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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28
29 #include <linux/kernel.h>
30 #include <linux/compiler.h>
31 #include <linux/init.h>
32 #include <linux/module.h>
33 #include <linux/miscdevice.h>
34 #include <linux/watchdog.h>
35 #include <linux/fs.h>
36 #include <linux/of.h>
37 #include <linux/of_platform.h>
38 #include <linux/io.h>
39 #include <linux/uaccess.h>
40
41 #include <sysdev/fsl_soc.h>
42
43 /*
44 * The watchdog configuration register contains a pair of 2-bit fields,
45 * 1. a reload field, bits 27-26, which triggers a reload of
46 * the countdown register, and
47 * 2. an enable field, bits 25-24, which toggles between
48 * enabling and disabling the watchdog timer.
49 * Bit 31 is a read-only field which indicates whether the
50 * watchdog timer is currently enabled.
51 *
52 * The low 24 bits contain the timer reload value.
53 */
54 #define GEF_WDC_ENABLE_SHIFT 24
55 #define GEF_WDC_SERVICE_SHIFT 26
56 #define GEF_WDC_ENABLED_SHIFT 31
57
58 #define GEF_WDC_ENABLED_TRUE 1
59 #define GEF_WDC_ENABLED_FALSE 0
60
61 /* Flags bits */
62 #define GEF_WDOG_FLAG_OPENED 0
63
64 static unsigned long wdt_flags;
65 static int wdt_status;
66 static void __iomem *gef_wdt_regs;
67 static int gef_wdt_timeout;
68 static int gef_wdt_count;
69 static unsigned int bus_clk;
70 static char expect_close;
71 static DEFINE_SPINLOCK(gef_wdt_spinlock);
72
73 static bool nowayout = WATCHDOG_NOWAYOUT;
74 module_param(nowayout, bool, 0);
75 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
76 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
77
78
gef_wdt_toggle_wdc(int enabled_predicate,int field_shift)79 static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
80 {
81 u32 data;
82 u32 enabled;
83 int ret = 0;
84
85 spin_lock(&gef_wdt_spinlock);
86 data = ioread32be(gef_wdt_regs);
87 enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;
88
89 /* only toggle the requested field if enabled state matches predicate */
90 if ((enabled ^ enabled_predicate) == 0) {
91 /* We write a 1, then a 2 -- to the appropriate field */
92 data = (1 << field_shift) | gef_wdt_count;
93 iowrite32be(data, gef_wdt_regs);
94
95 data = (2 << field_shift) | gef_wdt_count;
96 iowrite32be(data, gef_wdt_regs);
97 ret = 1;
98 }
99 spin_unlock(&gef_wdt_spinlock);
100
101 return ret;
102 }
103
gef_wdt_service(void)104 static void gef_wdt_service(void)
105 {
106 gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
107 GEF_WDC_SERVICE_SHIFT);
108 }
109
gef_wdt_handler_enable(void)110 static void gef_wdt_handler_enable(void)
111 {
112 if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
113 GEF_WDC_ENABLE_SHIFT)) {
114 gef_wdt_service();
115 pr_notice("watchdog activated\n");
116 }
117 }
118
gef_wdt_handler_disable(void)119 static void gef_wdt_handler_disable(void)
120 {
121 if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
122 GEF_WDC_ENABLE_SHIFT))
123 pr_notice("watchdog deactivated\n");
124 }
125
gef_wdt_set_timeout(unsigned int timeout)126 static void gef_wdt_set_timeout(unsigned int timeout)
127 {
128 /* maximum bus cycle count is 0xFFFFFFFF */
129 if (timeout > 0xFFFFFFFF / bus_clk)
130 timeout = 0xFFFFFFFF / bus_clk;
131
132 /* Register only holds upper 24 bits, bit shifted into lower 24 */
133 gef_wdt_count = (timeout * bus_clk) >> 8;
134 gef_wdt_timeout = timeout;
135 }
136
137
gef_wdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)138 static ssize_t gef_wdt_write(struct file *file, const char __user *data,
139 size_t len, loff_t *ppos)
140 {
141 if (len) {
142 if (!nowayout) {
143 size_t i;
144
145 expect_close = 0;
146
147 for (i = 0; i != len; i++) {
148 char c;
149 if (get_user(c, data + i))
150 return -EFAULT;
151 if (c == 'V')
152 expect_close = 42;
153 }
154 }
155 gef_wdt_service();
156 }
157
158 return len;
159 }
160
gef_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)161 static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
162 unsigned long arg)
163 {
164 int timeout;
165 int options;
166 void __user *argp = (void __user *)arg;
