1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *      Intel Atom E6xx Watchdog driver
4 *
5 *      Copyright (C) 2011 Alexander Stein
6 *                <alexander.stein@systec-electronic.com>
7 */
8
9#include <linux/module.h>
10#include <linux/moduleparam.h>
11#include <linux/platform_device.h>
12#include <linux/io.h>
13#include <linux/kernel.h>
14#include <linux/types.h>
15#include <linux/watchdog.h>
16#include <linux/seq_file.h>
17#include <linux/debugfs.h>
18#include <linux/uaccess.h>
19#include <linux/spinlock.h>
20
21#define DRIVER_NAME "ie6xx_wdt"
22
23#define PV1	0x00
24#define PV2	0x04
25
26#define RR0	0x0c
27#define RR1	0x0d
28#define WDT_RELOAD	0x01
29#define WDT_TOUT	0x02
30
31#define WDTCR	0x10
32#define WDT_PRE_SEL	0x04
33#define WDT_RESET_SEL	0x08
34#define WDT_RESET_EN	0x10
35#define WDT_TOUT_EN	0x20
36
37#define DCR	0x14
38
39#define WDTLR	0x18
40#define WDT_LOCK	0x01
41#define WDT_ENABLE	0x02
42#define WDT_TOUT_CNF	0x03
43
44#define MIN_TIME	1
45#define MAX_TIME	(10 * 60) /* 10 minutes */
46#define DEFAULT_TIME	60
47
48static unsigned int timeout = DEFAULT_TIME;
49module_param(timeout, uint, 0);
50MODULE_PARM_DESC(timeout,
51		"Default Watchdog timer setting ("
52		__MODULE_STRING(DEFAULT_TIME) "s)."
53		"The range is from 1 to 600");
54
55static bool nowayout = WATCHDOG_NOWAYOUT;
56module_param(nowayout, bool, 0);
57MODULE_PARM_DESC(nowayout,
58	"Watchdog cannot be stopped once started (default="
59		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
60
61static u8 resetmode = 0x10;
62module_param(resetmode, byte, 0);
63MODULE_PARM_DESC(resetmode,
64	"Resetmode bits: 0x08 warm reset (cold reset otherwise), "
65	"0x10 reset enable, 0x20 disable toggle GPIO[4] (default=0x10)");
66
67static struct {
68	unsigned short sch_wdtba;
69	spinlock_t unlock_sequence;
70#ifdef CONFIG_DEBUG_FS
71	struct dentry *debugfs;
72#endif
73} ie6xx_wdt_data;
74
75/*
76 * This is needed to write to preload and reload registers
77 * struct ie6xx_wdt_data.unlock_sequence must be used
78 * to prevent sequence interrupts
79 */
80static void ie6xx_wdt_unlock_registers(void)
81{
82	outb(0x80, ie6xx_wdt_data.sch_wdtba + RR0);
83	outb(0x86, ie6xx_wdt_data.sch_wdtba + RR0);
84}
85
86static int ie6xx_wdt_ping(struct watchdog_device *wdd)
87{
88	spin_lock(&ie6xx_wdt_data.unlock_sequence);
89	ie6xx_wdt_unlock_registers();
90	outb(WDT_RELOAD, ie6xx_wdt_data.sch_wdtba + RR1);
91	spin_unlock(&ie6xx_wdt_data.unlock_sequence);
92	return 0;
93}
94
95static int ie6xx_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
96{
97	u32 preload;
98	u64 clock;
99	u8 wdtcr;
100
101	/* Watchdog clock is PCI Clock (33MHz) */
102	clock = 33000000;
103	/* and the preload value is loaded into [34:15] of the down counter */
104	preload = (t * clock) >> 15;
105	/*
106	 * Manual states preload must be one less.
