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
30static bool nowayout = WATCHDOG_NOWAYOUT;
31module_param(nowayout, bool, 0);
32MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
33	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
34
35static unsigned timeout;
36module_param(timeout, uint, 0);
37MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
38	__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
39
40static 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
53static int ebc_c384_wdt_stop(struct watchdog_device *wdev)
54{
55	outb(0x00, PET_ADDR);
56
57	return 0;
58}
59
60static 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
79static 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
85static const struct watchdog_info ebc_c384_wdt_info = {
86	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT,
87	.identity = MODULE_NAME
88};
89
90static 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
116static struct isa_driver ebc_c384_wdt_driver = {
117	.probe = ebc_c384_wdt_probe,
118	.driver = {
119		.name = MODULE_NAME
120	},
121};
122
123static 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
131static void __exit ebc_c384_wdt_exit(void)
132{
133	isa_unregister_driver(&ebc_c384_wdt_driver);
134}
135
136module_init(ebc_c384_wdt_init);
137module_exit(ebc_c384_wdt_exit);
138
139MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
140MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver");
141MODULE_LICENSE("GPL v2");
142MODULE_ALIAS("isa:" MODULE_NAME);
143