LXR linux/drivers/watchdog/ebc-c384

   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
  38static bool nowayout = WATCHDOG_NOWAYOUT;
  39module_param(nowayout, bool, 0);
  40MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  41        __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  42
  43static unsigned timeout;
  44module_param(timeout, uint, 0);
  45MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  46        __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  47
  48static 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
  61static int ebc_c384_wdt_stop(struct watchdog_device *wdev)
  62{
  63        outb(0x00, PET_ADDR);
  64
  65        return 0;
  66}
  67
  68static 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
  87static 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
  93static const struct watchdog_info ebc_c384_wdt_info = {
  94        .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT,
  95        .identity = MODULE_NAME
  96};
  97
  98static 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
 127static struct isa_driver ebc_c384_wdt_driver = {
 128        .probe = ebc_c384_wdt_probe,
 129        .driver = {
 130                .name = MODULE_NAME
 131        },
 132};
 133
 134static 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
 142static void __exit ebc_c384_wdt_exit(void)
 143{
 144        isa_unregister_driver(&ebc_c384_wdt_driver);
 145}
 146
 147module_init(ebc_c384_wdt_init);
 148module_exit(ebc_c384_wdt_exit);
 149
 150MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 151MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver");
 152MODULE_LICENSE("GPL v2");
 153MODULE_ALIAS("isa:" MODULE_NAME);
 154