drivers/watchdog/ebc-c384_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Watchdog timer driver for the WinSystems EBC-C384
   4  * Copyright (C) 2016 William Breathitt Gray
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License, version 2, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  */
  15 #include <linux/device.h>
  16 #include <linux/dmi.h>
  17 #include <linux/errno.h>
  18 #include <linux/io.h>
  19 #include <linux/ioport.h>
  20 #include <linux/isa.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/types.h>
  25 #include <linux/watchdog.h>
  26
  27 #define MODULE_NAME             "ebc-c384_wdt"
  28 #define WATCHDOG_TIMEOUT        60
  29 /*
  30  * The timeout value in minutes must fit in a single byte when sent to the
  31  * watchdog timer; the maximum timeout possible is 15300 (255 * 60) seconds.
  32  */
  33 #define WATCHDOG_MAX_TIMEOUT    15300
  34 #define BASE_ADDR               0x564
  35 #define ADDR_EXTENT             5
  36 #define CFG_ADDR                (BASE_ADDR + 1)
  37 #define PET_ADDR                (BASE_ADDR + 2)
  38
  39 static bool nowayout = WATCHDOG_NOWAYOUT;
  40 module_param(nowayout, bool, 0);
  41 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  42         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  43
  44 static unsigned timeout;
  45 module_param(timeout, uint, 0);
  46 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  47         __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  48
  49 static int ebc_c384_wdt_start(struct watchdog_device *wdev)
  50 {
  51         unsigned t = wdev->timeout;
  52
  53         /* resolution is in minutes for timeouts greater than 255 seconds */
  54         if (t > 255)
  55                 t = DIV_ROUND_UP(t, 60);
  56
  57         outb(t, PET_ADDR);
  58
  59         return 0;
  60 }
  61
  62 static int ebc_c384_wdt_stop(struct watchdog_device *wdev)
  63 {
  64         outb(0x00, PET_ADDR);
  65
  66         return 0;
  67 }
  68
  69 static int ebc_c384_wdt_set_timeout(struct watchdog_device *wdev, unsigned t)
  70 {
  71         /* resolution is in minutes for timeouts greater than 255 seconds */
  72         if (t > 255) {
  73                 /* round second resolution up to minute granularity */
  74                 wdev->timeout = roundup(t, 60);
  75
  76                 /* set watchdog timer for minutes */
  77                 outb(0x00, CFG_ADDR);
  78         } else {
  79                 wdev->timeout = t;
  80
  81                 /* set watchdog timer for seconds */
  82                 outb(0x80, CFG_ADDR);
  83         }
  84
  85         return 0;
  86 }
  87
  88 static const struct watchdog_ops ebc_c384_wdt_ops = {
  89         .start = ebc_c384_wdt_start,
  90         .stop = ebc_c384_wdt_stop,
  91         .set_timeout = ebc_c384_wdt_set_timeout
  92 };
  93
  94 static const struct watchdog_info ebc_c384_wdt_info = {
  95         .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT,
  96         .identity = MODULE_NAME
  97 };
  98
  99 static int ebc_c384_wdt_probe(struct device *dev, unsigned int id)
 100 {
 101         struct watchdog_device *wdd;
 102
 103         if (!devm_request_region(dev, BASE_ADDR, ADDR_EXTENT, dev_name(dev))) {
 104                 dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
 105                         BASE_ADDR, BASE_ADDR + ADDR_EXTENT);
 106                 return -EBUSY;
 107         }
 108
 109         wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
 110         if (!wdd)
 111                 return -ENOMEM;
 112
 113         wdd->info = &ebc_c384_wdt_info;
 114         wdd->ops = &ebc_c384_wdt_ops;
 115         wdd->timeout = WATCHDOG_TIMEOUT;
 116         wdd->min_timeout = 1;
 117         wdd->max_timeout = WATCHDOG_MAX_TIMEOUT;
 118
 119         watchdog_set_nowayout(wdd, nowayout);
 120
 121         if (watchdog_init_timeout(wdd, timeout, dev))
 122                 dev_warn(dev, "Invalid timeout (%u seconds), using default (%u seconds)\n",
 123                         timeout, WATCHDOG_TIMEOUT);
 124
 125         return devm_watchdog_register_device(dev, wdd);
 126 }
 127
 128 static struct isa_driver ebc_c384_wdt_driver = {
 129         .probe = ebc_c384_wdt_probe,
 130         .driver = {
 131                 .name = MODULE_NAME
 132         },
 133 };
 134
 135 static int __init ebc_c384_wdt_init(void)
 136 {
 137         if (!dmi_match(DMI_BOARD_NAME, "EBC-C384 SBC"))
 138                 return -ENODEV;
 139
 140         return isa_register_driver(&ebc_c384_wdt_driver, 1);
 141 }
 142
 143 static void __exit ebc_c384_wdt_exit(void)
 144 {
 145         isa_unregister_driver(&ebc_c384_wdt_driver);
 146 }
 147
 148 module_init(ebc_c384_wdt_init);
 149 module_exit(ebc_c384_wdt_exit);
 150
 151 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 152 MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver");
 153 MODULE_LICENSE("GPL v2");
 154 MODULE_ALIAS("isa:" MODULE_NAME);