xref: /openbmc/linux/drivers/watchdog/gef_wdt.c (revision 565d76cb) 
1 /*
2  * GE watchdog userspace interface
3  *
4  * Author:  Martyn Welch <martyn.welch@ge.com>
5  *
6  * Copyright 2008 GE 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/fs.h>
34 #include <linux/of.h>
35 #include <linux/of_platform.h>
36 #include <linux/io.h>
37 #include <linux/uaccess.h>
38 
39 #include <sysdev/fsl_soc.h>
40 
41 /*
42  * The watchdog configuration register contains a pair of 2-bit fields,
43  *   1.  a reload field, bits 27-26, which triggers a reload of
44  *       the countdown register, and
45  *   2.  an enable field, bits 25-24, which toggles between
46  *       enabling and disabling the watchdog timer.
47  * Bit 31 is a read-only field which indicates whether the
48  * watchdog timer is currently enabled.
49  *
50  * The low 24 bits contain the timer reload value.
51  */
52 #define GEF_WDC_ENABLE_SHIFT	24
53 #define GEF_WDC_SERVICE_SHIFT	26
54 #define GEF_WDC_ENABLED_SHIFT	31
55 
56 #define GEF_WDC_ENABLED_TRUE	1
57 #define GEF_WDC_ENABLED_FALSE	0
58 
59 /* Flags bits */
60 #define GEF_WDOG_FLAG_OPENED	0
61 
62 static unsigned long wdt_flags;
63 static int wdt_status;
64 static void __iomem *gef_wdt_regs;
65 static int gef_wdt_timeout;
66 static int gef_wdt_count;
67 static unsigned int bus_clk;
68 static char expect_close;
69 static DEFINE_SPINLOCK(gef_wdt_spinlock);
70 
71 static int nowayout = WATCHDOG_NOWAYOUT;
72 module_param(nowayout, int, 0);
73 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
74 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
75 
76 
77 static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
78 {
79 	u32 data;
80 	u32 enabled;
81 	int ret = 0;
82 
83 	spin_lock(&gef_wdt_spinlock);
84 	data = ioread32be(gef_wdt_regs);
85 	enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;
86 
87 	/* only toggle the requested field if enabled state matches predicate */
88 	if ((enabled ^ enabled_predicate) == 0) {
89 		/* We write a 1, then a 2 -- to the appropriate field */
90 		data = (1 << field_shift) | gef_wdt_count;
91 		iowrite32be(data, gef_wdt_regs);
92 
93 		data = (2 << field_shift) | gef_wdt_count;
94 		iowrite32be(data, gef_wdt_regs);
95 		ret = 1;
96 	}
97 	spin_unlock(&gef_wdt_spinlock);
98 
99 	return ret;
100 }
101 
102 static void gef_wdt_service(void)
103 {
104 	gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
105 		GEF_WDC_SERVICE_SHIFT);
106 }
107 
108 static void gef_wdt_handler_enable(void)
109 {
110 	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
111 				   GEF_WDC_ENABLE_SHIFT)) {
112 		gef_wdt_service();
113 		printk(KERN_NOTICE "gef_wdt: watchdog activated\n");
114 	}
115 }
116 
117 static void gef_wdt_handler_disable(void)
118 {
119 	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
120 				   GEF_WDC_ENABLE_SHIFT))
121 		printk(KERN_NOTICE "gef_wdt: watchdog deactivated\n");
122 }
123 
124 static void gef_wdt_set_timeout(unsigned int timeout)
125 {
126 	/* maximum bus cycle count is 0xFFFFFFFF */
127 	if (timeout > 0xFFFFFFFF / bus_clk)
128 		timeout = 0xFFFFFFFF / bus_clk;
129 
130 	/* Register only holds upper 24 bits, bit shifted into lower 24 */
131 	gef_wdt_count = (timeout * bus_clk) >> 8;
132 	gef_wdt_timeout = timeout;
133 }
134 
135 
136 static ssize_t gef_wdt_write(struct file *file, const char __user *data,
137 				 size_t len, loff_t *ppos)
138 {
139 	if (len) {
140 		if (!nowayout) {
141 			size_t i;
142 
143 			expect_close = 0;
144 
145 			for (i = 0; i != len; i++) {
146 				char c;
147 				if (get_user(c, data + i))
148 					return -EFAULT;
149 				if (c == 'V')
