watchdog: New watchdog driver for MEN A21 watchdogs

This patch adds the driver for the watchdog devices found on MEN Mikro Elektronik A21 VMEbus CPU Carrier Boards. It has DT-support and uses the watchdog framework.

drivers/watchdog/mena21_wdt.c new file +3 -1

+MODULE_DESCRIPTION("MEN A21 Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:a21-watchdog");
--

1.7.9.5

This patch adds the driver for the watchdog devices found on MEN Mikro Elektronik A21 VMEbus CPU Carrier Boards. It has DT-support and uses the watchdog framework.

Revision 2:
* Removed unneeded open flag in struct a21_wdt_drv
* Corrected 3bit reason code from gpio
* Additional sysfs files are now part of watchdog sysfs
* Changed OFF/ON delay in ping from 400ms to 10ns
* Reworked timeout setting
* Removed a21_wdt_ioctl(...)

Revision 3:
* Changed pr_{err,info} to dev_{err,info}
* Removed out of memory error print
* Transition from "fast" to "slow" mode not allowed by chip

Revision 4:
* Remove reboot_notifier and place disable code into platform_device's shutdown function
* Removed sysfs interface

Revision 5:

* Added setting of .bootstatus on driver init
* Added initial timeout on driver init

Signed-off-by Johannes Thumshirn <[email protected]>

---
 MAINTAINERS                   |    6 ++
 drivers/watchdog/Kconfig      |    8 ++
 drivers/watchdog/Makefile     |    1 +
 drivers/watchdog/mena21_wdt.c |  234 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 249 insertions(+)
 create mode 100644 drivers/watchdog/mena21_wdt.c

MAINTAINERS +6 -0

index 7714c3c..023945a 100644
@@ -5307,6 +5307,12 @@ F:	drivers/mtd/
 F:	include/linux/mtd/
 F:	include/uapi/mtd/
 
+MEN A21 WATCHDOG DRIVER
+M:  	Johannes Thumshirn <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/watchdog/mena21_wdt.c
+
 METAG ARCHITECTURE
 M:	James Hogan <[email protected]>
 S:	Supported

drivers/watchdog/Kconfig +8 -0

index e89fc31..192b84d 100644
@@ -1172,6 +1172,14 @@ config BOOKE_WDT_DEFAULT_TIMEOUT
 
 	  The value can be overridden by the wdt_period command-line parameter.
 
+config MEN_A21_WDT
+       tristate "MEN A21 VME CPU Carrier Board Watchdog Timer"
+       select WATCHDOG_CORE
+       help
+        Watchdog driver for MEN A21 VMEbus CPU Carrier Boards.
+
+	If unsure select N here.
+
 # PPC64 Architecture
 
 config WATCHDOG_RTAS

drivers/watchdog/Makefile +1 -0

index a300b94..bffdcb1 100644
@@ -143,6 +143,7 @@ obj-$(CONFIG_8xxx_WDT) += mpc8xxx_wdt.o
 obj-$(CONFIG_MV64X60_WDT) += mv64x60_wdt.o
 obj-$(CONFIG_PIKA_WDT) += pika_wdt.o
 obj-$(CONFIG_BOOKE_WDT) += booke_wdt.o
+obj-$(CONFIG_MEN_A21_WDT) += mena21_wdt.o
 
 # PPC64 Architecture
 obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o

drivers/watchdog/mena21_wdt.c new file +159 -0

new file mode 100644
index 0000000..e586c2e
@@ -0,0 +1,234 @@
+/*
+ * Watchdog driver for the A21 VME CPU Boards
+ *
+ * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
+ *
+ * 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
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+#include <linux/gpio.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+
+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+
+struct a21_wdt_drv {
+	struct watchdog_device wdt;
+	struct mutex lock;
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+			    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static int a21_wdt_get_bootstatus(unsigned int *reset)
+{
+	int i;
+
+	for (i = 0; i < 3; i++)
+		*reset |= gpio_get_value(GPIO_RST_CAUSE_BASE + i)
+			? (1 << i) : 0;
+
+	if (*reset >= 8)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int a21_wdt_start(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_ENAB, 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_stop(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	/* We don't stop if WDOG_NO_WAY_OUT is set */
+	if (test_bit(WDOG_NO_WAY_OUT, &wdt->status))
+		return -EINVAL;
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_ENAB, 0);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_ping(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_TRIG, 0);
+	ndelay(10);
+	gpio_set_value(GPIO_WD_TRIG, 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_set_timeout(struct watchdog_device *wdt,
+			       unsigned int timeout)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	if (timeout != 1 && timeout != 30) {
+		dev_err(wdt->dev, "Only 1 and 30 allowed as timeout\n");
+		return -EINVAL;
+	}
+
+	if (timeout == 30 && wdt->timeout == 1) {
+		dev_err(wdt->dev,
+			"Transition from fast to slow mode not allowed\n");
+		return -EINVAL;
+	}
+
+	mutex_lock(&drv->lock);
+
+	if (timeout == 1)
+		gpio_set_value(GPIO_WD_FAST, 1);
+	else
+		gpio_set_value(GPIO_WD_FAST, 0);
+
+	wdt->timeout = timeout;
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static const struct watchdog_info a21_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "MEN A21 Watchdog",
+};
+
+static const struct watchdog_ops a21_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = a21_wdt_start,
+	.stop = a21_wdt_stop,
+	.ping = a21_wdt_ping,
+	.set_timeout = a21_wdt_set_timeout,
+};
+
+static struct watchdog_device a21_wdt = {
+	.info = &a21_wdt_info,
+	.ops = &a21_wdt_ops,
+	.min_timeout = 1,
+	.max_timeout = 30,
+};
+
+static int a21_wdt_probe(struct platform_device *pdev)
+{
+	struct a21_wdt_drv *drv;
+	unsigned int reset = 0;
+	int ret;
+
+	dev_info(&pdev->dev, "MEN A21 watchdog timer driver enabled\n");
+
+	drv = devm_kzalloc(&pdev->dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
+	if (!drv)
+		return -ENOMEM;
+
+	mutex_init(&drv->lock);

drivers/watchdog/mena21_wdt.c new file +65 -1

+	ret = a21_wdt_get_bootstatus(&reset);
+	if (ret)
+		dev_warn(&pdev->dev, "Reset Cause contains invalid data\n");
+	else {
+		if (reset == 2)
+			a21_wdt.bootstatus |= WDIOF_EXTERN1;
+		else if (reset == 4)
+			a21_wdt.bootstatus |= WDIOF_CARDRESET;
+		else if (reset == 5)
+			a21_wdt.bootstatus |= WDIOF_POWERUNDER;
+		else if (reset == 7)
+			a21_wdt.bootstatus |= WDIOF_EXTERN2;
+	}
+
+	dev_set_drvdata(&pdev->dev, drv);
+
+	return 0;
+
+err_register_wd:
+	mutex_destroy(&drv->lock);
+
+	return ret;
+}
+
+static int a21_wdt_remove(struct platform_device *pdev)
+{
+	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
+
+	dev_warn(&pdev->dev,
+		"Unregistering A21 watchdog driver, board may reboot\n");
+
+
+	watchdog_unregister_device(&drv->wdt);
+
+	mutex_destroy(&drv->lock);
+
+	return 0;
+}
+
+static void a21_wdt_shutdown(struct platform_device *pdev)
+{
+	gpio_set_value(GPIO_WD_ENAB, 0);
+}
+
+static const struct of_device_id a21_wdt_ids[] = {
+	{ .compatible = "men,a021-wdt" },
+	{ },
+};
+
+static struct platform_driver a21_wdt_driver = {
+	.probe = a21_wdt_probe,
+	.remove = a21_wdt_remove,
+	.shutdown = a21_wdt_shutdown,
+	.driver = {
+		.name = "a21-watchdog",
+		.of_match_table = a21_wdt_ids,
+	},
+};
+
+module_platform_driver(a21_wdt_driver);
+
+MODULE_AUTHOR("MEN Mikro Elektronik");
+MODULE_DESCRIPTION("MEN A21 Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:a21-watchdog");
--

1.7.9.5

--
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Quoted 254 lines · Johannes Thumshirn

This patch adds the driver for the watchdog devices found on MEN Mikro Elektronik A21 VMEbus CPU Carrier Boards. It has DT-support and uses the watchdog framework.

Revision 2:
* Removed unneeded open flag in struct a21_wdt_drv
* Corrected 3bit reason code from gpio
* Additional sysfs files are now part of watchdog sysfs
* Changed OFF/ON delay in ping from 400ms to 10ns
* Reworked timeout setting
* Removed a21_wdt_ioctl(...)

Revision 3:
* Changed pr_{err,info} to dev_{err,info}
* Removed out of memory error print
* Transition from "fast" to "slow" mode not allowed by chip

Revision 4:
* Remove reboot_notifier and place disable code into platform_device's shutdown function
* Removed sysfs interface

Revision 5:

* Added setting of .bootstatus on driver init
* Added initial timeout on driver init

Signed-off-by Johannes Thumshirn <[email protected]>

---
 MAINTAINERS                   |    6 ++
 drivers/watchdog/Kconfig      |    8 ++
 drivers/watchdog/Makefile     |    1 +
 drivers/watchdog/mena21_wdt.c |  234 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 249 insertions(+)
 create mode 100644 drivers/watchdog/mena21_wdt.c

MAINTAINERS +6 -0

index 7714c3c..023945a 100644
@@ -5307,6 +5307,12 @@ F:	drivers/mtd/
 F:	include/linux/mtd/
 F:	include/uapi/mtd/
 
+MEN A21 WATCHDOG DRIVER
+M:  	Johannes Thumshirn <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/watchdog/mena21_wdt.c
+
 METAG ARCHITECTURE
 M:	James Hogan <[email protected]>
 S:	Supported

drivers/watchdog/Kconfig +8 -0

index e89fc31..192b84d 100644
@@ -1172,6 +1172,14 @@ config BOOKE_WDT_DEFAULT_TIMEOUT
 
 	  The value can be overridden by the wdt_period command-line parameter.
 
