1 // SPDX-License-Identifier: GPL-2.0-only
2 /* riowd.c - driver for hw watchdog inside Super I/O of RIO
3 *
4 * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)
5 */
6
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/types.h>
12 #include <linux/fs.h>
13 #include <linux/errno.h>
14 #include <linux/miscdevice.h>
15 #include <linux/watchdog.h>
16 #include <linux/of.h>
17 #include <linux/of_device.h>
18 #include <linux/io.h>
19 #include <linux/uaccess.h>
20 #include <linux/slab.h>
21
22
23 /* RIO uses the NatSemi Super I/O power management logical device
24 * as its' watchdog.
25 *
26 * When the watchdog triggers, it asserts a line to the BBC (Boot Bus
27 * Controller) of the machine. The BBC can only be configured to
28 * trigger a power-on reset when the signal is asserted. The BBC
29 * can be configured to ignore the signal entirely as well.
30 *
31 * The only Super I/O device register we care about is at index
32 * 0x05 (WDTO_INDEX) which is the watchdog time-out in minutes (1-255).
33 * If set to zero, this disables the watchdog. When set, the system
34 * must periodically (before watchdog expires) clear (set to zero) and
35 * re-set the watchdog else it will trigger.
36 *
37 * There are two other indexed watchdog registers inside this Super I/O
38 * logical device, but they are unused. The first, at index 0x06 is
39 * the watchdog control and can be used to make the watchdog timer re-set
40 * when the PS/2 mouse or serial lines show activity. The second, at
41 * index 0x07 is merely a sampling of the line from the watchdog to the
42 * BBC.
43 *
44 * The watchdog device generates no interrupts.
45 */
46
47 MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
48 MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
49 MODULE_SUPPORTED_DEVICE("watchdog");
50 MODULE_LICENSE("GPL");
51
52 #define DRIVER_NAME "riowd"
53 #define PFX DRIVER_NAME ": "
54
55 struct riowd {
56 void __iomem *regs;
57 spinlock_t lock;
58 };
59
60 static struct riowd *riowd_device;
61
62 #define WDTO_INDEX 0x05
63
64 static int riowd_timeout = 1; /* in minutes */
65 module_param(riowd_timeout, int, 0);
66 MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");
67
riowd_writereg(struct riowd * p,u8 val,int index)68 static void riowd_writereg(struct riowd *p, u8 val, int index)
69 {
70 unsigned long flags;
71
72 spin_lock_irqsave(&p->lock, flags);
73 writeb(index, p->regs + 0);
74 writeb(val, p->regs + 1);
75 spin_unlock_irqrestore(&p->lock, flags);
76 }
77
riowd_open(struct inode * inode,struct file * filp)78 static int riowd_open(struct inode *inode, struct file *filp)
79 {
80 stream_open(inode, filp);
81 return 0;
82 }
83
riowd_release(struct inode * inode,struct file * filp)84 static int riowd_release(struct inode *inode, struct file *filp)
85 {
86 return 0;
87 }
88
riowd_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)89 static long riowd_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
90 {
91 static const struct watchdog_info info = {
92 .options = WDIOF_SETTIMEOUT,
93 .firmware_version = 1,
94 .identity = DRIVER_NAME,
95 };
96 void __user *argp = (void __user *)arg;
97 struct riowd *p = riowd_device;
98 unsigned int options;
99 int new_margin;
100
101 switch (cmd) {
102 case WDIOC_GETSUPPORT:
103 if (copy_to_user(argp, &info, sizeof(info)))
104 return -EFAULT;
105 break;
106
107 case WDIOC_GETSTATUS:
108 case WDIOC_GETBOOTSTATUS:
109 if (put_user(0, (int __user *)argp))
110 return -EFAULT;
111 break;
112
113 case WDIOC_KEEPALIVE:
114 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
115 break;
116
117 case WDIOC_SETOPTIONS:
118 if (copy_from_user(&options, argp, sizeof(options)))
119 return -EFAULT;
120
121 if (options & WDIOS_DISABLECARD)
122 riowd_writereg(p, 0, WDTO_INDEX);
123 else if (options & WDIOS_ENABLECARD)
124 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
125 else
126 return -EINVAL;
127
128 break;
129
130 case WDIOC_SETTIMEOUT:
131 if (get_user(new_margin, (int __user *)argp))
132 return -EFAULT;
133 if ((new_margin < 60) || (new_margin > (255 * 60)))
134 return -EINVAL;
135 riowd_timeout = (new_margin + 59) / 60;
136 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
137 fallthrough;
138
139 case WDIOC_GETTIMEOUT:
140 return put_user(riowd_timeout * 60, (int __user *)argp);
141
142 default:
143 return -EINVAL;
144 }
145
146 return 0;
147 }
148
riowd_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)149 static ssize_t riowd_write(struct file *file, const char __user *buf,
150 size_t count, loff_t *ppos)
151 {
152 struct riowd *p = riowd_device;
153
154 if (count) {
155 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
156 return 1;
157 }
158
159 return 0;
160 }
161
162 static const struct file_operations riowd_fops = {
163 .owner = THIS_MODULE,
164 .llseek = no_llseek,
165 .unlocked_ioctl = riowd_ioctl,
166 .compat_ioctl = compat_ptr_ioctl,
167 .open = riowd_open,
168 .write = riowd_write,
169 .release = riowd_release,
170 };
171
172 static struct miscdevice riowd_miscdev = {
173 .minor = WATCHDOG_MINOR,
174 .name = "watchdog",
175 .fops = &riowd_fops
176 };
177
riowd_probe(struct platform_device * op)178 static int riowd_probe(struct platform_device *op)
179 {
180 struct riowd *p;
181 int err = -EINVAL;
182
183 if (riowd_device)
184 goto out;
185
186 err = -ENOMEM;
187 p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
188 if (!p)
189 goto out;
190
191 spin_lock_init(&p->lock);
192
193 p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
194 if (!p->regs) {
195 pr_err("Cannot map registers\n");
196 goto out;
197 }
198 /* Make miscdev useable right away */
199 riowd_device = p;
200
201 err = misc_register(&riowd_miscdev);
202 if (err) {
203 pr_err("Cannot register watchdog misc device\n");
204 goto out_iounmap;
205 }
206
207 pr_info("Hardware watchdog [%i minutes], regs at %p\n",
208 riowd_timeout, p->regs);
209
210 platform_set_drvdata(op, p);
211 return 0;
212
213 out_iounmap:
214 riowd_device = NULL;
215 of_iounmap(&op->resource[0], p->regs, 2);
216
217 out:
218 return err;
219 }
220
riowd_remove(struct platform_device * op)221 static int riowd_remove(struct platform_device *op)
222 {
223 struct riowd *p = platform_get_drvdata(op);
224
225 misc_deregister(&riowd_miscdev);
226 of_iounmap(&op->resource[0], p->regs, 2);
227
228 return 0;
229 }
230
231 static const struct of_device_id riowd_match[] = {
232 {
233 .name = "pmc",
234 },
235 {},
236 };
237 MODULE_DEVICE_TABLE(of, riowd_match);
238
239 static struct platform_driver riowd_driver = {
240 .driver = {
241 .name = DRIVER_NAME,
242 .of_match_table = riowd_match,
243 },
244 .probe = riowd_probe,
245 .remove = riowd_remove,
246 };
247
248 module_platform_driver(riowd_driver);
249