1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * GE watchdog userspace interface |
4 | * |
5 | * Author: Martyn Welch <martyn.welch@ge.com> |
6 | * |
7 | * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc. |
8 | * |
9 | * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface) |
10 | * Author: James Chapman <jchapman@katalix.com> |
11 | */ |
12 | |
13 | /* TODO: |
14 | * This driver does not provide support for the hardwares capability of sending |
15 | * an interrupt at a programmable threshold. |
16 | * |
17 | * This driver currently can only support 1 watchdog - there are 2 in the |
18 | * hardware that this driver supports. Thus one could be configured as a |
19 | * process-based watchdog (via /dev/watchdog), the second (using the interrupt |
20 | * capabilities) a kernel-based watchdog. |
21 | */ |
22 | |
23 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
24 | |
25 | #include <linux/kernel.h> |
26 | #include <linux/compiler.h> |
27 | #include <linux/init.h> |
28 | #include <linux/module.h> |
29 | #include <linux/miscdevice.h> |
30 | #include <linux/watchdog.h> |
31 | #include <linux/fs.h> |
32 | #include <linux/of.h> |
33 | #include <linux/of_address.h> |
34 | #include <linux/platform_device.h> |
35 | #include <linux/io.h> |
36 | #include <linux/uaccess.h> |
37 | |
38 | #include <sysdev/fsl_soc.h> |
39 | |
40 | /* |
41 | * The watchdog configuration register contains a pair of 2-bit fields, |
42 | * 1. a reload field, bits 27-26, which triggers a reload of |
43 | * the countdown register, and |
44 | * 2. an enable field, bits 25-24, which toggles between |
45 | * enabling and disabling the watchdog timer. |
46 | * Bit 31 is a read-only field which indicates whether the |
47 | * watchdog timer is currently enabled. |
48 | * |
49 | * The low 24 bits contain the timer reload value. |
50 | */ |
51 | #define GEF_WDC_ENABLE_SHIFT 24 |
52 | #define GEF_WDC_SERVICE_SHIFT 26 |
53 | #define GEF_WDC_ENABLED_SHIFT 31 |
54 | |
55 | #define GEF_WDC_ENABLED_TRUE 1 |
56 | #define GEF_WDC_ENABLED_FALSE 0 |
57 | |
58 | /* Flags bits */ |
59 | #define GEF_WDOG_FLAG_OPENED 0 |
60 | |
61 | static unsigned long wdt_flags; |
62 | static int wdt_status; |
63 | static void __iomem *gef_wdt_regs; |
64 | static int gef_wdt_timeout; |
65 | static int gef_wdt_count; |
66 | static unsigned int bus_clk; |
67 | static char expect_close; |
68 | static DEFINE_SPINLOCK(gef_wdt_spinlock); |
69 | |
70 | static bool nowayout = WATCHDOG_NOWAYOUT; |
71 | module_param(nowayout, bool, 0); |
72 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" |
73 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")" ); |
74 | |
75 | |
76 | static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift) |
77 | { |
78 | u32 data; |
79 | u32 enabled; |
80 | int ret = 0; |
81 | |
82 | spin_lock(lock: &gef_wdt_spinlock); |
83 | data = ioread32be(gef_wdt_regs); |
84 | enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1; |
85 | |
86 | /* only toggle the requested field if enabled state matches predicate */ |
87 | if ((enabled ^ enabled_predicate) == 0) { |
88 | /* We write a 1, then a 2 -- to the appropriate field */ |
89 | data = (1 << field_shift) | gef_wdt_count; |
90 | iowrite32be(data, gef_wdt_regs); |
91 | |
