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1// SPDX-License-Identifier: GPL-2.0-only2/* riowd.c - driver for hw watchdog inside Super I/O of RIO3 *4 * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)5 */6 7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt8 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 device24 * as its' watchdog.25 *26 * When the watchdog triggers, it asserts a line to the BBC (Boot Bus27 * Controller) of the machine. The BBC can only be configured to28 * trigger a power-on reset when the signal is asserted. The BBC29 * can be configured to ignore the signal entirely as well.30 *31 * The only Super I/O device register we care about is at index32 * 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 system34 * must periodically (before watchdog expires) clear (set to zero) and35 * re-set the watchdog else it will trigger.36 *37 * There are two other indexed watchdog registers inside this Super I/O38 * logical device, but they are unused. The first, at index 0x06 is39 * the watchdog control and can be used to make the watchdog timer re-set40 * when the PS/2 mouse or serial lines show activity. The second, at41 * index 0x07 is merely a sampling of the line from the watchdog to the42 * 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 0x0562 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 else125 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 .unlocked_ioctl = riowd_ioctl,164 .compat_ioctl = compat_ptr_ioctl,165 .open = riowd_open,166 .write = riowd_write,167 .release = riowd_release,168};169 170static struct miscdevice riowd_miscdev = {171 .minor = WATCHDOG_MINOR,172 .name = "watchdog",173 .fops = &riowd_fops174};175 176static 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 211out_iounmap:212 riowd_device = NULL;213 of_iounmap(&op->resource[0], p->regs, 2);214 215out:216 return err;217}218 219static void 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 227static const struct of_device_id riowd_match[] = {228 {229 .name = "pmc",230 },231 {},232};233MODULE_DEVICE_TABLE(of, riowd_match);234 235static struct platform_driver riowd_driver = {236 .driver = {237 .name = DRIVER_NAME,238 .of_match_table = riowd_match,239 },240 .probe = riowd_probe,241 .remove_new = riowd_remove,242};243 244module_platform_driver(riowd_driver);245