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 <smaclennan@pikatech.com> |
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 |
39 | static int heartbeat = WDT_HEARTBEAT; |
40 | module_param(heartbeat, int, 0); |
41 | MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. " |
42 | "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")" ); |
43 | |
44 | static bool nowayout = WATCHDOG_NOWAYOUT; |
45 | module_param(nowayout, bool, 0); |
46 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " |
47 | "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")" ); |
48 | |
49 | static 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 | |
58 | static 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 | */ |
69 | static 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 | */ |
89 | static 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(timer: &pikawdt_private.timer, expires: jiffies + WDT_TIMEOUT); |
95 | } else |
96 | pr_crit("I will reset your machine !\n" ); |
97 | } |
98 | |
99 | |
100 | static void pikawdt_keepalive(void) |
101 | { |
102 | pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ; |
103 | } |
104 | |
105 | static void pikawdt_start(void) |
106 | { |
107 | pikawdt_keepalive(); |
108 | mod_timer(timer: &pikawdt_private.timer, expires: jiffies + WDT_TIMEOUT); |
109 | } |
110 | |
111 | /* |
112 | * Watchdog device is opened, and watchdog starts running. |
113 | */ |
114 | static int pikawdt_open(struct inode *inode, struct file *file) |
115 | { |
116 | /* /dev/watchdog can only be opened once */ |
117 | if (test_and_set_bit(nr: 0, addr: &pikawdt_private.open)) |
118 | return -EBUSY; |
119 | |
120 | pikawdt_start(); |
121 | |
122 | return stream_open(inode, filp: file); |
123 | } |
124 | |
125 | /* |
126 | * Close the watchdog device. |
127 | */ |
128 | static int pikawdt_release(struct inode *inode, struct file *file) |
129 | { |
130 | /* stop internal ping */ |
131 | if (!pikawdt_private.expect_close) |
132 | del_timer(timer: &pikawdt_private.timer); |
133 | |
134 | clear_bit(nr: 0, addr: &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 | */ |
142 | static 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 | */ |
173 | static 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(to: argp, from: &ident, n: 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 | |
210 | static const struct file_operations pikawdt_fops = { |
211 | .owner = THIS_MODULE, |
212 | .llseek = no_llseek, |
213 | .open = pikawdt_open, |
214 | .release = pikawdt_release, |
215 | .write = pikawdt_write, |
216 | .unlocked_ioctl = pikawdt_ioctl, |
217 | .compat_ioctl = compat_ptr_ioctl, |
218 | }; |
219 | |
220 | static struct miscdevice pikawdt_miscdev = { |
221 | .minor = WATCHDOG_MINOR, |
222 | .name = "watchdog" , |
223 | .fops = &pikawdt_fops, |
224 | }; |
225 | |
226 | static int __init pikawdt_init(void) |
227 | { |
228 | struct device_node *np; |
229 | void __iomem *fpga; |
230 | u32 post1; |
231 | int ret; |
232 | |
233 | np = of_find_compatible_node(NULL, NULL, compat: "pika,fpga" ); |
234 | if (np == NULL) { |
235 | pr_err("Unable to find fpga\n" ); |
236 | return -ENOENT; |
237 | } |
238 | |
239 | pikawdt_private.fpga = of_iomap(node: np, index: 0); |
240 | of_node_put(node: np); |
241 | if (pikawdt_private.fpga == NULL) { |
242 | pr_err("Unable to map fpga\n" ); |
243 | return -ENOMEM; |
244 | } |
245 | |
246 | ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff; |
247 | |
248 | /* POST information is in the sd area. */ |
249 | np = of_find_compatible_node(NULL, NULL, compat: "pika,fpga-sd" ); |
250 | if (np == NULL) { |
251 | pr_err("Unable to find fpga-sd\n" ); |
252 | ret = -ENOENT; |
253 | goto out; |
254 | } |
255 | |
256 | fpga = of_iomap(node: np, index: 0); |
257 | of_node_put(node: np); |
258 | if (fpga == NULL) { |
259 | pr_err("Unable to map fpga-sd\n" ); |
260 | ret = -ENOMEM; |
261 | goto out; |
262 | } |
263 | |
264 | /* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) -- |
265 | * Bit 31, WDOG: Set to 1 when the last reset was caused by a watchdog |
266 | * timeout. |
267 | */ |
268 | post1 = in_be32(fpga + 0x40); |
269 | if (post1 & 0x80000000) |
270 | pikawdt_private.bootstatus = WDIOF_CARDRESET; |
271 | |
272 | iounmap(addr: fpga); |
273 | |
274 | timer_setup(&pikawdt_private.timer, pikawdt_ping, 0); |
275 | |
276 | ret = misc_register(misc: &pikawdt_miscdev); |
277 | if (ret) { |
278 | pr_err("Unable to register miscdev\n" ); |
279 | goto out; |
280 | } |
281 | |
282 | pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n" , |
283 | heartbeat, nowayout); |
284 | return 0; |
285 | |
286 | out: |
287 | iounmap(addr: pikawdt_private.fpga); |
288 | return ret; |
289 | } |
290 | |
291 | static void __exit pikawdt_exit(void) |
292 | { |
293 | misc_deregister(misc: &pikawdt_miscdev); |
294 | |
295 | iounmap(addr: pikawdt_private.fpga); |
296 | } |
297 | |
298 | module_init(pikawdt_init); |
299 | module_exit(pikawdt_exit); |
300 | |
301 | MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>" ); |
302 | MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer" ); |
303 | MODULE_LICENSE("GPL" ); |
304 | |