imx6 WatchDog驱动程序及测试例程
来源:互联网 发布:ubuntu lnmp环境搭建 编辑:程序博客网 时间:2024/05/16 05:07
/*
* Watchdog driver for IMX2 and later processors
*
* Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de>
*
* some parts adapted by similar drivers from Darius Augulis and Vladimir
* Zapolskiy, additional improvements by Wim Van Sebroeck.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* NOTE: MX1 has a slightly different Watchdog than MX2 and later:
*
* MX1: MX2+:
* ---- -----
* Registers: 32-bit 16-bit
* Stopable timer: Yes No
* Need to enable clk: No Yes
* Halt on suspend: Manual Can be automatic
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/clk.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>
#include <mach/hardware.h>
#include <mach/irqs.h>
#define DRIVER_NAME "imx2-wdt"
//定义一些宏,方便使用。
#define IMX2_WDT_WCR 0x00 /* Control Register */
#define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */
#define IMX2_WDT_WCR_WRE (1 << 3) /* -> WDOG Reset Enable */
#define IMX2_WDT_WCR_WDE (1 << 2) /* -> Watchdog Enable */
#define IMX2_WDT_WCR_WDZST (1 << 0) /* -> Watchdog timer Suspend */
#define IMX2_WDT_WSR 0x02 /* Service Register */
#define IMX2_WDT_SEQ1 0x5555 /* -> service sequence 1 */
#define IMX2_WDT_SEQ2 0xAAAA /* -> service sequence 2 */
#define IMX2_WDT_WICR 0x06 /*Interrupt Control Register*/
#define IMX2_WDT_WICR_WIE (1 << 15) /* -> Interrupt Enable */
#define IMX2_WDT_WICR_WTIS (1 << 14) /* -> Interrupt Status */
#define IMX2_WDT_WICR_WICT (0xFF << 0) /* -> Watchdog Interrupt Timeout Field */
#define IMX2_WDT_MAX_TIME 128
#define IMX2_WDT_DEFAULT_TIME 60 /* in seconds */
#define WDOG_SEC_TO_COUNT(s) ((s * 2 - 1) << 8)
#define WDOG_SEC_TO_PRECOUNT(s) (s * 2) /* set WDOG pre timeout count*/
#define IMX2_WDT_STATUS_OPEN 0
#define IMX2_WDT_STATUS_STARTED 1
#define IMX2_WDT_EXPECT_CLOSE 2
static struct {
struct clk *clk;
void __iomem *base;
unsigned timeout;
unsigned pretimeout;
unsigned long status;
struct timer_list timer; /* Pings the watchdog when closed */
} imx2_wdt;
static struct miscdevice imx2_wdt_miscdev;
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);//内核参数
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
module_param(timeout, uint, 0);//内核参数
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
__MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
//这个结构体很重要,描述了驱动所支持的操作。
//应用程序使用ioctl GETSUPPORT调用来获取这个结构体
//然后在应用层使用位与检测每一位的功能。
static const struct watchdog_info imx2_wdt_info = {
.identity = "imx2+ watchdog",
.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_PRETIMEOUT,
//支持喂狗
//支持设置超时时间
//支持魔幻字符关闭(关闭只能使用特殊字符)
//支持预超时设置
};
static inline void imx2_wdt_setup(void)
{
u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
/* Suspend watch dog timer in low power mode, write once-only */
val |= IMX2_WDT_WCR_WDZST;
/* Strip the old watchdog Time-Out value */
val &= ~IMX2_WDT_WCR_WT;
/* Generate reset if WDOG times out */
val &= ~IMX2_WDT_WCR_WRE;
/* Keep Watchdog Disabled */
val &= ~IMX2_WDT_WCR_WDE;
/* Set the watchdog's Time-Out value */
val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
/* enable the watchdog */
val |= IMX2_WDT_WCR_WDE;
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
}
//喂狗操作,根据手册就是往寄存器顺序写入0x5555,0xaaaa.
static inline void imx2_wdt_ping(void)
{
__raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
__raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
}
static void imx2_wdt_timer_ping(unsigned long arg)
{
/* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
imx2_wdt_ping();
//启动定时器,用于喂狗
mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
}
static void imx2_wdt_start(void)
{
if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
/* at our first start we enable clock and do initialisations */
clk_enable(imx2_wdt.clk);
imx2_wdt_setup();
} else /* delete the timer that pings the watchdog after close */
del_timer_sync(&imx2_wdt.timer);
/* Watchdog is enabled - time to reload the timeout value */
imx2_wdt_ping();
}
static void imx2_wdt_stop(void)
{
/* we don't need a clk_disable, it cannot be disabled once started.
