xref: /openbmc/linux/drivers/watchdog/gef_wdt.c (revision b627b4ed) 
1 /*
2  * GE Fanuc watchdog userspace interface
3  *
4  * Author:  Martyn Welch <martyn.welch@gefanuc.com>
5  *
6  * Copyright 2008 GE Fanuc Intelligent Platforms Embedded Systems, Inc.
7  *
8  * This program is free software; you can redistribute  it and/or modify it
9  * under  the terms of  the GNU General  Public License as published by the
10  * Free Software Foundation;  either version 2 of the  License, or (at your
11  * option) any later version.
12  *
13  * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
14  *   Author: James Chapman <jchapman@katalix.com>
15  */
16 
17 /* TODO:
18  * This driver does not provide support for the hardwares capability of sending
19  * an interrupt at a programmable threshold.
20  *
21  * This driver currently can only support 1 watchdog - there are 2 in the
22  * hardware that this driver supports. Thus one could be configured as a
23  * process-based watchdog (via /dev/watchdog), the second (using the interrupt
24  * capabilities) a kernel-based watchdog.
25  */
26 
27 #include <linux/kernel.h>
28 #include <linux/compiler.h>
29 #include <linux/init.h>
30 #include <linux/module.h>
31 #include <linux/miscdevice.h>
32 #include <linux/watchdog.h>
33 #include <linux/of.h>
34 #include <linux/of_platform.h>
35 #include <linux/io.h>
36 #include <linux/uaccess.h>
37 
38 #include <sysdev/fsl_soc.h>
39 
40 /*
41  * The watchdog configuration register contains a pair of 2-bit fields,
42  *   1.  a reload field, bits 27-26, which triggers a reload of
43  *       the countdown register, and
44  *   2.  an enable field, bits 25-24, which toggles between
45  *       enabling and disabling the watchdog timer.
46  * Bit 31 is a read-only field which indicates whether the
47  * watchdog timer is currently enabled.
48  *
49  * The low 24 bits contain the timer reload value.
50  */
51 #define GEF_WDC_ENABLE_SHIFT	24
52 #define GEF_WDC_SERVICE_SHIFT	26
53 #define GEF_WDC_ENABLED_SHIFT	31
54 
55 #define GEF_WDC_ENABLED_TRUE	1
56 #define GEF_WDC_ENABLED_FALSE	0
57 
58 /* Flags bits */
59 #define GEF_WDOG_FLAG_OPENED	0
60 
61 static unsigned long wdt_flags;
62 static int wdt_status;
63 static void __iomem *gef_wdt_regs;
64 static int gef_wdt_timeout;
65 static int gef_wdt_count;
66 static unsigned int bus_clk;
67 static char expect_close;
68 static DEFINE_SPINLOCK(gef_wdt_spinlock);
69 
70 static int nowayout = WATCHDOG_NOWAYOUT;
71 module_param(nowayout, int, 0);
72 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
73 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
74 
75 
76 static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
77 {
78 	u32 data;
79 	u32 enabled;
80 	int ret = 0;
81 
82 	spin_lock(&gef_wdt_spinlock);
83 	data = ioread32be(gef_wdt_regs);
84 	enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;
85 
86 	/* only toggle the requested field if enabled state matches predicate */
87 	if ((enabled ^ enabled_predicate) == 0) {
88 		/* We write a 1, then a 2 -- to the appropriate field */
89 		data = (1 << field_shift) | gef_wdt_count;
90 		iowrite32be(data, gef_wdt_regs);
91 
92 		data = (2 << field_shift) | gef_wdt_count;
93 		iowrite32be(data, gef_wdt_regs);
94 		ret = 1;
95 	}
96 	spin_unlock(&gef_wdt_spinlock);
97 
98 	return ret;
99 }
100 
101 static void gef_wdt_service(void)
102 {
103 	gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
104 		GEF_WDC_SERVICE_SHIFT);
105 }
106 
107 static void gef_wdt_handler_enable(void)
108 {
109 	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
110 				   GEF_WDC_ENABLE_SHIFT)) {
111 		gef_wdt_service();
112 		printk(KERN_NOTICE "gef_wdt: watchdog activated\n");
113 	}
114 }
115 
116 static void gef_wdt_handler_disable(void)
117 {
118 	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
119 				   GEF_WDC_ENABLE_SHIFT))
120 		printk(KERN_NOTICE "gef_wdt: watchdog deactivated\n");
121 }
122 
123 static void gef_wdt_set_timeout(unsigned int timeout)
124 {
125 	/* maximum bus cycle count is 0xFFFFFFFF */
126 	if (timeout > 0xFFFFFFFF / bus_clk)
127 		timeout = 0xFFFFFFFF / bus_clk;
128 
129 	/* Register only holds upper 24 bits, bit shifted into lower 24 */
130 	gef_wdt_count = (timeout * bus_clk) >> 8;
131 	gef_wdt_timeout = timeout;
132 }
133 
134 
135 static ssize_t gef_wdt_write(struct file *file, const char __user *data,
136 				 size_t len, loff_t *ppos)
137 {
138 	if (len) {
139 		if (!nowayout) {
140 			size_t i;
141 
142 			expect_close = 0;
143 
