cregit-Linux how code gets into the kernel

Release 4.7 drivers/watchdog/smsc37b787_wdt.c

Directory: drivers/watchdog
/*
 *      SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x
 *
 *      Based on acquirewdt.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
 *      and some other existing drivers
 *
 *      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.
 *
 *      The authors do NOT admit liability nor provide warranty for
 *      any of this software. This material is provided "AS-IS" in
 *      the hope that it may be useful for others.
 *
 *      (C) Copyright 2003-2006  Sven Anders <anders@anduras.de>
 *
 *  History:
 *      2003 - Created version 1.0 for Linux 2.4.x.
 *      2006 - Ported to Linux 2.6, added nowayout and MAGICCLOSE
 *             features. Released version 1.1
 *
 *  Theory of operation:
 *
 *      A Watchdog Timer (WDT) is a hardware circuit that can
 *      reset the computer system in case of a software fault.
 *      You probably knew that already.
 *
 *      Usually a userspace daemon will notify the kernel WDT driver
 *      via the /dev/watchdog special device file that userspace is
 *      still alive, at regular intervals.  When such a notification
 *      occurs, the driver will usually tell the hardware watchdog
 *      that everything is in order, and that the watchdog should wait
 *      for yet another little while to reset the system.
 *      If userspace fails (RAM error, kernel bug, whatever), the
 *      notifications cease to occur, and the hardware watchdog will
 *      reset the system (causing a reboot) after the timeout occurs.
 *
 * Create device with:
 *  mknod /dev/watchdog c 10 130
 *
 * For an example userspace keep-alive daemon, see:
 *   Documentation/watchdog/wdt.txt
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/uaccess.h>


/* enable support for minutes as units? */
/* (does not always work correctly, so disabled by default!) */

#define SMSC_SUPPORT_MINUTES

#undef SMSC_SUPPORT_MINUTES


#define MAX_TIMEOUT     255


#define UNIT_SECOND     0

#define UNIT_MINUTE     1


#define VERSION		"1.1"


#define IOPORT		0x3F0

#define IOPORT_SIZE     2

#define IODEV_NO	8


static int unit = UNIT_SECOND;	
/* timer's unit */

static int timeout = 60;	
/* timeout value: default is 60 "units" */

static unsigned long timer_enabled;   
/* is the timer enabled? */


static char expect_close;       
/* is the close expected? */

static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */


static bool nowayout = WATCHDOG_NOWAYOUT;

/* -- Low level function ----------------------------------------*/

/* unlock the IO chip */


static inline void open_io_config(void) { outb(0x55, IOPORT); mdelay(1); outb(0x55, IOPORT); }

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/* lock the IO chip */
static inline void close_io_config(void) { outb(0xAA, IOPORT); }

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/* select the IO device */
static inline void select_io_device(unsigned char devno) { outb(0x07, IOPORT); outb(devno, IOPORT+1); }

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/* write to the control register */
static inline void write_io_cr(unsigned char reg, unsigned char data) { outb(reg, IOPORT); outb(data, IOPORT+1); }

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/* read from the control register */
static inline char read_io_cr(unsigned char reg) { outb(reg, IOPORT); return inb(IOPORT+1); }

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/* -- Medium level functions ------------------------------------*/
static inline void gpio_bit12(unsigned char reg) { /* -- General Purpose I/O Bit 1.2 -- * Bit 0, In/Out: 0 = Output, 1 = Input * Bit 1, Polarity: 0 = No Invert, 1 = Invert * Bit 2, Group Enable Intr.: 0 = Disable, 1 = Enable * Bit 3/4, Function select: 00 = GPI/O, 01 = WDT, 10 = P17, * 11 = Either Edge Triggered Intr. 2 * Bit 5/6 (Reserved) * Bit 7, Output Type: 0 = Push Pull Bit, 1 = Open Drain */ write_io_cr(0xE2, reg); }

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alan coxalan cox15.26%150.00%
Total19100.00%2100.00%


static inline void gpio_bit13(unsigned char reg) { /* -- General Purpose I/O Bit 1.3 -- * Bit 0, In/Out: 0 = Output, 1 = Input * Bit 1, Polarity: 0 = No Invert, 1 = Invert * Bit 2, Group Enable Intr.: 0 = Disable, 1 = Enable * Bit 3, Function select: 0 = GPI/O, 1 = LED * Bit 4-6 (Reserved) * Bit 7, Output Type: 0 = Push Pull Bit, 1 = Open Drain */ write_io_cr(0xE3, reg); }