107	 * Does not wrap as t is at least 1
108	 */
109	preload -= 1;
110
111	spin_lock(&ie6xx_wdt_data.unlock_sequence);
112
113	/* Set ResetMode & Enable prescaler for range 10ms to 10 min */
114	wdtcr = resetmode & 0x38;
115	outb(wdtcr, ie6xx_wdt_data.sch_wdtba + WDTCR);
116
117	ie6xx_wdt_unlock_registers();
118	outl(0, ie6xx_wdt_data.sch_wdtba + PV1);
119
120	ie6xx_wdt_unlock_registers();
121	outl(preload, ie6xx_wdt_data.sch_wdtba + PV2);
122
123	ie6xx_wdt_unlock_registers();
124	outb(WDT_RELOAD | WDT_TOUT, ie6xx_wdt_data.sch_wdtba + RR1);
125
126	spin_unlock(&ie6xx_wdt_data.unlock_sequence);
127
128	wdd->timeout = t;
129	return 0;
130}
131
132static int ie6xx_wdt_start(struct watchdog_device *wdd)
133{
134	ie6xx_wdt_set_timeout(wdd, wdd->timeout);
135
136	/* Enable the watchdog timer */
137	spin_lock(&ie6xx_wdt_data.unlock_sequence);
138	outb(WDT_ENABLE, ie6xx_wdt_data.sch_wdtba + WDTLR);
139	spin_unlock(&ie6xx_wdt_data.unlock_sequence);
140
141	return 0;
142}
143
144static int ie6xx_wdt_stop(struct watchdog_device *wdd)
145{
146	if (inb(ie6xx_wdt_data.sch_wdtba + WDTLR) & WDT_LOCK)
147		return -1;
148
149	/* Disable the watchdog timer */
150	spin_lock(&ie6xx_wdt_data.unlock_sequence);
151	outb(0, ie6xx_wdt_data.sch_wdtba + WDTLR);
152	spin_unlock(&ie6xx_wdt_data.unlock_sequence);
153
154	return 0;
155}
156
157static const struct watchdog_info ie6xx_wdt_info = {
158	.identity =	"Intel Atom E6xx Watchdog",
159	.options =	WDIOF_SETTIMEOUT |
160			WDIOF_MAGICCLOSE |
161			WDIOF_KEEPALIVEPING,
162};
163
164static const struct watchdog_ops ie6xx_wdt_ops = {
165	.owner =	THIS_MODULE,
166	.start =	ie6xx_wdt_start,
167	.stop =		ie6xx_wdt_stop,
168	.ping =		ie6xx_wdt_ping,
169	.set_timeout =	ie6xx_wdt_set_timeout,
170};
171
172static struct watchdog_device ie6xx_wdt_dev = {
173	.info =		&ie6xx_wdt_info,
174	.ops =		&ie6xx_wdt_ops,
175	.min_timeout =	MIN_TIME,
176	.max_timeout =	MAX_TIME,
177};
178
179#ifdef CONFIG_DEBUG_FS
180
181static int ie6xx_wdt_show(struct seq_file *s, void *unused)
182{
183	seq_printf(s, "PV1   = 0x%08x\n",
184		inl(ie6xx_wdt_data.sch_wdtba + PV1));
185	seq_printf(s, "PV2   = 0x%08x\n",
186		inl(ie6xx_wdt_data.sch_wdtba + PV2));
187	seq_printf(s, "RR    = 0x%08x\n",
188		inw(ie6xx_wdt_data.sch_wdtba + RR0));
189	seq_printf(s, "WDTCR = 0x%08x\n",
190		inw(ie6xx_wdt_data.sch_wdtba + WDTCR));
191	seq_printf(s, "DCR   = 0x%08x\n",
192		inl(ie6xx_wdt_data.sch_wdtba + DCR));
193	seq_printf(s, "WDTLR = 0x%08x\n",
194		inw(ie6xx_wdt_data.sch_wdtba + WDTLR));
195
196	seq_printf(s, "\n");
197	return 0;
198}
199
200DEFINE_SHOW_ATTRIBUTE(ie6xx_wdt);
201
202static void ie6xx_wdt_debugfs_init(void)
203{
204	/* /sys/kernel/debug/ie6xx_wdt */
205	ie6xx_wdt_data.debugfs = debugfs_create_file("ie6xx_wdt",
206		S_IFREG | S_IRUGO, NULL, NULL, &ie6xx_wdt_fops);
