linux/drivers/watchdog/riowd.c
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   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
  47MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
  48MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
  49MODULE_LICENSE("GPL");
  50
  51#define DRIVER_NAME     "riowd"
  52#define PFX             DRIVER_NAME ": "
  53
  54struct riowd {
  55        void __iomem            *regs;
  56        spinlock_t              lock;
  57};
  58
  59static struct riowd *riowd_device;
  60
  61#define WDTO_INDEX      0x05
  62
  63static int riowd_timeout = 1;           /* in minutes */
  64module_param(riowd_timeout, int, 0);
  65MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");
  66
  67static 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
  77static int riowd_open(struct inode *inode, struct file *filp)
  78{
  79        stream_open(inode, filp);
  80        return 0;
  81}
  82
  83static int riowd_release(struct inode *inode, struct file *filp)
  84{
  85        return 0;
  86}
  87
  88static 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
 148static 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
 161static 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
 171static struct miscdevice riowd_miscdev = {
 172        .minor  = WATCHDOG_MINOR,
 173        .name   = "watchdog",
 174        .fops   = &riowd_fops
 175};
 176
 177static 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
 212out_iounmap:
 213        riowd_device = NULL;
 214        of_iounmap(&op->resource[0], p->regs, 2);
 215
 216out:
 217        return err;
 218}
 219
 220static 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
 230static const struct of_device_id riowd_match[] = {
 231        {
 232                .name = "pmc",
 233        },
 234        {},
 235};
 236MODULE_DEVICE_TABLE(of, riowd_match);
 237
 238static struct platform_driver riowd_driver = {
 239        .driver = {
 240                .name = DRIVER_NAME,
 241                .of_match_table = riowd_match,
 242        },
 243        .probe          = riowd_probe,
 244        .remove         = riowd_remove,
 245};
 246
 247module_platform_driver(riowd_driver);
 248