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 #include <linux/device.h>
   7 #include <linux/dmi.h>
   8 #include <linux/errno.h>
   9 #include <linux/io.h>
  10 #include <linux/ioport.h>
  11 #include <linux/isa.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/types.h>
  16 #include <linux/watchdog.h>
  17
  18 #define MODULE_NAME             "ebc-c384_wdt"
  19 #define WATCHDOG_TIMEOUT        60
  20 /*
  21  * The timeout value in minutes must fit in a single byte when sent to the
  22  * watchdog timer; the maximum timeout possible is 15300 (255 * 60) seconds.
  23  */
  24 #define WATCHDOG_MAX_TIMEOUT    15300
  25 #define BASE_ADDR               0x564
  26 #define ADDR_EXTENT             5
  27 #define CFG_ADDR                (BASE_ADDR + 1)
  28 #define PET_ADDR                (BASE_ADDR + 2)
  29
  30 static bool nowayout = WATCHDOG_NOWAYOUT;
  31 module_param(nowayout, bool, 0);
  32 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  33         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  34
  35 static unsigned timeout;
  36 module_param(timeout, uint, 0);
  37 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  38         __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  39
  40 static int ebc_c384_wdt_start(struct watchdog_device *wdev)
  41 {
  42         unsigned t = wdev->timeout;
  43
  44         /* resolution is in minutes for timeouts greater than 255 seconds */
  45         if (t > 255)
  46                 t = DIV_ROUND_UP(t, 60);
  47
  48         outb(t, PET_ADDR);
  49
  50         return 0;
  51 }
  52
  53 static int ebc_c384_wdt_stop(struct watchdog_device *wdev)
  54 {
  55         outb(0x00, PET_ADDR);
  56
  57         return 0;
  58 }
  59
  60 static int ebc_c384_wdt_set_timeout(struct watchdog_device *wdev, unsigned t)
  61 {
  62         /* resolution is in minutes for timeouts greater than 255 seconds */
  63         if (t > 255) {
  64                 /* round second resolution up to minute granularity */
  65                 wdev->timeout = roundup(t, 60);
  66
  67                 /* set watchdog timer for minutes */
  68                 outb(0x00, CFG_ADDR);
  69         } else {
  70                 wdev->timeout = t;
  71
  72                 /* set watchdog timer for seconds */
  73                 outb(0x80, CFG_ADDR);
  74         }
  75
  76         return 0;
  77 }
  78
  79 static const struct watchdog_ops ebc_c384_wdt_ops = {
  80         .start = ebc_c384_wdt_start,
  81         .stop = ebc_c384_wdt_stop,
  82         .set_timeout = ebc_c384_wdt_set_timeout
  83 };
  84
  85 static const struct watchdog_info ebc_c384_wdt_info = {
  86         .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT,
  87         .identity = MODULE_NAME
  88 };
  89
  90 static int ebc_c384_wdt_probe(struct device *dev, unsigned int id)
  91 {
  92         struct watchdog_device *wdd;
  93
  94         if (!devm_request_region(dev, BASE_ADDR, ADDR_EXTENT, dev_name(dev))) {
  95                 dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
  96                         BASE_ADDR, BASE_ADDR + ADDR_EXTENT);
  97                 return -EBUSY;
  98         }
  99
 100         wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
 101         if (!wdd)
 102                 return -ENOMEM;
 103
 104         wdd->info = &ebc_c384_wdt_info;
 105         wdd->ops = &ebc_c384_wdt_ops;
 106         wdd->timeout = WATCHDOG_TIMEOUT;
 107         wdd->min_timeout = 1;
 108         wdd->max_timeout = WATCHDOG_MAX_TIMEOUT;
 109
 110         watchdog_set_nowayout(wdd, nowayout);
 111         watchdog_init_timeout(wdd, timeout, dev);
 112
 113         return devm_watchdog_register_device(dev, wdd);
 114 }
 115
 116 static struct isa_driver ebc_c384_wdt_driver = {
 117         .probe = ebc_c384_wdt_probe,
 118         .driver = {
 119                 .name = MODULE_NAME
 120         },
 121 };
 122
 123 static int __init ebc_c384_wdt_init(void)
 124 {
 125         if (!dmi_match(DMI_BOARD_NAME, "EBC-C384 SBC"))
 126                 return -ENODEV;
 127
 128         return isa_register_driver(&ebc_c384_wdt_driver, 1);
 129 }
 130
 131 static void __exit ebc_c384_wdt_exit(void)
 132 {
 133         isa_unregister_driver(&ebc_c384_wdt_driver);
 134 }
 135
 136 module_init(ebc_c384_wdt_init);
 137 module_exit(ebc_c384_wdt_exit);
 138
 139 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 140 MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver");
 141 MODULE_LICENSE("GPL v2");
 142 MODULE_ALIAS("isa:" MODULE_NAME);