1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * drivers/char/watchdog/iop_wdt.c
4 *
5 * WDT driver for Intel I/O Processors
6 * Copyright (C) 2005, Intel Corporation.
7 *
8 * Based on ixp4xx driver, Copyright 2004 (c) MontaVista, Software, Inc.
9 *
10 * Curt E Bruns <curt.e.bruns@intel.com>
11 * Peter Milne <peter.milne@d-tacq.com>
12 * Dan Williams <dan.j.williams@intel.com>
13 */
14
15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16
17 #include <linux/module.h>
18 #include <linux/kernel.h>
19 #include <linux/fs.h>
20 #include <linux/init.h>
21 #include <linux/device.h>
22 #include <linux/miscdevice.h>
23 #include <linux/watchdog.h>
24 #include <linux/uaccess.h>
25 #include <mach/hardware.h>
26
27 static bool nowayout = WATCHDOG_NOWAYOUT;
28 static unsigned long wdt_status;
29 static unsigned long boot_status;
30 static DEFINE_SPINLOCK(wdt_lock);
31
32 #define WDT_IN_USE 0
33 #define WDT_OK_TO_CLOSE 1
34 #define WDT_ENABLED 2
35
iop_watchdog_timeout(void)36 static unsigned long iop_watchdog_timeout(void)
37 {
38 return (0xffffffffUL / get_iop_tick_rate());
39 }
40
41 /**
42 * wdt_supports_disable - determine if we are accessing a iop13xx watchdog
43 * or iop3xx by whether it has a disable command
44 */
wdt_supports_disable(void)45 static int wdt_supports_disable(void)
46 {
47 int can_disable;
48
49 if (IOP_WDTCR_EN_ARM != IOP_WDTCR_DIS_ARM)
50 can_disable = 1;
51 else
52 can_disable = 0;
53
54 return can_disable;
55 }
56
wdt_enable(void)57 static void wdt_enable(void)
58 {
59 /* Arm and enable the Timer to starting counting down from 0xFFFF.FFFF
60 * Takes approx. 10.7s to timeout
61 */
62 spin_lock(&wdt_lock);
63 write_wdtcr(IOP_WDTCR_EN_ARM);
64 write_wdtcr(IOP_WDTCR_EN);
65 spin_unlock(&wdt_lock);
66 }
67
68 /* returns 0 if the timer was successfully disabled */
wdt_disable(void)69 static int wdt_disable(void)
70 {
71 /* Stop Counting */
72 if (wdt_supports_disable()) {
73 spin_lock(&wdt_lock);
74 write_wdtcr(IOP_WDTCR_DIS_ARM);
75 write_wdtcr(IOP_WDTCR_DIS);
76 clear_bit(WDT_ENABLED, &wdt_status);
77 spin_unlock(&wdt_lock);
78 pr_info("Disabled\n");
79 return 0;
80 } else
81 return 1;
82 }
83
iop_wdt_open(struct inode * inode,struct file * file)84 static int iop_wdt_open(struct inode *inode, struct file *file)
85 {
86 if (test_and_set_bit(WDT_IN_USE, &wdt_status))
87 return -EBUSY;
88
89 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
90 wdt_enable();
91 set_bit(WDT_ENABLED, &wdt_status);
92 return stream_open(inode, file);
93 }
94
iop_wdt_write(struct file * file,const char * data,size_t len,loff_t * ppos)95 static ssize_t iop_wdt_write(struct file *file, const char *data, size_t len,
96 loff_t *ppos)
97 {
98 if (len) {
99 if (!nowayout) {
100 size_t i;
101
102 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
103
104 for (i = 0; i != len; i++) {
105 char c;
106
107 if (get_user(c, data + i))
108 return -EFAULT;
109 if (c == 'V')
110 set_bit(WDT_OK_TO_CLOSE, &wdt_status);
111 }
112 }
113 wdt_enable();
114 }
115 return len;
116 }
117
118 static const struct watchdog_info ident = {
119 .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
120 .identity = "iop watchdog",
121 };
122