* We use a timer to ping the watchdog while /dev/watchdog is closed */
imx2_wdt_timer_ping(0);
}
//设置超时时间,根本上就是读写寄存器。
static void imx2_wdt_set_timeout(int new_timeout)
{
u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
/* set the new timeout value in the WSR */
val &= ~IMX2_WDT_WCR_WT;
val |= WDOG_SEC_TO_COUNT(new_timeout);
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
}
static int imx2_wdt_check_pretimeout_set(void)
{
u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WICR);
return (val & IMX2_WDT_WICR_WIE) ? 1 : 0;
}
static void imx2_wdt_set_pretimeout(int new_timeout)
{
u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WICR);
/* set the new pre-timeout value in the WSR */
val &= ~IMX2_WDT_WICR_WICT;
val |= WDOG_SEC_TO_PRECOUNT(new_timeout);
if (!imx2_wdt_check_pretimeout_set())
val |= IMX2_WDT_WICR_WIE; /*enable*/
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WICR);
}
//预超时时间往往会引发一个中断
//例:
//如果设置超时时间为60秒,预超时为10秒
//则在50秒时会引发一个预超时中断,通过用于记录日志,刷新flash.
static irqreturn_t imx2_wdt_isr(int irq, void *dev_id)
{
//读取状态寄存器,因为中断可能是共享的,有好几个中断源能引发同一个中断
//所以我们需要知道是哪个源引起来的。
//__raw_readw/__raw_writew与readl/writel是有区别的。
//readl/writel是小端操作,__raw_readw/writew是native操作。
u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WICR);
if (val & IMX2_WDT_WICR_WTIS) {
/*clear interrupt status bit*/
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WICR);
printk(KERN_INFO "watchdog pre-timeout:%d, %d Seconds remained\n", \
imx2_wdt.pretimeout, imx2_wdt.timeout-imx2_wdt.pretimeout);
}
return IRQ_HANDLED;
}
//驱动确保这个特殊的设备只能打开1次。
//设备文件被打开则启动看门狗
//如果应用不喂狗则超时复位
static int imx2_wdt_open(struct inode *inode, struct file *file)
{
//set_bit和test_and_set_bit是内核定义的位操作函数
//原型为:set_bit(nr,addr):将addr的第nr位设置为1
//test_and_set_bit(nr,addr)将addr的第nr位设置为1并返回它原来的值
if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
return -EBUSY;
imx2_wdt_start();
return nonseekable_open(inode, file);
}
static int imx2_wdt_close(struct inode *inode, struct file *file)
{
if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
imx2_wdt_stop();
else {
dev_crit(imx2_wdt_miscdev.parent,
"Unexpected close: Expect reboot!\n");
imx2_wdt_ping();
}
//clear_bit是内核定义的位操作函数,原型为clear_bit(nr,addr)
//将addr的第nr位清0.
clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
return 0;
}
static long imx2_wdt_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: //应用获取驱动支持的信息,看来就是拷贝了一个结构体到用户空间。
//应该是这个结构体中包含了所支持的操作吧?
return copy_to_user(argp, &imx2_wdt_info,
sizeof(struct watchdog_info)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p); //难道这是不支持,直接返回0???