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alan coxalan cox15.26%150.00%
Total19100.00%2100.00%


static inline void wdt_timer_units(unsigned char new_units) { /* -- Watchdog timer units -- * Bit 0-6 (Reserved) * Bit 7, WDT Time-out Value Units Select * (0 = Minutes, 1 = Seconds) */ write_io_cr(0xF1, new_units); }

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static inline void wdt_timeout_value(unsigned char new_timeout) { /* -- Watchdog Timer Time-out Value -- * Bit 0-7 Binary coded units (0=Disabled, 1..255) */ write_io_cr(0xF2, new_timeout); }

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sven anderssven anders1894.74%150.00%
alan coxalan cox15.26%150.00%
Total19100.00%2100.00%


static inline void wdt_timer_conf(unsigned char conf) { /* -- Watchdog timer configuration -- * Bit 0 Joystick enable: 0* = No Reset, 1 = Reset WDT upon * Gameport I/O * Bit 1 Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr. * Bit 2 Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr * Bit 3 Reset the timer * (Wrong in SMsC documentation? Given as: PowerLED Timout * Enabled) * Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled, * 0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15) */ write_io_cr(0xF3, conf); }

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sven anderssven anders1894.74%150.00%
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Total19100.00%2100.00%


static inline void wdt_timer_ctrl(unsigned char reg) { /* -- Watchdog timer control -- * Bit 0 Status Bit: 0 = Timer counting, 1 = Timeout occurred * Bit 1 Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz * Bit 2 Force Timeout: 1 = Forces WD timeout event (self-cleaning) * Bit 3 P20 Force Timeout enabled: * 0 = P20 activity does not generate the WD timeout event * 1 = P20 Allows rising edge of P20, from the keyboard * controller, to force the WD timeout event. * Bit 4 (Reserved) * -- Soft power management -- * Bit 5 Stop Counter: 1 = Stop software power down counter * set via register 0xB8, (self-cleaning) * (Upon read: 0 = Counter running, 1 = Counter stopped) * Bit 6 Restart Counter: 1 = Restart software power down counter * set via register 0xB8, (self-cleaning) * Bit 7 SPOFF: 1 = Force software power down (self-cleaning) */ write_io_cr(0xF4, reg); }

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sven anderssven anders1894.74%150.00%
lucas de marchilucas de marchi15.26%150.00%
Total19100.00%2100.00%

/* -- Higher level functions ------------------------------------*/ /* initialize watchdog */
static void wb_smsc_wdt_initialize(void) { unsigned char old; spin_lock(&io_lock); open_io_config(); select_io_device(IODEV_NO); /* enable the watchdog */ gpio_bit13(0x08); /* Select pin 80 = LED not GPIO */ gpio_bit12(0x0A); /* Set pin 79 = WDT not GPIO/Output/Polarity=Invert */ /* disable the timeout */ wdt_timeout_value(0); /* reset control register */ wdt_timer_ctrl(0x00); /* reset configuration register */ wdt_timer_conf(0x00); /* read old (timer units) register */ old = read_io_cr(0xF1) & 0x7F; if (unit == UNIT_SECOND) old |= 0x80; /* set to seconds */ /* set the watchdog timer units */ wdt_timer_units(old); close_io_config(); spin_unlock(&io_lock); }

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sven anderssven anders7277.42%133.33%
wim van sebroeckwim van sebroeck1212.90%133.33%
alan coxalan cox99.68%133.33%
Total93100.00%3100.00%

/* shutdown the watchdog */
static void wb_smsc_wdt_shutdown(void) { spin_lock(&io_lock); open_io_config(); select_io_device(IODEV_NO); /* disable the watchdog */ gpio_bit13(0x09); gpio_bit12(0x09); /* reset watchdog config register */ wdt_timer_conf(0x00); /* reset watchdog control register */ wdt_timer_ctrl(0x00); /* disable timeout */ wdt_timeout_value(0x00); close_io_config(); spin_unlock(&io_lock); }

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sven anderssven anders4473.33%133.33%
wim van sebroeckwim van sebroeck1220.00%133.33%
alan coxalan cox46.67%133.33%
Total60100.00%3100.00%

/* set timeout => enable watchdog */
static void wb_smsc_wdt_set_timeout(unsigned char new_timeout) { spin_lock(&io_lock); open_io_config(); select_io_device(IODEV_NO); /* set Power LED to blink, if we enable the timeout */ wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02); /* set timeout value */ wdt_timeout_value(new_timeout); close_io_config(); spin_unlock(&io_lock); }

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sven anderssven anders3973.58%133.33%
wim van sebroeckwim van sebroeck1222.64%133.33%
alan coxalan cox23.77%133.33%
Total53100.00%3100.00%

