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3268b561 | 1 | /* |
cda61c94 | 2 | * GE watchdog userspace interface |
3268b561 | 3 | * |
cda61c94 | 4 | * Author: Martyn Welch <martyn.welch@ge.com> |
3268b561 | 5 | * |
cda61c94 | 6 | * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc. |
3268b561 MW |
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 | ||
27c766aa JP |
27 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
28 | ||
3268b561 MW |
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> | |
f6e0722f | 35 | #include <linux/fs.h> |
3268b561 MW |
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 | ||
86a1e189 WVS |
73 | static bool nowayout = WATCHDOG_NOWAYOUT; |
74 | module_param(nowayout, bool, 0); | |
3268b561 MW |
75 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" |
76 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
77 | ||
78 | ||
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 | ||
104 | static void gef_wdt_service(void) | |
105 | { | |
106 | gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE, | |
107 | GEF_WDC_SERVICE_SHIFT); | |
108 | } | |
109 | ||
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(); | |
27c766aa | 115 | pr_notice("watchdog activated\n"); |
3268b561 MW |
116 | } |
117 | } | |
118 | ||
119 | static void gef_wdt_handler_disable(void) | |
120 | { | |
121 | if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE, | |
122 | GEF_WDC_ENABLE_SHIFT)) | |
27c766aa | 123 | pr_notice("watchdog deactivated\n"); |
3268b561 MW |
124 | } |
125 | ||
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 | ||
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 | ||
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; | |
42747d71 | 167 | static const struct watchdog_info info = { |
3268b561 MW |
168 | .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | |
169 | WDIOF_KEEPALIVEPING, | |
170 | .firmware_version = 0, | |
cda61c94 | 171 | .identity = "GE watchdog", |
3268b561 MW |
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 | ||
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 | ||
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 { | |
27c766aa | 239 | pr_crit("unexpected close, not stopping timer!\n"); |
3268b561 MW |
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 | ||
2d991a16 | 265 | static int gef_wdt_probe(struct platform_device *dev) |
3268b561 MW |
266 | { |
267 | int timeout = 10; | |
268 | u32 freq; | |
269 | ||
270 | bus_clk = 133; /* in MHz */ | |
271 | ||
272 | freq = fsl_get_sys_freq(); | |
26952669 | 273 | if (freq != -1) |
3268b561 MW |
274 | bus_clk = freq; |
275 | ||
276 | /* Map devices registers into memory */ | |
b74dbf2a | 277 | gef_wdt_regs = of_iomap(dev->dev.of_node, 0); |
3268b561 MW |
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 | ||
4b12b896 | 288 | static int gef_wdt_remove(struct platform_device *dev) |
3268b561 MW |
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 | ||
1c48a5c9 | 306 | static struct platform_driver gef_wdt_driver = { |
4018294b GL |
307 | .driver = { |
308 | .name = "gef_wdt", | |
309 | .owner = THIS_MODULE, | |
310 | .of_match_table = gef_wdt_ids, | |
311 | }, | |
3268b561 | 312 | .probe = gef_wdt_probe, |
67371765 | 313 | .remove = gef_wdt_remove, |
3268b561 MW |
314 | }; |
315 | ||
316 | static int __init gef_wdt_init(void) | |
317 | { | |
27c766aa | 318 | pr_info("GE watchdog driver\n"); |
1c48a5c9 | 319 | return platform_driver_register(&gef_wdt_driver); |
3268b561 MW |
320 | } |
321 | ||
322 | static void __exit gef_wdt_exit(void) | |
323 | { | |
1c48a5c9 | 324 | platform_driver_unregister(&gef_wdt_driver); |
3268b561 MW |
325 | } |
326 | ||
327 | module_init(gef_wdt_init); | |
328 | module_exit(gef_wdt_exit); | |
329 | ||
cda61c94 MW |
330 | MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>"); |
331 | MODULE_DESCRIPTION("GE watchdog driver"); | |
3268b561 MW |
332 | MODULE_LICENSE("GPL"); |
333 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); | |
ae2a0060 | 334 | MODULE_ALIAS("platform:gef_wdt"); |