167 static const struct watchdog_info info = {
168 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
169 WDIOF_KEEPALIVEPING,
170 .firmware_version = 0,
171 .identity = "GE watchdog",
172 };
173
174 switch (cmd) {
175 case WDIOC_GETSUPPORT:
176 if (copy_to_user(argp, &info, sizeof(info)))
177 return -EFAULT;
178 break;
179
180 case WDIOC_GETSTATUS:
181 case WDIOC_GETBOOTSTATUS:
182 if (put_user(wdt_status, (int __user *)argp))
183 return -EFAULT;
184 wdt_status &= ~WDIOF_KEEPALIVEPING;
185 break;
186
187 case WDIOC_SETOPTIONS:
188 if (get_user(options, (int __user *)argp))
189 return -EFAULT;
190
191 if (options & WDIOS_DISABLECARD)
192 gef_wdt_handler_disable();
193
194 if (options & WDIOS_ENABLECARD)
195 gef_wdt_handler_enable();
196 break;
197
198 case WDIOC_KEEPALIVE:
199 gef_wdt_service();
200 wdt_status |= WDIOF_KEEPALIVEPING;
201 break;
202
203 case WDIOC_SETTIMEOUT:
204 if (get_user(timeout, (int __user *)argp))
205 return -EFAULT;
206 gef_wdt_set_timeout(timeout);
207 /* Fall through */
208
209 case WDIOC_GETTIMEOUT:
210 if (put_user(gef_wdt_timeout, (int __user *)argp))
211 return -EFAULT;
212 break;
213
214 default:
215 return -ENOTTY;
216 }
217
218 return 0;
219 }
220
gef_wdt_open(struct inode * inode,struct file * file)221 static int gef_wdt_open(struct inode *inode, struct file *file)
222 {
223 if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
224 return -EBUSY;
225
226 if (nowayout)
227 __module_get(THIS_MODULE);
228
229 gef_wdt_handler_enable();
230
231 return nonseekable_open(inode, file);
232 }
233
gef_wdt_release(struct inode * inode,struct file * file)234 static int gef_wdt_release(struct inode *inode, struct file *file)
235 {
236 if (expect_close == 42)
237 gef_wdt_handler_disable();
238 else {
239 pr_crit("unexpected close, not stopping timer!\n");
240 gef_wdt_service();
241 }
242 expect_close = 0;
243
244 clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);
245
246 return 0;
247 }
248
249 static const struct file_operations gef_wdt_fops = {
250 .owner = THIS_MODULE,
251 .llseek = no_llseek,
252 .write = gef_wdt_write,
253 .unlocked_ioctl = gef_wdt_ioctl,
254 .open = gef_wdt_open,
255 .release = gef_wdt_release,
256 };
257
258 static struct miscdevice gef_wdt_miscdev = {
259 .minor = WATCHDOG_MINOR,
260 .name = "watchdog",
261 .fops = &gef_wdt_fops,
262 };
263
264
gef_wdt_probe(struct platform_device * dev)265 static int gef_wdt_probe(struct platform_device *dev)
266 {
267 int timeout = 10;
268 u32 freq;
269
270 bus_clk = 133; /* in MHz */
271
272 freq = fsl_get_sys_freq();
273 if (freq != -1)
274 bus_clk = freq;
275
276 /* Map devices registers into memory */
277 gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
278 if (gef_wdt_regs == NULL)
279 return -ENOMEM;
280
281 gef_wdt_set_timeout(timeout);
282
283 gef_wdt_handler_disable(); /* in case timer was already running */
284
285 return misc_register(&gef_wdt_miscdev);
286 }
287
gef_wdt_remove(struct platform_device * dev)288 static int gef_wdt_remove(struct platform_device *dev)
289 {
290 misc_deregister(&gef_wdt_miscdev);
291
292 gef_wdt_handler_disable();
293
294 iounmap(gef_wdt_regs);
295
296 return 0;
297 }
298
299 static const struct of_device_id gef_wdt_ids[] = {
300 {
301 .compatible = "gef,fpga-wdt",
302 },
303 {},
304 };
305
306 static struct platform_driver gef_wdt_driver = {
307 .driver = {
308 .name = "gef_wdt",
309 .owner = THIS_MODULE,
310 .of_match_table = gef_wdt_ids,
311 },
312 .probe = gef_wdt_probe,
313 .remove = gef_wdt_remove,
314 };
315
gef_wdt_init(void)316 static int __init gef_wdt_init(void)
317 {
318 pr_info("GE watchdog driver\n");
319 return platform_driver_register(&gef_wdt_driver);
320 }
321
gef_wdt_exit(void)322 static void __exit gef_wdt_exit(void)
323 {
324 platform_driver_unregister(&gef_wdt_driver);
325 }
326
327 module_init(gef_wdt_init);
328 module_exit(gef_wdt_exit);
329
330 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
331 MODULE_DESCRIPTION("GE watchdog driver");
332 MODULE_LICENSE("GPL");
333 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
334 MODULE_ALIAS("platform:gef_wdt");
335