+config MEN_A21_WDT
+       tristate "MEN A21 VME CPU Carrier Board Watchdog Timer"
+       select WATCHDOG_CORE
+       help
+        Watchdog driver for MEN A21 VMEbus CPU Carrier Boards.
+
+	If unsure select N here.
+
 # PPC64 Architecture
 
 config WATCHDOG_RTAS

drivers/watchdog/Makefile +1 -0

index a300b94..bffdcb1 100644
@@ -143,6 +143,7 @@ obj-$(CONFIG_8xxx_WDT) += mpc8xxx_wdt.o
 obj-$(CONFIG_MV64X60_WDT) += mv64x60_wdt.o
 obj-$(CONFIG_PIKA_WDT) += pika_wdt.o
 obj-$(CONFIG_BOOKE_WDT) += booke_wdt.o
+obj-$(CONFIG_MEN_A21_WDT) += mena21_wdt.o
 
 # PPC64 Architecture
 obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o

drivers/watchdog/mena21_wdt.c new file +165 -0

new file mode 100644
index 0000000..e586c2e
@@ -0,0 +1,234 @@
+/*
+ * Watchdog driver for the A21 VME CPU Boards
+ *
+ * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
+ *
+ * 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
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+#include <linux/gpio.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+
+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+
+struct a21_wdt_drv {
+	struct watchdog_device wdt;
+	struct mutex lock;
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+			    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static int a21_wdt_get_bootstatus(unsigned int *reset)
+{
+	int i;
+
+	for (i = 0; i < 3; i++)
+		*reset |= gpio_get_value(GPIO_RST_CAUSE_BASE + i)
+			? (1 << i) : 0;
+
+	if (*reset >= 8)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int a21_wdt_start(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_ENAB, 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_stop(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	/* We don't stop if WDOG_NO_WAY_OUT is set */
+	if (test_bit(WDOG_NO_WAY_OUT, &wdt->status))
+		return -EINVAL;
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_ENAB, 0);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_ping(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_TRIG, 0);
+	ndelay(10);
+	gpio_set_value(GPIO_WD_TRIG, 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_set_timeout(struct watchdog_device *wdt,
+			       unsigned int timeout)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	if (timeout != 1 && timeout != 30) {
+		dev_err(wdt->dev, "Only 1 and 30 allowed as timeout\n");
+		return -EINVAL;
+	}
+
+	if (timeout == 30 && wdt->timeout == 1) {
+		dev_err(wdt->dev,
+			"Transition from fast to slow mode not allowed\n");
+		return -EINVAL;
+	}
+
+	mutex_lock(&drv->lock);
+
+	if (timeout == 1)
+		gpio_set_value(GPIO_WD_FAST, 1);
+	else
+		gpio_set_value(GPIO_WD_FAST, 0);
+
+	wdt->timeout = timeout;
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static const struct watchdog_info a21_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "MEN A21 Watchdog",
+};
+
+static const struct watchdog_ops a21_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = a21_wdt_start,
+	.stop = a21_wdt_stop,
+	.ping = a21_wdt_ping,
+	.set_timeout = a21_wdt_set_timeout,
+};
+
+static struct watchdog_device a21_wdt = {
+	.info = &a21_wdt_info,
+	.ops = &a21_wdt_ops,
+	.min_timeout = 1,
+	.max_timeout = 30,
+};
+
+static int a21_wdt_probe(struct platform_device *pdev)
+{
+	struct a21_wdt_drv *drv;
+	unsigned int reset = 0;
+	int ret;
+
+	dev_info(&pdev->dev, "MEN A21 watchdog timer driver enabled\n");
+
+	drv = devm_kzalloc(&pdev->dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
+	if (!drv)
+		return -ENOMEM;
+
+	mutex_init(&drv->lock);
+	watchdog_set_nowayout(&a21_wdt, nowayout);
+	watchdog_set_drvdata(&a21_wdt, drv);
+
+	ret = watchdog_register_device(&a21_wdt);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot register watchdog device\n");

drivers/watchdog/mena21_wdt.c line 169

Quoted 4 lines

drivers/watchdog/mena21_wdt.c new file +4 -0

+		goto err_register_wd;
+	}
+
+	a21_wdt.timeout = 30;

It would be better to use watchdog_init_timeout(), as it automatically supports setting the timeout through an fdt property. It should be set before registering the device with the watchdog subsystem.

This patch adds the driver for the watchdog devices found on MEN Mikro Elektronik A21 VMEbus CPU Carrier Boards. It has DT-support and uses the watchdog framework.

Revision 2:
* Removed unneeded open flag in struct a21_wdt_drv
* Corrected 3bit reason code from gpio
* Additional sysfs files are now part of watchdog sysfs
* Changed OFF/ON delay in ping from 400ms to 10ns
* Reworked timeout setting
* Removed a21_wdt_ioctl(...)

Revision 3:
* Changed pr_{err,info} to dev_{err,info}
* Removed out of memory error print
* Transition from "fast" to "slow" mode not allowed by chip

Revision 4:
* Remove reboot_notifier and place disable code into platform_device's shutdown function
* Removed sysfs interface

Revision 5:

* Added setting of .bootstatus on driver init
* Added initial timeout on driver init

Revision 6:
* Use watchdog_init_timeout() to initialize timeout

Signed-off-by Johannes Thumshirn <[email protected]>

---
 MAINTAINERS                   |    6 ++
 drivers/watchdog/Kconfig      |    8 ++
 drivers/watchdog/Makefile     |    1 +
 drivers/watchdog/mena21_wdt.c |  234 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 249 insertions(+)
 create mode 100644 drivers/watchdog/mena21_wdt.c

MAINTAINERS +6 -0

index 7714c3c..023945a 100644
@@ -5307,6 +5307,12 @@ F:	drivers/mtd/
 F:	include/linux/mtd/
 F:	include/uapi/mtd/
 
+MEN A21 WATCHDOG DRIVER
+M:  	Johannes Thumshirn <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/watchdog/mena21_wdt.c
+
 METAG ARCHITECTURE
 M:	James Hogan <[email protected]>
 S:	Supported

drivers/watchdog/Kconfig +8 -0

index e89fc31..192b84d 100644
@@ -1172,6 +1172,14 @@ config BOOKE_WDT_DEFAULT_TIMEOUT
 
 	  The value can be overridden by the wdt_period command-line parameter.
 
+config MEN_A21_WDT
+       tristate "MEN A21 VME CPU Carrier Board Watchdog Timer"
+       select WATCHDOG_CORE
+       help
+        Watchdog driver for MEN A21 VMEbus CPU Carrier Boards.
+
+	If unsure select N here.
+
 # PPC64 Architecture
 
 config WATCHDOG_RTAS

drivers/watchdog/Makefile +1 -0

index a300b94..bffdcb1 100644
@@ -143,6 +143,7 @@ obj-$(CONFIG_8xxx_WDT) += mpc8xxx_wdt.o
 obj-$(CONFIG_MV64X60_WDT) += mv64x60_wdt.o
 obj-$(CONFIG_PIKA_WDT) += pika_wdt.o
 obj-$(CONFIG_BOOKE_WDT) += booke_wdt.o
+obj-$(CONFIG_MEN_A21_WDT) += mena21_wdt.o
 
 # PPC64 Architecture
 obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o

drivers/watchdog/mena21_wdt.c new file +17 -0

new file mode 100644
index 0000000..9874c63
@@ -0,0 +1,234 @@
+/*
+ * Watchdog driver for the A21 VME CPU Boards
+ *
+ * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
+ *
+ * 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
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>

drivers/watchdog/mena21_wdt.c new file +75 -0

+struct a21_wdt_drv {
+	struct watchdog_device wdt;
+	struct mutex lock;
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+			    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static int a21_wdt_get_bootstatus(unsigned int *reset)
+{
+	int i;
+
+	for (i = 0; i < 3; i++)
+		*reset |= gpio_get_value(GPIO_RST_CAUSE_BASE + i)
+			? (1 << i) : 0;
+
+	if (*reset >= 8)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int a21_wdt_start(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_ENAB, 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_stop(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	/* We don't stop if WDOG_NO_WAY_OUT is set */
+	if (test_bit(WDOG_NO_WAY_OUT, &wdt->status))
+		return -EINVAL;
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_ENAB, 0);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_ping(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_TRIG, 0);
+	ndelay(10);
+	gpio_set_value(GPIO_WD_TRIG, 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_set_timeout(struct watchdog_device *wdt,
+			       unsigned int timeout)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	if (timeout != 1 && timeout != 30) {

drivers/watchdog/mena21_wdt.c new file +59 -0

+	mutex_lock(&drv->lock);
+
+	if (timeout == 1)
+		gpio_set_value(GPIO_WD_FAST, 1);
+	else
+		gpio_set_value(GPIO_WD_FAST, 0);
+
+	wdt->timeout = timeout;
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static const struct watchdog_info a21_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "MEN A21 Watchdog",
+};
+
+static const struct watchdog_ops a21_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = a21_wdt_start,
+	.stop = a21_wdt_stop,
+	.ping = a21_wdt_ping,
+	.set_timeout = a21_wdt_set_timeout,
+};
+
+static struct watchdog_device a21_wdt = {
+	.info = &a21_wdt_info,
+	.ops = &a21_wdt_ops,
+	.min_timeout = 1,
+	.max_timeout = 30,
+};
+
+static int a21_wdt_probe(struct platform_device *pdev)
+{
+	struct a21_wdt_drv *drv;
+	unsigned int reset = 0;
+	int ret;
+
+	dev_info(&pdev->dev, "MEN A21 watchdog timer driver enabled\n");
+
+	drv = devm_kzalloc(&pdev->dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
+	if (!drv)
+		return -ENOMEM;
+
+	mutex_init(&drv->lock);
+	watchdog_init_timeout(&a21_wdt, 30, &pdev->dev);
+	watchdog_set_nowayout(&a21_wdt, nowayout);
+	watchdog_set_drvdata(&a21_wdt, drv);
+
+	ret = watchdog_register_device(&a21_wdt);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot register watchdog device\n");
+		goto err_register_wd;
+	}
+
+	ret = a21_wdt_get_bootstatus(&reset);
+	if (ret)

drivers/watchdog/mena21_wdt.c new file +53 -1

+	}
+
+	dev_set_drvdata(&pdev->dev, drv);
+
+	return 0;
+
+err_register_wd:
+	mutex_destroy(&drv->lock);
+
+	return ret;
+}
+
+static int a21_wdt_remove(struct platform_device *pdev)
+{
+	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
+
+	dev_warn(&pdev->dev,
+		"Unregistering A21 watchdog driver, board may reboot\n");
+
+
+	watchdog_unregister_device(&drv->wdt);
+
+	mutex_destroy(&drv->lock);
+
+	return 0;
+}
+
+static void a21_wdt_shutdown(struct platform_device *pdev)
+{
+	gpio_set_value(GPIO_WD_ENAB, 0);
+}
+
+static const struct of_device_id a21_wdt_ids[] = {
+	{ .compatible = "men,a021-wdt" },
+	{ },
+};
+
+static struct platform_driver a21_wdt_driver = {
+	.probe = a21_wdt_probe,
+	.remove = a21_wdt_remove,
+	.shutdown = a21_wdt_shutdown,
+	.driver = {
+		.name = "a21-watchdog",
+		.of_match_table = a21_wdt_ids,
+	},
+};
+
+module_platform_driver(a21_wdt_driver);
+
+MODULE_AUTHOR("MEN Mikro Elektronik");
+MODULE_DESCRIPTION("MEN A21 Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:a21-watchdog");
--

1.7.9.5

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drivers/watchdog/mena21_wdt.c line 27

Quoted 6 lines

drivers/watchdog/mena21_wdt.c new file +6 -0

+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+

I think I asked that before ... as you are supporting devicetree, gpio pins should really be provided through devicetree properties and not be hardcoded.