/* get timeout */
static unsigned char wb_smsc_wdt_get_timeout(void) { unsigned char set_timeout; spin_lock(&io_lock); open_io_config(); select_io_device(IODEV_NO); set_timeout = read_io_cr(0xF2); close_io_config(); spin_unlock(&io_lock); return set_timeout; }

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sven anderssven anders3473.91%150.00%
wim van sebroeckwim van sebroeck1226.09%150.00%
Total46100.00%2100.00%

/* disable watchdog */
static void wb_smsc_wdt_disable(void) { /* set the timeout to 0 to disable the watchdog */ wb_smsc_wdt_set_timeout(0); }

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sven anderssven anders1392.86%150.00%
alan coxalan cox17.14%150.00%
Total14100.00%2100.00%

/* enable watchdog by setting the current timeout */
static void wb_smsc_wdt_enable(void) { /* set the current timeout... */ wb_smsc_wdt_set_timeout(timeout); }

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sven anderssven anders1392.86%150.00%
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Total14100.00%2100.00%

/* reset the timer */
static void wb_smsc_wdt_reset_timer(void) { spin_lock(&io_lock); open_io_config(); select_io_device(IODEV_NO); /* reset the timer */ wdt_timeout_value(timeout); wdt_timer_conf(0x08); close_io_config(); spin_unlock(&io_lock); }

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sven anderssven anders2969.05%133.33%
wim van sebroeckwim van sebroeck1228.57%133.33%
alan coxalan cox12.38%133.33%
Total42100.00%3100.00%

/* return, if the watchdog is enabled (timeout is set...) */
static int wb_smsc_wdt_status(void) { return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING; }

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sven anderssven anders20100.00%1100.00%
Total20100.00%1100.00%

/* -- File operations -------------------------------------------*/ /* open => enable watchdog and set initial timeout */
static int wb_smsc_wdt_open(struct inode *inode, struct file *file) { /* /dev/watchdog can only be opened once */ if (test_and_set_bit(0, &timer_enabled)) return -EBUSY; if (nowayout) __module_get(THIS_MODULE); /* Reload and activate timer */ wb_smsc_wdt_enable(); pr_info("Watchdog enabled. Timeout set to %d %s\n", timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)"); return nonseekable_open(inode, file); }

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joe perchesjoe perches1115.94%133.33%
wim van sebroeckwim van sebroeck68.70%133.33%
Total69100.00%3100.00%

/* close => shut off the timer */
static int wb_smsc_wdt_release(struct inode *inode, struct file *file) { /* Shut off the timer. */ if (expect_close == 42) { wb_smsc_wdt_disable(); pr_info("Watchdog disabled, sleeping again...\n"); } else { pr_crit("Unexpected close, not stopping watchdog!\n"); wb_smsc_wdt_reset_timer(); } clear_bit(0, &timer_enabled); expect_close = 0; return 0; }

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sven anderssven anders4983.05%133.33%
wim van sebroeckwim van sebroeck610.17%133.33%
joe perchesjoe perches46.78%133.33%
Total59100.00%3100.00%

/* write => update the timer to keep the machine alive */
static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data, size_t len, loff_t *ppos) { /* See if we got the magic character 'V' and reload the timer */ if (len) { if (!nowayout) { size_t i; /* reset expect flag */ expect_close = 0; /* scan to see whether or not we got the magic character */ for (i = 0; i != len; i++) { char c; if (get_user(c, data + i)) return -EFAULT; if (c == 'V') expect_close = 42; } } /* someone wrote to us, we should reload the timer */ wb_smsc_wdt_reset_timer(); } return len; }

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sven anderssven anders9698.97%150.00%
alan coxalan cox11.03%150.00%
Total97100.00%2100.00%

/* ioctl => control interface */
static long wb_smsc_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { int new_timeout; union { struct watchdog_info __user *ident; int __user *i; } uarg; static const struct watchdog_info ident = { .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, .firmware_version = 0, .identity = "SMsC 37B787 Watchdog", }; uarg.i = (int __user *)arg; switch (cmd) { case WDIOC_GETSUPPORT: return copy_to_user(uarg.ident, &ident, sizeof(ident)) ? -EFAULT : 0; case WDIOC_GETSTATUS: return put_user(wb_smsc_wdt_status(), uarg.i); case WDIOC_GETBOOTSTATUS: return put_user(0, uarg.i); case WDIOC_SETOPTIONS: { int options, retval = -EINVAL; if (get_user(options, uarg.i)) return -EFAULT; if (options & WDIOS_DISABLECARD) { wb_smsc_wdt_disable(); retval = 0; } if (options & WDIOS_ENABLECARD) { wb_smsc_wdt_enable(); retval = 0; } return retval; } case WDIOC_KEEPALIVE: wb_smsc_wdt_reset_timer(); return 0; case WDIOC_SETTIMEOUT: if (get_user(new_timeout, uarg.i)) return -EFAULT; /* the API states this is given in secs */ if (unit == UNIT_MINUTE) new_timeout /= 60; if (new_timeout < 0 || new_timeout > MAX_TIMEOUT) return -EINVAL; timeout = new_timeout; wb_smsc_wdt_set_timeout(timeout); /* fall through and return the new timeout... */ case WDIOC_GETTIMEOUT: new_timeout = timeout; if (unit == UNIT_MINUTE) new_timeout *= 60; return put_user(new_timeout, uarg.i); default: return -ENOTTY; } }

