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![Jean Delvare](/assets/img/avatar_default.png)
I just can't find any value in MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR) and MODULE_ALIAS_MISCDEV(TEMP_MINOR) statements. Either the device is enumerated and the driver already has a module alias (e.g. PCI, USB etc.) that will get the right driver loaded automatically. Or the device is not enumerated and loading its driver will lead to more or less intrusive hardware poking. Such hardware poking should be limited to a bare minimum, so the user should really decide which drivers should be tried and in what order. Trying them all in arbitrary order can't do any good. On top of that, loading that many drivers at once bloats the kernel log. Also many drivers will stay loaded afterward, bloating the output of "lsmod" and wasting memory. Some modules (cs5535_mfgpt which gets loaded as a dependency) can't even be unloaded! If defining char-major-10-130 is needed then it should happen in user-space. Signed-off-by: Jean Delvare <jdelvare@suse.de> Acked-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be> Cc: Stephen Warren <swarren@wwwdotorg.org> Cc: Mike Frysinger <vapier.adi@gmail.com> Cc: Wan ZongShun <mcuos.com@gmail.com> Cc: Ben Dooks <ben-linux@fluff.org> Cc: Kukjin Kim <kgene.kim@samsung.com> Cc: Zwane Mwaikambo <zwane@arm.linux.org.uk> Cc: Jim Cromie <jim.cromie@gmail.com>
361 lines
8.5 KiB
C
361 lines
8.5 KiB
C
/*
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* Watchdog driver for SiByte SB1 SoCs
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*
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* Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@lsi.com>
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*
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* This driver is intended to make the second of two hardware watchdogs
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* on the Sibyte 12XX and 11XX SoCs available to the user. There are two
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* such devices available on the SoC, but it seems that there isn't an
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* enumeration class for watchdogs in Linux like there is for RTCs.
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* The second is used rather than the first because it uses IRQ 1,
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* thereby avoiding all that IRQ 0 problematic nonsense.
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*
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* I have not tried this driver on a 1480 processor; it might work
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* just well enough to really screw things up.
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*
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* It is a simple timer, and there is an interrupt that is raised the
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* first time the timer expires. The second time it expires, the chip
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* is reset and there is no way to redirect that NMI. Which could
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* be problematic in some cases where this chip is sitting on the HT
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* bus and has just taken responsibility for providing a cache block.
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* Since the reset can't be redirected to the external reset pin, it is
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* possible that other HT connected processors might hang and not reset.
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* For Linux, a soft reset would probably be even worse than a hard reset.
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* There you have it.
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*
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* The timer takes 23 bits of a 64 bit register (?) as a count value,
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* and decrements the count every microsecond, for a max value of
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* 0x7fffff usec or about 8.3ish seconds.
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*
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* This watchdog borrows some user semantics from the softdog driver,
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* in that if you close the fd, it leaves the watchdog running, unless
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* you previously wrote a 'V' to the fd, in which case it disables
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* the watchdog when you close the fd like some other drivers.
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*
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* Based on various other watchdog drivers, which are probably all
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* loosely based on something Alan Cox wrote years ago.
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*
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* (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 1 or 2 as published by the Free Software Foundation.
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/io.h>
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#include <linux/uaccess.h>
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#include <linux/fs.h>
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#include <linux/reboot.h>
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#include <linux/miscdevice.h>
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#include <linux/watchdog.h>
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#include <linux/interrupt.h>
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#include <asm/sibyte/sb1250.h>
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#include <asm/sibyte/sb1250_regs.h>
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#include <asm/sibyte/sb1250_int.h>
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#include <asm/sibyte/sb1250_scd.h>
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static DEFINE_SPINLOCK(sbwd_lock);
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/*
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* set the initial count value of a timer
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*
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* wdog is the iomem address of the cfg register
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*/
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void sbwdog_set(char __iomem *wdog, unsigned long t)
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{
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spin_lock(&sbwd_lock);
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__raw_writeb(0, wdog);
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__raw_writeq(t & 0x7fffffUL, wdog - 0x10);
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spin_unlock(&sbwd_lock);
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}
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/*
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* cause the timer to [re]load it's initial count and start counting
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* all over again
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*
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* wdog is the iomem address of the cfg register
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*/
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void sbwdog_pet(char __iomem *wdog)
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{
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spin_lock(&sbwd_lock);
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__raw_writeb(__raw_readb(wdog) | 1, wdog);
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spin_unlock(&sbwd_lock);
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}
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static unsigned long sbwdog_gate; /* keeps it to one thread only */
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static char __iomem *kern_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_0));
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static char __iomem *user_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_1));
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static unsigned long timeout = 0x7fffffUL; /* useconds: 8.3ish secs. */
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static int expect_close;
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static const struct watchdog_info ident = {
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.options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT |
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WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
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.identity = "SiByte Watchdog",
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};
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/*
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* Allow only a single thread to walk the dog
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*/
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static int sbwdog_open(struct inode *inode, struct file *file)
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{
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nonseekable_open(inode, file);
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if (test_and_set_bit(0, &sbwdog_gate))
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return -EBUSY;
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__module_get(THIS_MODULE);
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/*
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* Activate the timer
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*/
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sbwdog_set(user_dog, timeout);
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__raw_writeb(1, user_dog);
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return 0;
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}
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/*
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* Put the dog back in the kennel.
