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Martyn Welch3268b562008-11-10 12:31:26 +00001/*
Martyn Welchcda61c92010-03-01 17:06:20 +00002 * GE watchdog userspace interface
Martyn Welch3268b562008-11-10 12:31:26 +00003 *
Martyn Welchcda61c92010-03-01 17:06:20 +00004 * Author: Martyn Welch <martyn.welch@ge.com>
Martyn Welch3268b562008-11-10 12:31:26 +00005 *
Martyn Welchcda61c92010-03-01 17:06:20 +00006 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
Martyn Welch3268b562008-11-10 12:31:26 +00007 *
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>
Wolfram Sang & Martyn Welchf6e07222010-12-02 00:11:16 +010033#include <linux/fs.h>
Martyn Welch3268b562008-11-10 12:31:26 +000034#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
62static unsigned long wdt_flags;
63static int wdt_status;
64static void __iomem *gef_wdt_regs;
65static int gef_wdt_timeout;
66static int gef_wdt_count;
67static unsigned int bus_clk;
68static char expect_close;
69static DEFINE_SPINLOCK(gef_wdt_spinlock);
70
71static int nowayout = WATCHDOG_NOWAYOUT;
72module_param(nowayout, int, 0);
73MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
74 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
75
76
77static 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
102static void gef_wdt_service(void)
103{
104 gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
105 GEF_WDC_SERVICE_SHIFT);
106}
107
108static 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
117static 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
124static 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
136static 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
159static 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;
Wim Van Sebroeck42747d72009-12-26 18:55:22 +0000165 static const struct watchdog_info info = {
Martyn Welch3268b562008-11-10 12:31:26 +0000166 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
167 WDIOF_KEEPALIVEPING,
168 .firmware_version = 0,
Martyn Welchcda61c92010-03-01 17:06:20 +0000169 .identity = "GE watchdog",
Martyn Welch3268b562008-11-10 12:31:26 +0000170 };
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
219static 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
232static 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
248static 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
257static struct miscdevice gef_wdt_miscdev = {
258 .minor = WATCHDOG_MINOR,
259 .name = "watchdog",
260 .fops = &gef_wdt_fops,
261};
262
263
Grant Likely2dc11582010-08-06 09:25:50 -0600264static int __devinit gef_wdt_probe(struct platform_device *dev,
Martyn Welch3268b562008-11-10 12:31:26 +0000265 const struct of_device_id *match)
266{
267 int timeout = 10;
268 u32 freq;
269
270 bus_clk = 133; /* in MHz */
271
272 freq = fsl_get_sys_freq();
Roel Kluin26952662009-03-03 15:10:05 +0100273 if (freq != -1)
Martyn Welch3268b562008-11-10 12:31:26 +0000274 bus_clk = freq;
275
276 /* Map devices registers into memory */
Anatolij Gustschinb74dbf22010-06-03 03:30:31 +0200277 gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
Martyn Welch3268b562008-11-10 12:31:26 +0000278 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
288static int __devexit 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
299static const struct of_device_id gef_wdt_ids[] = {
300 {
301 .compatible = "gef,fpga-wdt",
302 },
303 {},
304};
305
306static struct of_platform_driver gef_wdt_driver = {
Grant Likely40182942010-04-13 16:13:02 -0700307 .driver = {
308 .name = "gef_wdt",
309 .owner = THIS_MODULE,
310 .of_match_table = gef_wdt_ids,
311 },
Martyn Welch3268b562008-11-10 12:31:26 +0000312 .probe = gef_wdt_probe,
313};
314
315static int __init gef_wdt_init(void)
316{
Martyn Welchcda61c92010-03-01 17:06:20 +0000317 printk(KERN_INFO "GE watchdog driver\n");
Martyn Welch3268b562008-11-10 12:31:26 +0000318 return of_register_platform_driver(&gef_wdt_driver);
319}
320
321static void __exit gef_wdt_exit(void)
322{
323 of_unregister_platform_driver(&gef_wdt_driver);
324}
325
326module_init(gef_wdt_init);
327module_exit(gef_wdt_exit);
328
Martyn Welchcda61c92010-03-01 17:06:20 +0000329MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
330MODULE_DESCRIPTION("GE watchdog driver");
Martyn Welch3268b562008-11-10 12:31:26 +0000331MODULE_LICENSE("GPL");
332MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
333MODULE_ALIAS("platform: gef_wdt");