technologies
   6  * Based on ep93xx driver, bits from alim7101_wdt.c
   7  *
   8  * Authors: Ray Lehtiniemi <rayl@mail.com>,
   9  *      Alessandro Zummo <a.zummo@towertech.it>
  10  *
  11  * Copyright (c) 2012 H Hartley Sweeten <hsweeten@visionengravers.com>
  12  *      Convert to a platform device and use the watchdog framework API
  13  *
  14  * This file is licensed under the terms of the GNU General Public
  15  * License version 2. This program is licensed "as is" without any
  16  * warranty of any kind, whether express or implied.
  17  *
  18  * This watchdog fires after 250msec, which is a too short interval
  19  * for us to rely on the user space daemon alone. So we ping the
  20  * wdt each ~200msec and eventually stop doing it if the user space
  21  * daemon dies.
  22  *
  23  * TODO:
  24  *
  25  *      - Test last reset from watchdog status
  26  *      - Add a few missing ioctls
  27  */
  28
  29 #include <linux/platform_device.h>
  30 #include <linux/module.h>
  31 #include <linux/miscdevice.h>
  32 #include <linux/watchdog.h>
  33 #include <linux/timer.h>
  34 #include <linux/io.h>
  35
  36 #define WDT_VERSION     "0.4"
  37
  38 /* default timeout (secs) */
  39 #define WDT_TIMEOUT 30
  40
  41 static bool nowayout = WATCHDOG_NOWAYOUT;
  42 module_param(nowayout, bool, 0);
  43 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
  44
  45 static unsigned int timeout = WDT_TIMEOUT;
  46 module_param(timeout, uint, 0);
  47 MODULE_PARM_DESC(timeout,
  48         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
  49                                 __MODULE_STRING(WDT_TIMEOUT) ")");
  50
  51 static void __iomem *mmio_base;
  52 static struct timer_list timer;
  53 static unsigned long next_heartbeat;
  54
  55 #define EP93XX_WATCHDOG         0x00
  56 #define EP93XX_WDSTATUS         0x04
  57
  58 /* reset the wdt every ~200ms - the heartbeat of the device is 0.250 seconds*/
  59 #define WDT_INTERVAL (HZ/5)
  60
  61 static void ep93xx_wdt_timer_ping(unsigned long data)
  62 {
  63         if (time_before(jiffies, next_heartbeat))
  64                 writel(0x5555, mmio_base + EP93XX_WATCHDOG);
  65
  66         /* Re-set the timer interval */
  67         mod_timer(&timer, jiffies + WDT_INTERVAL);
  68 }
  69
  70 static int ep93xx_wdt_start(struct watchdog_device *wdd)
  71 {
  72         next_heartbeat = jiffies + (timeout * HZ);
  73
  74         writel(0xaaaa, mmio_base + EP93XX_WATCHDOG);
  75         mod_timer(&timer, jiffies + WDT_INTERVAL);
  76
  77         return 0;
  78 }
  79
  80 static int ep93xx_wdt_stop(struct watchdog_device *wdd)
  81 {
  82         del_timer_sync(&timer);
  83         writel(0xaa55, mmio_base + EP93XX_WATCHDOG);
  84
  85         return 0;
  86 }
  87
  88 static int ep93xx_wdt_keepalive(struct watchdog_device *wdd)
  89 {
  90         /* user land ping */
  91         next_heartbeat = jiffies + (timeout * HZ);
  92
  93         return 0;
  94 }
  95
  96 static const struct watchdog_info ep93xx_wdt_ident = {
  97         .options        = WDIOF_CARDRESET |
  98                           WDIOF_MAGICCLOSE |
  99                           WDIOF_KEEPALIVEPING,
 100         .identity       = "EP93xx Watchdog",
 101 };
 102
 103 static struct watchdog_ops ep93xx_wdt_ops = {
 104         .owner          = THIS_MODULE,
 105         .start          = ep93xx_wdt_start,
 106         .stop           = ep93xx_wdt_stop,
 107         .ping           = ep93xx_wdt_keepalive,
 108 };
 109
 110 static struct watchdog_device ep93xx_wdt_wdd = {
 111         .info           = &ep93xx_wdt_ident,
 112         .ops            = &ep93xx_wdt_ops,
 113 };
 114
 115 static int ep93xx_wdt_probe(struct platform_device *pdev)
 116 {
 117         struct resource *res;
 118         unsigned long val;
 119         int err;
 120
 121         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 122         if (!res)
 123                 return -ENXIO;
 124
 125         if (!devm_request_mem_region(&pdev->dev, res->start,
 126                                      resource_size(res), pdev->name))
 127                 return -EBUSY;
 128
 129         mmio_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
 130         if (!mmio_base)
 131                 return -ENXIO;
 132
 133         if (timeout < 1 || timeout > 3600) {
 134                 timeout = WDT_TIMEOUT;
 135                 dev_warn(&pdev->dev,
 136                         "timeout value must be 1<=x<=3600, using %d\n",
 137                         timeout);
 138         }
 139
 140         val = readl(mmio_base + EP93XX_WATCHDOG);
 141         ep93xx_wdt_wdd.bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
 142         ep93xx_wdt_wdd.timeout = timeout;
 143
 144         watchdog_set_nowayout(&ep93xx_wdt_wdd, nowayout);
 145
 146         setup_timer(&timer, ep93xx_wdt_timer_ping, 1);
 147
 148         err = watchdog_register_device(&ep93xx_wdt_wdd);
 149         if (err)
 150                 return err;
 151
 152         dev_info(&pdev->dev,
 153                 "EP93XX watchdog, driver version " WDT_VERSION "%s\n",
 154                 (val & 0x08) ? " (nCS1 disable detected)" : "");
 155
 156         return 0;
 157 }
 158
 159 static int ep93xx_wdt_remove(struct platform_device *pdev)
 160 {
 161         watchdog_unregister_device(&ep93xx_wdt_wdd);
 162         return 0;
 163 }
 164
 165 static struct platform_driver ep93xx_wdt_driver = {
 166         .driver         = {
 167                 .owner  = THIS_MODULE,
 168                 .name   = "ep93xx-wdt",
 169         },
 170         .probe          = ep93xx_wdt_probe,
 171         .remove         = ep93xx_wdt_remove,
 172 };
 173
 174 module_platform_driver(ep93xx_wdt_driver);
 175
 176 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
 177                 "Alessandro Zummo <a.zummo@towertech.it>,"
 178                 "H Hartley Sweeten <hsweeten@visionengravers.com>");
 179 MODULE_DESCRIPTION("EP93xx Watchdog");
 180 MODULE_LICENSE("GPL");
 181 MODULE_VERSION(WDT_VERSION);
 182 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);