Quoted 6 lines

drivers/watchdog/mena21_wdt.c new file +6 -0

+struct a21_wdt_drv {
+	struct watchdog_device wdt;
+	struct mutex lock;
+	}
+
+	if (timeout == 30 && wdt->timeout == 1) {

drivers/watchdog/mena21_wdt.c line 112

Quoted 5 lines

drivers/watchdog/mena21_wdt.c new file +5 -0

+		dev_err(wdt->dev,
+			"Transition from fast to slow mode not allowed\n");
+		return -EINVAL;
+	}
+

I dislike that [2 .. 29] timeout values are not supported, and would rather have you accept that range and set the timeout to 30. Also, it is somewhat undesirable that the timeout can not be changed back to 30 after being set to 1.

As Wim recommended, a softdog on top of the hardware watchdog would be the best solution. I'll leave it up to him to decide if he wants to accept the code as-is.

Quoted 15 lines

drivers/watchdog/mena21_wdt.c new file +14 -0

+	mutex_lock(&drv->lock);
+
+	ret = watchdog_register_device(&a21_wdt);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot register watchdog device\n");
+		goto err_register_wd;
+	}
+
+	ret = a21_wdt_get_bootstatus(&reset);
+	if (ret)
+		dev_warn(&pdev->dev, "Reset Cause contains invalid data\n");
+	else {
+		if (reset == 2)
+			a21_wdt.bootstatus |= WDIOF_EXTERN1;

drivers/watchdog/mena21_wdt.c line 181

Quoted 6 lines

drivers/watchdog/mena21_wdt.c new file +6 -0

+		else if (reset == 4)
+			a21_wdt.bootstatus |= WDIOF_CARDRESET;
+		else if (reset == 5)
+			a21_wdt.bootstatus |= WDIOF_POWERUNDER;
+		else if (reset == 7)
+			a21_wdt.bootstatus |= WDIOF_EXTERN2;

What about other causes ? No useful match ?

I think bootstatus should be set prior to registering the watchdog device to avoid race conditions where an application reads it prior to being set.

Quoted 1 line

(quoted diff) +1 -0

+	}

Hi Guenther,

Quoted 10 lines · Guenter Roeck

drivers/watchdog/mena21_wdt.c line 27

Quoted 6 lines

drivers/watchdog/mena21_wdt.c new file +6 -0

+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+

I think I asked that before ... as you are supporting devicetree, gpio pins should really be provided through devicetree properties and not be hardcoded.

Yes you did and I didn't come up with a solution to this problem yet. I understand and agree to your concerns but I'm lacking example code/documentation for it, maybe you can point me to an example on that and then I'll update my code accordingly.

Quoted 6 lines

Quoted 6 lines

drivers/watchdog/mena21_wdt.c new file +6 -0

+struct a21_wdt_drv {
+	struct watchdog_device wdt;
+	struct mutex lock;
+	}
+
+	if (timeout == 30 && wdt->timeout == 1) {

Quoted 8 lines

drivers/watchdog/mena21_wdt.c line 112

Quoted 5 lines

drivers/watchdog/mena21_wdt.c new file +5 -0

+		dev_err(wdt->dev,
+			"Transition from fast to slow mode not allowed\n");
+		return -EINVAL;
+	}
+

I dislike that [2 .. 29] timeout values are not supported, and would rather have you accept that range and set the timeout to 30. Also, it is somewhat undesirable that the timeout can not be changed back to 30 after being set to 1.

The not changing back issue was a hardware design criterion and I have no influence on that one. I've already checked with the IC developer and he said, this is intended. I don't quite understand why I should accept the timeout and set it to 30? In my opinion this only introduces some magic the user won't understand. Instead failing and giving an error message is something a user can take as a hint for investigating.

Quoted 3 lines

As Wim recommended, a softdog on top of the hardware watchdog would be the best solution. I'll leave it up to him to decide if he wants to accept the code as-is.

Yes let's see what he's saying.

Quoted 15 lines

Quoted 15 lines

drivers/watchdog/mena21_wdt.c new file +14 -0

+	mutex_lock(&drv->lock);
+
+	ret = watchdog_register_device(&a21_wdt);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot register watchdog device\n");
+		goto err_register_wd;
+	}
+
+	ret = a21_wdt_get_bootstatus(&reset);
+	if (ret)
+		dev_warn(&pdev->dev, "Reset Cause contains invalid data\n");
+	else {
+		if (reset == 2)
+			a21_wdt.bootstatus |= WDIOF_EXTERN1;

Quoted 9 lines

drivers/watchdog/mena21_wdt.c line 181

Quoted 6 lines

drivers/watchdog/mena21_wdt.c new file +6 -0

+		else if (reset == 4)
+			a21_wdt.bootstatus |= WDIOF_CARDRESET;
+		else if (reset == 5)
+			a21_wdt.bootstatus |= WDIOF_POWERUNDER;
+		else if (reset == 7)
+			a21_wdt.bootstatus |= WDIOF_EXTERN2;

What about other causes ? No useful match ?

None I could find. Actually WDIOF_EXTERN[12] already are a pretty creative mapping in my opinion. EXTERN1 is a "Push Button" event, EXTERN2 is a reset caused by a JTAG/BDM adapter...

Quoted 3 lines

I think bootstatus should be set prior to registering the watchdog device to avoid race conditions where an application reads it prior to being set.

Agreed, didn't see that one *doh*, must be fixed before inclusion.

Quoted 12 lines · Johannes Thumshirn

Hi Guenther,

Quoted 10 lines · Guenter Roeck

drivers/watchdog/mena21_wdt.c line 27

Quoted 6 lines

drivers/watchdog/mena21_wdt.c new file +6 -0

+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+

I think I asked that before ... as you are supporting devicetree, gpio pins should really be provided through devicetree properties and not be hardcoded.

Quoted 4 lines

Yes you did and I didn't come up with a solution to this problem yet. I understand and agree to your concerns but I'm lacking example code/documentation for it, maybe you can point me to an example on that and then I'll update my code accordingly.

Have a look at Documentation/devicetree/bindings/gpio/gpio-fan.txt and drivers/hwmon/gpio-fan.c.

Quoted 13 lines · Guenter Roeck

Quoted 12 lines · Johannes Thumshirn

Hi Guenther,

Quoted 10 lines · Guenter Roeck

drivers/watchdog/mena21_wdt.c line 27

Quoted 6 lines

drivers/watchdog/mena21_wdt.c new file +6 -0

+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+

I think I asked that before ... as you are supporting devicetree, gpio pins should really be provided through devicetree properties and not be hardcoded.

Quoted 7 lines

Quoted 4 lines

Yes you did and I didn't come up with a solution to this problem yet. I understand and agree to your concerns but I'm lacking example code/documentation for it, maybe you can point me to an example on that and then I'll update my code accordingly.

Have a look at Documentation/devicetree/bindings/gpio/gpio-fan.txt and drivers/hwmon/gpio-fan.c.

Thanks a lot, this really helped me out. Updated patch is comming today including the bindings document Arnd Bergmann requested. I only need to rebase the sysfs patch on top of that changes.

Regards,
Johannes

Quoted 22 lines · Johannes Thumshirn

Quoted 13 lines · Guenter Roeck

Quoted 12 lines · Johannes Thumshirn

Hi Guenther,

Quoted 10 lines · Guenter Roeck

drivers/watchdog/mena21_wdt.c line 27

Quoted 6 lines

drivers/watchdog/mena21_wdt.c new file +6 -0

+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+

I think I asked that before ... as you are supporting devicetree, gpio pins should really be provided through devicetree properties and not be hardcoded.

Quoted 7 lines

Quoted 4 lines

Yes you did and I didn't come up with a solution to this problem yet. I understand and agree to your concerns but I'm lacking example code/documentation for it, maybe you can point me to an example on that and then I'll update my code accordingly.

Have a look at Documentation/devicetree/bindings/gpio/gpio-fan.txt and drivers/hwmon/gpio-fan.c.

Quoted 6 lines

Thanks a lot, this really helped me out. Updated patch is comming today including the bindings document Arnd Bergmann requested. I only need to rebase the sysfs patch on top of that changes.

Regards,
Johannes

Regarding the sysfs patch, I have a funny effect in my (rebased) sysfs code.

Given the following code:

(quoted diff) +15 -0

+static ssize_t rebootcause_show(struct device *dev,
+                               struct device_attribute *attr,
+                               char *buf)
+{
+       struct a21_wdt_drv *drv = dev_get_drvdata(dev);
+       unsigned int reset = 0;
+
+       if (!drv)
+               return -EIO;
+
+       reset = a21_wdt_get_bootstatus(drv);
+
+       return sprintf(buf, "%s\n", reset_causes[reset]);
+}
+static DEVICE_ATTR(rebootcause, S_IRUGO, rebootcause_show, NULL);

I actually need the check for if (!drv) to prevent an OOPS, as dev_get_drvdata(dev) returns NULL., though it is set at the end of my probe function via:

[...]

drivers/watchdog/mena21_wdt.c new file +9 -0

+       ret = watchdog_register_device(&a21_wdt);
+       if (ret) {
+               dev_err(&pdev->dev, "Cannot register watchdog device\n");
+               goto err_register_wd;
+       }
+
+       dev_set_drvdata(&pdev->dev, drv);
+
+       return 0;
[...]

The watchdog driver itself is working without any troubles.

Some advice here would be worth its weight in gold.

