![Joe Perches](/assets/img/avatar_default.png)
Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Adrian Bunk <bunk@kernel.org>
486 lines
12 KiB
C
486 lines
12 KiB
C
/*
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* drivers/char/watchdog/shwdt.c
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*
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* Watchdog driver for integrated watchdog in the SuperH processors.
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*
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* Copyright (C) 2001, 2002, 2003 Paul Mundt <lethal@linux-sh.org>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
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* Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
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*
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* 19-Apr-2002 Rob Radez <rob@osinvestor.com>
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* Added expect close support, made emulated timeout runtime changeable
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* general cleanups, add some ioctls
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*/
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/init.h>
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#include <linux/types.h>
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#include <linux/miscdevice.h>
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#include <linux/watchdog.h>
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#include <linux/reboot.h>
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#include <linux/notifier.h>
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#include <linux/ioport.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <asm/io.h>
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#include <asm/uaccess.h>
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#include <asm/watchdog.h>
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#define PFX "shwdt: "
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/*
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* Default clock division ratio is 5.25 msecs. For an additional table of
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* values, consult the asm-sh/watchdog.h. Overload this at module load
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* time.
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*
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* In order for this to work reliably we need to have HZ set to 1000 or
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* something quite higher than 100 (or we need a proper high-res timer
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* implementation that will deal with this properly), otherwise the 10ms
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* resolution of a jiffy is enough to trigger the overflow. For things like
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* the SH-4 and SH-5, this isn't necessarily that big of a problem, though
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* for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely
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* necssary.
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*
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* As a result of this timing problem, the only modes that are particularly
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* feasible are the 4096 and the 2048 divisors, which yeild 5.25 and 2.62ms
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* overflow periods respectively.
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*
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* Also, since we can't really expect userspace to be responsive enough
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* before the overflow happens, we maintain two separate timers .. One in
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* the kernel for clearing out WOVF every 2ms or so (again, this depends on
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* HZ == 1000), and another for monitoring userspace writes to the WDT device.
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*
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* As such, we currently use a configurable heartbeat interval which defaults
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* to 30s. In this case, the userspace daemon is only responsible for periodic
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* writes to the device before the next heartbeat is scheduled. If the daemon
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* misses its deadline, the kernel timer will allow the WDT to overflow.
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*/
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static int clock_division_ratio = WTCSR_CKS_4096;
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#define next_ping_period(cks) msecs_to_jiffies(cks - 4)
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static void sh_wdt_ping(unsigned long data);
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static unsigned long shwdt_is_open;
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static struct watchdog_info sh_wdt_info;
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static char shwdt_expect_close;
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static DEFINE_TIMER(timer, sh_wdt_ping, 0, 0);
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static unsigned long next_heartbeat;
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#define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */
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static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */
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static int nowayout = WATCHDOG_NOWAYOUT;
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/**
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* sh_wdt_start - Start the Watchdog
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*
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* Starts the watchdog.
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*/
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static void sh_wdt_start(void)
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{
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__u8 csr;
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next_heartbeat = jiffies + (heartbeat * HZ);
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mod_timer(&timer, next_ping_period(clock_division_ratio));
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csr = sh_wdt_read_csr();
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csr |= WTCSR_WT | clock_division_ratio;
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sh_wdt_write_csr(csr);
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sh_wdt_write_cnt(0);
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/*
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* These processors have a bit of an inconsistent initialization
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* process.. starting with SH-3, RSTS was moved to WTCSR, and the
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* RSTCSR register was removed.
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*
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* On the SH-2 however, in addition with bits being in different
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* locations, we must deal with RSTCSR outright..
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*/
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csr = sh_wdt_read_csr();
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csr |= WTCSR_TME;
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csr &= ~WTCSR_RSTS;
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sh_wdt_write_csr(csr);
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#ifdef CONFIG_CPU_SH2
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/*
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* Whoever came up with the RSTCSR semantics must've been smoking
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* some of the good stuff, since in addition to the WTCSR/WTCNT write
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* brain-damage, it's managed to fuck things up one step further..
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*
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* If we need to clear the WOVF bit, the upper byte has to be 0xa5..
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* but if we want to touch RSTE or RSTS, the upper byte has to be
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* 0x5a..
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*/
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csr = sh_wdt_read_rstcsr();
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csr &= ~RSTCSR_RSTS;
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sh_wdt_write_rstcsr(csr);
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#endif
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}
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/**
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* sh_wdt_stop - Stop the Watchdog
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* Stops the watchdog.
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*/
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static void sh_wdt_stop(void)
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{
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__u8 csr;
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del_timer(&timer);
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csr = sh_wdt_read_csr();
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csr &= ~WTCSR_TME;
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sh_wdt_write_csr(csr);
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}
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/**
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* sh_wdt_keepalive - Keep the Userspace Watchdog Alive
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* The Userspace watchdog got a KeepAlive: schedule the next heartbeat.
