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 /* Fall through */ 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); 249