项目中需要实现watchdog功能，研究了下系统中的watchdog。硬件watchdog使用芯片max6371，看芯片资料，结合硬件设计，发现需要控制的信号有两个，是系统的GPIO，GPIO1是使能watchdog的信号，连接到max6371的set2引脚 ，GPIO2是喂狗的信号，连接到max6371的wdi引脚。如下图：
系统使用linux内核版本4.9.75，内核配置CONFIG_MAX63XX_WATCHDOG=y 后，系统下未生成/dev/watchdog。 走读代码发下max63xx_wdt.c源码和硬件设计不符，不支持GPIO，源码注释中也有说明：
* This driver assumes the watchdog pins are memory mapped (as it is
* the case for the Arcom Zeus). Should it be connected over GPIOs or
* another interface, some abstraction will have to be introduced.
网上找了一些资料，有支持GPIO的补丁，参考补丁链接：https://lore.kernel.org/patchwork/patch/571616/，支持了GPIO的配置后，发现还是未生成/dev/watchdog 设备文件。经过调试发现，没有进入probe函数，所以没有注册。走读代码发现，驱动是以platform driver形式注册了驱动，但是没有注册platform device，因此不能进入probe。加上platform device add之后，可以生成/dev/watchdog了。
补丁：
diff -ruNa a/drivers/watchdog/max63xx_wdt.c b/drivers/watchdog/max63xx_wdt.c
--- a/drivers/watchdog/max63xx_wdt.c 2018-11-20 18:17:19.969287012 +0800
+++ b/drivers/watchdog/max63xx_wdt.c 2018-11-20 17:43:32.605287012 +0800
@@ -20,6 +20,7 @@
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/watchdog.h>
+#include <linux/gpio.h>
#include <linux/bitops.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
@@ -28,6 +29,7 @@
#define DEFAULT_HEARTBEAT 60
#define MAX_HEARTBEAT 60
+#define MAX63XX_DISABLED 3
static unsigned int heartbeat = DEFAULT_HEARTBEAT;
static bool nowayout = WATCHDOG_NOWAYOUT;
@@ -43,10 +45,25 @@
static int nodelay;
+ /* struct max63xx_platform_data - MAX63xx connectivity info
+ * @wdi: Watchdog Input GPIO number.
+ * @set0: Watchdog SET0 GPIO number.
+ * @set1: Watchdog SET1 GPIO number.
+ * @set2: Watchdog SET2 GPIO number.
+ */
+struct max63xx_platform_data {
+ unsigned int wdi;
+ unsigned int set0, set1, set2;
+};
+
+static struct max63xx_platform_data st_max63xx_gpio_data = {382, 0, 0, 387};
+
struct max63xx_wdt {
struct watchdog_device wdd;
+ struct platform_device *pdev;
const struct max63xx_timeout *timeout;
-
+ /* platform settings e.g. GPIO */
+ struct max63xx_platform_data *pdata;
/* memory mapping */
void __iomem *base;
spinlock_t lock;
@@ -56,6 +73,9 @@
void (*set)(struct max63xx_wdt *wdt, u8 set);
};
+
+static struct max63xx_wdt *max63xx_wdt_data = NULL;
+
/*
* The timeout values used are actually the absolute minimum the chip
* offers. Typical values on my board are slightly over twice as long
@@ -116,129 +136,121 @@
return NULL;
}
-static int max63xx_wdt_ping(struct watchdog_device *wdd)
-{
- struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
-
- wdt->ping(wdt);
- return 0;
-}
-
-static int max63xx_wdt_start(struct watchdog_device *wdd)
-{
- struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
-
- wdt->set(wdt, wdt->timeout->wdset);
-
- /* check for a edge triggered startup */
- if (wdt->timeout->tdelay == 0)
- wdt->ping(wdt);
- return 0;
-}
-
-static int max63xx_wdt_stop(struct watchdog_device *wdd)
-{
- struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
-
- wdt->set(wdt, MAX6369_WDSET_DISABLED);
- return 0;
-}
-
-static const struct watchdog_ops max63xx_wdt_ops = {