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*/
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static inline void sh_wdt_keepalive(void)
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{
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next_heartbeat = jiffies + (heartbeat * HZ);
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}
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/**
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* sh_wdt_set_heartbeat - Set the Userspace Watchdog heartbeat
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* Set the Userspace Watchdog heartbeat
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*/
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static int sh_wdt_set_heartbeat(int t)
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{
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if (unlikely((t < 1) || (t > 3600))) /* arbitrary upper limit */
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return -EINVAL;
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heartbeat = t;
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return 0;
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}
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/**
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* sh_wdt_ping - Ping the Watchdog
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* @data: Unused
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*
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* Clears overflow bit, resets timer counter.
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*/
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static void sh_wdt_ping(unsigned long data)
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{
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if (time_before(jiffies, next_heartbeat)) {
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__u8 csr;
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csr = sh_wdt_read_csr();
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csr &= ~WTCSR_IOVF;
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sh_wdt_write_csr(csr);
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sh_wdt_write_cnt(0);
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mod_timer(&timer, next_ping_period(clock_division_ratio));
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} else
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printk(KERN_WARNING PFX "Heartbeat lost! Will not ping "
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"the watchdog\n");
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}
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/**
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* sh_wdt_open - Open the Device
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* @inode: inode of device
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* @file: file handle of device
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*
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* Watchdog device is opened and started.
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*/
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static int sh_wdt_open(struct inode *inode, struct file *file)
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{
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if (test_and_set_bit(0, &shwdt_is_open))
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return -EBUSY;
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if (nowayout)
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__module_get(THIS_MODULE);
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sh_wdt_start();
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return nonseekable_open(inode, file);
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}
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/**
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* sh_wdt_close - Close the Device
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* @inode: inode of device
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* @file: file handle of device
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*
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* Watchdog device is closed and stopped.
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*/
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static int sh_wdt_close(struct inode *inode, struct file *file)
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{
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if (shwdt_expect_close == 42) {
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sh_wdt_stop();
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} else {
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printk(KERN_CRIT PFX "Unexpected close, not "
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"stopping watchdog!\n");
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sh_wdt_keepalive();
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}
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clear_bit(0, &shwdt_is_open);
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shwdt_expect_close = 0;
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return 0;
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}
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/**
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* sh_wdt_write - Write to Device
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* @file: file handle of device
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* @buf: buffer to write
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* @count: length of buffer
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* @ppos: offset
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*
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* Pings the watchdog on write.
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*/
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static ssize_t sh_wdt_write(struct file *file, const char *buf,
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size_t count, loff_t *ppos)
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{
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if (count) {
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if (!nowayout) {
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size_t i;
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shwdt_expect_close = 0;
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for (i = 0; i != count; i++) {
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char c;
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if (get_user(c, buf + i))
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return -EFAULT;
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if (c == 'V')
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shwdt_expect_close = 42;
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}
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}
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sh_wdt_keepalive();
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}
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return count;
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}
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/**
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* sh_wdt_mmap - map WDT/CPG registers into userspace
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* @file: file structure for the device
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* @vma: VMA to map the registers into
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*
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* A simple mmap() implementation for the corner cases where the counter
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* needs to be mapped in userspace directly. Due to the relatively small
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* size of the area, neighbouring registers not necessarily tied to the
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* CPG will also be accessible through the register page, so this remains
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* configurable for users that really know what they're doing.
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*
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* Additionaly, the register page maps in the CPG register base relative
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* to the nearest page-aligned boundary, which requires that userspace do
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* the appropriate CPU subtype math for calculating the page offset for
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* the counter value.
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*/
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static int sh_wdt_mmap(struct file *file, struct vm_area_struct *vma)
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{
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int ret = -ENOSYS;
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#ifdef CONFIG_SH_WDT_MMAP
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unsigned long addr;
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/* Only support the simple cases where we map in a register page. */
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if (((vma->vm_end - vma->vm_start) != PAGE_SIZE) || vma->vm_pgoff)
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return -EINVAL;
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/*
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* Pick WTCNT as the start, it's usually the first register after the
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* FRQCR, and neither one are generally page-aligned out of the box.
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*/
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addr = WTCNT & ~(PAGE_SIZE - 1);
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vma->vm_flags |= VM_IO;
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vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
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if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT,
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PAGE_SIZE, vma->vm_page_prot)) {
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printk(KERN_ERR PFX "%s: io_remap_pfn_range failed\n",
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__FUNCTION__);
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return -EAGAIN;
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}
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ret = 0;
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#endif
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return ret;
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}
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/**
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* sh_wdt_ioctl - Query Device
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* @inode: inode of device
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* @file: file handle of device
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* @cmd: watchdog command
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* @arg: argument
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*
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* Query basic information from the device or ping it, as outlined by the
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* watchdog API.
