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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * PIKA FPGA based Watchdog Timer
4 *
5 * Copyright (c) 2008 PIKA Technologies
6 * Sean MacLennan <[email protected]>
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/init.h>
12#include <linux/errno.h>
13#include <linux/module.h>
14#include <linux/moduleparam.h>
15#include <linux/types.h>
16#include <linux/kernel.h>
17#include <linux/fs.h>
18#include <linux/miscdevice.h>
19#include <linux/watchdog.h>
20#include <linux/reboot.h>
21#include <linux/jiffies.h>
22#include <linux/timer.h>
23#include <linux/bitops.h>
24#include <linux/uaccess.h>
25#include <linux/io.h>
26#include <linux/of.h>
27#include <linux/of_address.h>
28
29#define DRV_NAME "PIKA-WDT"
30
31/* Hardware timeout in seconds */
32#define WDT_HW_TIMEOUT 2
33
34/* Timer heartbeat (500ms) */
35#define WDT_TIMEOUT (HZ/2)
36
37/* User land timeout */
38#define WDT_HEARTBEAT 15
39static int heartbeat = WDT_HEARTBEAT;
40module_param(heartbeat, int, 0);
41MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
42 "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
43
44static bool nowayout = WATCHDOG_NOWAYOUT;
45module_param(nowayout, bool, 0);
46MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
47 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
48
49static struct {
50 void __iomem *fpga;
51 unsigned long next_heartbeat; /* the next_heartbeat for the timer */
52 unsigned long open;
53 char expect_close;
54 int bootstatus;
55 struct timer_list timer; /* The timer that pings the watchdog */
56} pikawdt_private;
57
58static struct watchdog_info ident __ro_after_init = {
59 .identity = DRV_NAME,
60 .options = WDIOF_CARDRESET |
61 WDIOF_SETTIMEOUT |
62 WDIOF_KEEPALIVEPING |
63 WDIOF_MAGICCLOSE,
64};
65
66/*
67 * Reload the watchdog timer. (ie, pat the watchdog)
68 */
69static inline void pikawdt_reset(void)
70{
71 /* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --
72 * Bit 7, WTCHDG_EN: When set to 1, the watchdog timer is enabled.
73 * Once enabled, it cannot be disabled. The watchdog can be
74 * kicked by performing any write access to the reset
75 * control register (this register).
76 * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in
77 * seconds. Valid ranges are 1 to 15 seconds. The value can
78 * be modified dynamically.
79 */
80 unsigned reset = in_be32(pikawdt_private.fpga + 0x14);
81 /* enable with max timeout - 15 seconds */
82 reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);
83 out_be32(pikawdt_private.fpga + 0x14, reset);
84}
85
86/*
87 * Timer tick
88 */
89static void pikawdt_ping(struct timer_list *unused)
90{
91 if (time_before(jiffies, pikawdt_private.next_heartbeat) ||
92 (!nowayout && !pikawdt_private.open)) {
93 pikawdt_reset();
94 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
95 } else
96 pr_crit("I will reset your machine !\n");
97}
98
99
100static void pikawdt_keepalive(void)
101{
102 pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
103}
104
105static void pikawdt_start(void)
106{
107 pikawdt_keepalive();
108 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
109}
110
111/*
112 * Watchdog device is opened, and watchdog starts running.
113 */
114static int pikawdt_open(struct inode *inode, struct file *file)
115{
116 /* /dev/watchdog can only be opened once */
117 if (test_and_set_bit(0, &pikawdt_private.open))
118 return -EBUSY;
119
120 pikawdt_start();
121
122 return stream_open(inode, file);
123}
124
125/*
126 * Close the watchdog device.
127 */
128static int pikawdt_release(struct inode *inode, struct file *file)
129{
130 /* stop internal ping */
131 if (!pikawdt_private.expect_close)
132 timer_delete(&pikawdt_private.timer);
133
134 clear_bit(0, &pikawdt_private.open);
135 pikawdt_private.expect_close = 0;
136 return 0;
137}
138
139/*
140 * Pat the watchdog whenever device is written to.