207}
208
209static void ie6xx_wdt_debugfs_exit(void)
210{
211	debugfs_remove(ie6xx_wdt_data.debugfs);
212}
213
214#else
215static void ie6xx_wdt_debugfs_init(void)
216{
217}
218
219static void ie6xx_wdt_debugfs_exit(void)
220{
221}
222#endif
223
224static int ie6xx_wdt_probe(struct platform_device *pdev)
225{
226	struct resource *res;
227	u8 wdtlr;
228	int ret;
229
230	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
231	if (!res)
232		return -ENODEV;
233
234	if (!request_region(res->start, resource_size(res), pdev->name)) {
235		dev_err(&pdev->dev, "Watchdog region 0x%llx already in use!\n",
236			(u64)res->start);
237		return -EBUSY;
238	}
239
240	ie6xx_wdt_data.sch_wdtba = res->start;
241	dev_dbg(&pdev->dev, "WDT = 0x%X\n", ie6xx_wdt_data.sch_wdtba);
242
243	ie6xx_wdt_dev.timeout = timeout;
244	watchdog_set_nowayout(&ie6xx_wdt_dev, nowayout);
245	ie6xx_wdt_dev.parent = &pdev->dev;
246
247	spin_lock_init(&ie6xx_wdt_data.unlock_sequence);
248
249	wdtlr = inb(ie6xx_wdt_data.sch_wdtba + WDTLR);
250	if (wdtlr & WDT_LOCK)
251		dev_warn(&pdev->dev,
252			"Watchdog Timer is Locked (Reg=0x%x)\n", wdtlr);
253
254	ie6xx_wdt_debugfs_init();
255
256	ret = watchdog_register_device(&ie6xx_wdt_dev);
257	if (ret)
258		goto misc_register_error;
259
260	return 0;
261
262misc_register_error:
263	ie6xx_wdt_debugfs_exit();
264	release_region(res->start, resource_size(res));
265	ie6xx_wdt_data.sch_wdtba = 0;
266	return ret;
267}
268
269static void ie6xx_wdt_remove(struct platform_device *pdev)
270{
271	struct resource *res;
272
273	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
274	ie6xx_wdt_stop(NULL);
275	watchdog_unregister_device(&ie6xx_wdt_dev);
276	ie6xx_wdt_debugfs_exit();
277	release_region(res->start, resource_size(res));
278	ie6xx_wdt_data.sch_wdtba = 0;
279}
280
281static struct platform_driver ie6xx_wdt_driver = {
282	.probe		= ie6xx_wdt_probe,
283	.remove_new	= ie6xx_wdt_remove,
284	.driver		= {
285		.name	= DRIVER_NAME,
286	},
287};
288
289static int __init ie6xx_wdt_init(void)
290{
291	/* Check boot parameters to verify that their initial values */
292	/* are in range. */
293	if ((timeout < MIN_TIME) ||
294	    (timeout > MAX_TIME)) {
295		pr_err("Watchdog timer: value of timeout %d (dec) "
296		  "is out of range from %d to %d (dec)\n",
297		  timeout, MIN_TIME, MAX_TIME);
298		return -EINVAL;
299	}
300
301	return platform_driver_register(&ie6xx_wdt_driver);
302}
303
304static void __exit ie6xx_wdt_exit(void)
305{
306	platform_driver_unregister(&ie6xx_wdt_driver);
307}
308
309late_initcall(ie6xx_wdt_init);
310module_exit(ie6xx_wdt_exit);
311
312MODULE_AUTHOR("Alexander Stein <alexander.stein@systec-electronic.com>");
313MODULE_DESCRIPTION("Intel Atom E6xx Watchdog Device Driver");
314MODULE_LICENSE("GPL");
315MODULE_ALIAS("platform:" DRIVER_NAME);
316