1 /* riowd.c - driver for hw watchdog inside Super I/O of RIO 2 * 3 * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net) 4 */ 5 6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 7 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 #include <linux/types.h> 11 #include <linux/fs.h> 12 #include <linux/errno.h> 13 #include <linux/miscdevice.h> 14 #include <linux/watchdog.h> 15 #include <linux/of.h> 16 #include <linux/of_device.h> 17 #include <linux/io.h> 18 #include <linux/uaccess.h> 19 #include <linux/slab.h> 20 21 22 /* RIO uses the NatSemi Super I/O power management logical device 23 * as its' watchdog. 24 * 25 * When the watchdog triggers, it asserts a line to the BBC (Boot Bus 26 * Controller) of the machine. The BBC can only be configured to 27 * trigger a power-on reset when the signal is asserted. The BBC 28 * can be configured to ignore the signal entirely as well. 29 * 30 * The only Super I/O device register we care about is at index 31 * 0x05 (WDTO_INDEX) which is the watchdog time-out in minutes (1-255). 32 * If set to zero, this disables the watchdog. When set, the system 33 * must periodically (before watchdog expires) clear (set to zero) and 34 * re-set the watchdog else it will trigger. 35 * 36 * There are two other indexed watchdog registers inside this Super I/O 37 * logical device, but they are unused. The first, at index 0x06 is 38 * the watchdog control and can be used to make the watchdog timer re-set 39 * when the PS/2 mouse or serial lines show activity. The second, at 40 * index 0x07 is merely a sampling of the line from the watchdog to the 41 * BBC. 42 * 43 * The watchdog device generates no interrupts. 44 */ 45 46 MODULE_AUTHOR("David S. Miller <davem@davemloft.net>"); 47 MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO"); 48 MODULE_SUPPORTED_DEVICE("watchdog"); 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 nonseekable_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 /* Fall */ 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 .open = riowd_open, 166 .write = riowd_write, 167 .release = riowd_release, 168 }; 169 170 static struct miscdevice riowd_miscdev = { 171 .minor = WATCHDOG_MINOR, 172 .name = "watchdog", 173 .fops = &riowd_fops 174 }; 175 176 static 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; 210 211 out_iounmap: 212 riowd_device = NULL; 213 of_iounmap(&op->resource[0], p->regs, 2); 214 215 out: 216 return err; 217 } 218 219 static int 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 return 0; 227 } 228 229 static const struct of_device_id riowd_match[] = { 230 { 231 .name = "pmc", 232 }, 233 {}, 234 }; 235 MODULE_DEVICE_TABLE(of, riowd_match); 236 237 static struct platform_driver riowd_driver = { 238 .driver = { 239 .name = DRIVER_NAME, 240 .of_match_table = riowd_match, 241 }, 242 .probe = riowd_probe, 243 .remove = riowd_remove, 244 }; 245 246 module_platform_driver(riowd_driver); 247