141 */
142static ssize_t pikawdt_write(struct file *file, const char __user *data,
143 size_t len, loff_t *ppos)
144{
145 if (!len)
146 return 0;
147
148 /* Scan for magic character */
149 if (!nowayout) {
150 size_t i;
151
152 pikawdt_private.expect_close = 0;
153
154 for (i = 0; i < len; i++) {
155 char c;
156 if (get_user(c, data + i))
157 return -EFAULT;
158 if (c == 'V') {
159 pikawdt_private.expect_close = 42;
160 break;
161 }
162 }
163 }
164
165 pikawdt_keepalive();
166
167 return len;
168}
169
170/*
171 * Handle commands from user-space.
172 */
173static long pikawdt_ioctl(struct file *file,
174 unsigned int cmd, unsigned long arg)
175{
176 void __user *argp = (void __user *)arg;
177 int __user *p = argp;
178 int new_value;
179
180 switch (cmd) {
181 case WDIOC_GETSUPPORT:
182 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
183
184 case WDIOC_GETSTATUS:
185 return put_user(0, p);
186
187 case WDIOC_GETBOOTSTATUS:
188 return put_user(pikawdt_private.bootstatus, p);
189
190 case WDIOC_KEEPALIVE:
191 pikawdt_keepalive();
192 return 0;
193
194 case WDIOC_SETTIMEOUT:
195 if (get_user(new_value, p))
196 return -EFAULT;
197
198 heartbeat = new_value;
199 pikawdt_keepalive();
200
201 return put_user(new_value, p); /* return current value */
202
203 case WDIOC_GETTIMEOUT:
204 return put_user(heartbeat, p);
205 }
206 return -ENOTTY;
207}
208
209
210static const struct file_operations pikawdt_fops = {
211 .owner = THIS_MODULE,
212 .open = pikawdt_open,
213 .release = pikawdt_release,
214 .write = pikawdt_write,
215 .unlocked_ioctl = pikawdt_ioctl,
216 .compat_ioctl = compat_ptr_ioctl,
217};
218
219static struct miscdevice pikawdt_miscdev = {
220 .minor = WATCHDOG_MINOR,
221 .name = "watchdog",
222 .fops = &pikawdt_fops,
223};
224
225static int __init pikawdt_init(void)
226{
227 struct device_node *np;
228 void __iomem *fpga;
229 u32 post1;
230 int ret;
231
232 np = of_find_compatible_node(NULL, NULL, "pika,fpga");
233 if (np == NULL) {
234 pr_err("Unable to find fpga\n");
235 return -ENOENT;
236 }
237
238 pikawdt_private.fpga = of_iomap(np, 0);
239 of_node_put(np);
240 if (pikawdt_private.fpga == NULL) {
241 pr_err("Unable to map fpga\n");
242 return -ENOMEM;
243 }
244
245 ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;
246
247 /* POST information is in the sd area. */
248 np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
249 if (np == NULL) {
250 pr_err("Unable to find fpga-sd\n");
251 ret = -ENOENT;
252 goto out;
253 }
254
255 fpga = of_iomap(np, 0);
256 of_node_put(np);
257 if (fpga == NULL) {
258 pr_err("Unable to map fpga-sd\n");
259 ret = -ENOMEM;
260 goto out;
261 }
262
263 /* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
264 * Bit 31, WDOG: Set to 1 when the last reset was caused by a watchdog
265 * timeout.
266 */
267 post1 = in_be32(fpga + 0x40);
268 if (post1 & 0x80000000)
269 pikawdt_private.bootstatus = WDIOF_CARDRESET;
270
271 iounmap(fpga);
272
273 timer_setup(&pikawdt_private.timer, pikawdt_ping, 0);
274
275 ret = misc_register(&pikawdt_miscdev);
276 if (ret) {
277 pr_err("Unable to register miscdev\n");
278 goto out;
279 }
280
281 pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
282 heartbeat, nowayout);
283 return 0;
284
285out:
286 iounmap(pikawdt_private.fpga);
287 return ret;
288}
289
290static void __exit pikawdt_exit(void)
291{
292 misc_deregister(&pikawdt_miscdev);
293
294 iounmap(pikawdt_private.fpga);
295}
296
297module_init(pikawdt_init);
298module_exit(pikawdt_exit);
299
300MODULE_AUTHOR("Sean MacLennan <[email protected]>");
301MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
302MODULE_LICENSE("GPL");