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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 <[email protected]>");
140MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver");
141MODULE_LICENSE("GPL v2");
142MODULE_ALIAS("isa:" MODULE_NAME);