| 1 | /* |
| 2 | * PIKA FPGA based Watchdog Timer |
| 3 | * |
| 4 | * Copyright (c) 2008 PIKA Technologies |
| 5 | * Sean MacLennan <smaclennan@pikatech.com> |
| 6 | */ |
| 7 | |
| 8 | #include <linux/init.h> |
| 9 | #include <linux/errno.h> |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/moduleparam.h> |
| 12 | #include <linux/types.h> |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/fs.h> |
| 15 | #include <linux/miscdevice.h> |
| 16 | #include <linux/watchdog.h> |
| 17 | #include <linux/reboot.h> |
| 18 | #include <linux/jiffies.h> |
| 19 | #include <linux/timer.h> |
| 20 | #include <linux/bitops.h> |
| 21 | #include <linux/uaccess.h> |
| 22 | #include <linux/io.h> |
| 23 | #include <linux/of_platform.h> |
| 24 | |
| 25 | #define DRV_NAME "PIKA-WDT" |
| 26 | #define PFX DRV_NAME ": " |
| 27 | |
| 28 | /* Hardware timeout in seconds */ |
| 29 | #define WDT_HW_TIMEOUT 2 |
| 30 | |
| 31 | /* Timer heartbeat (500ms) */ |
| 32 | #define WDT_TIMEOUT (HZ/2) |
| 33 | |
| 34 | /* User land timeout */ |
| 35 | #define WDT_HEARTBEAT 15 |
| 36 | static int heartbeat = WDT_HEARTBEAT; |
| 37 | module_param(heartbeat, int, 0); |
| 38 | MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. " |
| 39 | "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")"); |
| 40 | |
| 41 | static int nowayout = WATCHDOG_NOWAYOUT; |
| 42 | module_param(nowayout, int, 0); |
| 43 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " |
| 44 | "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
| 45 | |
| 46 | static struct { |
| 47 | void __iomem *fpga; |
| 48 | unsigned long next_heartbeat; /* the next_heartbeat for the timer */ |
| 49 | unsigned long open; |
| 50 | char expect_close; |
| 51 | int bootstatus; |
| 52 | struct timer_list timer; /* The timer that pings the watchdog */ |
| 53 | } pikawdt_private; |
| 54 | |
| 55 | static struct watchdog_info ident = { |
| 56 | .identity = DRV_NAME, |
| 57 | .options = WDIOF_CARDRESET | |
| 58 | WDIOF_SETTIMEOUT | |
| 59 | WDIOF_KEEPALIVEPING | |
| 60 | WDIOF_MAGICCLOSE, |
| 61 | }; |
| 62 | |
| 63 | /* |
| 64 | * Reload the watchdog timer. (ie, pat the watchdog) |
| 65 | */ |
| 66 | static inline void pikawdt_reset(void) |
| 67 | { |
| 68 | /* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) -- |
| 69 | * Bit 7, WTCHDG_EN: When set to 1, the watchdog timer is enabled. |
| 70 | * Once enabled, it cannot be disabled. The watchdog can be |
| 71 | * kicked by performing any write access to the reset |
| 72 | * control register (this register). |
| 73 | * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in |
| 74 | * seconds. Valid ranges are 1 to 15 seconds. The value can |
| 75 | * be modified dynamically. |
| 76 | */ |
| 77 | unsigned reset = in_be32(pikawdt_private.fpga + 0x14); |
| 78 | /* enable with max timeout - 15 seconds */ |
| 79 | reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8); |
| 80 | out_be32(pikawdt_private.fpga + 0x14, reset); |
| 81 | } |
| 82 | |
| 83 | /* |
| 84 | * Timer tick |
| 85 | */ |
| 86 | static void pikawdt_ping(unsigned long data) |
| 87 | { |
| 88 | if (time_before(jiffies, pikawdt_private.next_heartbeat) || |
