/*
* Watchdog timer for PowerPC Book-E systems
*
* Author: Matthew McClintock
* Maintainer: Kumar Gala <galak@kernel.crashing.org>
*
* Copyright 2005, 2008, 2010-2011 Freescale Semiconductor Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/smp.h>
#include <linux/miscdevice.h>
#include <linux/notifier.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>
#include <asm/reg_booke.h>
#include <asm/time.h>
#include <asm/div64.h>
/* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
* Also, the wdt_period sets the watchdog timer period timeout.
* For E500 cpus the wdt_period sets which bit changing from 0->1 will
* trigger a watchog timeout. This watchdog timeout will occur 3 times, the
* first time nothing will happen, the second time a watchdog exception will
* occur, and the final time the board will reset.
*/
u32 booke_wdt_enabled;
u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
#ifdef CONFIG_PPC_FSL_BOOK3E
#define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
#define WDTP_MASK (WDTP(0x3f))
#else
#define WDTP(x) (TCR_WP(x))
#define WDTP_MASK (TCR_WP_MASK)
#endif
static DEFINE_SPINLOCK(booke_wdt_lock);
/* For the specified period, determine the number of seconds
* corresponding to the reset time. There will be a watchdog
* exception at approximately 3/5 of this time.
*
* The formula to calculate this is given by:
* 2.5 * (2^(63-period+1)) / timebase_freq
*
* In order to simplify things, we assume that period is
* at least 1. This will still result in a very long timeout.
*/
static unsigned long long period_to_sec(unsigned int period)
{
unsigned long long tmp = 1ULL << (64 - period);
unsigned long tmp2 = ppc_tb_freq;
/* tmp may be a very large number and we don't want to overflow,
* so divide the timebase freq instead of multiplying tmp
*/
tmp2 = tmp2 / 5 * 2;
do_div(tmp, tmp2);
return tmp;
}
/*
* This procedure will find the highest period which will give a timeout
* greater than the one required. e.g. for a bus speed of 66666666 and
* and a parameter of 2 secs, then this procedure will return a value of 38.
*/
static unsigned int sec_to_period(unsigned int secs)
{
unsigned int period;
for (period = 63; period > 0; period--) {
if (period_to_sec(period) >= secs)
return period;
}
return 0;
}
static void __booke_wdt_set(void *data)
{
u32 val;
val = mfspr(SPRN_TCR);
val &= ~WDTP_MASK;
val |= WDTP(booke_wdt_period);
mtspr(SPRN_TCR, val);
}
static void booke_wdt_set(void)
{
on_each_cpu(__booke_wdt_set, NULL, 0);
}
static void __booke_wdt_ping(void *data)
{
mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
}
static void booke_wdt_ping(void)
{
on_each_cpu(__booke_wdt_ping, NULL, 0);
}
static void __booke_wdt_enable(void *data)
{
u32 val;
/* clear status before enabling watchdog */
__booke_wdt_ping(NULL);
val = mfspr(SPRN_TCR);
val &= ~WDTP_MASK;
val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
mtspr(SPRN_TCR, val);
}
/**
* booke_wdt_disable - disable the watchdog on the given CPU
*
* This function is called on each CPU. It disables the watchdog on that CPU.
*
* TCR[WRC] cannot be changed once it has been set to non-zero, but we can
* effectively disable the watchdog by setting its period to the maximum value.
*/
static void __booke_wdt_disable(void *data)
{
u32 val;
val = mfspr(SPRN_TCR);
val &= ~(TCR_WIE | WDTP_MASK);
mtspr(SPRN_TCR, val);
/* clear status to make sure nothing is pending */
__booke_wdt_ping(NULL);
}
static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
booke_wdt_ping();
return count;
}
static struct watchdog_info ident = {
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
.identity = "PowerPC Book-E Watchdog",
};
static long booke_wdt_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
u32 tmp = 0;
u32 __user *p = (u32 __user *)arg;
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(p, &ident, sizeof(ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
return put_user(0, p);
case WDIOC_GETBOOTSTATUS:
/* XXX: something is clearing TSR */
tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
/* returns CARDRESET if last reset was caused by the WDT */
return put_user((tmp ? WDIOF_CARDRESET : 0), p);
case WDIOC_SETOPTIONS:
if (get_user(tmp, p))
return -EFAULT;
if (tmp == WDIOS_ENABLECARD) {
booke_wdt_ping();
break;
} else
return -EINVAL;
return 0;
case WDIOC_KEEPALIVE:
booke_wdt_ping();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(tmp, p))
return -EFAULT;
#ifdef CONFIG_PPC_FSL_BOOK3E
/* period of 1 gives the largest possible timeout */
if (tmp > period_to_sec(1))
return -EINVAL;
booke_wdt_period = sec_to_period(tmp);
#else
booke_wdt_period = tmp;
#endif
booke_wdt_set();
/* Fall */
case WDIOC_GETTIMEOUT:
#ifdef CONFIG_FSL_BOOKE
return put_user(period_to_sec(booke_wdt_period), p);
#else
return put_user(booke_wdt_period, p);
#endif
default:
return -ENOTTY;
}
return 0;
}
/* wdt_is_active stores wether or not the /dev/watchdog device is opened */
static unsigned long wdt_is_active;
static int booke_wdt_open(struct inode *inode, struct file *file)
{
/* /dev/watchdog can only be opened once */
if (test_and_set_bit(0, &wdt_is_active))
return -EBUSY;
spin_lock(&booke_wdt_lock);
if (booke_wdt_enabled == 0) {
booke_wdt_enabled = 1;
on_each_cpu(__booke_wdt_enable, NULL, 0);
pr_debug("watchdog enabled (timeout = %llu sec)\n",
period_to_sec(booke_wdt_period));
}
spin_unlock(&booke_wdt_lock);
return nonseekable_open(inode, file);
}
static int booke_wdt_release(struct inode *inode, struct file *file)
{
#ifndef CONFIG_WATCHDOG_NOWAYOUT
/* Normally, the watchdog is disabled when /dev/watchdog is closed, but
* if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the
* watchdog should remain enabled. So we disable it only if
* CONFIG_WATCHDOG_NOWAYOUT is not defined.
*/
on_each_cpu(__booke_wdt_disable, NULL, 0);
booke_wdt_enabled = 0;
pr_debug("watchdog disabled\n");
#endif
clear_bit(0, &wdt_is_active);
return 0;
}
static const struct file_operations booke_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = booke_wdt_write,
.unlocked_ioctl = booke_wdt_ioctl,
.open = booke_wdt_open,
.release = booke_wdt_release,
};
static struct miscdevice booke_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &booke_wdt_fops,
};
static void __exit booke_wdt_exit(void)
{
misc_deregister(&booke_wdt_miscdev);
}
static int __init booke_wdt_init(void)
{
int ret = 0;
pr_info("powerpc book-e watchdog driver loaded\n");
ident.firmware_version = cur_cpu_spec->pvr_value;
ret = misc_register(&booke_wdt_miscdev);
if (ret) {
pr_err("cannot register device (minor=%u, ret=%i)\n",
WATCHDOG_MINOR, ret);
return ret;
}
spin_lock(&booke_wdt_lock);
if (booke_wdt_enabled == 1) {
pr_info("watchdog enabled (timeout = %llu sec)\n",
period_to_sec(booke_wdt_period));
on_each_cpu(__booke_wdt_enable, NULL, 0);
}
spin_unlock(&booke_wdt_lock);
return ret;
}
module_init(booke_wdt_init);
module_exit(booke_wdt_exit);
MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
MODULE_LICENSE("GPL");