Thanks,
Johannes

Quoted 68 lines · Johannes Thumshirn

Quoted 22 lines · Johannes Thumshirn

Quoted 13 lines · Guenter Roeck

Quoted 12 lines · Johannes Thumshirn

Hi Guenther,

Quoted 10 lines · Guenter Roeck

Review

Quoted 6 lines

(quoted diff) +6 -0

+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+

I think I asked that before ... as you are supporting devicetree, gpio pins should really be provided through devicetree properties and not be hardcoded.

Quoted 7 lines

Quoted 4 lines

Yes you did and I didn't come up with a solution to this problem yet. I understand and agree to your concerns but I'm lacking example code/documentation for it, maybe you can point me to an example on that and then I'll update my code accordingly.

Have a look at Documentation/devicetree/bindings/gpio/gpio-fan.txt and drivers/hwmon/gpio-fan.c.

Quoted 6 lines

Thanks a lot, this really helped me out. Updated patch is comming today including the bindings document Arnd Bergmann requested. I only need to rebase the sysfs patch on top of that changes.

Regards,
Johannes

Regarding the sysfs patch, I have a funny effect in my (rebased) sysfs code.

Given the following code:

(quoted diff) +15 -0

+static ssize_t rebootcause_show(struct device *dev,
+                               struct device_attribute *attr,
+                               char *buf)
+{
+       struct a21_wdt_drv *drv = dev_get_drvdata(dev);
+       unsigned int reset = 0;
+
+       if (!drv)
+               return -EIO;
+
+       reset = a21_wdt_get_bootstatus(drv);
+
+       return sprintf(buf, "%s\n", reset_causes[reset]);
+}
+static DEVICE_ATTR(rebootcause, S_IRUGO, rebootcause_show, NULL);

I actually need the check for if (!drv) to prevent an OOPS, as dev_get_drvdata(dev) returns NULL., though it is set at the end of my probe function via:

[...]

(quoted diff) +9 -0

+       ret = watchdog_register_device(&a21_wdt);
+       if (ret) {
+               dev_err(&pdev->dev, "Cannot register watchdog device\n");
+               goto err_register_wd;
+       }
+
+       dev_set_drvdata(&pdev->dev, drv);
+
+       return 0;
[...]

The watchdog driver itself is working without any troubles.

Quoted 2 lines

Some advice here would be worth its weight in gold.

It has to be set before the attribute is created. Are you doing that ? Also, is 'dev' the same device pointer (ie is the 'dev' in your function the same as &pdev->dev) ?

Guenter

Quoted 69 lines · Guenter Roeck

Quoted 68 lines · Johannes Thumshirn

Quoted 22 lines · Johannes Thumshirn

Quoted 13 lines · Guenter Roeck

Quoted 12 lines · Johannes Thumshirn

Hi Guenther,

Quoted 10 lines · Guenter Roeck

Review

Quoted 6 lines

(quoted diff) +6 -0

+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+

I think I asked that before ... as you are supporting devicetree, gpio pins should really be provided through devicetree properties and not be hardcoded.

Quoted 7 lines

Quoted 4 lines

Yes you did and I didn't come up with a solution to this problem yet. I understand and agree to your concerns but I'm lacking example code/documentation for it, maybe you can point me to an example on that and then I'll update my code accordingly.

Have a look at Documentation/devicetree/bindings/gpio/gpio-fan.txt and drivers/hwmon/gpio-fan.c.

Quoted 6 lines

Thanks a lot, this really helped me out. Updated patch is comming today including the bindings document Arnd Bergmann requested. I only need to rebase the sysfs patch on top of that changes.

Regards,
Johannes

Regarding the sysfs patch, I have a funny effect in my (rebased) sysfs code.

Given the following code:

(quoted diff) +15 -0

+static ssize_t rebootcause_show(struct device *dev,
+                               struct device_attribute *attr,
+                               char *buf)
+{
+       struct a21_wdt_drv *drv = dev_get_drvdata(dev);
+       unsigned int reset = 0;
+
+       if (!drv)
+               return -EIO;
+
+       reset = a21_wdt_get_bootstatus(drv);
+
+       return sprintf(buf, "%s\n", reset_causes[reset]);
+}
+static DEVICE_ATTR(rebootcause, S_IRUGO, rebootcause_show, NULL);

I actually need the check for if (!drv) to prevent an OOPS, as dev_get_drvdata(dev) returns NULL., though it is set at the end of my probe function via:

[...]

(quoted diff) +9 -0

+       ret = watchdog_register_device(&a21_wdt);
+       if (ret) {
+               dev_err(&pdev->dev, "Cannot register watchdog device\n");
+               goto err_register_wd;
+       }
+
+       dev_set_drvdata(&pdev->dev, drv);
+
+       return 0;
[...]

The watchdog driver itself is working without any troubles.

Quoted 7 lines

Quoted 2 lines

Some advice here would be worth its weight in gold.

It has to be set before the attribute is created. Are you doing that ? Also, is 'dev' the same device pointer (ie is the 'dev' in your function the same as &pdev->dev) ?

Guenter

Hi Guenter,

Thanks for the quick reply. Indeed 'dev' in my function is a struct watchdog_device's dev (for device_create_file) and not &pdev->dev. Which in turn are not the same.

A call to dev_set_drvdata(a21_wdt.dev, drv); solved the NULL pointer access. So last question, is it save to set the drvdata of a dev inside the struct watchdog_device or do I break something vital that way?

Quoted 80 lines · Johannes Thumshirn

Quoted 69 lines · Guenter Roeck

Quoted 68 lines · Johannes Thumshirn

Quoted 22 lines · Johannes Thumshirn

Quoted 13 lines · Guenter Roeck

Quoted 12 lines · Johannes Thumshirn

Hi Guenther,

Quoted 10 lines · Guenter Roeck

Review

Quoted 6 lines

(quoted diff) +6 -0

+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+

I think I asked that before ... as you are supporting devicetree, gpio pins should really be provided through devicetree properties and not be hardcoded.

Quoted 7 lines

Quoted 4 lines

Yes you did and I didn't come up with a solution to this problem yet. I understand and agree to your concerns but I'm lacking example code/documentation for it, maybe you can point me to an example on that and then I'll update my code accordingly.

Have a look at Documentation/devicetree/bindings/gpio/gpio-fan.txt and drivers/hwmon/gpio-fan.c.

Quoted 6 lines

Thanks a lot, this really helped me out. Updated patch is comming today including the bindings document Arnd Bergmann requested. I only need to rebase the sysfs patch on top of that changes.

Regards,
Johannes

Regarding the sysfs patch, I have a funny effect in my (rebased) sysfs code.

Given the following code:

(quoted diff) +15 -0

+static ssize_t rebootcause_show(struct device *dev,
+                               struct device_attribute *attr,
+                               char *buf)
+{
+       struct a21_wdt_drv *drv = dev_get_drvdata(dev);
+       unsigned int reset = 0;
+
+       if (!drv)
+               return -EIO;
+
+       reset = a21_wdt_get_bootstatus(drv);
+
+       return sprintf(buf, "%s\n", reset_causes[reset]);
+}
+static DEVICE_ATTR(rebootcause, S_IRUGO, rebootcause_show, NULL);

I actually need the check for if (!drv) to prevent an OOPS, as dev_get_drvdata(dev) returns NULL., though it is set at the end of my probe function via:

[...]

(quoted diff) +9 -0

+       ret = watchdog_register_device(&a21_wdt);
+       if (ret) {
+               dev_err(&pdev->dev, "Cannot register watchdog device\n");
+               goto err_register_wd;
+       }
+
+       dev_set_drvdata(&pdev->dev, drv);
+
+       return 0;
[...]

The watchdog driver itself is working without any troubles.

Quoted 7 lines

Quoted 2 lines

Some advice here would be worth its weight in gold.

It has to be set before the attribute is created. Are you doing that ? Also, is 'dev' the same device pointer (ie is the 'dev' in your function the same as &pdev->dev) ?

Guenter

Hi Guenter,

Quoted 8 lines

Thanks for the quick reply. Indeed 'dev' in my function is a struct watchdog_device's dev (for device_create_file) and not &pdev->dev. Which in turn are not the same.

A call to dev_set_drvdata(a21_wdt.dev, drv); solved the NULL pointer access. So last question, is it save to set the drvdata of a dev inside the struct watchdog_device or do I break something vital that way?

Good question. At issue is if your driver 'owns' struct watchdog_device, or if the watchdog core owns it.

However, since you know that a21_wdt.dev is the device, you can use container_of() to get a reference to a21_wdt, and watchdog_get_drvdata to get access to drv from a21_wdt. So you should not really need it.

Thanks,
Guenter

Quoted 96 lines · Guenter Roeck

Quoted 80 lines · Johannes Thumshirn

Quoted 69 lines · Guenter Roeck

Quoted 68 lines · Johannes Thumshirn

Quoted 22 lines · Johannes Thumshirn

Quoted 13 lines · Guenter Roeck

Quoted 12 lines · Johannes Thumshirn

Hi Guenther,

Quoted 10 lines · Guenter Roeck

Review

Quoted 6 lines

(quoted diff) +6 -0

+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+

I think I asked that before ... as you are supporting devicetree, gpio pins should really be provided through devicetree properties and not be hardcoded.

Quoted 7 lines

Quoted 4 lines

Yes you did and I didn't come up with a solution to this problem yet. I understand and agree to your concerns but I'm lacking example code/documentation for it, maybe you can point me to an example on that and then I'll update my code accordingly.

Have a look at Documentation/devicetree/bindings/gpio/gpio-fan.txt and drivers/hwmon/gpio-fan.c.

Quoted 6 lines

Thanks a lot, this really helped me out. Updated patch is comming today including the bindings document Arnd Bergmann requested. I only need to rebase the sysfs patch on top of that changes.

Regards,
Johannes

Regarding the sysfs patch, I have a funny effect in my (rebased) sysfs code.

Given the following code:

(quoted diff) +15 -0

+static ssize_t rebootcause_show(struct device *dev,
+                               struct device_attribute *attr,
+                               char *buf)
+{
+       struct a21_wdt_drv *drv = dev_get_drvdata(dev);
+       unsigned int reset = 0;
+
+       if (!drv)
+               return -EIO;
+
+       reset = a21_wdt_get_bootstatus(drv);
+
+       return sprintf(buf, "%s\n", reset_causes[reset]);
+}
+static DEVICE_ATTR(rebootcause, S_IRUGO, rebootcause_show, NULL);

I actually need the check for if (!drv) to prevent an OOPS, as dev_get_drvdata(dev) returns NULL., though it is set at the end of my probe function via:

[...]