92 | data = (2 << field_shift) | gef_wdt_count; |
93 | iowrite32be(data, gef_wdt_regs); |
94 | ret = 1; |
95 | } |
96 | spin_unlock(lock: &gef_wdt_spinlock); |
97 | |
98 | return ret; |
99 | } |
100 | |
101 | static void gef_wdt_service(void) |
102 | { |
103 | gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE, |
104 | GEF_WDC_SERVICE_SHIFT); |
105 | } |
106 | |
107 | static void gef_wdt_handler_enable(void) |
108 | { |
109 | if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE, |
110 | GEF_WDC_ENABLE_SHIFT)) { |
111 | gef_wdt_service(); |
112 | pr_notice("watchdog activated\n" ); |
113 | } |
114 | } |
115 | |
116 | static void gef_wdt_handler_disable(void) |
117 | { |
118 | if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE, |
119 | GEF_WDC_ENABLE_SHIFT)) |
120 | pr_notice("watchdog deactivated\n" ); |
121 | } |
122 | |
123 | static void gef_wdt_set_timeout(unsigned int timeout) |
124 | { |
125 | /* maximum bus cycle count is 0xFFFFFFFF */ |
126 | if (timeout > 0xFFFFFFFF / bus_clk) |
127 | timeout = 0xFFFFFFFF / bus_clk; |
128 | |
129 | /* Register only holds upper 24 bits, bit shifted into lower 24 */ |
130 | gef_wdt_count = (timeout * bus_clk) >> 8; |
131 | gef_wdt_timeout = timeout; |
132 | } |
133 | |
134 | |
135 | static ssize_t gef_wdt_write(struct file *file, const char __user *data, |
136 | size_t len, loff_t *ppos) |
137 | { |
138 | if (len) { |
139 | if (!nowayout) { |
140 | size_t i; |
141 | |
142 | expect_close = 0; |
143 | |
144 | for (i = 0; i != len; i++) { |
145 | char c; |
146 | if (get_user(c, data + i)) |
147 | return -EFAULT; |
148 | if (c == 'V') |
149 | expect_close = 42; |
150 | } |
151 | } |
152 | gef_wdt_service(); |
153 | } |
154 | |
155 | return len; |
156 | } |
157 | |
158 | static long gef_wdt_ioctl(struct file *file, unsigned int cmd, |
159 | unsigned long arg) |
160 | { |
161 | int timeout; |
162 | int options; |
163 | void __user *argp = (void __user *)arg; |
164 | static const struct watchdog_info info = { |
165 | .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | |
166 | WDIOF_KEEPALIVEPING, |
167 | .firmware_version = 0, |
168 | .identity = "GE watchdog" , |
169 | }; |
170 | |
171 | switch (cmd) { |
172 | case WDIOC_GETSUPPORT: |
173 | if (copy_to_user(to: argp, from: &info, n: sizeof(info))) |
174 | return -EFAULT; |
175 | break; |
176 | |
177 | case WDIOC_GETSTATUS: |
178 | case WDIOC_GETBOOTSTATUS: |
179 | if (put_user(wdt_status, (int __user *)argp)) |
180 | return -EFAULT; |
181 | wdt_status &= ~WDIOF_KEEPALIVEPING; |
182 | break; |
183 | |
184 | case WDIOC_SETOPTIONS: |
185 | if (get_user(options, (int __user *)argp)) |
186 | return -EFAULT; |
187 | |
188 | if (options & WDIOS_DISABLECARD) |
189 | gef_wdt_handler_disable(); |
190 | |
191 | if (options & WDIOS_ENABLECARD) |
192 | gef_wdt_handler_enable(); |
193 | break; |
194 | |
195 | case WDIOC_KEEPALIVE: |
196 | gef_wdt_service(); |
197 | wdt_status |= WDIOF_KEEPALIVEPING; |
198 | break; |
199 | |
200 | case WDIOC_SETTIMEOUT: |
201 | if (get_user(timeout, (int __user *)argp)) |
202 | return -EFAULT; |
203 | gef_wdt_set_timeout(timeout); |
204 | fallthrough; |
205 | |
206 | case WDIOC_GETTIMEOUT: |
207 | if (put_user(gef_wdt_timeout, (int __user *)argp)) |
208 | return -EFAULT; |
209 | break; |