- .owner = THIS_MODULE,
- .start = max63xx_wdt_start,
- .stop = max63xx_wdt_stop,
- .ping = max63xx_wdt_ping,
-};
static const struct watchdog_info max63xx_wdt_info = {
.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
.identity = "max63xx Watchdog",
};
-static void max63xx_mmap_ping(struct max63xx_wdt *wdt)
-{
- u8 val;
-
- spin_lock(&wdt->lock);
-
- val = __raw_readb(wdt->base);
-
- __raw_writeb(val | MAX6369_WDI, wdt->base);
- __raw_writeb(val & ~MAX6369_WDI, wdt->base);
-
- spin_unlock(&wdt->lock);
-}
-
-static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set)
-{
- u8 val;
-
- spin_lock(&wdt->lock);
-
- val = __raw_readb(wdt->base);
- val &= ~MAX6369_WDSET;
- val |= set & MAX6369_WDSET;
- __raw_writeb(val, wdt->base);
-
- spin_unlock(&wdt->lock);
-}
-
-static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt)
-{
- struct resource *mem = platform_get_resource(p, IORESOURCE_MEM, 0);
-
- wdt->base = devm_ioremap_resource(&p->dev, mem);
- if (IS_ERR(wdt->base))
- return PTR_ERR(wdt->base);
+static int max63xx_gpio_ping(struct watchdog_device *wdev)
+{
+ max63xx_wdt_data = watchdog_get_drvdata(wdev);
+
+ gpio_set_value(max63xx_wdt_data->pdata->wdi, 1);
+ gpio_set_value(max63xx_wdt_data->pdata->wdi, 0);
+
+ return 0;
+}
+
+static inline void max63xx_gpio_set(struct watchdog_device *wdev, u8 set)
+{
+ max63xx_wdt_data = watchdog_get_drvdata(wdev);
+
+ gpio_set_value(max63xx_wdt_data->pdata->set2, 1);
+}
+
+static int max63xx_gpio_start(struct watchdog_device *wdev)
+{
+ max63xx_wdt_data = watchdog_get_drvdata(wdev);
+
+ gpio_set_value(max63xx_wdt_data->pdata->set2, 1);
+
+ /* Check for an edge triggered startup */
+ if (max63xx_wdt_data->timeout->tdelay == 0)
+ max63xx_gpio_ping(wdev);
+ return 0;
+}
+
+static int max63xx_gpio_stop(struct watchdog_device *wdev)
+{
+ max63xx_wdt_data = watchdog_get_drvdata(wdev);
+ gpio_set_value(max63xx_wdt_data->pdata->set2, 0);
+ return 0;
+}
+
+static const struct watchdog_ops max63xx_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = max63xx_gpio_start,
+ .stop = max63xx_gpio_stop,
+ .ping = max63xx_gpio_ping,
+};
+ static int max63xx_gpio_init(struct platform_device *p, struct max63xx_wdt *wdt)
+ {
+ int err;
- spin_lock_init(&wdt->lock);
+ pinctrl_free_gpio(wdt->pdata->wdi);
+ err = gpio_request_one( wdt->pdata->wdi, GPIOF_OUT_INIT_LOW, "max63xx_wdt WDI");
+ if (err)
+ return err;
- wdt->ping = max63xx_mmap_ping;
- wdt->set = max63xx_mmap_set;
+ pinctrl_free_gpio(wdt->pdata->set2);
+ err = gpio_request_one(wdt->pdata->set2, GPIOF_OUT_INIT_LOW, "max63xx_wdt SET2");
+ if (err)
+ return err;
+
+ wdt->ping = max63xx_gpio_ping;
+ wdt->set = max63xx_gpio_set;
return 0;
}
-
static int max63xx_wdt_probe(struct platform_device *pdev)
{
- struct max63xx_wdt *wdt;
- struct max63xx_timeout *table;
- int err;
-
- wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
- if (!wdt)
- return -ENOMEM;
-
- table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
+ struct max63xx_wdt *wdt;
