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Linux/drivers/watchdog/riowd.c

  1 /* riowd.c - driver for hw watchdog inside Super I/O of RIO
  2  *
  3  * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)
  4  */
  5 
  6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  7 
  8 #include <linux/kernel.h>
  9 #include <linux/module.h>
 10 #include <linux/types.h>
 11 #include <linux/fs.h>
 12 #include <linux/errno.h>
 13 #include <linux/init.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 
 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 
 78 static int riowd_open(struct inode *inode, struct file *filp)
 79 {
 80         nonseekable_open(inode, filp);
 81         return 0;
 82 }
 83 
 84 static int riowd_release(struct inode *inode, struct file *filp)
 85 {
 86         return 0;
 87 }
 88 
 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                 /* Fall */
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 
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         .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(&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 
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                 .owner = THIS_MODULE,
242                 .of_match_table = riowd_match,
243         },
244         .probe          = riowd_probe,
245         .remove         = riowd_remove,
246 };
247 
248 module_platform_driver(riowd_driver);
249 

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