drivers/watchdog/pika_wdt.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * PIKA FPGA based Watchdog Timer
0004  *
0005  * Copyright (c) 2008 PIKA Technologies
0006  *   Sean MacLennan <smaclennan@pikatech.com>
0007  */
0008
0009 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0010
0011 #include <linux/init.h>
0012 #include <linux/errno.h>
0013 #include <linux/module.h>
0014 #include <linux/moduleparam.h>
0015 #include <linux/types.h>
0016 #include <linux/kernel.h>
0017 #include <linux/fs.h>
0018 #include <linux/miscdevice.h>
0019 #include <linux/watchdog.h>
0020 #include <linux/reboot.h>
0021 #include <linux/jiffies.h>
0022 #include <linux/timer.h>
0023 #include <linux/bitops.h>
0024 #include <linux/uaccess.h>
0025 #include <linux/io.h>
0026 #include <linux/of_address.h>
0027 #include <linux/of_platform.h>
0028
0029 #define DRV_NAME "PIKA-WDT"
0030
0031 /* Hardware timeout in seconds */
0032 #define WDT_HW_TIMEOUT 2
0033
0034 /* Timer heartbeat (500ms) */
0035 #define WDT_TIMEOUT (HZ/2)
0036
0037 /* User land timeout */
0038 #define WDT_HEARTBEAT 15
0039 static int heartbeat = WDT_HEARTBEAT;
0040 module_param(heartbeat, int, 0);
0041 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
0042     "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
0043
0044 static bool nowayout = WATCHDOG_NOWAYOUT;
0045 module_param(nowayout, bool, 0);
0046 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
0047     "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
0048
0049 static struct {
0050     void __iomem *fpga;
0051     unsigned long next_heartbeat;   /* the next_heartbeat for the timer */
0052     unsigned long open;
0053     char expect_close;
0054     int bootstatus;
0055     struct timer_list timer;    /* The timer that pings the watchdog */
0056 } pikawdt_private;
0057
0058 static struct watchdog_info ident __ro_after_init = {
0059     .identity   = DRV_NAME,
0060     .options    = WDIOF_CARDRESET |
0061               WDIOF_SETTIMEOUT |
0062               WDIOF_KEEPALIVEPING |
0063               WDIOF_MAGICCLOSE,
0064 };
0065
0066 /*
0067  * Reload the watchdog timer.  (ie, pat the watchdog)
0068  */
0069 static inline void pikawdt_reset(void)
0070 {
0071     /* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --
0072      * Bit 7,    WTCHDG_EN: When set to 1, the watchdog timer is enabled.
0073      *           Once enabled, it cannot be disabled. The watchdog can be
0074      *           kicked by performing any write access to the reset
0075      *           control register (this register).
0076      * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in
0077      *           seconds. Valid ranges are 1 to 15 seconds. The value can
0078      *           be modified dynamically.
0079      */
0080     unsigned reset = in_be32(pikawdt_private.fpga + 0x14);
0081     /* enable with max timeout - 15 seconds */
0082     reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);
0083     out_be32(pikawdt_private.fpga + 0x14, reset);
0084 }
0085
0086 /*
0087  * Timer tick
0088  */
0089 static void pikawdt_ping(struct timer_list *unused)
0090 {
0091     if (time_before(jiffies, pikawdt_private.next_heartbeat) ||
0092             (!nowayout && !pikawdt_private.open)) {
0093         pikawdt_reset();
0094         mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
0095     } else
0096         pr_crit("I will reset your machine !\n");
0097 }
0098
0099
0100 static void pikawdt_keepalive(void)
0101 {
0102     pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
0103 }
0104
0105 static void pikawdt_start(void)
0106 {
0107     pikawdt_keepalive();
0108     mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
0109 }
0110
0111 /*
0112  * Watchdog device is opened, and watchdog starts running.
0113  */
0114 static int pikawdt_open(struct inode *inode, struct file *file)
0115 {
0116     /* /dev/watchdog can only be opened once */
0117     if (test_and_set_bit(0, &pikawdt_private.open))
0118         return -EBUSY;
0119
0120     pikawdt_start();
0121
0122     return stream_open(inode, file);
0123 }
0124
0125 /*
0126  * Close the watchdog device.
0127  */
0128 static int pikawdt_release(struct inode *inode, struct file *file)
0129 {
0130     /* stop internal ping */
0131     if (!pikawdt_private.expect_close)
0132         del_timer(&pikawdt_private.timer);
0133
0134     clear_bit(0, &pikawdt_private.open);
0135     pikawdt_private.expect_close = 0;
0136     return 0;
0137 }
0138
0139 /*
0140  * Pat the watchdog whenever device is written to.