case WDIOC_KEEPALIVE: //应用程序调用这个ioctl来喂狗。
imx2_wdt_ping();//喂狗函数
return 0;
case WDIOC_SETTIMEOUT://设置超时时间
if (get_user(new_value, p))//get_user应该跟copy_from_user()差不多的功能。
return -EFAULT;
if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
return -EINVAL;
imx2_wdt_set_timeout(new_value); //将该值设置到寄存器中
imx2_wdt.timeout = new_value; //更新结构体中保存的值
imx2_wdt_ping();
/* Fallthrough to return current value */
case WDIOC_GETTIMEOUT: //获取超时值,直接返回保存在结构体中的值。
return put_user(imx2_wdt.timeout, p);
case WDIOC_SETPRETIMEOUT: // 设置预超时值
if (get_user(new_value, p))
return -EFAULT;
if ((new_value < 0) || (new_value >= imx2_wdt.timeout))
return -EINVAL;
imx2_wdt_set_pretimeout(new_value);
imx2_wdt.pretimeout = new_value; //保存起来,以便一会儿用户获取时直接返回
case WDIOC_GETPRETIMEOUT: //获取预超时值
return put_user(imx2_wdt.pretimeout, p);
default:
return -ENOTTY; //这应该是不支持的操作吧
}
}
static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
size_t i;
char c;
if (len == 0) /* Can we see this even ? */
return 0;
clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
/* scan to see whether or not we got the magic character */
for (i = 0; i != len; i++) {
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V') //如果这一串数据中有魔幻字符V则表示用户期望关闭看门狗
//但是这里只是设置了一个标志位。具体在哪里关闭呢?
//内核中老是喜欢用set_bit/clear_bit来位来保存信息为了节省内存吗?
set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
}
imx2_wdt_ping();
return len;
}
//具体的操作指针
static const struct file_operations imx2_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,//这个函数应该是内核提供的,表示这个驱动不支持lseek操作。
.unlocked_ioctl = imx2_wdt_ioctl,
.open = imx2_wdt_open,
.release = imx2_wdt_close,
.write = imx2_wdt_write,
};
//混杂设备属于一类设备,所有混杂设备都拥有同一个主设备号
//根据次设备号来区分
//使用传统的文件结构指针
static struct miscdevice imx2_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &imx2_wdt_fops, //函数指针
};
//驱动注册时使用遍历设备总线,根据驱动名称查找到设备名称一致的设备
//若一致则调用驱动的这个probe()函数并将找到的设备作为参数传输进来!
static int __init imx2_wdt_probe(struct platform_device *pdev)
{
int ret;
int res_size;
int irq;
struct resource *res;
//内核的这个定义很奇特:驱动跟设备分开,驱动向设备要数据,这里请求的内存地址!
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(&pdev->dev, "can't get device resources\n");
return -ENODEV;
}
//这里是驱动向设备要中断号!
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(&pdev->dev, "can't get device irq number\n");
return -ENODEV;
}
res_size = resource_size(res);
//向内核注册这段地址,说这段地址已经有人在用了,别的模块请不要使用。
if (!devm_request_mem_region(&pdev->dev, res->start, res_size,
res->name)) {
dev_err(&pdev->dev, "can't allocate %d bytes at %d address\n",
res_size, res->start);
return -ENOMEM;
}
//物理地址映射到虚拟地址,以便进行读写操作
imx2_wdt.base = devm_ioremap_nocache(&pdev->dev, res->start, res_size);
if (!imx2_wdt.base) {
dev_err(&pdev->dev, "ioremap failed\n");
return -ENOMEM;
}
//这里不明白?
//这是驱动从哪里提取时钟呢?驱动根据一个设备结构体就能得到时钟?
//难道时钟也有时钟链表,挂接在链表上,根据设备或名称来驱动??
imx2_wdt.clk = clk_get(&pdev->dev, NULL);
if (IS_ERR(imx2_wdt.clk)) {
dev_err(&pdev->dev, "can't get Watchdog clock\n");
return PTR_ERR(imx2_wdt.clk);
}
//这里是申请中断了
ret = request_irq(irq, imx2_wdt_isr, 0, pdev->name, NULL);
if (ret) {
dev_err(&pdev->dev, "can't claim irq %d\n", irq);
goto fail;
}
imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
if (imx2_wdt.timeout != timeout)
dev_warn(&pdev->dev, "Initial timeout out of range! "
"Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
//这应该是启动定时器,定时喂狗操作!
setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
imx2_wdt_miscdev.parent = &pdev->dev;
//注册混杂设备,看门狗没有分类了吗?
