drivers/watchdog/ebc-c384_wdt.c

   1 /*
   2  * Watchdog timer driver for the WinSystems EBC-C384
   3  * Copyright (C) 2016 William Breathitt Gray
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  */
  14 #include <linux/device.h>
  15 #include <linux/dmi.h>
  16 #include <linux/errno.h>
  17 #include <linux/io.h>
  18 #include <linux/ioport.h>
  19 #include <linux/isa.h>
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/types.h>
  24 #include <linux/watchdog.h>
  25
  26 #define MODULE_NAME             "ebc-c384_wdt"
  27 #define WATCHDOG_TIMEOUT        60
  28 /*
  29  * The timeout value in minutes must fit in a single byte when sent to the
  30  * watchdog timer; the maximum timeout possible is 15300 (255 * 60) seconds.
  31  */
  32 #define WATCHDOG_MAX_TIMEOUT    15300
  33 #define BASE_ADDR               0x564
  34 #define ADDR_EXTENT             5
  35 #define CFG_ADDR                (BASE_ADDR + 1)
  36 #define PET_ADDR                (BASE_ADDR + 2)
  37
  38 static bool nowayout = WATCHDOG_NOWAYOUT;
  39 module_param(nowayout, bool, 0);
  40 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  41         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  42
  43 static unsigned timeout;
  44 module_param(timeout, uint, 0);
  45 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  46         __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  47
  48 static int ebc_c384_wdt_start(struct watchdog_device *wdev)
  49 {
  50         unsigned t = wdev->timeout;
  51
  52         /* resolution is in minutes for timeouts greater than 255 seconds */
  53         if (t > 255)
  54                 t = DIV_ROUND_UP(t, 60);
  55
  56         outb(t, PET_ADDR);
  57
  58         return 0;
  59 }
  60
  61 static int ebc_c384_wdt_stop(struct watchdog_device *wdev)
  62 {
  63         outb(0x00, PET_ADDR);
  64
  65         return 0;
  66 }
  67
  68 static int ebc_c384_wdt_set_timeout(struct watchdog_device *wdev, unsigned t)
  69 {
  70         /* resolution is in minutes for timeouts greater than 255 seconds */
  71         if (t > 255) {
  72                 /* round second resolution up to minute granularity */
  73                 wdev->timeout = roundup(t, 60);
  74
  75                 /* set watchdog timer for minutes */
  76                 outb(0x00, CFG_ADDR);
  77         } else {
  78                 wdev->timeout = t;
  79
  80                 /* set watchdog timer for seconds */
  81                 outb(0x80, CFG_ADDR);
  82         }
  83
  84         return 0;
  85 }
  86
  87 static const struct watchdog_ops ebc_c384_wdt_ops = {
  88         .start = ebc_c384_wdt_start,
  89         .stop = ebc_c384_wdt_stop,
  90         .set_timeout = ebc_c384_wdt_set_timeout
  91 };
  92
  93 static const struct watchdog_info ebc_c384_wdt_info = {
  94         .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT,
  95         .identity = MODULE_NAME
  96 };
  97
  98 static int ebc_c384_wdt_probe(struct device *dev, unsigned int id)
  99 {
 100         struct watchdog_device *wdd;
 101
 102         if (!devm_request_region(dev, BASE_ADDR, ADDR_EXTENT, dev_name(dev))) {
 103                 dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
 104                         BASE_ADDR, BASE_ADDR + ADDR_EXTENT);
 105                 return -EBUSY;
 106         }
 107
 108         wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
 109         if (!wdd)
 110                 return -ENOMEM;
 111
 112         wdd->info = &ebc_c384_wdt_info;
 113         wdd->ops = &ebc_c384_wdt_ops;
 114         wdd->timeout = WATCHDOG_TIMEOUT;
 115         wdd->min_timeout = 1;
 116         wdd->max_timeout = WATCHDOG_MAX_TIMEOUT;
 117
 118         watchdog_set_nowayout(wdd, nowayout);
 119
 120         if (watchdog_init_timeout(wdd, timeout, dev))
 121                 dev_warn(dev, "Invalid timeout (%u seconds), using default (%u seconds)\n",
 122                         timeout, WATCHDOG_TIMEOUT);
 123
 124         return devm_watchdog_register_device(dev, wdd);
 125 }
 126
 127 static struct isa_driver ebc_c384_wdt_driver = {
 128         .probe = ebc_c384_wdt_probe,
 129         .driver = {
 130                 .name = MODULE_NAME
 131         },
 132 };
 133
 134 static int __init ebc_c384_wdt_init(void)
 135 {
 136         if (!dmi_match(DMI_BOARD_NAME, "EBC-C384 SBC"))
 137                 return -ENODEV;
 138
 139         return isa_register_driver(&ebc_c384_wdt_driver, 1);
 140 }
 141
 142 static void __exit ebc_c384_wdt_exit(void)
 143 {
 144         isa_unregister_driver(&ebc_c384_wdt_driver);
 145 }
 146
 147 module_init(ebc_c384_wdt_init);
 148 module_exit(ebc_c384_wdt_exit);
 149
 150 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 151 MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver");
 152 MODULE_LICENSE("GPL v2");
 153 MODULE_ALIAS("isa:" MODULE_NAME);