drivers/watchdog/riowd.c

   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_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         stream_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                 fallthrough;
 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         .compat_ioctl   =       compat_ptr_ioctl,
 167         .open =                 riowd_open,
 168         .write =                riowd_write,
 169         .release =              riowd_release,
 170 };
 171
 172 static struct miscdevice riowd_miscdev = {
 173         .minor  = WATCHDOG_MINOR,
 174         .name   = "watchdog",
 175         .fops   = &riowd_fops
 176 };
 177
 178 static int riowd_probe(struct platform_device *op)
 179 {
 180         struct riowd *p;
 181         int err = -EINVAL;
 182
 183         if (riowd_device)
 184                 goto out;
 185
 186         err = -ENOMEM;
 187         p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
 188         if (!p)
 189                 goto out;
 190
 191         spin_lock_init(&p->lock);
 192
 193         p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
 194         if (!p->regs) {
 195                 pr_err("Cannot map registers\n");
 196                 goto out;
 197         }
 198         /* Make miscdev useable right away */
 199         riowd_device = p;
 200
 201         err = misc_register(&riowd_miscdev);
 202         if (err) {
 203                 pr_err("Cannot register watchdog misc device\n");
 204                 goto out_iounmap;
 205         }
 206
 207         pr_info("Hardware watchdog [%i minutes], regs at %p\n",
 208                 riowd_timeout, p->regs);
 209
 210         platform_set_drvdata(op, p);
 211         return 0;
 212
 213 out_iounmap:
 214         riowd_device = NULL;
 215         of_iounmap(&op->resource[0], p->regs, 2);
 216
 217 out:
 218         return err;
 219 }
 220
 221 static int riowd_remove(struct platform_device *op)
 222 {
 223         struct riowd *p = platform_get_drvdata(op);
 224
 225         misc_deregister(&riowd_miscdev);
 226         of_iounmap(&op->resource[0], p->regs, 2);
 227
 228         return 0;
 229 }
 230
 231 static const struct of_device_id riowd_match[] = {
 232         {
 233                 .name = "pmc",
 234         },
 235         {},
 236 };
 237 MODULE_DEVICE_TABLE(of, riowd_match);
 238
 239 static struct platform_driver riowd_driver = {
 240         .driver = {
 241                 .name = DRIVER_NAME,
 242                 .of_match_table = riowd_match,
 243         },
 244         .probe          = riowd_probe,
 245         .remove         = riowd_remove,
 246 };
 247
 248 module_platform_driver(riowd_driver);