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alan coxalan cox93.12%120.00%
Total288100.00%5100.00%

/* -- Notifier funtions -----------------------------------------*/
static int wb_smsc_wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused) { if (code == SYS_DOWN || code == SYS_HALT) { /* set timeout to 0, to avoid possible race-condition */ timeout = 0; wb_smsc_wdt_disable(); } return NOTIFY_DONE; }

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alan coxalan cox12.38%150.00%
Total42100.00%2100.00%

/* -- Module's structures ---------------------------------------*/ static const struct file_operations wb_smsc_wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .write = wb_smsc_wdt_write, .unlocked_ioctl = wb_smsc_wdt_ioctl, .open = wb_smsc_wdt_open, .release = wb_smsc_wdt_release, }; static struct notifier_block wb_smsc_wdt_notifier = { .notifier_call = wb_smsc_wdt_notify_sys, }; static struct miscdevice wb_smsc_wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &wb_smsc_wdt_fops, }; /* -- Module init functions -------------------------------------*/ /* module's "constructor" */
static int __init wb_smsc_wdt_init(void) { int ret; pr_info("SMsC 37B787 watchdog component driver " VERSION " initialising...\n"); if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) { pr_err("Unable to register IO port %#x\n", IOPORT); ret = -EBUSY; goto out_pnp; } /* set new maximum, if it's too big */ if (timeout > MAX_TIMEOUT) timeout = MAX_TIMEOUT; /* init the watchdog timer */ wb_smsc_wdt_initialize(); ret = register_reboot_notifier(&wb_smsc_wdt_notifier); if (ret) { pr_err("Unable to register reboot notifier err = %d\n", ret); goto out_io; } ret = misc_register(&wb_smsc_wdt_miscdev); if (ret) { pr_err("Unable to register miscdev on minor %d\n", WATCHDOG_MINOR); goto out_rbt; } /* output info */ pr_info("Timeout set to %d %s\n", timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)"); pr_info("Watchdog initialized and sleeping (nowayout=%d)...\n", nowayout); out_clean: return ret; out_rbt: unregister_reboot_notifier(&wb_smsc_wdt_notifier); out_io: release_region(IOPORT, IOPORT_SIZE); out_pnp: goto out_clean; }

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wim van sebroeckwim van sebroeck137.98%125.00%
alan coxalan cox31.84%125.00%
Total163100.00%4100.00%

/* module's "destructor" */
static void __exit wb_smsc_wdt_exit(void) { /* Stop the timer before we leave */ if (!nowayout) { wb_smsc_wdt_shutdown(); pr_info("Watchdog disabled\n"); } misc_deregister(&wb_smsc_wdt_miscdev); unregister_reboot_notifier(&wb_smsc_wdt_notifier); release_region(IOPORT, IOPORT_SIZE); pr_info("SMsC 37B787 watchdog component driver removed\n"); }

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joe perchesjoe perches510.20%150.00%
Total49100.00%2100.00%

module_init(wb_smsc_wdt_init); module_exit(wb_smsc_wdt_exit); MODULE_AUTHOR("Sven Anders <anders@anduras.de>"); MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version " VERSION ")"); MODULE_LICENSE("GPL"); #ifdef SMSC_SUPPORT_MINUTES module_param(unit, int, 0); MODULE_PARM_DESC(unit, "set unit to use, 0=seconds or 1=minutes, default is 0"); #endif module_param(timeout, int, 0); MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60"); module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

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sven anderssven anders139083.79%18.33%
wim van sebroeckwim van sebroeck17110.31%541.67%
joe perchesjoe perches513.07%18.33%
alan coxalan cox402.41%18.33%
alexey dobriyanalexey dobriyan40.24%18.33%
arjan van de venarjan van de ven10.06%18.33%
paul bollepaul bolle10.06%18.33%
lucas de marchilucas de marchi10.06%18.33%
Total1659100.00%12100.00%
Directory: drivers/watchdog
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