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