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 | |
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(val: index, addr: p->regs + 0); |
73 | writeb(val, addr: p->regs + 1); |
74 | spin_unlock_irqrestore(lock: &p->lock, flags); |
75 | } |
76 | |
77 | static int riowd_open(struct inode *inode, struct file *filp) |
78 | { |
79 | stream_open(inode, filp); |
80 | return 0; |
81 | } |
82 | |
83 | static int riowd_release(struct inode *inode, struct file *filp) |
84 | { |
85 | return 0; |
86 | } |
87 | |
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(to: argp, from: &info, n: 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, val: riowd_timeout, WDTO_INDEX); |
114 | break; |
115 | |
116 | case WDIOC_SETOPTIONS: |
117 | if (copy_from_user(to: &options, from: argp, n: sizeof(options))) |
118 | return -EFAULT; |
119 | |
120 | if (options & WDIOS_DISABLECARD) |
121 | riowd_writereg(p, val: 0, WDTO_INDEX); |
122 | else if (options & WDIOS_ENABLECARD) |
123 | riowd_writereg(p, val: 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, val: 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 | |
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, val: 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 | |
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(dev: &op->dev, size: 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(misc: &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(pdev: op, data: 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 | |
220 | static void riowd_remove(struct platform_device *op) |
221 | { |
222 | struct riowd *p = platform_get_drvdata(pdev: op); |
223 | |
224 | misc_deregister(misc: &riowd_miscdev); |
225 | of_iounmap(&op->resource[0], p->regs, 2); |
226 | } |
227 | |
228 | static const struct of_device_id riowd_match[] = { |
229 | { |
230 | .name = "pmc" , |
231 | }, |
232 | {}, |
233 | }; |
234 | MODULE_DEVICE_TABLE(of, riowd_match); |
235 | |
236 | static struct platform_driver riowd_driver = { |
237 | .driver = { |
238 | .name = DRIVER_NAME, |
239 | .of_match_table = riowd_match, |
240 | }, |
241 | .probe = riowd_probe, |
242 | .remove_new = riowd_remove, |
243 | }; |
244 | |
245 | module_platform_driver(riowd_driver); |
246 | |