ret = misc_register(&imx2_wdt_miscdev);
if (ret)
goto fail;
dev_info(&pdev->dev,
"IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
imx2_wdt.timeout, nowayout);
return 0;
fail:
imx2_wdt_miscdev.parent = NULL;
clk_put(imx2_wdt.clk);
return ret;
}
static int __exit imx2_wdt_remove(struct platform_device *pdev)
{
misc_deregister(&imx2_wdt_miscdev);
if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
del_timer_sync(&imx2_wdt.timer);
dev_crit(imx2_wdt_miscdev.parent,
"Device removed: Expect reboot!\n");
} else
clk_put(imx2_wdt.clk);
imx2_wdt_miscdev.parent = NULL;
return 0;
}
static void imx2_wdt_shutdown(struct platform_device *pdev)
{
if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
/* we are running, we need to delete the timer but will give
* max timeout before reboot will take place */
del_timer_sync(&imx2_wdt.timer);
imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
imx2_wdt_ping();
dev_crit(imx2_wdt_miscdev.parent,
"Device shutdown: Expect reboot!\n");
}
}
//看门狗属于SoC设备,所以这里使用平台驱动实现。
//很奇怪这里没有probe域的定义,可能是因为下面使用了platform_driver_probe()进行了注册!
static struct platform_driver imx2_wdt_driver = {
.remove = __exit_p(imx2_wdt_remove),
.shutdown = imx2_wdt_shutdown,//驱动移除时会调用的函数
.driver = {
.name = DRIVER_NAME,//驱动名称必须跟设备名称一致才能probe成功!
.owner = THIS_MODULE,
},
};
static int __init imx2_wdt_init(void)
{
//这里的platform_driver_probe()跟platform_driver_register()是一样的
//唯一的区别是它不能再被以后其他的设备probe了
//也就是说这个driver只能跟一个device绑定!
return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
}
module_init(imx2_wdt_init);
static void __exit imx2_wdt_exit(void)
{
platform_driver_unregister(&imx2_wdt_driver);
}
module_exit(imx2_wdt_exit);
MODULE_AUTHOR("Wolfram Sang");
MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:" DRIVER_NAME);
下面是应用程序,更简单了,基本流程就是open设备文件,此时驱动就启动看门狗了。
然后再使用write()或ioctl()来触发驱动喂狗。
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <linux/watchdog.h>
#include <sys/ioctl.h>
#include <unistd.h>
void help_info(void);
int main(int argc, const char *argv[])
{
int fd, timeout, sleep_sec, test;
if (argc < 2) {
help_info();
return 1;
}
timeout = atoi(argv[1]);
sleep_sec = atoi(argv[2]);
if (sleep_sec <= 0) {
sleep_sec = 1;
printf("correct 0 or negative sleep time to %d seconds\n",
sleep_sec);
}
test = atoi(argv[3]);
printf("Starting wdt_driver (timeout: %d, sleep: %d, test: %s)\n",
timeout, sleep_sec, (test == 0) ? "ioctl" : "write");
fd = open("/dev/watchdog", O_WRONLY);
if (fd == -1) {
perror("watchdog");
exit(1);
}
printf("Trying to set timeout value=%d seconds\n", timeout);
ioctl(fd, WDIOC_SETTIMEOUT, &timeout);
printf("The actual timeout was set to %d seconds\n", timeout);
ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
printf("Now reading back -- The timeout is %d seconds\n", timeout);
while (1) {
if (test == 0) {
ioctl(fd, WDIOC_KEEPALIVE, 0); //使用ioctl()方法喂狗
} else {
write(fd, "\0", 1); //使用write()方法喂狗。
}
sleep(sleep_sec);
}
return 0;
}
void help_info(void)
{
printf("Usage: wdt_driver_test <timeout> <sleep> <test>\n");
printf(" timeout: value in seconds to cause wdt timeout/reset\n");
printf(" sleep: value in seconds to service the wdt\n");
printf(" test: 0 - Service wdt with ioctl(), 1 - with write()\n");
}
* Watchdog driver for IMX2 and later processors
*
* Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de>
*
* some parts adapted by similar drivers from Darius Augulis and Vladimir
* Zapolskiy, additional improvements by Wim Van Sebroeck.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* NOTE: MX1 has a slightly different Watchdog than MX2 and later:
*
* MX1: MX2+:
* ---- -----
