fmql之Linux WDT

正点原子第52章。

基础知识

正点原子教程

fmql-dts

代码

APP代码（不需要编写驱动代码）

static int dw_wdt_drv_probe(struct platform_device *pdev)
{struct device *dev = &pdev->dev;struct watchdog_device *wdd;struct dw_wdt *dw_wdt;    /* 描述SDWT设备 */struct resource *mem;struct dw_wdt_of_data *of_data = NULL;int ret;/* 实例化wdt对象 */ dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);if (!dw_wdt)return -ENOMEM;/* 获取SWDT的寄存器基地址(物理地址)* 并将其转换为内核当中操作使用的虚拟地址* 将其存放在dw_wdt->regs中*/mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);dw_wdt->regs = devm_ioremap_resource(dev, mem);if (IS_ERR(dw_wdt->regs))return PTR_ERR(dw_wdt->regs);/* 获取输入时钟 */dw_wdt->clk = devm_clk_get(dev, NULL);if (IS_ERR(dw_wdt->clk))return PTR_ERR(dw_wdt->clk);/* 使能时钟 */ret = clk_prepare_enable(dw_wdt->clk);if (ret)return ret;/* 获取时钟频率 */dw_wdt->rate = clk_get_rate(dw_wdt->clk);if (dw_wdt->rate == 0) {ret = -EINVAL;goto out_disable_clk;}dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);if (IS_ERR(dw_wdt->rst)) {ret = PTR_ERR(dw_wdt->rst);goto out_disable_clk;}reset_control_deassert(dw_wdt->rst);/* 对 struct watchdog_device 对象成员变量进行了初始化 */wdd = &dw_wdt->wdd;wdd->info = &dw_wdt_ident;wdd->ops = &dw_wdt_ops;wdd->min_timeout = 1;wdd->max_hw_heartbeat_ms =dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP) * 1000;wdd->parent = dev;/* 调用函数：* 初始化WDT*/watchdog_set_drvdata(wdd, dw_wdt);      watchdog_set_nowayout(wdd, nowayout);  // 设置WDT status为WDOG_NO_WAY_OUTwatchdog_init_timeout(wdd, 0, dev);    // 超时时间值/** If the watchdog is already running, use its already configured* timeout. Otherwise use the default or the value provided through* devicetree.*/if (dw_wdt_is_enabled(dw_wdt)) {wdd->timeout = dw_wdt_get_top(dw_wdt);set_bit(WDOG_HW_RUNNING, &wdd->status);} else {wdd->timeout = DW_WDT_DEFAULT_SECONDS;watchdog_init_timeout(wdd, 0, dev);}platform_set_drvdata(pdev, dw_wdt);watchdog_set_restart_priority(wdd, 128);/* 向看门狗核心层注册一个WDT设备 */ret = watchdog_register_device(wdd);if (ret)goto out_disable_clk;of_data = dev_to_ofdata(&pdev->dev);if (of_data && of_data->init) {ret = of_data->init(&pdev->dev);if (ret)goto out_disable_clk;}return 0;out_disable_clk:clk_disable_unprepare(dw_wdt->clk);return ret;
}

static const struct watchdog_info dw_wdt_ident = {.options	= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |WDIOF_MAGICCLOSE,.identity	= "Synopsys DesignWare Watchdog",
};
/* options:* WDIOF_KEEPALIVEPING    支持喂狗* WDIOF_SETTIMEOUT       设置超时时间* WDIOF_MAGICCLOSE       当应用层关闭设备时，WDT不会停止运行*/static const struct watchdog_ops dw_wdt_ops = {.owner		= THIS_MODULE,.start		= dw_wdt_start,.stop		= dw_wdt_stop,.ping		= dw_wdt_ping,.set_timeout	= dw_wdt_set_timeout,.get_timeleft	= dw_wdt_get_timeleft,.restart	= dw_wdt_restart,
};