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Linux/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);
174 

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