210 | |
211 | default: |
212 | return -ENOTTY; |
213 | } |
214 | |
215 | return 0; |
216 | } |
217 | |
218 | static int gef_wdt_open(struct inode *inode, struct file *file) |
219 | { |
220 | if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, addr: &wdt_flags)) |
221 | return -EBUSY; |
222 | |
223 | if (nowayout) |
224 | __module_get(THIS_MODULE); |
225 | |
226 | gef_wdt_handler_enable(); |
227 | |
228 | return stream_open(inode, filp: file); |
229 | } |
230 | |
231 | static int gef_wdt_release(struct inode *inode, struct file *file) |
232 | { |
233 | if (expect_close == 42) |
234 | gef_wdt_handler_disable(); |
235 | else { |
236 | pr_crit("unexpected close, not stopping timer!\n" ); |
237 | gef_wdt_service(); |
238 | } |
239 | expect_close = 0; |
240 | |
241 | clear_bit(GEF_WDOG_FLAG_OPENED, addr: &wdt_flags); |
242 | |
243 | return 0; |
244 | } |
245 | |
246 | static const struct file_operations gef_wdt_fops = { |
247 | .owner = THIS_MODULE, |
248 | .llseek = no_llseek, |
249 | .write = gef_wdt_write, |
250 | .unlocked_ioctl = gef_wdt_ioctl, |
251 | .compat_ioctl = compat_ptr_ioctl, |
252 | .open = gef_wdt_open, |
253 | .release = gef_wdt_release, |
254 | }; |
255 | |
256 | static struct miscdevice gef_wdt_miscdev = { |
257 | .minor = WATCHDOG_MINOR, |
258 | .name = "watchdog" , |
259 | .fops = &gef_wdt_fops, |
260 | }; |
261 | |
262 | |
263 | static int gef_wdt_probe(struct platform_device *dev) |
264 | { |
265 | int timeout = 10; |
266 | u32 freq; |
267 | |
268 | bus_clk = 133; /* in MHz */ |
269 | |
270 | freq = fsl_get_sys_freq(); |
271 | if (freq != -1) |
272 | bus_clk = freq; |
273 | |
274 | /* Map devices registers into memory */ |
275 | gef_wdt_regs = of_iomap(node: dev->dev.of_node, index: 0); |
276 | if (gef_wdt_regs == NULL) |
277 | return -ENOMEM; |
278 | |
279 | gef_wdt_set_timeout(timeout); |
280 | |
281 | gef_wdt_handler_disable(); /* in case timer was already running */ |
282 | |
283 | return misc_register(misc: &gef_wdt_miscdev); |
284 | } |
285 | |
286 | static void gef_wdt_remove(struct platform_device *dev) |
287 | { |
288 | misc_deregister(misc: &gef_wdt_miscdev); |
289 | |
290 | gef_wdt_handler_disable(); |
291 | |
292 | iounmap(addr: gef_wdt_regs); |
293 | } |
294 | |
295 | static const struct of_device_id gef_wdt_ids[] = { |
296 | { |
297 | .compatible = "gef,fpga-wdt" , |
298 | }, |
299 | {}, |
300 | }; |
301 | MODULE_DEVICE_TABLE(of, gef_wdt_ids); |
302 | |
303 | static struct platform_driver gef_wdt_driver = { |
304 | .driver = { |
305 | .name = "gef_wdt" , |
306 | .of_match_table = gef_wdt_ids, |
307 | }, |
308 | .probe = gef_wdt_probe, |
309 | .remove_new = gef_wdt_remove, |
310 | }; |
311 | |
312 | static int __init gef_wdt_init(void) |
313 | { |
314 | pr_info("GE watchdog driver\n" ); |
315 | return platform_driver_register(&gef_wdt_driver); |
316 | } |
317 | |
318 | static void __exit gef_wdt_exit(void) |
319 | { |
320 | platform_driver_unregister(&gef_wdt_driver); |
321 | } |
322 | |
323 | module_init(gef_wdt_init); |
324 | module_exit(gef_wdt_exit); |
325 | |
326 | MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>" ); |
327 | MODULE_DESCRIPTION("GE watchdog driver" ); |
328 | MODULE_LICENSE("GPL" ); |
329 | MODULE_ALIAS("platform:gef_wdt" ); |
330 | |