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/platform_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 .unlocked_ioctl = riowd_ioctl,
164 .compat_ioctl = compat_ptr_ioctl,
165 .open = riowd_open,
166 .write = riowd_write,
167 .release = riowd_release,
168 };
169
170 static struct miscdevice riowd_miscdev = {
171 .minor = WATCHDOG_MINOR,
172 .name = "watchdog",
173 .fops = &riowd_fops
174 };
175
riowd_probe(struct platform_device * op)176 static int riowd_probe(struct platform_device *op)
177 {
178 struct riowd *p;
179 int err = -EINVAL;
180
181 if (riowd_device)
182 goto out;
183
184 err = -ENOMEM;
185 p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
186 if (!p)
187 goto out;
188
189 spin_lock_init(&p->lock);
190
191 p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
192 if (!p->regs) {
193 pr_err("Cannot map registers\n");
194 goto out;
195 }
196 /* Make miscdev useable right away */
197 riowd_device = p;
198
199 err = misc_register(&riowd_miscdev);
200 if (err) {
201 pr_err("Cannot register watchdog misc device\n");
202 goto out_iounmap;
203 }
204
205 pr_info("Hardware watchdog [%i minutes], regs at %p\n",
206 riowd_timeout, p->regs);
207
208 platform_set_drvdata(op, p);
209 return 0;
210
211 out_iounmap:
212 riowd_device = NULL;
213 of_iounmap(&op->resource[0], p->regs, 2);
214
215 out:
216 return err;
217 }
218
riowd_remove(struct platform_device * op)219 static void riowd_remove(struct platform_device *op)
220 {
221 struct riowd *p = platform_get_drvdata(op);
222
223 misc_deregister(&riowd_miscdev);
224 of_iounmap(&op->resource[0], p->regs, 2);
225 }
226
227 static const struct of_device_id riowd_match[] = {
228 {
229 .name = "pmc",
230 },
231 {},
232 };
233 MODULE_DEVICE_TABLE(of, riowd_match);
234
235 static struct platform_driver riowd_driver = {
236 .driver = {
237 .name = DRIVER_NAME,
238 .of_match_table = riowd_match,
239 },
240 .probe = riowd_probe,
241 .remove = riowd_remove,
242 };
243
244 module_platform_driver(riowd_driver);
245