* Registers: 32-bit 16-bit
* Stopable timer: Yes No
* Need to enable clk: No Yes
* Halt on suspend: Manual Can be automatic
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/clk.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>
#include <mach/hardware.h>
#include <mach/irqs.h>
#define DRIVER_NAME "imx2-wdt"
//定义一些宏,方便使用。
#define IMX2_WDT_WCR 0x00 /* Control Register */
#define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */
#define IMX2_WDT_WCR_WRE (1 << 3) /* -> WDOG Reset Enable */
#define IMX2_WDT_WCR_WDE (1 << 2) /* -> Watchdog Enable */
#define IMX2_WDT_WCR_WDZST (1 << 0) /* -> Watchdog timer Suspend */
#define IMX2_WDT_WSR 0x02 /* Service Register */
#define IMX2_WDT_SEQ1 0x5555 /* -> service sequence 1 */
#define IMX2_WDT_SEQ2 0xAAAA /* -> service sequence 2 */
#define IMX2_WDT_WICR 0x06 /*Interrupt Control Register*/
#define IMX2_WDT_WICR_WIE (1 << 15) /* -> Interrupt Enable */
#define IMX2_WDT_WICR_WTIS (1 << 14) /* -> Interrupt Status */
#define IMX2_WDT_WICR_WICT (0xFF << 0) /* -> Watchdog Interrupt Timeout Field */
#define IMX2_WDT_MAX_TIME 128
#define IMX2_WDT_DEFAULT_TIME 60 /* in seconds */
#define WDOG_SEC_TO_COUNT(s) ((s * 2 - 1) << 8)
#define WDOG_SEC_TO_PRECOUNT(s) (s * 2) /* set WDOG pre timeout count*/
#define IMX2_WDT_STATUS_OPEN 0
#define IMX2_WDT_STATUS_STARTED 1
#define IMX2_WDT_EXPECT_CLOSE 2
static struct {
struct clk *clk;
void __iomem *base;
unsigned timeout;
unsigned pretimeout;
unsigned long status;
struct timer_list timer; /* Pings the watchdog when closed */
} imx2_wdt;
static struct miscdevice imx2_wdt_miscdev;
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);//内核参数
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
module_param(timeout, uint, 0);//内核参数
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
__MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
//这个结构体很重要,描述了驱动所支持的操作。
//应用程序使用ioctl GETSUPPORT调用来获取这个结构体
//然后在应用层使用位与检测每一位的功能。
static const struct watchdog_info imx2_wdt_info = {
.identity = "imx2+ watchdog",
.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_PRETIMEOUT,
//支持喂狗
//支持设置超时时间
//支持魔幻字符关闭(关闭只能使用特殊字符)
//支持预超时设置
};
static inline void imx2_wdt_setup(void)
{
u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
/* Suspend watch dog timer in low power mode, write once-only */
val |= IMX2_WDT_WCR_WDZST;
/* Strip the old watchdog Time-Out value */
val &= ~IMX2_WDT_WCR_WT;
/* Generate reset if WDOG times out */
val &= ~IMX2_WDT_WCR_WRE;
/* Keep Watchdog Disabled */
val &= ~IMX2_WDT_WCR_WDE;
/* Set the watchdog's Time-Out value */
val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
/* enable the watchdog */
val |= IMX2_WDT_WCR_WDE;
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
}
//喂狗操作,根据手册就是往寄存器顺序写入0x5555,0xaaaa.
static inline void imx2_wdt_ping(void)
{
__raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
__raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
}
static void imx2_wdt_timer_ping(unsigned long arg)
{
/* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
imx2_wdt_ping();
//启动定时器,用于喂狗
mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
}
static void imx2_wdt_start(void)
{
if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
/* at our first start we enable clock and do initialisations */
clk_enable(imx2_wdt.clk);
imx2_wdt_setup();
} else /* delete the timer that pings the watchdog after close */
del_timer_sync(&imx2_wdt.timer);
/* Watchdog is enabled - time to reload the timeout value */
imx2_wdt_ping();
}
static void imx2_wdt_stop(void)
{
/* we don't need a clk_disable, it cannot be disabled once started.
