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_LICENSE("GPL");
50
51 #define DRIVER_NAME "riowd"
52 #define PFX DRIVER_NAME ": "
53
54 struct riowd {
55 void __iomem *regs;
56 spinlock_t lock;
57 };
58
59 static struct riowd *riowd_device;
60
61 #define WDTO_INDEX 0x05
62
63 static int riowd_timeout = 1; /* in minutes */
64 module_param(riowd_timeout, int, 0);
65 MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");
66
riowd_writereg(struct riowd * p,u8 val,int index)67 static void riowd_writereg(struct riowd *p, u8 val, int index)
68 {
69 unsigned long flags;
70
71 spin_lock_irqsave(&p->lock, flags);
72 writeb(index, p->regs + 0);
73 writeb(val, p->regs + 1);
74 spin_unlock_irqrestore(&p->lock, flags);
75 }
76
riowd_open(struct inode * inode,struct file * filp)77 static int riowd_open(struct inode *inode, struct file *filp)
78 {
79 stream_open(inode, filp);
80 return 0;
81 }
82
riowd_release(struct inode * inode,struct file * filp)83 static int riowd_release(struct inode *inode, struct file *filp)
84 {
85 return 0;
86 }
87
riowd_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)88 static long riowd_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
89 {
90 static const struct watchdog_info info = {
91 .options = WDIOF_SETTIMEOUT,
92 .firmware_version = 1,
93 .identity = DRIVER_NAME,
94 };
95 void __user *argp = (void __user *)arg;
96 struct riowd *p = riowd_device;
97 unsigned int options;
98 int new_margin;
99
100 switch (cmd) {
101 case WDIOC_GETSUPPORT:
102 if (copy_to_user(argp, &info, sizeof(info)))
103 return -EFAULT;
104 break;
105
106 case WDIOC_GETSTATUS:
107 case WDIOC_GETBOOTSTATUS:
108 if (put_user(0, (int __user *)argp))
109 return -EFAULT;
110 break;
111
112 case WDIOC_KEEPALIVE:
113 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
114 break;
115
116 case WDIOC_SETOPTIONS:
117 if (copy_from_user(&options, argp, sizeof(options)))
118 return -EFAULT;
119
120 if (options & WDIOS_DISABLECARD)
121 riowd_writereg(p, 0, WDTO_INDEX);
122 else if (options & WDIOS_ENABLECARD)
123 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
124 else
125 return -EINVAL;
126
127 break;
128
129 case WDIOC_SETTIMEOUT:
130 if (get_user(new_margin, (int __user *)argp))
131 return -EFAULT;
132 if ((new_margin < 60) || (new_margin > (255 * 60)))
133 return -EINVAL;
134 riowd_timeout = (new_margin + 59) / 60;
135 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
136 fallthrough;
137
138 case WDIOC_GETTIMEOUT:
139 return put_user(riowd_timeout * 60, (int __user *)argp);
140
141 default:
142 return -EINVAL;
143 }
144
145 return 0;
146 }
147
riowd_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)148 static ssize_t riowd_write(struct file *file, const char __user *buf,
149 size_t count, loff_t *ppos)
150 {
151 struct riowd *p = riowd_device;
152
153 if (count) {
154 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
155 return 1;
156 }
157
158 return 0;
159 }
160
161 static const struct file_operations riowd_fops = {
162 .owner = THIS_MODULE,
163 .llseek = no_llseek,
164 .unlocked_ioctl = riowd_ioctl,
165 .compat_ioctl = compat_ptr_ioctl,
166 .open = riowd_open,
167 .write = riowd_write,
168 .release = riowd_release,
169 };
170
171 static struct miscdevice riowd_miscdev = {
172 .minor = WATCHDOG_MINOR,
173 .name = "watchdog",
174 .fops = &riowd_fops
175 };
176
riowd_probe(struct platform_device * op)177 static int riowd_probe(struct platform_device *op)
178 {
179 struct riowd *p;
180 int err = -EINVAL;
181
182 if (riowd_device)
183 goto out;
184
185 err = -ENOMEM;
186 p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
187 if (!p)
188 goto out;
189
190 spin_lock_init(&p->lock);
191
192 p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
193 if (!p->regs) {
194 pr_err("Cannot map registers\n");
195 goto out;
196 }
197 /* Make miscdev useable right away */
198 riowd_device = p;
199
200 err = misc_register(&riowd_miscdev);
201 if (err) {
202 pr_err("Cannot register watchdog misc device\n");
203 goto out_iounmap;
204 }
205
206 pr_info("Hardware watchdog [%i minutes], regs at %p\n",
207 riowd_timeout, p->regs);
208
209 platform_set_drvdata(op, p);
210 return 0;
211
212 out_iounmap:
213 riowd_device = NULL;
214 of_iounmap(&op->resource[0], p->regs, 2);
215
216 out:
217 return err;
218 }
219
riowd_remove(struct platform_device * op)220 static int riowd_remove(struct platform_device *op)
221 {
222 struct riowd *p = platform_get_drvdata(op);
223
224 misc_deregister(&riowd_miscdev);
225 of_iounmap(&op->resource[0], p->regs, 2);
226
227 return 0;
228 }
229
230 static const struct of_device_id riowd_match[] = {
231 {
232 .name = "pmc",
233 },
234 {},
235 };
236 MODULE_DEVICE_TABLE(of, riowd_match);
237
238 static struct platform_driver riowd_driver = {
239 .driver = {
240 .name = DRIVER_NAME,
241 .of_match_table = riowd_match,
242 },
243 .probe = riowd_probe,
244 .remove = riowd_remove,
245 };
246
247 module_platform_driver(riowd_driver);
248