iop_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)123 static long iop_wdt_ioctl(struct file *file,
124 unsigned int cmd, unsigned long arg)
125 {
126 int options;
127 int ret = -ENOTTY;
128 int __user *argp = (int __user *)arg;
129
130 switch (cmd) {
131 case WDIOC_GETSUPPORT:
132 if (copy_to_user(argp, &ident, sizeof(ident)))
133 ret = -EFAULT;
134 else
135 ret = 0;
136 break;
137
138 case WDIOC_GETSTATUS:
139 ret = put_user(0, argp);
140 break;
141
142 case WDIOC_GETBOOTSTATUS:
143 ret = put_user(boot_status, argp);
144 break;
145
146 case WDIOC_SETOPTIONS:
147 if (get_user(options, (int *)arg))
148 return -EFAULT;
149
150 if (options & WDIOS_DISABLECARD) {
151 if (!nowayout) {
152 if (wdt_disable() == 0) {
153 set_bit(WDT_OK_TO_CLOSE, &wdt_status);
154 ret = 0;
155 } else
156 ret = -ENXIO;
157 } else
158 ret = 0;
159 }
160 if (options & WDIOS_ENABLECARD) {
161 wdt_enable();
162 ret = 0;
163 }
164 break;
165
166 case WDIOC_KEEPALIVE:
167 wdt_enable();
168 ret = 0;
169 break;
170
171 case WDIOC_GETTIMEOUT:
172 ret = put_user(iop_watchdog_timeout(), argp);
173 break;
174 }
175 return ret;
176 }
177
iop_wdt_release(struct inode * inode,struct file * file)178 static int iop_wdt_release(struct inode *inode, struct file *file)
179 {
180 int state = 1;
181 if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
182 if (test_bit(WDT_ENABLED, &wdt_status))
183 state = wdt_disable();
184
185 /* if the timer is not disabled reload and notify that we are still
186 * going down
187 */
188 if (state != 0) {
189 wdt_enable();
190 pr_crit("Device closed unexpectedly - reset in %lu seconds\n",
191 iop_watchdog_timeout());
192 }
193
194 clear_bit(WDT_IN_USE, &wdt_status);
195 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
196
197 return 0;
198 }
199
200 static const struct file_operations iop_wdt_fops = {
201 .owner = THIS_MODULE,
202 .llseek = no_llseek,
203 .write = iop_wdt_write,
204 .unlocked_ioctl = iop_wdt_ioctl,
205 .compat_ioctl = compat_ptr_ioctl,
206 .open = iop_wdt_open,
207 .release = iop_wdt_release,
208 };
209
210 static struct miscdevice iop_wdt_miscdev = {
211 .minor = WATCHDOG_MINOR,
212 .name = "watchdog",
213 .fops = &iop_wdt_fops,
214 };
215
iop_wdt_init(void)216 static int __init iop_wdt_init(void)
217 {
218 int ret;
219
220 /* check if the reset was caused by the watchdog timer */
221 boot_status = (read_rcsr() & IOP_RCSR_WDT) ? WDIOF_CARDRESET : 0;
222
223 /* Configure Watchdog Timeout to cause an Internal Bus (IB) Reset
224 * NOTE: An IB Reset will Reset both cores in the IOP342
225 */
226 write_wdtsr(IOP13XX_WDTCR_IB_RESET);
227
228 /* Register after we have the device set up so we cannot race
229 with an open */
230 ret = misc_register(&iop_wdt_miscdev);
231 if (ret == 0)
232 pr_info("timeout %lu sec\n", iop_watchdog_timeout());
233
234 return ret;
235 }
236
iop_wdt_exit(void)237 static void __exit iop_wdt_exit(void)
238 {
239 misc_deregister(&iop_wdt_miscdev);
240 }
241
242 module_init(iop_wdt_init);
243 module_exit(iop_wdt_exit);
244
245 module_param(nowayout, bool, 0);
246 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
247
248 MODULE_AUTHOR("Curt E Bruns <curt.e.bruns@intel.com>");
249 MODULE_DESCRIPTION("iop watchdog timer driver");
250 MODULE_LICENSE("GPL");
251
