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/watchdog.h>
  32 #include <linux/timer.h>
  33 #include <linux/io.h>
  34
  35 #define WDT_VERSION     "0.4"
  36
  37 /* default timeout (secs) */
  38 #define WDT_TIMEOUT 30
  39
  40 static bool nowayout = WATCHDOG_NOWAYOUT;
  41 module_param(nowayout, bool, 0);
  42 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
  43
  44 static unsigned int timeout = WDT_TIMEOUT;
  45 module_param(timeout, uint, 0);
  46 MODULE_PARM_DESC(timeout,
  47         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
  48                                 __MODULE_STRING(WDT_TIMEOUT) ")");
  49
  50 static void __iomem *mmio_base;
  51 static struct timer_list timer;
  52 static unsigned long next_heartbeat;
  53
  54 #define EP93XX_WATCHDOG         0x00
  55 #define EP93XX_WDSTATUS         0x04
  56
  57 /* reset the wdt every ~200ms - the heartbeat of the device is 0.250 seconds*/
  58 #define WDT_INTERVAL (HZ/5)
  59
  60 static void ep93xx_wdt_timer_ping(unsigned long data)
  61 {
  62         if (time_before(jiffies, next_heartbeat))
  63                 writel(0x5555, mmio_base + EP93XX_WATCHDOG);
  64
  65         /* Re-set the timer interval */
  66         mod_timer(&timer, jiffies + WDT_INTERVAL);
  67 }
  68
  69 static int ep93xx_wdt_start(struct watchdog_device *wdd)
  70 {
  71         next_heartbeat = jiffies + (timeout * HZ);
  72
  73         writel(0xaaaa, mmio_base + EP93XX_WATCHDOG);
  74         mod_timer(&timer, jiffies + WDT_INTERVAL);
  75
  76         return 0;
  77 }
  78
  79 static int ep93xx_wdt_stop(struct watchdog_device *wdd)
  80 {
  81         del_timer_sync(&timer);
  82         writel(0xaa55, mmio_base + EP93XX_WATCHDOG);
  83
  84         return 0;
  85 }
  86
  87 static int ep93xx_wdt_keepalive(struct watchdog_device *wdd)
  88 {
  89         /* user land ping */
  90         next_heartbeat = jiffies + (timeout * HZ);
  91
  92         return 0;
  93 }
  94
  95 static const struct watchdog_info ep93xx_wdt_ident = {
  96         .options        = WDIOF_CARDRESET |
  97                           WDIOF_MAGICCLOSE |
  98                           WDIOF_KEEPALIVEPING,
  99         .identity       = "EP93xx Watchdog",
 100 };
 101
 102 static struct watchdog_ops ep93xx_wdt_ops = {
 103         .owner          = THIS_MODULE,
 104         .start          = ep93xx_wdt_start,
 105         .stop           = ep93xx_wdt_stop,
 106         .ping           = ep93xx_wdt_keepalive,
 107 };
 108
 109 static struct watchdog_device ep93xx_wdt_wdd = {
 110         .info           = &ep93xx_wdt_ident,
 111         .ops            = &ep93xx_wdt_ops,
 112 };
 113
 114 static int ep93xx_wdt_probe(struct platform_device *pdev)
 115 {
 116         struct resource *res;
 117         unsigned long val;
 118         int err;
 119
 120         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 121         mmio_base = devm_ioremap_resource(&pdev->dev, res);
 122         if (IS_ERR(mmio_base))
 123                 return PTR_ERR(mmio_base);
 124
 125         if (timeout < 1 || timeout > 3600) {
 126                 timeout = WDT_TIMEOUT;
 127                 dev_warn(&pdev->dev,
 128                         "timeout value must be 1<=x<=3600, using %d\n",
 129                         timeout);
 130         }
 131
 132         val = readl(mmio_base + EP93XX_WATCHDOG);
 133         ep93xx_wdt_wdd.bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
 134         ep93xx_wdt_wdd.timeout = timeout;
 135
 136         watchdog_set_nowayout(&ep93xx_wdt_wdd, nowayout);
 137
 138         setup_timer(&timer, ep93xx_wdt_timer_ping, 1);
 139
 140         err = watchdog_register_device(&ep93xx_wdt_wdd);
 141         if (err)
 142                 return err;
 143
 144         dev_info(&pdev->dev,
 145                 "EP93XX watchdog, driver version " WDT_VERSION "%s\n",
 146                 (val & 0x08) ? " (nCS1 disable detected)" : "");
 147
 148         return 0;
 149 }
 150
 151 static int ep93xx_wdt_remove(struct platform_device *pdev)
 152 {
 153         watchdog_unregister_device(&ep93xx_wdt_wdd);
 154         return 0;
 155 }
 156
 157 static struct platform_driver ep93xx_wdt_driver = {
 158         .driver         = {
 159                 .owner  = THIS_MODULE,
 160                 .name   = "ep93xx-wdt",
 161         },
 162         .probe          = ep93xx_wdt_probe,
 163         .remove         = ep93xx_wdt_remove,
 164 };
 165
 166 module_platform_driver(ep93xx_wdt_driver);
 167
 168 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>");
 169 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 170 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 171 MODULE_DESCRIPTION("EP93xx Watchdog");
 172 MODULE_LICENSE("GPL");
 173 MODULE_VERSION(WDT_VERSION);