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*/
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static int sbwdog_release(struct inode *inode, struct file *file)
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{
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if (expect_close == 42) {
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__raw_writeb(0, user_dog);
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module_put(THIS_MODULE);
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} else {
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pr_crit("%s: Unexpected close, not stopping watchdog!\n",
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ident.identity);
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sbwdog_pet(user_dog);
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}
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clear_bit(0, &sbwdog_gate);
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expect_close = 0;
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return 0;
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}
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/*
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* 42 - the answer
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*/
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static ssize_t sbwdog_write(struct file *file, const char __user *data,
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size_t len, loff_t *ppos)
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{
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int i;
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if (len) {
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/*
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* restart the timer
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*/
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expect_close = 0;
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for (i = 0; i != len; i++) {
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char c;
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if (get_user(c, data + i))
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return -EFAULT;
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if (c == 'V')
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expect_close = 42;
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}
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sbwdog_pet(user_dog);
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}
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return len;
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}
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static long sbwdog_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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int ret = -ENOTTY;
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unsigned long time;
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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
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break;
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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ret = put_user(0, p);
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break;
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case WDIOC_KEEPALIVE:
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sbwdog_pet(user_dog);
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ret = 0;
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break;
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case WDIOC_SETTIMEOUT:
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ret = get_user(time, p);
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if (ret)
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break;
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time *= 1000000;
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if (time > 0x7fffffUL) {
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ret = -EINVAL;
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break;
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}
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timeout = time;
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sbwdog_set(user_dog, timeout);
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sbwdog_pet(user_dog);
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case WDIOC_GETTIMEOUT:
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/*
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* get the remaining count from the ... count register
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* which is 1*8 before the config register
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*/
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ret = put_user((u32)__raw_readq(user_dog - 8) / 1000000, p);
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break;
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}
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return ret;
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}
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/*
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* Notifier for system down
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*/
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static int sbwdog_notify_sys(struct notifier_block *this, unsigned long code,
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void *erf)
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{
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if (code == SYS_DOWN || code == SYS_HALT) {
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/*
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* sit and sit
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*/
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__raw_writeb(0, user_dog);
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__raw_writeb(0, kern_dog);
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}
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return NOTIFY_DONE;
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}
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static const struct file_operations sbwdog_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = sbwdog_write,
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.unlocked_ioctl = sbwdog_ioctl,
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.open = sbwdog_open,
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.release = sbwdog_release,
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};
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static struct miscdevice sbwdog_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &sbwdog_fops,
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};
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static struct notifier_block sbwdog_notifier = {
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.notifier_call = sbwdog_notify_sys,
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};
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/*
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* interrupt handler
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*
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* doesn't do a whole lot for user, but oh so cleverly written so kernel
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* code can use it to re-up the watchdog, thereby saving the kernel from
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* having to create and maintain a timer, just to tickle another timer,
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* which is just so wrong.
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*/
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irqreturn_t sbwdog_interrupt(int irq, void *addr)
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{
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unsigned long wd_init;
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char *wd_cfg_reg = (char *)addr;
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u8 cfg;
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cfg = __raw_readb(wd_cfg_reg);
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wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff;
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/*
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* if it's the second watchdog timer, it's for those users
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*/
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if (wd_cfg_reg == user_dog)
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pr_crit("%s in danger of initiating system reset "
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"in %ld.%01ld seconds\n",
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ident.identity,
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wd_init / 1000000, (wd_init / 100000) % 10);
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else
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cfg |= 1;
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__raw_writeb(cfg, wd_cfg_reg);
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return IRQ_HANDLED;
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}
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static int __init sbwdog_init(void)
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{
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int ret;
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/*
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* register a reboot notifier
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*/
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ret = register_reboot_notifier(&sbwdog_notifier);
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if (ret) {
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pr_err("%s: cannot register reboot notifier (err=%d)\n",
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ident.identity, ret);
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return ret;
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}
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/*
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* get the resources
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*/
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ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED,
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ident.identity, (void *)user_dog);
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if (ret) {
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pr_err("%s: failed to request irq 1 - %d\n",
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ident.identity, ret);
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goto out;
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}
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ret = misc_register(&sbwdog_miscdev);
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if (ret == 0) {
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pr_info("%s: timeout is %ld.%ld secs\n",
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ident.identity,
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timeout / 1000000, (timeout / 100000) % 10);
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return 0;
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}
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free_irq(1, (void *)user_dog);
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out:
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unregister_reboot_notifier(&sbwdog_notifier);
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return ret;
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}
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static void __exit sbwdog_exit(void)
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{
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misc_deregister(&sbwdog_miscdev);
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free_irq(1, (void *)user_dog);
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unregister_reboot_notifier(&sbwdog_notifier);
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}
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module_init(sbwdog_init);
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module_exit(sbwdog_exit);
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MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");
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MODULE_DESCRIPTION("SiByte Watchdog");
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module_param(timeout, ulong, 0);
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MODULE_PARM_DESC(timeout,
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"Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)");
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MODULE_LICENSE("GPL");
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/*
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* example code that can be put in a platform code area to utilize the
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* first watchdog timer for the kernels own purpose.
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void platform_wd_setup(void)
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{
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int ret;
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ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED,
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"Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
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if (ret) {
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pr_crit("Watchdog IRQ zero(0) failed to be requested - %d\n", ret);
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}
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}
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*/
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