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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * PIKA FPGA based Watchdog Timer4 *5 * Copyright (c) 2008 PIKA Technologies6 * Sean MacLennan <smaclennan@pikatech.com>7 */8 9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt10 11#include <linux/init.h>12#include <linux/errno.h>13#include <linux/module.h>14#include <linux/moduleparam.h>15#include <linux/types.h>16#include <linux/kernel.h>17#include <linux/fs.h>18#include <linux/miscdevice.h>19#include <linux/watchdog.h>20#include <linux/reboot.h>21#include <linux/jiffies.h>22#include <linux/timer.h>23#include <linux/bitops.h>24#include <linux/uaccess.h>25#include <linux/io.h>26#include <linux/of.h>27#include <linux/of_address.h>28 29#define DRV_NAME "PIKA-WDT"30 31/* Hardware timeout in seconds */32#define WDT_HW_TIMEOUT 233 34/* Timer heartbeat (500ms) */35#define WDT_TIMEOUT (HZ/2)36 37/* User land timeout */38#define WDT_HEARTBEAT 1539static int heartbeat = WDT_HEARTBEAT;40module_param(heartbeat, int, 0);41MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "42 "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");43 44static bool nowayout = WATCHDOG_NOWAYOUT;45module_param(nowayout, bool, 0);46MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "47 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");48 49static struct {50 void __iomem *fpga;51 unsigned long next_heartbeat; /* the next_heartbeat for the timer */52 unsigned long open;53 char expect_close;54 int bootstatus;55 struct timer_list timer; /* The timer that pings the watchdog */56} pikawdt_private;57 58static struct watchdog_info ident __ro_after_init = {59 .identity = DRV_NAME,60 .options = WDIOF_CARDRESET |61 WDIOF_SETTIMEOUT |62 WDIOF_KEEPALIVEPING |63 WDIOF_MAGICCLOSE,64};65 66/*67 * Reload the watchdog timer. (ie, pat the watchdog)68 */69static inline void pikawdt_reset(void)70{71 /* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --72 * Bit 7, WTCHDG_EN: When set to 1, the watchdog timer is enabled.73 * Once enabled, it cannot be disabled. The watchdog can be74 * kicked by performing any write access to the reset75 * control register (this register).76 * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in77 * seconds. Valid ranges are 1 to 15 seconds. The value can78 * be modified dynamically.79 */80 unsigned reset = in_be32(pikawdt_private.fpga + 0x14);81 /* enable with max timeout - 15 seconds */82 reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);83 out_be32(pikawdt_private.fpga + 0x14, reset);84}85 86/*87 * Timer tick88 */89static void pikawdt_ping(struct timer_list *unused)90{91 if (time_before(jiffies, pikawdt_private.next_heartbeat) ||92 (!nowayout && !pikawdt_private.open)) {93 pikawdt_reset();94 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);95 } else96 pr_crit("I will reset your machine !\n");97}98 99 100static void pikawdt_keepalive(void)101{102 pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;103}104 105static void pikawdt_start(void)106{107 pikawdt_keepalive();108 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);109}110 111/*112 * Watchdog device is opened, and watchdog starts running.113 */114static int pikawdt_open(struct inode *inode, struct file *file)115{116 /* /dev/watchdog can only be opened once */117 if (test_and_set_bit(0, &pikawdt_private.open))118 return -EBUSY;119 120 pikawdt_start();121 122 return stream_open(inode, file);123}124 125/*126 * Close the watchdog device.127 */128static int pikawdt_release(struct inode *inode, struct file *file)129{130 /* stop internal ping */131 if (!pikawdt_private.expect_close)132 del_timer(&pikawdt_private.timer);133 134 