(quoted diff) +9 -0

+       ret = watchdog_register_device(&a21_wdt);
+       if (ret) {
+               dev_err(&pdev->dev, "Cannot register watchdog device\n");
+               goto err_register_wd;
+       }
+
+       dev_set_drvdata(&pdev->dev, drv);
+
+       return 0;
[...]

The watchdog driver itself is working without any troubles.

Quoted 7 lines

Quoted 2 lines

Some advice here would be worth its weight in gold.

It has to be set before the attribute is created. Are you doing that ? Also, is 'dev' the same device pointer (ie is the 'dev' in your function the same as &pdev->dev) ?

Guenter

Hi Guenter,

Quoted 8 lines

Thanks for the quick reply. Indeed 'dev' in my function is a struct watchdog_device's dev (for device_create_file) and not &pdev->dev. Which in turn are not the same.

A call to dev_set_drvdata(a21_wdt.dev, drv); solved the NULL pointer access. So last question, is it save to set the drvdata of a dev inside the struct watchdog_device or do I break something vital that way?

Good question. At issue is if your driver 'owns' struct watchdog_device, or if the watchdog core owns it.

However, since you know that a21_wdt.dev is the device, you can use container_of() to get a reference to a21_wdt, and watchdog_get_drvdata to get access to drv from a21_wdt. So you should not really need it.

Quoted 2 lines

Thanks,
Guenter

OK, but doesn't the container_of() macro only work if the parent struct embeds the child struct and not a pointer to it? But struct watchdog_device only has a pointer to a struct device (checked my 3.10-rc4 as well as watchdog-next/master, just in case I missed something).

Quoted 100 lines · Johannes Thumshirn

Quoted 98 lines · Guenter Roeck

Quoted 80 lines · Johannes Thumshirn

Quoted 69 lines · Guenter Roeck

Quoted 68 lines · Johannes Thumshirn

Quoted 22 lines · Johannes Thumshirn

Quoted 13 lines · Guenter Roeck

Quoted 12 lines · Johannes Thumshirn

Hi Guenther,

Quoted 10 lines · Guenter Roeck

Review

Quoted 6 lines

(quoted diff) +6 -0

+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+

I think I asked that before ... as you are supporting devicetree, gpio pins should really be provided through devicetree properties and not be hardcoded.

Quoted 7 lines

Quoted 4 lines

Yes you did and I didn't come up with a solution to this problem yet. I understand and agree to your concerns but I'm lacking example code/documentation for it, maybe you can point me to an example on that and then I'll update my code accordingly.

Have a look at Documentation/devicetree/bindings/gpio/gpio-fan.txt and drivers/hwmon/gpio-fan.c.

Quoted 6 lines

Thanks a lot, this really helped me out. Updated patch is comming today including the bindings document Arnd Bergmann requested. I only need to rebase the sysfs patch on top of that changes.

Regards,
Johannes

Regarding the sysfs patch, I have a funny effect in my (rebased) sysfs code.

Given the following code:

(quoted diff) +15 -0

+static ssize_t rebootcause_show(struct device *dev,
+                               struct device_attribute *attr,
+                               char *buf)
+{
+       struct a21_wdt_drv *drv = dev_get_drvdata(dev);
+       unsigned int reset = 0;
+
+       if (!drv)
+               return -EIO;
+
+       reset = a21_wdt_get_bootstatus(drv);
+
+       return sprintf(buf, "%s\n", reset_causes[reset]);
+}
+static DEVICE_ATTR(rebootcause, S_IRUGO, rebootcause_show, NULL);

I actually need the check for if (!drv) to prevent an OOPS, as dev_get_drvdata(dev) returns NULL., though it is set at the end of my probe function via:

[...]

(quoted diff) +9 -0

+       ret = watchdog_register_device(&a21_wdt);
+       if (ret) {
+               dev_err(&pdev->dev, "Cannot register watchdog device\n");
+               goto err_register_wd;
+       }
+
+       dev_set_drvdata(&pdev->dev, drv);
+
+       return 0;
[...]

The watchdog driver itself is working without any troubles.

Quoted 7 lines

Quoted 2 lines

Some advice here would be worth its weight in gold.

It has to be set before the attribute is created. Are you doing that ? Also, is 'dev' the same device pointer (ie is the 'dev' in your function the same as &pdev->dev) ?

Guenter

Hi Guenter,

Quoted 8 lines

Thanks for the quick reply. Indeed 'dev' in my function is a struct watchdog_device's dev (for device_create_file) and not &pdev->dev. Which in turn are not the same.

A call to dev_set_drvdata(a21_wdt.dev, drv); solved the NULL pointer access. So last question, is it save to set the drvdata of a dev inside the struct watchdog_device or do I break something vital that way?

Good question. At issue is if your driver 'owns' struct watchdog_device, or if the watchdog core owns it.

However, since you know that a21_wdt.dev is the device, you can use container_of() to get a reference to a21_wdt, and watchdog_get_drvdata to get access to drv from a21_wdt. So you should not really need it.

Thanks,
Guenter

Quoted 5 lines

OK, but doesn't the container_of() macro only work if the parent struct embeds the child struct and not a pointer to it? But struct watchdog_device only has a pointer to a struct device (checked my 3.10-rc4 as well as watchdog-next/master, just in case I missed something).

Yes, you are right, sorry for the noise.

Guenter

This patch adds the driver for the watchdog devices found on MEN Mikro Elektronik A21 VMEbus CPU Carrier Boards. It has DT-support and uses the watchdog framework.

Revision 2:
* Removed unneeded open flag in struct a21_wdt_drv
* Corrected 3bit reason code from gpio
* Additional sysfs files are now part of watchdog sysfs
* Changed OFF/ON delay in ping from 400ms to 10ns
* Reworked timeout setting
* Removed a21_wdt_ioctl(...)

Revision 3:
* Changed pr_{err,info} to dev_{err,info}
* Removed out of memory error print
* Transition from "fast" to "slow" mode not allowed by chip

Revision 4:
* Remove reboot_notifier and place disable code into platform_device's shutdown function
* Removed sysfs interface

Revision 5:

* Added setting of .bootstatus on driver init
* Added initial timeout on driver init

Revision 6:
* Use watchdog_init_timeout() to initialize timeout

Revision 7:
* Fix possible get_bootstatus race condition

Signed-off-by Johannes Thumshirn <[email protected]>

---
 MAINTAINERS                   |    6 ++
 drivers/watchdog/Kconfig      |    8 ++
 drivers/watchdog/Makefile     |    1 +
 drivers/watchdog/mena21_wdt.c |  234 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 249 insertions(+)
 create mode 100644 drivers/watchdog/mena21_wdt.c

MAINTAINERS +6 -0

index 7714c3c..023945a 100644
@@ -5307,6 +5307,12 @@ F:	drivers/mtd/
 F:	include/linux/mtd/
 F:	include/uapi/mtd/
 
+MEN A21 WATCHDOG DRIVER
+M:  	Johannes Thumshirn <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/watchdog/mena21_wdt.c
+
 METAG ARCHITECTURE
 M:	James Hogan <[email protected]>
 S:	Supported

drivers/watchdog/Kconfig +8 -0

index e89fc31..192b84d 100644
@@ -1172,6 +1172,14 @@ config BOOKE_WDT_DEFAULT_TIMEOUT
 
 	  The value can be overridden by the wdt_period command-line parameter.
 
+config MEN_A21_WDT
+       tristate "MEN A21 VME CPU Carrier Board Watchdog Timer"
+       select WATCHDOG_CORE
+       help
+        Watchdog driver for MEN A21 VMEbus CPU Carrier Boards.
+
+	If unsure select N here.
+
 # PPC64 Architecture
 
 config WATCHDOG_RTAS

drivers/watchdog/Makefile +1 -0

index a300b94..bffdcb1 100644
@@ -143,6 +143,7 @@ obj-$(CONFIG_8xxx_WDT) += mpc8xxx_wdt.o
 obj-$(CONFIG_MV64X60_WDT) += mv64x60_wdt.o
 obj-$(CONFIG_PIKA_WDT) += pika_wdt.o
 obj-$(CONFIG_BOOKE_WDT) += booke_wdt.o
+obj-$(CONFIG_MEN_A21_WDT) += mena21_wdt.o
 
 # PPC64 Architecture
 obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o

drivers/watchdog/mena21_wdt.c new file +38 -0

new file mode 100644
index 0000000..dec35ec
@@ -0,0 +1,234 @@
+/*
+ * Watchdog driver for the A21 VME CPU Boards
+ *
+ * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
+ *
+ * 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
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+#include <linux/gpio.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+
+#define GPIO_WD_ENAB	169
+#define GPIO_WD_FAST	170
+#define GPIO_WD_TRIG	171
+
+#define GPIO_RST_CAUSE_BASE 166
+
+struct a21_wdt_drv {
+	struct watchdog_device wdt;
+	struct mutex lock;
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+			    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static int a21_wdt_get_bootstatus(unsigned int *reset)