144 			for (i = 0; i != len; i++) {
145 				char c;
146 				if (get_user(c, data + i))
147 					return -EFAULT;
148 				if (c == 'V')
149 					expect_close = 42;
150 			}
151 		}
152 		gef_wdt_service();
153 	}
154 
155 	return len;
156 }
157 
158 static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
159 							unsigned long arg)
160 {
161 	int timeout;
162 	int options;
163 	void __user *argp = (void __user *)arg;
164 	static struct watchdog_info info = {
165 		.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
166 				WDIOF_KEEPALIVEPING,
167 		.firmware_version = 0,
168 		.identity = "GE Fanuc watchdog",
169 	};
170 
171 	switch (cmd) {
172 	case WDIOC_GETSUPPORT:
173 		if (copy_to_user(argp, &info, sizeof(info)))
174 			return -EFAULT;
175 		break;
176 
177 	case WDIOC_GETSTATUS:
178 	case WDIOC_GETBOOTSTATUS:
179 		if (put_user(wdt_status, (int __user *)argp))
180 			return -EFAULT;
181 		wdt_status &= ~WDIOF_KEEPALIVEPING;
182 		break;
183 
184 	case WDIOC_SETOPTIONS:
185 		if (get_user(options, (int __user *)argp))
186 			return -EFAULT;
187 
188 		if (options & WDIOS_DISABLECARD)
189 			gef_wdt_handler_disable();
190 
191 		if (options & WDIOS_ENABLECARD)
192 			gef_wdt_handler_enable();
193 		break;
194 
195 	case WDIOC_KEEPALIVE:
196 		gef_wdt_service();
197 		wdt_status |= WDIOF_KEEPALIVEPING;
198 		break;
199 
200 	case WDIOC_SETTIMEOUT:
201 		if (get_user(timeout, (int __user *)argp))
202 			return -EFAULT;
203 		gef_wdt_set_timeout(timeout);
204 		/* Fall through */
205 
206 	case WDIOC_GETTIMEOUT:
207 		if (put_user(gef_wdt_timeout, (int __user *)argp))
208 			return -EFAULT;
209 		break;
210 
211 	default:
212 		return -ENOTTY;
213 	}
214 
215 	return 0;
216 }
217 
218 static int gef_wdt_open(struct inode *inode, struct file *file)
219 {
220 	if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
221 		return -EBUSY;
222 
223 	if (nowayout)
224 		__module_get(THIS_MODULE);
225 
226 	gef_wdt_handler_enable();
227 
228 	return nonseekable_open(inode, file);
229 }
230 
231 static int gef_wdt_release(struct inode *inode, struct file *file)
232 {
233 	if (expect_close == 42)
234 		gef_wdt_handler_disable();
235 	else {
236 		printk(KERN_CRIT
237 		       "gef_wdt: unexpected close, not stopping timer!\n");
238 		gef_wdt_service();
239 	}
240 	expect_close = 0;
241 
242 	clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);
243 
244 	return 0;
245 }
246 
247 static const struct file_operations gef_wdt_fops = {
248 	.owner = THIS_MODULE,
249 	.llseek = no_llseek,
250 	.write = gef_wdt_write,
251 	.unlocked_ioctl = gef_wdt_ioctl,
252 	.open = gef_wdt_open,
253 	.release = gef_wdt_release,
254 };
255 
256 static struct miscdevice gef_wdt_miscdev = {
257 	.minor = WATCHDOG_MINOR,
258 	.name = "watchdog",
259 	.fops = &gef_wdt_fops,
260 };
261 
262 
263 static int __devinit gef_wdt_probe(struct of_device *dev,
264 	const struct of_device_id *match)
265 {
266 	int timeout = 10;
267 	u32 freq;
268 
269 	bus_clk = 133; /* in MHz */
270 
271 	freq = fsl_get_sys_freq();
272 	if (freq != -1)
273 		bus_clk = freq;
274 
275 	/* Map devices registers into memory */
276 	gef_wdt_regs = of_iomap(dev->node, 0);
277 	if (gef_wdt_regs == NULL)
278 		return -ENOMEM;
279 
280 	gef_wdt_set_timeout(timeout);
281 
282 	gef_wdt_handler_disable();	/* in case timer was already running */
283 
284 	return misc_register(&gef_wdt_miscdev);
285 }
286 
287 static int __devexit gef_wdt_remove(struct platform_device *dev)
288 {
289 	misc_deregister(&gef_wdt_miscdev);
290 
291 	gef_wdt_handler_disable();
292 
293 	iounmap(gef_wdt_regs);
294 
295 	return 0;
296 }
297 
298 static const struct of_device_id gef_wdt_ids[] = {
299 	{
300 		.compatible = "gef,fpga-wdt",
301 	},
302 	{},
303 };
304 
305 static struct of_platform_driver gef_wdt_driver = {
306 	.owner		= THIS_MODULE,
307 	.name		= "gef_wdt",
308 	.match_table	= gef_wdt_ids,
309 	.probe		= gef_wdt_probe,
310 };
311 
312 static int __init gef_wdt_init(void)
313 {
314 	printk(KERN_INFO "GE Fanuc watchdog driver\n");
315 	return of_register_platform_driver(&gef_wdt_driver);
316 }
317 
318 static void __exit gef_wdt_exit(void)
319 {
320 	of_unregister_platform_driver(&gef_wdt_driver);
321 }
322 
323 module_init(gef_wdt_init);
324 module_exit(gef_wdt_exit);
325 
326 MODULE_AUTHOR("Martyn Welch <martyn.welch@gefanuc.com>");
327 MODULE_DESCRIPTION("GE Fanuc watchdog driver");
328 MODULE_LICENSE("GPL");
329 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
330 MODULE_ALIAS("platform: gef_wdt");
331