1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * drivers/watchdog/ar7_wdt.c |
4 | * |
5 | * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org> |
6 | * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org> |
7 | * |
8 | * Some code taken from: |
9 | * National Semiconductor SCx200 Watchdog support |
10 | * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> |
11 | * |
12 | */ |
13 | |
14 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
15 | |
16 | #include <linux/module.h> |
17 | #include <linux/moduleparam.h> |
18 | #include <linux/errno.h> |
19 | #include <linux/miscdevice.h> |
20 | #include <linux/platform_device.h> |
21 | #include <linux/watchdog.h> |
22 | #include <linux/fs.h> |
23 | #include <linux/ioport.h> |
24 | #include <linux/io.h> |
25 | #include <linux/uaccess.h> |
26 | #include <linux/clk.h> |
27 | |
28 | #include <asm/addrspace.h> |
29 | #include <asm/mach-ar7/ar7.h> |
30 | |
31 | #define LONGNAME "TI AR7 Watchdog Timer" |
32 | |
33 | MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>" ); |
34 | MODULE_DESCRIPTION(LONGNAME); |
35 | MODULE_LICENSE("GPL" ); |
36 | |
37 | static int margin = 60; |
38 | module_param(margin, int, 0); |
39 | MODULE_PARM_DESC(margin, "Watchdog margin in seconds" ); |
40 | |
41 | static bool nowayout = WATCHDOG_NOWAYOUT; |
42 | module_param(nowayout, bool, 0); |
43 | MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close" ); |
44 | |
45 | #define READ_REG(x) readl((void __iomem *)&(x)) |
46 | #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x)) |
47 | |
48 | struct ar7_wdt { |
49 | u32 kick_lock; |
50 | u32 kick; |
51 | u32 change_lock; |
52 | u32 change; |
53 | u32 disable_lock; |
54 | u32 disable; |
55 | u32 prescale_lock; |
56 | u32 prescale; |
57 | }; |
58 | |
59 | static unsigned long wdt_is_open; |
60 | static unsigned expect_close; |
61 | static DEFINE_SPINLOCK(wdt_lock); |
62 | |
63 | /* XXX currently fixed, allows max margin ~68.72 secs */ |
64 | #define prescale_value 0xffff |
65 | |
66 | /* Pointer to the remapped WDT IO space */ |
67 | static struct ar7_wdt *ar7_wdt; |
68 | |
69 | static struct clk *vbus_clk; |
70 | |
71 | static void ar7_wdt_kick(u32 value) |
72 | { |
73 | WRITE_REG(ar7_wdt->kick_lock, 0x5555); |
74 | if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) { |
75 | WRITE_REG(ar7_wdt->kick_lock, 0xaaaa); |
76 | if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) { |
77 | WRITE_REG(ar7_wdt->kick, value); |
78 | return; |
79 | } |
80 | } |
81 | pr_err("failed to unlock WDT kick reg\n" ); |
82 | } |
83 | |
84 | static void ar7_wdt_prescale(u32 value) |
85 | { |
86 | WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a); |
87 | if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) { |
88 | WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5); |
89 | if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) { |
90 | WRITE_REG(ar7_wdt->prescale, value); |
91 | return; |
92 | } |
93 | } |
94 | pr_err("failed to unlock WDT prescale reg\n" ); |
95 | } |
96 | |
97 | static void ar7_wdt_change(u32 value) |
98 | { |
99 | WRITE_REG(ar7_wdt->change_lock, 0x6666); |