| 89 | (!nowayout && !pikawdt_private.open)) { |
| 90 | pikawdt_reset(); |
| 91 | mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT); |
| 92 | } else |
| 93 | printk(KERN_CRIT PFX "I will reset your machine !\n"); |
| 94 | } |
| 95 | |
| 96 | |
| 97 | static void pikawdt_keepalive(void) |
| 98 | { |
| 99 | pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ; |
| 100 | } |
| 101 | |
| 102 | static void pikawdt_start(void) |
| 103 | { |
| 104 | pikawdt_keepalive(); |
| 105 | mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT); |
| 106 | } |
| 107 | |
| 108 | /* |
| 109 | * Watchdog device is opened, and watchdog starts running. |
| 110 | */ |
| 111 | static int pikawdt_open(struct inode *inode, struct file *file) |
| 112 | { |
| 113 | /* /dev/watchdog can only be opened once */ |
| 114 | if (test_and_set_bit(0, &pikawdt_private.open)) |
| 115 | return -EBUSY; |
| 116 | |
| 117 | pikawdt_start(); |
| 118 | |
| 119 | return nonseekable_open(inode, file); |
| 120 | } |
| 121 | |
| 122 | /* |
| 123 | * Close the watchdog device. |
| 124 | */ |
| 125 | static int pikawdt_release(struct inode *inode, struct file *file) |
| 126 | { |
| 127 | /* stop internal ping */ |
| 128 | if (!pikawdt_private.expect_close) |
| 129 | del_timer(&pikawdt_private.timer); |
| 130 | |
| 131 | clear_bit(0, &pikawdt_private.open); |
| 132 | pikawdt_private.expect_close = 0; |
| 133 | return 0; |
| 134 | } |
| 135 | |
| 136 | /* |
| 137 | * Pat the watchdog whenever device is written to. |
| 138 | */ |
| 139 | static ssize_t pikawdt_write(struct file *file, const char __user *data, |
| 140 | size_t len, loff_t *ppos) |
| 141 | { |
| 142 | if (!len) |
| 143 | return 0; |
| 144 | |
| 145 | /* Scan for magic character */ |
| 146 | if (!nowayout) { |
| 147 | size_t i; |
| 148 | |
| 149 | pikawdt_private.expect_close = 0; |
| 150 | |
| 151 | for (i = 0; i < len; i++) { |
| 152 | char c; |
| 153 | if (get_user(c, data + i)) |
| 154 | return -EFAULT; |
| 155 | if (c == 'V') { |
| 156 | pikawdt_private.expect_close = 42; |
| 157 | break; |
| 158 | } |
| 159 | } |
| 160 | } |
| 161 | |
| 162 | pikawdt_keepalive(); |
| 163 | |
| 164 | return len; |
| 165 | } |
| 166 | |
| 167 | /* |
| 168 | * Handle commands from user-space. |
| 169 | */ |
| 170 | static long pikawdt_ioctl(struct file *file, |
| 171 | unsigned int cmd, unsigned long arg) |
| 172 | { |
| 173 | void __user *argp = (void __user *)arg; |
| 174 | int __user *p = argp; |
| 175 | int new_value; |
| 176 | |
| 177 | switch (cmd) { |
| 178 | case WDIOC_GETSUPPORT: |
| 179 | return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; |
| 180 | |
| 181 | case WDIOC_GETSTATUS: |
| 182 | return put_user(0, p); |
| 183 | |
| 184 | case WDIOC_GETBOOTSTATUS: |
| 185 | return put_user(pikawdt_private.bootstatus, p); |
| 186 | |
| 187 | case WDIOC_KEEPALIVE: |
| 188 | pikawdt_keepalive(); |
| 189 | return 0; |
| 190 | |
| 191 | case WDIOC_SETTIMEOUT: |
| 192 | if (get_user(new_value, p)) |
| 193 | return -EFAULT; |
| 194 | |
| 195 | heartbeat = new_value; |
| 196 | pikawdt_keepalive(); |
| 197 | |
| 198 | return put_user(new_value, p); /* return current value */ |