150 					expect_close = 42;
151 			}
152 		}
153 		gef_wdt_service();
154 	}
155 
156 	return len;
157 }
158 
159 static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
160 							unsigned long arg)
161 {
162 	int timeout;
163 	int options;
164 	void __user *argp = (void __user *)arg;
165 	static const struct watchdog_info info = {
166 		.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
167 				WDIOF_KEEPALIVEPING,
168 		.firmware_version = 0,
169 		.identity = "GE watchdog",
170 	};
171 
172 	switch (cmd) {
173 	case WDIOC_GETSUPPORT:
174 		if (copy_to_user(argp, &info, sizeof(info)))
175 			return -EFAULT;
176 		break;
177 
178 	case WDIOC_GETSTATUS:
179 	case WDIOC_GETBOOTSTATUS:
180 		if (put_user(wdt_status, (int __user *)argp))
181 			return -EFAULT;
182 		wdt_status &= ~WDIOF_KEEPALIVEPING;
183 		break;
184 
185 	case WDIOC_SETOPTIONS:
186 		if (get_user(options, (int __user *)argp))
187 			return -EFAULT;
188 
189 		if (options & WDIOS_DISABLECARD)
190 			gef_wdt_handler_disable();
191 
192 		if (options & WDIOS_ENABLECARD)
193 			gef_wdt_handler_enable();
194 		break;
195 
196 	case WDIOC_KEEPALIVE:
197 		gef_wdt_service();
198 		wdt_status |= WDIOF_KEEPALIVEPING;
199 		break;
200 
201 	case WDIOC_SETTIMEOUT:
202 		if (get_user(timeout, (int __user *)argp))
203 			return -EFAULT;
204 		gef_wdt_set_timeout(timeout);
205 		/* Fall through */
206 
207 	case WDIOC_GETTIMEOUT:
208 		if (put_user(gef_wdt_timeout, (int __user *)argp))
209 			return -EFAULT;
210 		break;
211 
212 	default:
213 		return -ENOTTY;
214 	}
215 
216 	return 0;
217 }
218 
219 static int gef_wdt_open(struct inode *inode, struct file *file)
220 {
221 	if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
222 		return -EBUSY;
223 
224 	if (nowayout)
225 		__module_get(THIS_MODULE);
226 
227 	gef_wdt_handler_enable();
228 
229 	return nonseekable_open(inode, file);
230 }
231 
232 static int gef_wdt_release(struct inode *inode, struct file *file)
233 {
234 	if (expect_close == 42)
235 		gef_wdt_handler_disable();
236 	else {
237 		printk(KERN_CRIT
238 		       "gef_wdt: unexpected close, not stopping timer!\n");
239 		gef_wdt_service();
240 	}
241 	expect_close = 0;
242 
243 	clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);
244 
245 	return 0;
246 }
247 
248 static const struct file_operations gef_wdt_fops = {
249 	.owner = THIS_MODULE,
250 	.llseek = no_llseek,
251 	.write = gef_wdt_write,
252 	.unlocked_ioctl = gef_wdt_ioctl,
253 	.open = gef_wdt_open,
254 	.release = gef_wdt_release,
255 };
256 
257 static struct miscdevice gef_wdt_miscdev = {
258 	.minor = WATCHDOG_MINOR,
259 	.name = "watchdog",
260 	.fops = &gef_wdt_fops,
261 };
262 
263 
264 static int __devinit gef_wdt_probe(struct platform_device *dev)
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->dev.of_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 platform_driver gef_wdt_driver = {
306 	.driver = {
307 		.name = "gef_wdt",
308 		.owner = THIS_MODULE,
309 		.of_match_table = gef_wdt_ids,
310 	},
311 	.probe		= gef_wdt_probe,
312 };
313 
314 static int __init gef_wdt_init(void)
315 {
316 	printk(KERN_INFO "GE watchdog driver\n");
317 	return platform_driver_register(&gef_wdt_driver);
318 }
319 
320 static void __exit gef_wdt_exit(void)
321 {
322 	platform_driver_unregister(&gef_wdt_driver);
323 }
324 
325 module_init(gef_wdt_init);
326 module_exit(gef_wdt_exit);
327 
328 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
329 MODULE_DESCRIPTION("GE watchdog driver");
330 MODULE_LICENSE("GPL");
331 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
332 MODULE_ALIAS("platform: gef_wdt");
333