[PATCH v8] watchdog: New watchdog driver for MEN A21 watchdogs

[Johannes Thumshirn <johannes.thumshirn@men.de>]

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 <johannes.thumshirn@men.de>
---
 .../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

diff --git a/Documentation/devicetree/bindings/gpio/men-a021-wdt.txt b/Documentation/devicetree/bindings/gpio/men-a021-wdt.txt
new file mode 100644
index 0000000..370dee3
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/men-a021-wdt.txt
@@ -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] */
+	};
diff --git a/MAINTAINERS b/MAINTAINERS
index f35a259..bd86661 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5307,6 +5307,12 @@ F:	drivers/mtd/
 F:	include/linux/mtd/
 F:	include/uapi/mtd/

+MEN A21 WATCHDOG DRIVER
+M:  	Johannes Thumshirn <johannes.thumshirn@men.de>
+L:	linux-watchdog@vger.kernel.org
+S:	Supported
+F:	drivers/watchdog/mena21_wdt.c
+
 METAG ARCHITECTURE
 M:	James Hogan <james.hogan@imgtec.com>
 S:	Supported
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index e89fc31..8b143ee 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -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
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a300b94..bffdcb1 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -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
diff --git a/drivers/watchdog/mena21_wdt.c b/drivers/watchdog/mena21_wdt.c
new file mode 100644
index 0000000..29f9c0d
--- /dev/null
+++ b/drivers/watchdog/mena21_wdt.c
@@ -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)
+		return -ENOMEM;
+
+	/* Fill GPIO pin array */
+	node = pdev->dev.of_node;
+
+	drv->num_gpios = of_gpio_count(node);
+	if (drv->num_gpios <= 0) {
+		dev_err(&pdev->dev, "gpios DT property empty / missing");
+		return -ENODEV;
+	}
+
+	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