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);