drivers/watchdog/mena21_wdt.c new file +186 -1

+	return 0;
+}
+
+static int a21_wdt_start(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_ENAB, 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_stop(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	/* We don't stop if WDOG_NO_WAY_OUT is set */
+	if (test_bit(WDOG_NO_WAY_OUT, &wdt->status))
+		return -EINVAL;
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_ENAB, 0);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_ping(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(GPIO_WD_TRIG, 0);
+	ndelay(10);
+	gpio_set_value(GPIO_WD_TRIG, 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_set_timeout(struct watchdog_device *wdt,
+			       unsigned int timeout)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	if (timeout != 1 && timeout != 30) {
+		dev_err(wdt->dev, "Only 1 and 30 allowed as timeout\n");
+		return -EINVAL;
+	}
+
+	if (timeout == 30 && wdt->timeout == 1) {
+		dev_err(wdt->dev,
+			"Transition from fast to slow mode not allowed\n");
+		return -EINVAL;
+	}
+
+	mutex_lock(&drv->lock);
+
+	if (timeout == 1)
+		gpio_set_value(GPIO_WD_FAST, 1);
+	else
+		gpio_set_value(GPIO_WD_FAST, 0);
+
+	wdt->timeout = timeout;
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static const struct watchdog_info a21_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "MEN A21 Watchdog",
+};
+
+static const struct watchdog_ops a21_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = a21_wdt_start,
+	.stop = a21_wdt_stop,
+	.ping = a21_wdt_ping,
+	.set_timeout = a21_wdt_set_timeout,
+};
+
+static struct watchdog_device a21_wdt = {
+	.info = &a21_wdt_info,
+	.ops = &a21_wdt_ops,
+	.min_timeout = 1,
+	.max_timeout = 30,
+};
+
+static int a21_wdt_probe(struct platform_device *pdev)
+{
+	struct a21_wdt_drv *drv;
+	unsigned int reset = 0;
+	int ret;
+
+	dev_info(&pdev->dev, "MEN A21 watchdog timer driver enabled\n");
+
+	drv = devm_kzalloc(&pdev->dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
+	if (!drv)
+		return -ENOMEM;
+
+	mutex_init(&drv->lock);
+	watchdog_init_timeout(&a21_wdt, 30, &pdev->dev);
+	watchdog_set_nowayout(&a21_wdt, nowayout);
+	watchdog_set_drvdata(&a21_wdt, drv);
+
+	ret = a21_wdt_get_bootstatus(&reset);
+	if (ret)
+		dev_warn(&pdev->dev, "Reset Cause contains invalid data\n");
+	else {
+		if (reset == 2)
+			a21_wdt.bootstatus |= WDIOF_EXTERN1;
+		else if (reset == 4)
+			a21_wdt.bootstatus |= WDIOF_CARDRESET;
+		else if (reset == 5)
+			a21_wdt.bootstatus |= WDIOF_POWERUNDER;
+		else if (reset == 7)
+			a21_wdt.bootstatus |= WDIOF_EXTERN2;
+	}
+
+	ret = watchdog_register_device(&a21_wdt);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot register watchdog device\n");
+		goto err_register_wd;
+	}
+
+	dev_set_drvdata(&pdev->dev, drv);
+
+	return 0;
+
+err_register_wd:
+	mutex_destroy(&drv->lock);
+
+	return ret;
+}
+
+static int a21_wdt_remove(struct platform_device *pdev)
+{
+	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
+
+	dev_warn(&pdev->dev,
+		"Unregistering A21 watchdog driver, board may reboot\n");
+
+
+	watchdog_unregister_device(&drv->wdt);
+
+	mutex_destroy(&drv->lock);
+
+	return 0;
+}
+
+static void a21_wdt_shutdown(struct platform_device *pdev)
+{
+	gpio_set_value(GPIO_WD_ENAB, 0);
+}
+
+static const struct of_device_id a21_wdt_ids[] = {
+	{ .compatible = "men,a021-wdt" },
+	{ },
+};
+
+static struct platform_driver a21_wdt_driver = {
+	.probe = a21_wdt_probe,
+	.remove = a21_wdt_remove,
+	.shutdown = a21_wdt_shutdown,
+	.driver = {
+		.name = "a21-watchdog",
+		.of_match_table = a21_wdt_ids,
+	},
+};
+
+module_platform_driver(a21_wdt_driver);
+
+MODULE_AUTHOR("MEN Mikro Elektronik");
+MODULE_DESCRIPTION("MEN A21 Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:a21-watchdog");
--

1.7.9.5

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This patch adds the driver for the watchdog devices found on MEN Mikro Elektronik A21 VMEbus CPU Carrier Boards. It has DT-support and uses the watchdog framework.

Revision 2:
* Removed unneeded open flag in struct a21_wdt_drv
* Corrected 3bit reason code from gpio
* Additional sysfs files are now part of watchdog sysfs
* Changed OFF/ON delay in ping from 400ms to 10ns
* Reworked timeout setting
* Removed a21_wdt_ioctl(...)

Revision 3:
* Changed pr_{err,info} to dev_{err,info}
* Removed out of memory error print
* Transition from "fast" to "slow" mode not allowed by chip

Revision 4:
* Remove reboot_notifier and place disable code into platform_device's shutdown function
* Removed sysfs interface

Revision 5:
* Added setting of .bootstatus on driver init
* Added initial timeout on driver init

Revision 6:
* Use watchdog_init_timeout() to initialize timeout

Revision 7:
* Fix possible get_bootstatus race condition

Revision 8:
* a21_wdt_get_bootstatus() should return reset code
* GPIOs are supplied via DT instead of being hardcoded. Code derived from (drivers/hwmon/gpio-fan.c)
* Added Devicetree binding document
* Driver now depends on GPIOLIB

Signed-off-by Johannes Thumshirn <[email protected]>

---
 .../devicetree/bindings/gpio/men-a021-wdt.txt      |   25 ++
 MAINTAINERS                                        |    6 +
 drivers/watchdog/Kconfig                           |   12 +
 drivers/watchdog/Makefile                          |    1 +
 drivers/watchdog/mena21_wdt.c                      |  277 ++++++++++++++++++++
 5 files changed, 321 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/men-a021-wdt.txt
 create mode 100644 drivers/watchdog/mena21_wdt.c

Documentation/devicetree/bindings/gpio/men-a021-wdt.txt new file +25 -0

new file mode 100644
index 0000000..370dee3
@@ -0,0 +1,25 @@
+Bindings for MEN A21 Watchdog device connected to GPIO lines
+
+Required properties:
+- compatible: "men,a021-wdt"
+- gpios: Specifies the pins that control the Watchdog, order:
+  1: Watchdog enable
+  2: Watchdog fast-mode
+  3: Watchdog trigger
+  4: Watchdog reset cause bit 0
+  5: Watchdog reset cause bit 1
+  6: Watchdog reset cause bit 2
+
+Optional properties:
+- None
+
+Example:
+	watchdog {
+		compatible ="men,a021-wdt";
+		gpios = <&gpio3 9  1	/* WD_EN */
+			 &gpio3 10 1	/* WD_FAST */
+			 &gpio3 11 1	/* WD_TRIG */
+			 &gpio3 6  1	/* RST_CAUSE[0] */
+			 &gpio3 7  1	/* RST_CAUSE[1] */
+			 &gpio3 8  1>;	/* RST_CAUSE[2] */
+	};

MAINTAINERS +6 -0

index f35a259..bd86661 100644
@@ -5307,6 +5307,12 @@ F:	drivers/mtd/
 F:	include/linux/mtd/
 F:	include/uapi/mtd/
 
+MEN A21 WATCHDOG DRIVER
+M:  	Johannes Thumshirn <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/watchdog/mena21_wdt.c
+
 METAG ARCHITECTURE
 M:	James Hogan <[email protected]>
 S:	Supported

drivers/watchdog/Kconfig +12 -0

index e89fc31..8b143ee 100644
@@ -1172,6 +1172,18 @@ config BOOKE_WDT_DEFAULT_TIMEOUT
 
 	  The value can be overridden by the wdt_period command-line parameter.
 
+config MEN_A21_WDT
+       tristate "MEN A21 VME CPU Carrier Board Watchdog Timer"
+       select WATCHDOG_CORE
+       depends on GPIOLIB
+       help
+        Watchdog driver for MEN A21 VMEbus CPU Carrier Boards.
+
+	The driver can also be built as a module. If so, the module will be
+	called mena21_wdt.
+
+	If unsure select N here.
+
 # PPC64 Architecture
 
 config WATCHDOG_RTAS

drivers/watchdog/Makefile +1 -0

index a300b94..bffdcb1 100644
@@ -143,6 +143,7 @@ obj-$(CONFIG_8xxx_WDT) += mpc8xxx_wdt.o
 obj-$(CONFIG_MV64X60_WDT) += mv64x60_wdt.o
 obj-$(CONFIG_PIKA_WDT) += pika_wdt.o
 obj-$(CONFIG_BOOKE_WDT) += booke_wdt.o
+obj-$(CONFIG_MEN_A21_WDT) += mena21_wdt.o
 
 # PPC64 Architecture
 obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o

drivers/watchdog/mena21_wdt.c new file +162 -0

new file mode 100644
index 0000000..29f9c0d
@@ -0,0 +1,277 @@
+/*
+ * Watchdog driver for the A21 VME CPU Boards
+ *
+ * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
+ *
+ * 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
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+
+enum a21_wdt_gpios {
+	GPIO_WD_ENAB,
+	GPIO_WD_FAST,
+	GPIO_WD_TRIG,
+	GPIO_WD_RST0,
+	GPIO_WD_RST1,
+	GPIO_WD_RST2,
+};
+
+struct a21_wdt_drv {
+	struct watchdog_device wdt;
+	struct mutex lock;
+	int num_gpios;
+	unsigned *gpios;
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+			    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static unsigned int a21_wdt_get_bootstatus(struct a21_wdt_drv *drv)
+{
+	int reset = 0;
+
+	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
+	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
+	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST2]) ? (1 << 2) : 0;
+
+	return reset;
+}
+
+static int a21_wdt_start(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_stop(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	/* We don't stop if WDOG_NO_WAY_OUT is set */
+	if (test_bit(WDOG_NO_WAY_OUT, &wdt->status))
+		return -EINVAL;
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_ping(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(drv->gpios[GPIO_WD_TRIG], 0);
+	ndelay(10);
+	gpio_set_value(drv->gpios[GPIO_WD_TRIG], 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_set_timeout(struct watchdog_device *wdt,
+			       unsigned int timeout)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	if (timeout != 1 && timeout != 30) {
+		dev_err(wdt->dev, "Only 1 and 30 allowed as timeout\n");
+		return -EINVAL;
+	}
+
+	if (timeout == 30 && wdt->timeout == 1) {
+		dev_err(wdt->dev,
+			"Transition from fast to slow mode not allowed\n");
+		return -EINVAL;
+	}
+
+	mutex_lock(&drv->lock);
+
+	if (timeout == 1)
+		gpio_set_value(drv->gpios[GPIO_WD_FAST], 1);
+	else
+		gpio_set_value(drv->gpios[GPIO_WD_FAST], 0);
+
+	wdt->timeout = timeout;
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static const struct watchdog_info a21_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "MEN A21 Watchdog",
+};
+
+static const struct watchdog_ops a21_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = a21_wdt_start,
+	.stop = a21_wdt_stop,
+	.ping = a21_wdt_ping,
+	.set_timeout = a21_wdt_set_timeout,
+};
+
+static struct watchdog_device a21_wdt = {
+	.info = &a21_wdt_info,
+	.ops = &a21_wdt_ops,
+	.min_timeout = 1,
+	.max_timeout = 30,
+};
+
+static int a21_wdt_probe(struct platform_device *pdev)
+{
+	struct device_node *node;
+	struct a21_wdt_drv *drv;
+	unsigned int reset = 0;
+	unsigned *gpios;
+	int ret;
+	int i;
+
+	dev_info(&pdev->dev, "MEN A21 watchdog timer driver enabled\n");
+
+	drv = devm_kzalloc(&pdev->dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
+	if (!drv)