* We use a timer to ping the watchdog while /dev/watchdog is closed */
imx2_wdt_timer_ping(0);
}
//设置超时时间,根本上就是读写寄存器。
static void imx2_wdt_set_timeout(int new_timeout)
{
u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
/* set the new timeout value in the WSR */
val &= ~IMX2_WDT_WCR_WT;
val |= WDOG_SEC_TO_COUNT(new_timeout);
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
}
static int imx2_wdt_check_pretimeout_set(void)
{
u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WICR);
return (val & IMX2_WDT_WICR_WIE) ? 1 : 0;
}
static void imx2_wdt_set_pretimeout(int new_timeout)
{
u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WICR);
/* set the new pre-timeout value in the WSR */
val &= ~IMX2_WDT_WICR_WICT;
val |= WDOG_SEC_TO_PRECOUNT(new_timeout);
if (!imx2_wdt_check_pretimeout_set())
val |= IMX2_WDT_WICR_WIE; /*enable*/
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WICR);
}
//预超时时间往往会引发一个中断
//例:
//如果设置超时时间为60秒,预超时为10秒
//则在50秒时会引发一个预超时中断,通过用于记录日志,刷新flash.
static irqreturn_t imx2_wdt_isr(int irq, void *dev_id)
{
//读取状态寄存器,因为中断可能是共享的,有好几个中断源能引发同一个中断
//所以我们需要知道是哪个源引起来的。
//__raw_readw/__raw_writew与readl/writel是有区别的。
//readl/writel是小端操作,__raw_readw/writew是native操作。
u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WICR);
if (val & IMX2_WDT_WICR_WTIS) {
/*clear interrupt status bit*/
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WICR);
printk(KERN_INFO "watchdog pre-timeout:%d, %d Seconds remained\n", \
imx2_wdt.pretimeout, imx2_wdt.timeout-imx2_wdt.pretimeout);
}
return IRQ_HANDLED;
}
//驱动确保这个特殊的设备只能打开1次。
//设备文件被打开则启动看门狗
//如果应用不喂狗则超时复位
static int imx2_wdt_open(struct inode *inode, struct file *file)
{
//set_bit和test_and_set_bit是内核定义的位操作函数
//原型为:set_bit(nr,addr):将addr的第nr位设置为1
//test_and_set_bit(nr,addr)将addr的第nr位设置为1并返回它原来的值
if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
return -EBUSY;
imx2_wdt_start();
return nonseekable_open(inode, file);
}
static int imx2_wdt_close(struct inode *inode, struct file *file)
{
if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
imx2_wdt_stop();
else {
dev_crit(imx2_wdt_miscdev.parent,
"Unexpected close: Expect reboot!\n");
imx2_wdt_ping();
}
//clear_bit是内核定义的位操作函数,原型为clear_bit(nr,addr)
//将addr的第nr位清0.
clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
return 0;
}
static long imx2_wdt_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: //应用获取驱动支持的信息,看来就是拷贝了一个结构体到用户空间。
//应该是这个结构体中包含了所支持的操作吧?
return copy_to_user(argp, &imx2_wdt_info,
sizeof(struct watchdog_info)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p); //难道这是不支持,直接返回0???
case WDIOC_KEEPALIVE: //应用程序调用这个ioctl来喂狗。
imx2_wdt_ping();//喂狗函数
return 0;
case WDIOC_SETTIMEOUT://设置超时时间
if (get_user(new_value, p))//get_user应该跟copy_from_user()差不多的功能。
return -EFAULT;
if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
return -EINVAL;
imx2_wdt_set_timeout(new_value); //将该值设置到寄存器中
imx2_wdt.timeout = new_value; //更新结构体中保存的值
imx2_wdt_ping();
/* Fallthrough to return current value */
case WDIOC_GETTIMEOUT: //获取超时值,直接返回保存在结构体中的值。
return put_user(imx2_wdt.timeout, p);
case WDIOC_SETPRETIMEOUT: // 设置预超时值
if (get_user(new_value, p))
return -EFAULT;
if ((new_value < 0) || (new_value >= imx2_wdt.timeout))
return -EINVAL;
imx2_wdt_set_pretimeout(new_value);
imx2_wdt.pretimeout = new_value; //保存起来,以便一会儿用户获取时直接返回
case WDIOC_GETPRETIMEOUT: //获取预超时值
return put_user(imx2_wdt.pretimeout, p);
default:
return -ENOTTY; //这应该是不支持的操作吧
}
}
static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
size_t i;
char c;
if (len == 0) /* Can we see this even ? */
return 0;
clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
/* scan to see whether or not we got the magic character */
for (i = 0; i != len; i++) {
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V') //如果这一串数据中有魔幻字符V则表示用户期望关闭看门狗
//但是这里只是设置了一个标志位。具体在哪里关闭呢?
