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
gef_wdt_toggle_wdc(int enabled_predicate,int field_shift)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(&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(&gef_wdt_spinlock);
97
98 return ret;
99 }
100
gef_wdt_service(void)101 static void gef_wdt_service(void)
102 {
103 gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
104 GEF_WDC_SERVICE_SHIFT);
105 }
106
gef_wdt_handler_enable(void)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
gef_wdt_handler_disable(void)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
gef_wdt_set_timeout(unsigned int timeout)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
gef_wdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)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
gef_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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(argp, &info, 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
gef_wdt_open(struct inode * inode,struct file * file)218 static int gef_wdt_open(struct inode *inode, struct file *file)
219 {
220 if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &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, file);
229 }
230
gef_wdt_release(struct inode * inode,struct file * file)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, &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
gef_wdt_probe(struct platform_device * dev)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(dev->dev.of_node, 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(&gef_wdt_miscdev);
284 }
285
gef_wdt_remove(struct platform_device * dev)286 static void gef_wdt_remove(struct platform_device *dev)
287 {
288 misc_deregister(&gef_wdt_miscdev);
289
290 gef_wdt_handler_disable();
291
292 iounmap(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
gef_wdt_init(void)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
gef_wdt_exit(void)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