drivers/watchdog/mena21_wdt.c new file +105 -1

+
+	gpios = devm_kzalloc(&pdev->dev, drv->num_gpios * sizeof(unsigned),
+			     GFP_KERNEL);
+	if (!gpios)
+		return -ENOMEM;
+
+	for (i = 0; i < drv->num_gpios; i++) {
+		int val;
+
+		val = of_get_gpio(node, i);
+		if (val < 0)
+			return val;
+
+		gpios[i] = val;
+	}
+	drv->gpios = gpios;
+
+	/* Request the used GPIOs */
+	for (i = 0; i < drv->num_gpios; i++) {
+		ret = devm_gpio_request(&pdev->dev, drv->gpios[i],
+					"MEN A21 Watchdog");
+		if (ret)
+			return ret;
+
+		ret = gpio_direction_output(drv->gpios[i],
+					    gpio_get_value(drv->gpios[i]));
+		if (ret)
+			return ret;
+	}
+
+	mutex_init(&drv->lock);
+	watchdog_init_timeout(&a21_wdt, 30, &pdev->dev);
+	watchdog_set_nowayout(&a21_wdt, nowayout);
+	watchdog_set_drvdata(&a21_wdt, drv);
+
+	reset = a21_wdt_get_bootstatus(drv);
+	if (reset == 2)
+		a21_wdt.bootstatus |= WDIOF_EXTERN1;
+	else if (reset == 4)
+		a21_wdt.bootstatus |= WDIOF_CARDRESET;
+	else if (reset == 5)
+		a21_wdt.bootstatus |= WDIOF_POWERUNDER;
+	else if (reset == 7)
+		a21_wdt.bootstatus |= WDIOF_EXTERN2;
+
+
+	ret = watchdog_register_device(&a21_wdt);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot register watchdog device\n");
+		goto err_register_wd;
+	}
+
+	dev_set_drvdata(&pdev->dev, drv);
+
+	return 0;
+
+err_register_wd:
+	mutex_destroy(&drv->lock);
+
+	return ret;
+}
+
+static int a21_wdt_remove(struct platform_device *pdev)
+{
+	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
+
+	dev_warn(&pdev->dev,
+		"Unregistering A21 watchdog driver, board may reboot\n");
+
+
+	watchdog_unregister_device(&drv->wdt);
+
+	mutex_destroy(&drv->lock);
+
+	return 0;
+}
+
+static void a21_wdt_shutdown(struct platform_device *pdev)
+{
+	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
+
+	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
+}
+
+static const struct of_device_id a21_wdt_ids[] = {
+	{ .compatible = "men,a021-wdt" },
+	{ },
+};
+
+static struct platform_driver a21_wdt_driver = {
+	.probe = a21_wdt_probe,
+	.remove = a21_wdt_remove,
+	.shutdown = a21_wdt_shutdown,
+	.driver = {
+		.name = "a21-watchdog",
+		.of_match_table = a21_wdt_ids,
+	},
+};
+
+module_platform_driver(a21_wdt_driver);
+
+MODULE_AUTHOR("MEN Mikro Elektronik");
+MODULE_DESCRIPTION("MEN A21 Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:a21-watchdog");
--

1.7.9.5

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Quoted 1 line

Signed-off-by Johannes Thumshirn <[email protected]>

Almost good. One comment below.

Thanks,
Guenter

drivers/watchdog/mena21_wdt.c line 172

Quoted 6 lines

drivers/watchdog/mena21_wdt.c new file +6 -0

+
+	drv->num_gpios = of_gpio_count(node);
+	if (drv->num_gpios <= 0) {
+		dev_err(&pdev->dev, "gpios DT property empty / missing");
+		return -ENODEV;
+	}

Not happy with this. Code accepts one gpio pin, but then assumes throughout the driver that all pins are defined. I am quite sure I can get it to crash if I specify only a single gpio pin. num_gpios will be 1, you allocate a single entry, but then access all 6 of them.

I think it would be easier if you expect a fixed number of gpio pins (6) and abort if it is not correct. You can then make drv->gpios an array and don't have to allocate it separately, and you don't need drv->num_gpios (which you don't need anyway as it is not used outside this function).

This patch adds the driver for the watchdog devices found on MEN Mikro Elektronik A21 VMEbus CPU Carrier Boards. It has DT-support and uses the watchdog framework.

Signed-off-by Johannes Thumshirn <[email protected]>

---

Revision 2:
* Removed unneeded open flag in struct a21_wdt_drv
* Corrected 3bit reason code from gpio
* Additional sysfs files are now part of watchdog sysfs
* Changed OFF/ON delay in ping from 400ms to 10ns
* Reworked timeout setting
* Removed a21_wdt_ioctl(...)

Revision 3:
* Changed pr_{err,info} to dev_{err,info}
* Removed out of memory error print
* Transition from "fast" to "slow" mode not allowed by chip

Revision 4:
* Remove reboot_notifier and place disable code into platform_device's shutdown function
* Removed sysfs interface

Revision 5:
* Added setting of .bootstatus on driver init
* Added initial timeout on driver init

Revision 6:
* Use watchdog_init_timeout() to initialize timeout

Revision 7:
* Fix possible get_bootstatus race condition

Revision 8:
* a21_wdt_get_bootstatus() should return reset code
* GPIOs are supplied via DT instead of being hardcoded. Code derived from (drivers/hwmon/gpio-fan.c)
* Added Devicetree binding document
* Driver now depends on GPIOLIB

Revision 9:
* We need 6 GPIOs not only 1 to work
* GPIO_WD_RST[0..2] are inputs

 .../devicetree/bindings/gpio/men-a021-wdt.txt      |   25 ++
 MAINTAINERS                                        |    6 +
 drivers/watchdog/Kconfig                           |   12 +
 drivers/watchdog/Makefile                          |    1 +
 drivers/watchdog/mena21_wdt.c                      |  276 ++++++++++++++++++++
 5 files changed, 320 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/men-a021-wdt.txt
 create mode 100644 drivers/watchdog/mena21_wdt.c

Documentation/devicetree/bindings/gpio/men-a021-wdt.txt new file +25 -0

new file mode 100644
index 0000000..370dee3
@@ -0,0 +1,25 @@
+Bindings for MEN A21 Watchdog device connected to GPIO lines
+
+Required properties:
+- compatible: "men,a021-wdt"
+- gpios: Specifies the pins that control the Watchdog, order:
+  1: Watchdog enable
+  2: Watchdog fast-mode
+  3: Watchdog trigger
+  4: Watchdog reset cause bit 0
+  5: Watchdog reset cause bit 1
+  6: Watchdog reset cause bit 2
+
+Optional properties:
+- None
+
+Example:
+	watchdog {
+		compatible ="men,a021-wdt";
+		gpios = <&gpio3 9  1	/* WD_EN */
+			 &gpio3 10 1	/* WD_FAST */
+			 &gpio3 11 1	/* WD_TRIG */
+			 &gpio3 6  1	/* RST_CAUSE[0] */
+			 &gpio3 7  1	/* RST_CAUSE[1] */
+			 &gpio3 8  1>;	/* RST_CAUSE[2] */
+	};

MAINTAINERS +6 -0

index 5be702c..824261e 100644
@@ -5317,6 +5317,12 @@ F:	drivers/mtd/
 F:	include/linux/mtd/
 F:	include/uapi/mtd/
 
+MEN A21 WATCHDOG DRIVER
+M:  	Johannes Thumshirn <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/watchdog/mena21_wdt.c
+
 METAG ARCHITECTURE
 M:	James Hogan <[email protected]>
 S:	Supported

drivers/watchdog/Kconfig +12 -0

index e89fc31..8b143ee 100644
@@ -1172,6 +1172,18 @@ config BOOKE_WDT_DEFAULT_TIMEOUT
 
 	  The value can be overridden by the wdt_period command-line parameter.
 
+config MEN_A21_WDT
+       tristate "MEN A21 VME CPU Carrier Board Watchdog Timer"
+       select WATCHDOG_CORE
+       depends on GPIOLIB
+       help
+        Watchdog driver for MEN A21 VMEbus CPU Carrier Boards.
+
+	The driver can also be built as a module. If so, the module will be
+	called mena21_wdt.
+
+	If unsure select N here.
+
 # PPC64 Architecture
 
 config WATCHDOG_RTAS

drivers/watchdog/Makefile +1 -0

index a300b94..bffdcb1 100644
@@ -143,6 +143,7 @@ obj-$(CONFIG_8xxx_WDT) += mpc8xxx_wdt.o
 obj-$(CONFIG_MV64X60_WDT) += mv64x60_wdt.o
 obj-$(CONFIG_PIKA_WDT) += pika_wdt.o
 obj-$(CONFIG_BOOKE_WDT) += booke_wdt.o
+obj-$(CONFIG_MEN_A21_WDT) += mena21_wdt.o
 