100 | if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) { |
101 | WRITE_REG(ar7_wdt->change_lock, 0xbbbb); |
102 | if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) { |
103 | WRITE_REG(ar7_wdt->change, value); |
104 | return; |
105 | } |
106 | } |
107 | pr_err("failed to unlock WDT change reg\n" ); |
108 | } |
109 | |
110 | static void ar7_wdt_disable(u32 value) |
111 | { |
112 | WRITE_REG(ar7_wdt->disable_lock, 0x7777); |
113 | if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) { |
114 | WRITE_REG(ar7_wdt->disable_lock, 0xcccc); |
115 | if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) { |
116 | WRITE_REG(ar7_wdt->disable_lock, 0xdddd); |
117 | if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) { |
118 | WRITE_REG(ar7_wdt->disable, value); |
119 | return; |
120 | } |
121 | } |
122 | } |
123 | pr_err("failed to unlock WDT disable reg\n" ); |
124 | } |
125 | |
126 | static void ar7_wdt_update_margin(int new_margin) |
127 | { |
128 | u32 change; |
129 | u32 vbus_rate; |
130 | |
131 | vbus_rate = clk_get_rate(clk: vbus_clk); |
132 | change = new_margin * (vbus_rate / prescale_value); |
133 | if (change < 1) |
134 | change = 1; |
135 | if (change > 0xffff) |
136 | change = 0xffff; |
137 | ar7_wdt_change(value: change); |
138 | margin = change * prescale_value / vbus_rate; |
139 | pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n" , |
140 | margin, prescale_value, change, vbus_rate); |
141 | } |
142 | |
143 | static void ar7_wdt_enable_wdt(void) |
144 | { |
145 | pr_debug("enabling watchdog timer\n" ); |
146 | ar7_wdt_disable(value: 1); |
147 | ar7_wdt_kick(value: 1); |
148 | } |
149 | |
150 | static void ar7_wdt_disable_wdt(void) |
151 | { |
152 | pr_debug("disabling watchdog timer\n" ); |
153 | ar7_wdt_disable(value: 0); |
154 | } |
155 | |
156 | static int ar7_wdt_open(struct inode *inode, struct file *file) |
157 | { |
158 | /* only allow one at a time */ |
159 | if (test_and_set_bit(nr: 0, addr: &wdt_is_open)) |
160 | return -EBUSY; |
161 | ar7_wdt_enable_wdt(); |
162 | expect_close = 0; |
163 | |
164 | return stream_open(inode, filp: file); |
165 | } |
166 | |
167 | static int ar7_wdt_release(struct inode *inode, struct file *file) |
168 | { |
169 | if (!expect_close) |
170 | pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n" ); |
171 | else if (!nowayout) |
172 | ar7_wdt_disable_wdt(); |
173 | clear_bit(nr: 0, addr: &wdt_is_open); |
174 | return 0; |
175 | } |
176 | |
177 | static ssize_t ar7_wdt_write(struct file *file, const char *data, |
178 | size_t len, loff_t *ppos) |
179 | { |
180 | /* check for a magic close character */ |
181 | if (len) { |
182 | size_t i; |
183 | |
184 | spin_lock(lock: &wdt_lock); |
185 | ar7_wdt_kick(value: 1); |
186 | spin_unlock(lock: &wdt_lock); |
187 | |
188 | expect_close = 0; |
189 | for (i = 0; i < len; ++i) { |
190 | char c; |
191 | if (get_user(c, data + i)) |
192 | return -EFAULT; |
193 | if (c == 'V') |
194 | expect_close = 1; |
195 | } |
196 | |
197 | } |
198 | return len; |
199 | } |
200 | |
201 | static long ar7_wdt_ioctl(struct file *file, |
202 | unsigned int cmd, unsigned long arg) |
203 | { |
