// SPDX-License-Identifier: GPL-2.0-only
/*
* PIKA FPGA based Watchdog Timer
*
* Copyright (c) 2008 PIKA Technologies
* Sean MacLennan <smaclennan@pikatech.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/bitops.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#define DRV_NAME "PIKA-WDT"
/* Hardware timeout in seconds */
#define WDT_HW_TIMEOUT 2
/* Timer heartbeat (500ms) */
#define WDT_TIMEOUT (HZ/2)
/* User land timeout */
#define WDT_HEARTBEAT 15
static int heartbeat = WDT_HEARTBEAT;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static struct {
void __iomem *fpga;
unsigned long next_heartbeat; /* the next_heartbeat for the timer */
unsigned long open;
char expect_close;
int bootstatus;
struct timer_list timer; /* The timer that pings the watchdog */
} pikawdt_private;
static struct watchdog_info ident __ro_after_init = {
.identity = DRV_NAME,
.options = WDIOF_CARDRESET |
WDIOF_SETTIMEOUT |
WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE,
};
/*
* Reload the watchdog timer. (ie, pat the watchdog)
*/
static inline void pikawdt_reset(void)
{
/* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --
* Bit 7, WTCHDG_EN: When set to 1, the watchdog timer is enabled.
* Once enabled, it cannot be disabled. The watchdog can be
* kicked by performing any write access to the reset
* control register (this register).
* Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in
* seconds. Valid ranges are 1 to 15 seconds. The value can
* be modified dynamically.
*/
unsigned reset = in_be32(pikawdt_private.fpga + 0x14);
/* enable with max timeout - 15 seconds */
reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);
out_be32(pikawdt_private.fpga + 0x14, reset);
}
/*
* Timer tick
*/
static void pikawdt_ping(struct timer_list *unused)
{
if (time_before(jiffies, pikawdt_private.next_heartbeat) ||
(!nowayout && !pikawdt_private.open)) {
pikawdt_reset();
mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
} else
pr_crit("I will reset your machine !\n");
}
static void pikawdt_keepalive(void)
{
pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
}
static void pikawdt_start(void)
{
pikawdt_keepalive();
mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
}
/*
* Watchdog device is opened, and watchdog starts running.
*/
static int pikawdt_open(struct inode *inode, struct file *file)
{
/* /dev/watchdog can only be opened once */
if (test_and_set_bit(0, &pikawdt_private.open))
return -EBUSY;
pikawdt_start();
return stream_open(inode, file);
}
/*
* Close the watchdog device.
*/
static int pikawdt_release(struct inode *inode, struct file *file)
{
/* stop internal ping */
if (!pikawdt_private.expect_close)
del_timer(&pikawdt_private.timer);
clear_bit(0, &pikawdt_private.open);
pikawdt_private.expect_close = 0;
return 0;
}
/*
* Pat the watchdog whenever device is written to.
*/
static ssize_t pikawdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
if (!len)
return 0;
/* Scan for magic character */
if (!nowayout) {
size_t i;
pikawdt_private.expect_close = 0;
for (i = 0; i < len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V') {
pikawdt_private.expect_close = 42;
break;
}
}
}
pikawdt_keepalive();
return len;
}
/*
* Handle commands from user-space.
*/
static long pikawdt_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
int new_value;
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
return put_user(0, p);
case WDIOC_GETBOOTSTATUS:
return put_user(pikawdt_private.bootstatus, p);
case WDIOC_KEEPALIVE:
pikawdt_keepalive();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_value, p))
return -EFAULT;
heartbeat = new_value;
pikawdt_keepalive();
return put_user(new_value, p); /* return current value */
case WDIOC_GETTIMEOUT:
return put_user(heartbeat, p);
}
return -ENOTTY;
}
static const struct file_operations pikawdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.open = pikawdt_open,
.release = pikawdt_release,
.write = pikawdt_write,
.unlocked_ioctl = pikawdt_ioctl,
};
static struct miscdevice pikawdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &pikawdt_fops,
};
static int __init pikawdt_init(void)
{
struct device_node *np;
void __iomem *fpga;
u32 post1;
int ret;
np = of_find_compatible_node(NULL, NULL, "pika,fpga");
if (np == NULL) {
pr_err("Unable to find fpga\n");
return -ENOENT;
}
pikawdt_private.fpga = of_iomap(np, 0);
of_node_put(np);
if (pikawdt_private.fpga == NULL) {
pr_err("Unable to map fpga\n");
return -ENOMEM;
}
ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;
/* POST information is in the sd area. */
np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
if (np == NULL) {
pr_err("Unable to find fpga-sd\n");
ret = -ENOENT;
goto out;
}
fpga = of_iomap(np, 0);
of_node_put(np);
if (fpga == NULL) {
pr_err("Unable to map fpga-sd\n");
ret = -ENOMEM;
goto out;
}
/* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
* Bit 31, WDOG: Set to 1 when the last reset was caused by a watchdog
* timeout.
*/
post1 = in_be32(fpga + 0x40);
if (post1 & 0x80000000)
pikawdt_private.bootstatus = WDIOF_CARDRESET;
iounmap(fpga);
timer_setup(&pikawdt_private.timer, pikawdt_ping, 0);
ret = misc_register(&pikawdt_miscdev);
if (ret) {
pr_err("Unable to register miscdev\n");
goto out;
}
pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
heartbeat, nowayout);
return 0;
out:
iounmap(pikawdt_private.fpga);
return ret;
}
static void __exit pikawdt_exit(void)
{
misc_deregister(&pikawdt_miscdev);
iounmap(pikawdt_private.fpga);
}
module_init(pikawdt_init);
module_exit(pikawdt_exit);
MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");
MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
MODULE_LICENSE("GPL");
