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 
48 static unsigned int timeout = DEFAULT_TIME;
49 module_param(timeout, uint, 0);
50 MODULE_PARM_DESC(timeout,
51 		"Default Watchdog timer setting ("
52 		__MODULE_STRING(DEFAULT_TIME) "s)."
53 		"The range is from 1 to 600");
54 
55 static bool nowayout = WATCHDOG_NOWAYOUT;
56 module_param(nowayout, bool, 0);
57 MODULE_PARM_DESC(nowayout,
58 	"Watchdog cannot be stopped once started (default="
59 		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
60 
61 static u8 resetmode = 0x10;
62 module_param(resetmode, byte, 0);
63 MODULE_PARM_DESC(resetmode,
64 	"Resetmode bits: 0x08 warm reset (cold reset otherwise), "
65 	"0x10 reset enable, 0x20 disable toggle GPIO[4] (default=0x10)");
66 
67 static 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  */
ie6xx_wdt_unlock_registers(void)80 static 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 
ie6xx_wdt_ping(struct watchdog_device * wdd)86 static 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 
ie6xx_wdt_set_timeout(struct watchdog_device * wdd,unsigned int t)95 static 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 
ie6xx_wdt_start(struct watchdog_device * wdd)132 static 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 
ie6xx_wdt_stop(struct watchdog_device * wdd)144 static 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 
157 static 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 
164 static 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 
172 static 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 
ie6xx_wdt_show(struct seq_file * s,void * unused)181 static 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 
200 DEFINE_SHOW_ATTRIBUTE(ie6xx_wdt);
201 
ie6xx_wdt_debugfs_init(void)202 static 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 
ie6xx_wdt_debugfs_exit(void)209 static void ie6xx_wdt_debugfs_exit(void)
210 {
211 	debugfs_remove(ie6xx_wdt_data.debugfs);
212 }
213 
214 #else
ie6xx_wdt_debugfs_init(void)215 static void ie6xx_wdt_debugfs_init(void)
216 {
217 }
218 
ie6xx_wdt_debugfs_exit(void)219 static void ie6xx_wdt_debugfs_exit(void)
220 {
221 }
222 #endif
223 
ie6xx_wdt_probe(struct platform_device * pdev)224 static 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 
262 misc_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 
ie6xx_wdt_remove(struct platform_device * pdev)269 static int 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 	return 0;
281 }
282 
283 static struct platform_driver ie6xx_wdt_driver = {
284 	.probe		= ie6xx_wdt_probe,
285 	.remove		= ie6xx_wdt_remove,
286 	.driver		= {
287 		.name	= DRIVER_NAME,
288 	},
289 };
290 
ie6xx_wdt_init(void)291 static int __init ie6xx_wdt_init(void)
292 {
293 	/* Check boot parameters to verify that their initial values */
294 	/* are in range. */
295 	if ((timeout < MIN_TIME) ||
296 	    (timeout > MAX_TIME)) {
297 		pr_err("Watchdog timer: value of timeout %d (dec) "
298 		  "is out of range from %d to %d (dec)\n",
299 		  timeout, MIN_TIME, MAX_TIME);
300 		return -EINVAL;
301 	}
302 
303 	return platform_driver_register(&ie6xx_wdt_driver);
304 }
305 
ie6xx_wdt_exit(void)306 static void __exit ie6xx_wdt_exit(void)
307 {
308 	platform_driver_unregister(&ie6xx_wdt_driver);
309 }
310 
311 late_initcall(ie6xx_wdt_init);
312 module_exit(ie6xx_wdt_exit);
313 
314 MODULE_AUTHOR("Alexander Stein <alexander.stein@systec-electronic.com>");
315 MODULE_DESCRIPTION("Intel Atom E6xx Watchdog Device Driver");
316 MODULE_LICENSE("GPL");
317 MODULE_ALIAS("platform:" DRIVER_NAME);
318