204 | static const struct watchdog_info ident = { |
205 | .identity = LONGNAME, |
206 | .firmware_version = 1, |
207 | .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | |
208 | WDIOF_MAGICCLOSE), |
209 | }; |
210 | int new_margin; |
211 | |
212 | switch (cmd) { |
213 | case WDIOC_GETSUPPORT: |
214 | if (copy_to_user(to: (struct watchdog_info *)arg, from: &ident, |
215 | n: sizeof(ident))) |
216 | return -EFAULT; |
217 | return 0; |
218 | case WDIOC_GETSTATUS: |
219 | case WDIOC_GETBOOTSTATUS: |
220 | if (put_user(0, (int *)arg)) |
221 | return -EFAULT; |
222 | return 0; |
223 | case WDIOC_KEEPALIVE: |
224 | ar7_wdt_kick(value: 1); |
225 | return 0; |
226 | case WDIOC_SETTIMEOUT: |
227 | if (get_user(new_margin, (int *)arg)) |
228 | return -EFAULT; |
229 | if (new_margin < 1) |
230 | return -EINVAL; |
231 | |
232 | spin_lock(lock: &wdt_lock); |
233 | ar7_wdt_update_margin(new_margin); |
234 | ar7_wdt_kick(value: 1); |
235 | spin_unlock(lock: &wdt_lock); |
236 | fallthrough; |
237 | case WDIOC_GETTIMEOUT: |
238 | if (put_user(margin, (int *)arg)) |
239 | return -EFAULT; |
240 | return 0; |
241 | default: |
242 | return -ENOTTY; |
243 | } |
244 | } |
245 | |
246 | static const struct file_operations ar7_wdt_fops = { |
247 | .owner = THIS_MODULE, |
248 | .write = ar7_wdt_write, |
249 | .unlocked_ioctl = ar7_wdt_ioctl, |
250 | .compat_ioctl = compat_ptr_ioctl, |
251 | .open = ar7_wdt_open, |
252 | .release = ar7_wdt_release, |
253 | .llseek = no_llseek, |
254 | }; |
255 | |
256 | static struct miscdevice ar7_wdt_miscdev = { |
257 | .minor = WATCHDOG_MINOR, |
258 | .name = "watchdog" , |
259 | .fops = &ar7_wdt_fops, |
260 | }; |
261 | |
262 | static int ar7_wdt_probe(struct platform_device *pdev) |
263 | { |
264 | int rc; |
265 | |
266 | ar7_wdt = devm_platform_ioremap_resource_byname(pdev, name: "regs" ); |
267 | if (IS_ERR(ptr: ar7_wdt)) |
268 | return PTR_ERR(ptr: ar7_wdt); |
269 | |
270 | vbus_clk = clk_get(NULL, id: "vbus" ); |
271 | if (IS_ERR(ptr: vbus_clk)) { |
272 | pr_err("could not get vbus clock\n" ); |
273 | return PTR_ERR(ptr: vbus_clk); |
274 | } |
275 | |
276 | ar7_wdt_disable_wdt(); |
277 | ar7_wdt_prescale(prescale_value); |
278 | ar7_wdt_update_margin(new_margin: margin); |
279 | |
280 | rc = misc_register(misc: &ar7_wdt_miscdev); |
281 | if (rc) { |
282 | pr_err("unable to register misc device\n" ); |
283 | goto out; |
284 | } |
285 | return 0; |
286 | |
287 | out: |
288 | clk_put(clk: vbus_clk); |
289 | vbus_clk = NULL; |
290 | return rc; |
291 | } |
292 | |
293 | static void ar7_wdt_remove(struct platform_device *pdev) |
294 | { |
295 | misc_deregister(misc: &ar7_wdt_miscdev); |
296 | clk_put(clk: vbus_clk); |
297 | vbus_clk = NULL; |
298 | } |
299 | |
300 | static void ar7_wdt_shutdown(struct platform_device *pdev) |
301 | { |
302 | if (!nowayout) |
303 | ar7_wdt_disable_wdt(); |
304 | } |
305 | |
306 | static struct platform_driver ar7_wdt_driver = { |
307 | .probe = ar7_wdt_probe, |
308 | .remove_new = ar7_wdt_remove, |
309 | .shutdown = ar7_wdt_shutdown, |
310 | .driver = { |
311 | .name = "ar7_wdt" , |
312 | }, |
313 | }; |
314 | |
315 | module_platform_driver(ar7_wdt_driver); |
316 | |