 # PPC64 Architecture
 obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o

drivers/watchdog/mena21_wdt.c new file +66 -0

new file mode 100644
index 0000000..0d3409a
@@ -0,0 +1,276 @@
+/*
+ * Watchdog driver for the A21 VME CPU Boards
+ *
+ * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
+ *
+ * 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
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+
+#define NUM_GPIOS 6
+
+enum a21_wdt_gpios {
+	GPIO_WD_ENAB,
+	GPIO_WD_FAST,
+	GPIO_WD_TRIG,
+	GPIO_WD_RST0,
+	GPIO_WD_RST1,
+	GPIO_WD_RST2,
+};
+
+struct a21_wdt_drv {
+	struct watchdog_device wdt;
+	struct mutex lock;
+	unsigned gpios[NUM_GPIOS];
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+			    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static unsigned int a21_wdt_get_bootstatus(struct a21_wdt_drv *drv)
+{
+	int reset = 0;
+
+	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
+	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
+	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST2]) ? (1 << 2) : 0;
+
+	return reset;
+}
+
+static int a21_wdt_start(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;

drivers/watchdog/mena21_wdt.c new file +7 -0

+	mutex_lock(&drv->lock);
+
+	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;

drivers/watchdog/mena21_wdt.c new file +58 -0

+	gpio_set_value(drv->gpios[GPIO_WD_TRIG], 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_set_timeout(struct watchdog_device *wdt,
+			       unsigned int timeout)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	if (timeout != 1 && timeout != 30) {
+		dev_err(wdt->dev, "Only 1 and 30 allowed as timeout\n");
+		return -EINVAL;
+	}
+
+	if (timeout == 30 && wdt->timeout == 1) {
+		dev_err(wdt->dev,
+			"Transition from fast to slow mode not allowed\n");
+		return -EINVAL;
+	}
+
+	mutex_lock(&drv->lock);
+
+	if (timeout == 1)
+		gpio_set_value(drv->gpios[GPIO_WD_FAST], 1);
+	else
+		gpio_set_value(drv->gpios[GPIO_WD_FAST], 0);
+
+	wdt->timeout = timeout;
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static const struct watchdog_info a21_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "MEN A21 Watchdog",
+};
+
+static const struct watchdog_ops a21_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = a21_wdt_start,
+	.stop = a21_wdt_stop,
+	.ping = a21_wdt_ping,
+	.set_timeout = a21_wdt_set_timeout,
+};
+
+static struct watchdog_device a21_wdt = {
+	.info = &a21_wdt_info,
+	.ops = &a21_wdt_ops,
+	.min_timeout = 1,
+	.max_timeout = 30,
+};
+
+static int a21_wdt_probe(struct platform_device *pdev)

drivers/watchdog/mena21_wdt.c new file +46 -0

+	drv = devm_kzalloc(&pdev->dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
+	if (!drv)
+		return -ENOMEM;
+
+	/* Fill GPIO pin array */
+	node = pdev->dev.of_node;
+
+	num_gpios = of_gpio_count(node);
+	if (num_gpios != NUM_GPIOS) {
+		dev_err(&pdev->dev, "gpios DT property wrong, got %d want %d",
+			num_gpios, NUM_GPIOS);
+		return -ENODEV;
+	}
+
+	for (i = 0; i < num_gpios; i++) {
+		int val;
+
+		val = of_get_gpio(node, i);
+		if (val < 0)
+			return val;
+
+		drv->gpios[i] = val;
+	}
+
+	/* Request the used GPIOs */
+	for (i = 0; i < num_gpios; i++) {
+		ret = devm_gpio_request(&pdev->dev, drv->gpios[i],
+					"MEN A21 Watchdog");
+		if (ret)
+			return ret;
+
+		if (i < GPIO_WD_RST0)
+			ret = gpio_direction_output(drv->gpios[i],
+						gpio_get_value(drv->gpios[i]));
+		else		/* GPIO_WD_RST[0..2] are inputs */
+			ret = gpio_direction_input(drv->gpios[i]);
+		if (ret)
+			return ret;
+	}
+
+	mutex_init(&drv->lock);
+	watchdog_init_timeout(&a21_wdt, 30, &pdev->dev);
+	watchdog_set_nowayout(&a21_wdt, nowayout);
+	watchdog_set_drvdata(&a21_wdt, drv);
+
+	reset = a21_wdt_get_bootstatus(drv);

drivers/watchdog/mena21_wdt.c new file +14 -0

+	ret = watchdog_register_device(&a21_wdt);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot register watchdog device\n");
+		goto err_register_wd;
+	}
+
+	dev_set_drvdata(&pdev->dev, drv);
+
+	return 0;
+
+err_register_wd:
+	mutex_destroy(&drv->lock);
+
+	return ret;

drivers/watchdog/mena21_wdt.c new file +35 -1

+	watchdog_unregister_device(&drv->wdt);
+
+	mutex_destroy(&drv->lock);
+
+	return 0;
+}
+
+static void a21_wdt_shutdown(struct platform_device *pdev)
+{
+	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
+
+	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
+}
+
+static const struct of_device_id a21_wdt_ids[] = {
+	{ .compatible = "men,a021-wdt" },
+	{ },
+};
+
+static struct platform_driver a21_wdt_driver = {
+	.probe = a21_wdt_probe,
+	.remove = a21_wdt_remove,
+	.shutdown = a21_wdt_shutdown,
+	.driver = {
+		.name = "a21-watchdog",
+		.of_match_table = a21_wdt_ids,
+	},
+};
+
+module_platform_driver(a21_wdt_driver);
+
+MODULE_AUTHOR("MEN Mikro Elektronik");
+MODULE_DESCRIPTION("MEN A21 Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:a21-watchdog");
--

1.7.9.5

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Quoted 5 lines · Johannes Thumshirn

This patch adds the driver for the watchdog devices found on MEN Mikro Elektronik A21 VMEbus CPU Carrier Boards. It has DT-support and uses the watchdog framework.

Signed-off-by Johannes Thumshirn <[email protected]>

Only nitpicks this time.

Quoted 207 lines

---

Revision 2:
* Removed unneeded open flag in struct a21_wdt_drv
* Corrected 3bit reason code from gpio
* Additional sysfs files are now part of watchdog sysfs
* Changed OFF/ON delay in ping from 400ms to 10ns
* Reworked timeout setting
* Removed a21_wdt_ioctl(...)

Revision 3:
* Changed pr_{err,info} to dev_{err,info}
* Removed out of memory error print
* Transition from "fast" to "slow" mode not allowed by chip

Revision 4:
* Remove reboot_notifier and place disable code into platform_device's shutdown function
* Removed sysfs interface

Revision 5:
* Added setting of .bootstatus on driver init
* Added initial timeout on driver init

Revision 6:
* Use watchdog_init_timeout() to initialize timeout

Revision 7:
* Fix possible get_bootstatus race condition

Revision 8:
* a21_wdt_get_bootstatus() should return reset code
* GPIOs are supplied via DT instead of being hardcoded. Code derived from (drivers/hwmon/gpio-fan.c)
* Added Devicetree binding document
* Driver now depends on GPIOLIB

Revision 9:
* We need 6 GPIOs not only 1 to work
* GPIO_WD_RST[0..2] are inputs

 .../devicetree/bindings/gpio/men-a021-wdt.txt      |   25 ++
 MAINTAINERS                                        |    6 +
 drivers/watchdog/Kconfig                           |   12 +
 drivers/watchdog/Makefile                          |    1 +
 drivers/watchdog/mena21_wdt.c                      |  276 ++++++++++++++++++++
 5 files changed, 320 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/men-a021-wdt.txt
 create mode 100644 drivers/watchdog/mena21_wdt.c

Documentation/devicetree/bindings/gpio/men-a021-wdt.txt new file +25 -0

new file mode 100644
index 0000000..370dee3
@@ -0,0 +1,25 @@
+Bindings for MEN A21 Watchdog device connected to GPIO lines
+
+Required properties:
+- compatible: "men,a021-wdt"
+- gpios: Specifies the pins that control the Watchdog, order:
+  1: Watchdog enable
+  2: Watchdog fast-mode
+  3: Watchdog trigger
+  4: Watchdog reset cause bit 0
+  5: Watchdog reset cause bit 1
+  6: Watchdog reset cause bit 2
+
+Optional properties:
+- None
+
+Example:
+	watchdog {
+		compatible ="men,a021-wdt";
+		gpios = <&gpio3 9  1	/* WD_EN */
+			 &gpio3 10 1	/* WD_FAST */
+			 &gpio3 11 1	/* WD_TRIG */
+			 &gpio3 6  1	/* RST_CAUSE[0] */
+			 &gpio3 7  1	/* RST_CAUSE[1] */
+			 &gpio3 8  1>;	/* RST_CAUSE[2] */
+	};

MAINTAINERS +6 -0

index 5be702c..824261e 100644
@@ -5317,6 +5317,12 @@ F:	drivers/mtd/
 F:	include/linux/mtd/
 F:	include/uapi/mtd/
 
+MEN A21 WATCHDOG DRIVER
+M:  	Johannes Thumshirn <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/watchdog/mena21_wdt.c
+
 METAG ARCHITECTURE
 M:	James Hogan <[email protected]>
 S:	Supported

drivers/watchdog/Kconfig +12 -0

index e89fc31..8b143ee 100644
@@ -1172,6 +1172,18 @@ config BOOKE_WDT_DEFAULT_TIMEOUT
 
 	  The value can be overridden by the wdt_period command-line parameter.
 
+config MEN_A21_WDT
+       tristate "MEN A21 VME CPU Carrier Board Watchdog Timer"
+       select WATCHDOG_CORE
+       depends on GPIOLIB
+       help
+        Watchdog driver for MEN A21 VMEbus CPU Carrier Boards.
+
+	The driver can also be built as a module. If so, the module will be
+	called mena21_wdt.
+
+	If unsure select N here.
+
 # PPC64 Architecture
 
 config WATCHDOG_RTAS

drivers/watchdog/Makefile +1 -0

index a300b94..bffdcb1 100644
@@ -143,6 +143,7 @@ obj-$(CONFIG_8xxx_WDT) += mpc8xxx_wdt.o
 obj-$(CONFIG_MV64X60_WDT) += mv64x60_wdt.o
 obj-$(CONFIG_PIKA_WDT) += pika_wdt.o
 obj-$(CONFIG_BOOKE_WDT) += booke_wdt.o
+obj-$(CONFIG_MEN_A21_WDT) += mena21_wdt.o
 
 # PPC64 Architecture
 obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o

drivers/watchdog/mena21_wdt.c new file +69 -0

new file mode 100644
index 0000000..0d3409a
@@ -0,0 +1,276 @@
+/*
+ * Watchdog driver for the A21 VME CPU Boards
+ *
+ * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
+ *
+ * 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
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+
+#define NUM_GPIOS 6
+
+enum a21_wdt_gpios {
+	GPIO_WD_ENAB,
+	GPIO_WD_FAST,
+	GPIO_WD_TRIG,
+	GPIO_WD_RST0,
+	GPIO_WD_RST1,
+	GPIO_WD_RST2,
+};
+
+struct a21_wdt_drv {
+	struct watchdog_device wdt;
+	struct mutex lock;
+	unsigned gpios[NUM_GPIOS];
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+			    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static unsigned int a21_wdt_get_bootstatus(struct a21_wdt_drv *drv)
+{
+	int reset = 0;
+
+	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
+	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
+	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST2]) ? (1 << 2) : 0;
+
+	return reset;
+}
+
+static int a21_wdt_start(struct watchdog_device *wdt)
+{
+	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
+
+	mutex_lock(&drv->lock);
+
+	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 1);
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int a21_wdt_stop(struct watchdog_device *wdt)