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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/miscdevice.h>
 14 #include <linux/watchdog.h>
 15 #include <linux/of.h>
 16 #include <linux/of_device.h>
 17 #include <linux/io.h>
 18 #include <linux/uaccess.h>
 19 #include <linux/slab.h>
 20 
 21 
 22 /* RIO uses the NatSemi Super I/O power management logical device
 23  * as its' watchdog.
 24  *
 25  * When the watchdog triggers, it asserts a line to the BBC (Boot Bus
 26  * Controller) of the machine.  The BBC can only be configured to
 27  * trigger a power-on reset when the signal is asserted.  The BBC
 28  * can be configured to ignore the signal entirely as well.
 29  *
 30  * The only Super I/O device register we care about is at index
 31  * 0x05 (WDTO_INDEX) which is the watchdog time-out in minutes (1-255).
 32  * If set to zero, this disables the watchdog.  When set, the system
 33  * must periodically (before watchdog expires) clear (set to zero) and
 34  * re-set the watchdog else it will trigger.
 35  *
 36  * There are two other indexed watchdog registers inside this Super I/O
 37  * logical device, but they are unused.  The first, at index 0x06 is
 38  * the watchdog control and can be used to make the watchdog timer re-set
 39  * when the PS/2 mouse or serial lines show activity.  The second, at
 40  * index 0x07 is merely a sampling of the line from the watchdog to the
 41  * BBC.
 42  *
 43  * The watchdog device generates no interrupts.
 44  */
 45 
 46 MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
 47 MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
 48 MODULE_SUPPORTED_DEVICE("watchdog");
 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(index, p->regs + 0);
 73         writeb(val, p->regs + 1);
 74         spin_unlock_irqrestore(&p->lock, flags);
 75 }
 76 
 77 static int riowd_open(struct inode *inode, struct file *filp)
 78 {
 79         nonseekable_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(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                 /* Fall */
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, 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         .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 
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 
219 static int 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         return 0;
227 }
228 
229 static const struct of_device_id riowd_match[] = {
230         {
231                 .name = "pmc",
232         },
233         {},
234 };
235 MODULE_DEVICE_TABLE(of, riowd_match);
236 
237 static struct platform_driver riowd_driver = {
238         .driver = {
239                 .name = DRIVER_NAME,
240                 .owner = THIS_MODULE,
241                 .of_match_table = riowd_match,
242         },
243         .probe          = riowd_probe,
244         .remove         = riowd_remove,
245 };
246 
247 module_platform_driver(riowd_driver);
248 

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