LXR linux/drivers/watchdog/ebc-c384

   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
  39static bool nowayout = WATCHDOG_NOWAYOUT;
  40module_param(nowayout, bool, 0);
  41MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  42        __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  43
  44static unsigned timeout;
  45module_param(timeout, uint, 0);
  46MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  47        __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  48
  49static 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
  62static int ebc_c384_wdt_stop(struct watchdog_device *wdev)
  63{
  64        outb(0x00, PET_ADDR);
  65
  66        return 0;
  67}
  68
  69static 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
  88static 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
  94static const struct watchdog_info ebc_c384_wdt_info = {
  95        .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT,
  96        .identity = MODULE_NAME
  97};
  98
  99static 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
 128static struct isa_driver ebc_c384_wdt_driver = {
 129        .probe = ebc_c384_wdt_probe,
 130        .driver = {
 131                .name = MODULE_NAME
 132        },
 133};
 134
 135static 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
 143static void __exit ebc_c384_wdt_exit(void)
 144{
 145        isa_unregister_driver(&ebc_c384_wdt_driver);
 146}
 147
 148module_init(ebc_c384_wdt_init);
 149module_exit(ebc_c384_wdt_exit);
 150
 151MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 152MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver");
 153MODULE_LICENSE("GPL v2");
 154MODULE_ALIAS("isa:" MODULE_NAME);
 155