+ struct max63xx_timeout *table;
+ int err;
+
+ wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+ if (!wdt)
+ return -ENOMEM;
+
+ table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
+ if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
+ heartbeat = DEFAULT_HEARTBEAT;
+
+ wdt->timeout = max63xx_select_timeout(table, heartbeat);
+ if (!wdt->timeout) {
+ dev_err(&pdev->dev, "unable to satisfy %ds heartbeat request\n",
+ heartbeat);
+ return -EINVAL;
+ }
+ wdt->pdata = dev_get_platdata(&pdev->dev);
if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
heartbeat = DEFAULT_HEARTBEAT;
-
wdt->timeout = max63xx_select_timeout(table, heartbeat);
if (!wdt->timeout) {
dev_err(&pdev->dev, "unable to satisfy %ds heartbeat request\n",
heartbeat);
return -EINVAL;
}
+ /* GPIO or memory mapped? */
- err = max63xx_mmap_init(pdev, wdt);
+ wdt->pdata = &st_max63xx_gpio_data;
+
+ err = max63xx_gpio_init(pdev, wdt);
if (err)
return err;
-
+
platform_set_drvdata(pdev, &wdt->wdd);
watchdog_set_drvdata(&wdt->wdd, wdt);
-
wdt->wdd.parent = &pdev->dev;
wdt->wdd.timeout = wdt->timeout->twd;
wdt->wdd.info = &max63xx_wdt_info;
wdt->wdd.ops = &max63xx_wdt_ops;
-
watchdog_set_nowayout(&wdt->wdd, nowayout);
err = watchdog_register_device(&wdt->wdd);
if (err)
return err;
-
dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n",
wdt->timeout->twd, wdt->timeout->tdelay);
return 0;
@@ -268,11 +280,52 @@
.remove = max63xx_wdt_remove,
.id_table = max63xx_id_table,
.driver = {
- .name = "max63xx_wdt",
+ .name = "max6371_wdt",
},
};
+static int __init max63xx_wdt_init_module(void)
+{
+ int err;
+
+ pr_info("Intel max63xx WatchDog Timer Driver \n" );
+
+ err = platform_driver_register(&max63xx_wdt_driver);
+ pr_info("Intel max63xx WatchDog Timer Driver err %d\n", err);
+ if (err)
+ return err;
-module_platform_driver(max63xx_wdt_driver);
+ max63xx_wdt_data = kzalloc(sizeof(struct max63xx_wdt), GFP_KERNEL);
+ if (!max63xx_wdt_data) {
+ err = -ENOMEM;
+ platform_driver_unregister(&max63xx_wdt_driver);
+ return err;
+ }
+
+
+ max63xx_wdt_data->pdev = platform_device_register_simple("max6371_wdt", -1, NULL, 0);
+ if (IS_ERR(max63xx_wdt_data->pdev)) {
+ err = PTR_ERR(max63xx_wdt_data->pdev);
+ platform_driver_unregister(&max63xx_wdt_driver);
+ kfree(max63xx_wdt_data);
+ return err;
+ }
+
+ return 0;
+}
+
+static void __exit max63xx_wdt_cleanup_module(void)
+{
+ platform_device_unregister(max63xx_wdt_data->pdev);
+ platform_driver_unregister(&max63xx_wdt_driver);
+ pr_info("Watchdog Module Unloaded\n");
+
+
+}
+
+module_init(max63xx_wdt_init_module);
+module_exit(max63xx_wdt_cleanup_module);
+
+//module_platform_driver(max63xx_wdt_driver);
MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
MODULE_DESCRIPTION("max63xx Watchdog Driver");
@@ -293,3 +346,4 @@
"(max6373/74 only, default=0)");
MODULE_LICENSE("GPL v2");
+
看了一些linux内核的watchdog的驱动都是max63xx_wdt.c驱动类型，注册了platform的driver，但并没有注册设备驱动，是如何进入probe函数呢？这点值得研究？
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