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_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 stream_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 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 } 147 148 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 .compat_ioctl = compat_ptr_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 void 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 } 227 228 static const struct of_device_id riowd_match[] = { 229 { 230 .name = "pmc", 231 }, 232 {}, 233 }; 234 MODULE_DEVICE_TABLE(of, riowd_match); 235 236 static struct platform_driver riowd_driver = { 237 .driver = { 238 .name = DRIVER_NAME, 239 .of_match_table = riowd_match, 240 }, 241 .probe = riowd_probe, 242 .remove_new = riowd_remove, 243 }; 244 245 module_platform_driver(riowd_driver); 246