0141  */
0142 static ssize_t pikawdt_write(struct file *file, const char __user *data,
0143                  size_t len, loff_t *ppos)
0144 {
0145     if (!len)
0146         return 0;
0147
0148     /* Scan for magic character */
0149     if (!nowayout) {
0150         size_t i;
0151
0152         pikawdt_private.expect_close = 0;
0153
0154         for (i = 0; i < len; i++) {
0155             char c;
0156             if (get_user(c, data + i))
0157                 return -EFAULT;
0158             if (c == 'V') {
0159                 pikawdt_private.expect_close = 42;
0160                 break;
0161             }
0162         }
0163     }
0164
0165     pikawdt_keepalive();
0166
0167     return len;
0168 }
0169
0170 /*
0171  * Handle commands from user-space.
0172  */
0173 static long pikawdt_ioctl(struct file *file,
0174         unsigned int cmd, unsigned long arg)
0175 {
0176     void __user *argp = (void __user *)arg;
0177     int __user *p = argp;
0178     int new_value;
0179
0180     switch (cmd) {
0181     case WDIOC_GETSUPPORT:
0182         return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
0183
0184     case WDIOC_GETSTATUS:
0185         return put_user(0, p);
0186
0187     case WDIOC_GETBOOTSTATUS:
0188         return put_user(pikawdt_private.bootstatus, p);
0189
0190     case WDIOC_KEEPALIVE:
0191         pikawdt_keepalive();
0192         return 0;
0193
0194     case WDIOC_SETTIMEOUT:
0195         if (get_user(new_value, p))
0196             return -EFAULT;
0197
0198         heartbeat = new_value;
0199         pikawdt_keepalive();
0200
0201         return put_user(new_value, p);  /* return current value */
0202
0203     case WDIOC_GETTIMEOUT:
0204         return put_user(heartbeat, p);
0205     }
0206     return -ENOTTY;
0207 }
0208
0209
0210 static const struct file_operations pikawdt_fops = {
0211     .owner      = THIS_MODULE,
0212     .llseek     = no_llseek,
0213     .open       = pikawdt_open,
0214     .release    = pikawdt_release,
0215     .write      = pikawdt_write,
0216     .unlocked_ioctl = pikawdt_ioctl,
0217     .compat_ioctl   = compat_ptr_ioctl,
0218 };
0219
0220 static struct miscdevice pikawdt_miscdev = {
0221     .minor  = WATCHDOG_MINOR,
0222     .name   = "watchdog",
0223     .fops   = &pikawdt_fops,
0224 };
0225
0226 static int __init pikawdt_init(void)
0227 {
0228     struct device_node *np;
0229     void __iomem *fpga;
0230     u32 post1;
0231     int ret;
0232
0233     np = of_find_compatible_node(NULL, NULL, "pika,fpga");
0234     if (np == NULL) {
0235         pr_err("Unable to find fpga\n");
0236         return -ENOENT;
0237     }
0238
0239     pikawdt_private.fpga = of_iomap(np, 0);
0240     of_node_put(np);
0241     if (pikawdt_private.fpga == NULL) {
0242         pr_err("Unable to map fpga\n");
0243         return -ENOMEM;
0244     }
0245
0246     ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;
0247
0248     /* POST information is in the sd area. */
0249     np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
0250     if (np == NULL) {
0251         pr_err("Unable to find fpga-sd\n");
0252         ret = -ENOENT;
0253         goto out;
0254     }
0255
0256     fpga = of_iomap(np, 0);
0257     of_node_put(np);
0258     if (fpga == NULL) {
0259         pr_err("Unable to map fpga-sd\n");
0260         ret = -ENOMEM;
0261         goto out;
0262     }
0263
0264     /* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
0265      * Bit 31,   WDOG: Set to 1 when the last reset was caused by a watchdog
0266      *           timeout.
0267      */
0268     post1 = in_be32(fpga + 0x40);
0269     if (post1 & 0x80000000)
0270         pikawdt_private.bootstatus = WDIOF_CARDRESET;
0271
0272     iounmap(fpga);
0273
0274     timer_setup(&pikawdt_private.timer, pikawdt_ping, 0);
0275
0276     ret = misc_register(&pikawdt_miscdev);
0277     if (ret) {
0278         pr_err("Unable to register miscdev\n");
0279         goto out;
0280     }
0281
0282     pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
0283         heartbeat, nowayout);
0284     return 0;
0285
0286 out:
0287     iounmap(pikawdt_private.fpga);
0288     return ret;
0289 }
0290
0291 static void __exit pikawdt_exit(void)
0292 {
0293     misc_deregister(&pikawdt_miscdev);
0294
0295     iounmap(pikawdt_private.fpga);
0296 }
0297
0298 module_init(pikawdt_init);
0299 module_exit(pikawdt_exit);
0300
0301 MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");
0302 MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
0303 MODULE_LICENSE("GPL");