//内核中老是喜欢用set_bit/clear_bit来位来保存信息为了节省内存吗?
set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
}
imx2_wdt_ping();
return len;
}
//具体的操作指针
static const struct file_operations imx2_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,//这个函数应该是内核提供的,表示这个驱动不支持lseek操作。
.unlocked_ioctl = imx2_wdt_ioctl,
.open = imx2_wdt_open,
.release = imx2_wdt_close,
.write = imx2_wdt_write,
};
//混杂设备属于一类设备,所有混杂设备都拥有同一个主设备号
//根据次设备号来区分
//使用传统的文件结构指针
static struct miscdevice imx2_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &imx2_wdt_fops, //函数指针
};
//驱动注册时使用遍历设备总线,根据驱动名称查找到设备名称一致的设备
//若一致则调用驱动的这个probe()函数并将找到的设备作为参数传输进来!
static int __init imx2_wdt_probe(struct platform_device *pdev)
{
int ret;
int res_size;
int irq;
struct resource *res;
//内核的这个定义很奇特:驱动跟设备分开,驱动向设备要数据,这里请求的内存地址!
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(&pdev->dev, "can't get device resources\n");
return -ENODEV;
}
//这里是驱动向设备要中断号!
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(&pdev->dev, "can't get device irq number\n");
return -ENODEV;
}
res_size = resource_size(res);
//向内核注册这段地址,说这段地址已经有人在用了,别的模块请不要使用。
if (!devm_request_mem_region(&pdev->dev, res->start, res_size,
res->name)) {
dev_err(&pdev->dev, "can't allocate %d bytes at %d address\n",
res_size, res->start);
return -ENOMEM;
}
//物理地址映射到虚拟地址,以便进行读写操作
imx2_wdt.base = devm_ioremap_nocache(&pdev->dev, res->start, res_size);
if (!imx2_wdt.base) {
dev_err(&pdev->dev, "ioremap failed\n");
return -ENOMEM;
}
//这里不明白?
//这是驱动从哪里提取时钟呢?驱动根据一个设备结构体就能得到时钟?
//难道时钟也有时钟链表,挂接在链表上,根据设备或名称来驱动??
imx2_wdt.clk = clk_get(&pdev->dev, NULL);
if (IS_ERR(imx2_wdt.clk)) {
dev_err(&pdev->dev, "can't get Watchdog clock\n");
return PTR_ERR(imx2_wdt.clk);
}
//这里是申请中断了
ret = request_irq(irq, imx2_wdt_isr, 0, pdev->name, NULL);
if (ret) {
dev_err(&pdev->dev, "can't claim irq %d\n", irq);
goto fail;
}
imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
if (imx2_wdt.timeout != timeout)
dev_warn(&pdev->dev, "Initial timeout out of range! "
"Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
//这应该是启动定时器,定时喂狗操作!
setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
imx2_wdt_miscdev.parent = &pdev->dev;
//注册混杂设备,看门狗没有分类了吗?
ret = misc_register(&imx2_wdt_miscdev);
if (ret)
goto fail;
dev_info(&pdev->dev,
"IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
imx2_wdt.timeout, nowayout);
return 0;
fail:
imx2_wdt_miscdev.parent = NULL;
clk_put(imx2_wdt.clk);
return ret;
}
static int __exit imx2_wdt_remove(struct platform_device *pdev)
{
misc_deregister(&imx2_wdt_miscdev);
if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
del_timer_sync(&imx2_wdt.timer);
dev_crit(imx2_wdt_miscdev.parent,
"Device removed: Expect reboot!\n");
} else
clk_put(imx2_wdt.clk);
imx2_wdt_miscdev.parent = NULL;
return 0;
}
static void imx2_wdt_shutdown(struct platform_device *pdev)
{
if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
/* we are running, we need to delete the timer but will give
* max timeout before reboot will take place */
del_timer_sync(&imx2_wdt.timer);
imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
imx2_wdt_ping();
dev_crit(imx2_wdt_miscdev.parent,
"Device shutdown: Expect reboot!\n");
}
}
//看门狗属于SoC设备,所以这里使用平台驱动实现。
//很奇怪这里没有probe域的定义,可能是因为下面使用了platform_driver_probe()进行了注册!
static struct platform_driver imx2_wdt_driver = {
.remove = __exit_p(imx2_wdt_remove),
.shutdown = imx2_wdt_shutdown,//驱动移除时会调用的函数
.driver = {
.name = DRIVER_NAME,//驱动名称必须跟设备名称一致才能probe成功!
