linux中编写看门狗驱动的示例分析
小编给大家分享一下linux中编写看门狗驱动的示例分析,相信大部分人都还不怎么了解,因此分享这篇文章给大家参考一下,希望大家阅读完这篇文章后大有收获,下面让我们一起去了解一下吧!
“只有客户发展了,才有我们的生存与发展!”这是创新互联公司的服务宗旨!把网站当作互联网产品,产品思维更注重全局思维、需求分析和迭代思维,在网站建设中就是为了建设一个不仅审美在线,而且实用性极高的网站。创新互联对网站设计制作、成都网站设计、网站制作、网站开发、网页设计、网站优化、网络推广、探索永无止境。
看门狗是linux驱动的一个重要环节。某些特殊的设备,有时候需要放在一些环境恶劣的地方,比如电信设备。但是,任何软件都不可能100%没有bug。如何保证软件在遇到严重bug、死机的时候也能正常运行呢,那么看门狗就是有效的一种方法。看门狗一般要求用户定时喂狗,如果一段时间没有喂狗的话,那么系统就会自动重启。
1、代码目录
drivers/watchdog
2、阅读目录下的Kconfig,可以找一个s3c模块macro
config HAVE_S3C2410_WATCHDOG bool help This will include watchdog timer support for Samsung SoCs. If you want to include watchdog support for any machine, kindly select this in the respective mach-XXXX/Kconfig file. config S3C2410_WATCHDOG tristate "S3C2410 Watchdog" depends on HAVE_S3C2410_WATCHDOG || COMPILE_TEST select WATCHDOG_CORE select MFD_SYSCON if ARCH_EXYNOS help Watchdog timer block in the Samsung SoCs. This will reboot the system when the timer expires with the watchdog enabled. The driver is limited by the speed of the system's PCLK signal, so with reasonably fast systems (PCLK around 50-66MHz) then watchdog intervals of over approximately 20seconds are unavailable. The driver can be built as a module by choosing M, and will be called s3c2410_wdt
3、S3C2410_WATCHDOG主要依赖WATCHDOG_CORE,可以继续跟踪Makefile
obj-$(CONFIG_S3C2410_WATCHDOG) += s3c2410_wdt.o
4、macro只依赖一个s3c2410_wdt.c文件,继续查看
static SIMPLE_DEV_PM_OPS(s3c2410wdt_pm_ops, s3c2410wdt_suspend, s3c2410wdt_resume); static struct platform_driver s3c2410wdt_driver = { .probe = s3c2410wdt_probe, .remove = s3c2410wdt_remove, .shutdown = s3c2410wdt_shutdown, .id_table = s3c2410_wdt_ids, .driver = { .name = "s3c2410-wdt", .pm = &s3c2410wdt_pm_ops, .of_match_table = of_match_ptr(s3c2410_wdt_match), }, }; module_platform_driver(s3c2410wdt_driver);
5、确认driver为platform类型,继续在probe函数中查找有用的code
ret = watchdog_register_device(&wdt->wdt_device); if (ret) { dev_err(dev, "cannot register watchdog (%d)\n", ret); goto err_cpufreq; }
6、网上继续查找,寻找到和watchdog有关的数据结构
static const struct watchdog_info s3c2410_wdt_ident = { .options = OPTIONS, .firmware_version = 0, .identity = "S3C2410 Watchdog", }; static const struct watchdog_ops s3c2410wdt_ops = { .owner = THIS_MODULE, .start = s3c2410wdt_start, .stop = s3c2410wdt_stop, .ping = s3c2410wdt_keepalive, .set_timeout = s3c2410wdt_set_heartbeat, .restart = s3c2410wdt_restart, }; static const struct watchdog_device s3c2410_wdd = { .info = &s3c2410_wdt_ident, .ops = &s3c2410wdt_ops, .timeout = S3C2410_WATCHDOG_DEFAULT_TIME, };
7、找到设备注册函数、函数结构基本就算结束了,当然有中断的话,也可以确认一下
ret = devm_request_irq(dev, wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev); if (ret != 0) { dev_err(dev, "failed to install irq (%d)\n", ret); goto err_cpufreq; }
8、有兴趣的话,可以找一个函数阅读一下。比如下面这个重启函数,可以和spec对比者来看
static int s3c2410wdt_restart(struct watchdog_device *wdd, unsigned long action, void *data) { struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd); void __iomem *wdt_base = wdt->reg_base; /* disable watchdog, to be safe */ writel(0, wdt_base + S3C2410_WTCON); /* put initial values into count and data */ writel(0x80, wdt_base + S3C2410_WTCNT); writel(0x80, wdt_base + S3C2410_WTDAT); /* set the watchdog to go and reset... */ writel(S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV16 | S3C2410_WTCON_RSTEN | S3C2410_WTCON_PRESCALE(0x20), wdt_base + S3C2410_WTCON); /* wait for reset to assert... */ mdelay(500); return 0; }
以上是“linux中编写看门狗驱动的示例分析”这篇文章的所有内容,感谢各位的阅读!相信大家都有了一定的了解,希望分享的内容对大家有所帮助,如果还想学习更多知识,欢迎关注创新互联行业资讯频道!
网页标题:linux中编写看门狗驱动的示例分析
当前路径:http://scyanting.com/article/iiihep.html