clear_bit(0, &pikawdt_private.open);135 pikawdt_private.expect_close = 0;136 return 0;137}138 139/*140 * Pat the watchdog whenever device is written to.141 */142static ssize_t pikawdt_write(struct file *file, const char __user *data,143 size_t len, loff_t *ppos)144{145 if (!len)146 return 0;147 148 /* Scan for magic character */149 if (!nowayout) {150 size_t i;151 152 pikawdt_private.expect_close = 0;153 154 for (i = 0; i < len; i++) {155 char c;156 if (get_user(c, data + i))157 return -EFAULT;158 if (c == 'V') {159 pikawdt_private.expect_close = 42;160 break;161 }162 }163 }164 165 pikawdt_keepalive();166 167 return len;168}169 170/*171 * Handle commands from user-space.172 */173static long pikawdt_ioctl(struct file *file,174 unsigned int cmd, unsigned long arg)175{176 void __user *argp = (void __user *)arg;177 int __user *p = argp;178 int new_value;179 180 switch (cmd) {181 case WDIOC_GETSUPPORT:182 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;183 184 case WDIOC_GETSTATUS:185 return put_user(0, p);186 187 case WDIOC_GETBOOTSTATUS:188 return put_user(pikawdt_private.bootstatus, p);189 190 case WDIOC_KEEPALIVE:191 pikawdt_keepalive();192 return 0;193 194 case WDIOC_SETTIMEOUT:195 if (get_user(new_value, p))196 return -EFAULT;197 198 heartbeat = new_value;199 pikawdt_keepalive();200 201 return put_user(new_value, p); /* return current value */202 203 case WDIOC_GETTIMEOUT:204 return put_user(heartbeat, p);205 }206 return -ENOTTY;207}208 209 210static const struct file_operations pikawdt_fops = {211 .owner = THIS_MODULE,212 .open = pikawdt_open,213 .release = pikawdt_release,214 .write = pikawdt_write,215 .unlocked_ioctl = pikawdt_ioctl,216 .compat_ioctl = compat_ptr_ioctl,217};218 219static struct miscdevice pikawdt_miscdev = {220 .minor = WATCHDOG_MINOR,221 .name = "watchdog",222 .fops = &pikawdt_fops,223};224 225static int __init pikawdt_init(void)226{227 struct device_node *np;228 void __iomem *fpga;229 u32 post1;230 int ret;231 232 np = of_find_compatible_node(NULL, NULL, "pika,fpga");233 if (np == NULL) {234 pr_err("Unable to find fpga\n");235 return -ENOENT;236 }237 238 pikawdt_private.fpga = of_iomap(np, 0);239 of_node_put(np);240 if (pikawdt_private.fpga == NULL) {241 pr_err("Unable to map fpga\n");242 return -ENOMEM;243 }244 245 ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;246 247 /* POST information is in the sd area. */248 np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");249 if (np == NULL) {250 pr_err("Unable to find fpga-sd\n");251 ret = -ENOENT;252 goto out;253 }254 255 fpga = of_iomap(np, 0);256 of_node_put(np);257 if (fpga == NULL) {258 pr_err("Unable to map fpga-sd\n");259 ret = -ENOMEM;260 goto out;261 }262 263 /* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --264 * Bit 31, WDOG: Set to 1 when the last reset was caused by a watchdog265 * timeout.266 */267 post1 = in_be32(fpga + 0x40);268 if (post1 & 0x80000000)269 pikawdt_private.bootstatus = WDIOF_CARDRESET;270 271 iounmap(fpga);272 273 timer_setup(&pikawdt_private.timer, pikawdt_ping, 0);274 275 ret = misc_register(&pikawdt_miscdev);276 if (ret) {277 pr_err("Unable to register miscdev\n");278 goto out;279 }280 281 pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",282 heartbeat, nowayout);283 return 0;284 285out:286 iounmap(pikawdt_private.fpga);287 return ret;288}289 290static void __exit pikawdt_exit(void)291{292 misc_deregister(&pikawdt_miscdev);293 294 iounmap(pikawdt_private.fpga);295}296 297module_init(pikawdt_init);298module_exit(pikawdt_exit);299 300MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");301MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");302MODULE_LICENSE("GPL");303