.owner = THIS_MODULE,
},
};
static int __init imx2_wdt_init(void)
{
//这里的platform_driver_probe()跟platform_driver_register()是一样的
//唯一的区别是它不能再被以后其他的设备probe了
//也就是说这个driver只能跟一个device绑定!
return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
}
module_init(imx2_wdt_init);
static void __exit imx2_wdt_exit(void)
{
platform_driver_unregister(&imx2_wdt_driver);
}
module_exit(imx2_wdt_exit);
MODULE_AUTHOR("Wolfram Sang");
MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:" DRIVER_NAME);
下面是应用程序,更简单了,基本流程就是open设备文件,此时驱动就启动看门狗了。
然后再使用write()或ioctl()来触发驱动喂狗。
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <linux/watchdog.h>
#include <sys/ioctl.h>
#include <unistd.h>
void help_info(void);
int main(int argc, const char *argv[])
{
int fd, timeout, sleep_sec, test;
if (argc < 2) {
help_info();
return 1;
}
timeout = atoi(argv[1]);
sleep_sec = atoi(argv[2]);
if (sleep_sec <= 0) {
sleep_sec = 1;
printf("correct 0 or negative sleep time to %d seconds\n",
sleep_sec);
}
test = atoi(argv[3]);
printf("Starting wdt_driver (timeout: %d, sleep: %d, test: %s)\n",
timeout, sleep_sec, (test == 0) ? "ioctl" : "write");
fd = open("/dev/watchdog", O_WRONLY);
if (fd == -1) {
perror("watchdog");
exit(1);
}
printf("Trying to set timeout value=%d seconds\n", timeout);
ioctl(fd, WDIOC_SETTIMEOUT, &timeout);
printf("The actual timeout was set to %d seconds\n", timeout);
ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
printf("Now reading back -- The timeout is %d seconds\n", timeout);
while (1) {
if (test == 0) {
ioctl(fd, WDIOC_KEEPALIVE, 0); //使用ioctl()方法喂狗
} else {
write(fd, "\0", 1); //使用write()方法喂狗。
}
sleep(sleep_sec);
}
return 0;
}
void help_info(void)
{
printf("Usage: wdt_driver_test <timeout> <sleep> <test>\n");
printf(" timeout: value in seconds to cause wdt timeout/reset\n");
printf(" sleep: value in seconds to service the wdt\n");
printf(" test: 0 - Service wdt with ioctl(), 1 - with write()\n");
}
0 0
- imx6 WatchDog驱动程序及测试例程
- imx6------watchdog导致不进系统
- 详解kernel中watchdog 驱动程序
- imx6 项目的按键驱动程序
- imx6 项目的按键驱动程序
- imx6 ar8031网卡驱动程序分析
- 基于IMX6的GPIO驱动程序
- FLIE结构成员值得测试例程及文本读取例程
- nmi-watchdog测试
- Watchdog驱动测试程序
- Android实现简单字符驱动程序及测试
- atmega8 例程:5110液晶驱动程序
- Linux驱动程序的结构例程
- DirectShow开发环境配置及测试例程(VC6)
- java例程练习(Point类及简单测试)
- PAT乙级测试题及JAVA参考例程
- Ubuntu14.04+caffe实现cifar10例程及单张图片测试
- watchdog
- Popupwindow 属性设置
- html5游戏开发实战-----大家来找茬
- thinkphp 安全整理
- jquery easyui datagrid 获取Checked选择行(勾选行)数据
- Centos7安装Mysql
- imx6 WatchDog驱动程序及测试例程
- C++实现循环队列之顺序存储
- Hyper-V 高可用性 (创建及配置Hyper-V群集)
- JS高级程序设计 读书笔记(1)
- jvm运行时的数据区域
- 【剑指Offer学习】【面试题39:二叉树的深度】
- spinlock与mutex对比
- 18、find命令之xargs(还没实践用)
- HDOJ 4009 Transfer water 最小树形图