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*/
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static int sh_wdt_ioctl(struct inode *inode, struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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int new_heartbeat;
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int options, retval = -EINVAL;
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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return copy_to_user((struct watchdog_info *)arg,
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&sh_wdt_info,
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sizeof(sh_wdt_info)) ? -EFAULT : 0;
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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return put_user(0, (int *)arg);
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case WDIOC_KEEPALIVE:
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sh_wdt_keepalive();
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return 0;
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case WDIOC_SETTIMEOUT:
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if (get_user(new_heartbeat, (int *)arg))
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return -EFAULT;
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if (sh_wdt_set_heartbeat(new_heartbeat))
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return -EINVAL;
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sh_wdt_keepalive();
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/* Fall */
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case WDIOC_GETTIMEOUT:
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return put_user(heartbeat, (int *)arg);
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case WDIOC_SETOPTIONS:
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if (get_user(options, (int *)arg))
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return -EFAULT;
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if (options & WDIOS_DISABLECARD) {
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sh_wdt_stop();
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retval = 0;
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}
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if (options & WDIOS_ENABLECARD) {
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sh_wdt_start();
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retval = 0;
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}
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return retval;
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default:
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return -ENOTTY;
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}
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return 0;
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}
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/**
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* sh_wdt_notify_sys - Notifier Handler
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* @this: notifier block
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* @code: notifier event
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* @unused: unused
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*
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* Handles specific events, such as turning off the watchdog during a
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* shutdown event.
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*/
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static int sh_wdt_notify_sys(struct notifier_block *this,
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unsigned long code, void *unused)
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{
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if (code == SYS_DOWN || code == SYS_HALT)
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sh_wdt_stop();
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return NOTIFY_DONE;
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}
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static const struct file_operations sh_wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = sh_wdt_write,
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.ioctl = sh_wdt_ioctl,
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.open = sh_wdt_open,
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.release = sh_wdt_close,
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.mmap = sh_wdt_mmap,
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};
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static struct watchdog_info sh_wdt_info = {
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.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
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WDIOF_MAGICCLOSE,
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.firmware_version = 1,
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.identity = "SH WDT",
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};
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static struct notifier_block sh_wdt_notifier = {
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.notifier_call = sh_wdt_notify_sys,
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};
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static struct miscdevice sh_wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &sh_wdt_fops,
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};
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/**
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* sh_wdt_init - Initialize module
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* Registers the device and notifier handler. Actual device
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* initialization is handled by sh_wdt_open().
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*/
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static int __init sh_wdt_init(void)
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{
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int rc;
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if ((clock_division_ratio < 0x5) || (clock_division_ratio > 0x7)) {
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clock_division_ratio = WTCSR_CKS_4096;
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printk(KERN_INFO PFX "clock_division_ratio value must "
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"be 0x5<=x<=0x7, using %d\n", clock_division_ratio);
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}
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rc = sh_wdt_set_heartbeat(heartbeat);
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if (unlikely(rc)) {
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heartbeat = WATCHDOG_HEARTBEAT;
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printk(KERN_INFO PFX "heartbeat value must "
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"be 1<=x<=3600, using %d\n", heartbeat);
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}
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rc = register_reboot_notifier(&sh_wdt_notifier);
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if (unlikely(rc)) {
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printk(KERN_ERR PFX "Can't register reboot notifier (err=%d)\n",
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rc);
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return rc;
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}
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rc = misc_register(&sh_wdt_miscdev);
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if (unlikely(rc)) {
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printk(KERN_ERR PFX "Can't register miscdev on "
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"minor=%d (err=%d)\n", sh_wdt_miscdev.minor, rc);
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unregister_reboot_notifier(&sh_wdt_notifier);
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return rc;
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}
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printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n",
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heartbeat, nowayout);
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return 0;
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}
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/**
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* sh_wdt_exit - Deinitialize module
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* Unregisters the device and notifier handler. Actual device
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* deinitialization is handled by sh_wdt_close().
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*/
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static void __exit sh_wdt_exit(void)
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{
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misc_deregister(&sh_wdt_miscdev);
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unregister_reboot_notifier(&sh_wdt_notifier);
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}
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MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
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MODULE_DESCRIPTION("SuperH watchdog driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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module_param(clock_division_ratio, int, 0);
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MODULE_PARM_DESC(clock_division_ratio, "Clock division ratio. Valid ranges are from 0x5 (1.31ms) to 0x7 (5.25ms). (default=" __MODULE_STRING(clock_division_ratio) ")");
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module_param(heartbeat, int, 0);
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MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (1<=heartbeat<=3600, default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
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module_param(nowayout, int, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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module_init(sh_wdt_init);
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module_exit(sh_wdt_exit);
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