| 199 | |
| 200 | case WDIOC_GETTIMEOUT: |
| 201 | return put_user(heartbeat, p); |
| 202 | } |
| 203 | return -ENOTTY; |
| 204 | } |
| 205 | |
| 206 | |
| 207 | static const struct file_operations pikawdt_fops = { |
| 208 | .owner = THIS_MODULE, |
| 209 | .llseek = no_llseek, |
| 210 | .open = pikawdt_open, |
| 211 | .release = pikawdt_release, |
| 212 | .write = pikawdt_write, |
| 213 | .unlocked_ioctl = pikawdt_ioctl, |
| 214 | }; |
| 215 | |
| 216 | static struct miscdevice pikawdt_miscdev = { |
| 217 | .minor = WATCHDOG_MINOR, |
| 218 | .name = "watchdog", |
| 219 | .fops = &pikawdt_fops, |
| 220 | }; |
| 221 | |
| 222 | static int __init pikawdt_init(void) |
| 223 | { |
| 224 | struct device_node *np; |
| 225 | void __iomem *fpga; |
| 226 | static u32 post1; |
| 227 | int ret; |
| 228 | |
| 229 | np = of_find_compatible_node(NULL, NULL, "pika,fpga"); |
| 230 | if (np == NULL) { |
| 231 | printk(KERN_ERR PFX "Unable to find fpga.\n"); |
| 232 | return -ENOENT; |
| 233 | } |
| 234 | |
| 235 | pikawdt_private.fpga = of_iomap(np, 0); |
| 236 | of_node_put(np); |
| 237 | if (pikawdt_private.fpga == NULL) { |
| 238 | printk(KERN_ERR PFX "Unable to map fpga.\n"); |
| 239 | return -ENOMEM; |
| 240 | } |
| 241 | |
| 242 | ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff; |
| 243 | |
| 244 | /* POST information is in the sd area. */ |
| 245 | np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd"); |
| 246 | if (np == NULL) { |
| 247 | printk(KERN_ERR PFX "Unable to find fpga-sd.\n"); |
| 248 | ret = -ENOENT; |
| 249 | goto out; |
| 250 | } |
| 251 | |
| 252 | fpga = of_iomap(np, 0); |
| 253 | of_node_put(np); |
| 254 | if (fpga == NULL) { |
| 255 | printk(KERN_ERR PFX "Unable to map fpga-sd.\n"); |
| 256 | ret = -ENOMEM; |
| 257 | goto out; |
| 258 | } |
| 259 | |
| 260 | /* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) -- |
| 261 | * Bit 31, WDOG: Set to 1 when the last reset was caused by a watchdog |
| 262 | * timeout. |
| 263 | */ |
| 264 | post1 = in_be32(fpga + 0x40); |
| 265 | if (post1 & 0x80000000) |
| 266 | pikawdt_private.bootstatus = WDIOF_CARDRESET; |
| 267 | |
| 268 | iounmap(fpga); |
| 269 | |
| 270 | setup_timer(&pikawdt_private.timer, pikawdt_ping, 0); |
| 271 | |
| 272 | ret = misc_register(&pikawdt_miscdev); |
| 273 | if (ret) { |
| 274 | printk(KERN_ERR PFX "Unable to register miscdev.\n"); |
| 275 | goto out; |
| 276 | } |
| 277 | |
| 278 | printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n", |
| 279 | heartbeat, nowayout); |
| 280 | return 0; |
| 281 | |
| 282 | out: |
| 283 | iounmap(pikawdt_private.fpga); |
| 284 | return ret; |
| 285 | } |
| 286 | |
| 287 | static void __exit pikawdt_exit(void) |
| 288 | { |
| 289 | misc_deregister(&pikawdt_miscdev); |
| 290 | |
| 291 | iounmap(pikawdt_private.fpga); |
| 292 | } |
| 293 | |
| 294 | module_init(pikawdt_init); |
| 295 | module_exit(pikawdt_exit); |
| 296 | |
| 297 | MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>"); |
| 298 | MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer"); |
| 299 | MODULE_LICENSE("GPL"); |
| 300 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
| 301 | |