[PATCH v3] watchdog: Add watchdog timer support for the WinSystems EBC-C384

[William Breathitt Gray]

The WinSystems EBC-C384 has an onboard watchdog timer. The timeout range
supported by the watchdog timer is 1 second to 255 minutes. Timeouts
under 256 seconds have a 1 second resolution, while the rest have a 1
minute resolution.

This driver adds watchdog timer support for this onboard watchdog timer.
The timeout may be configured via the timeout module parameter.

Signed-off-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
---
Changes in v3:
  - Remove unnecessary explicit initialization of the timeout parameter
  - Move dmi_match call to beginning of init function
  - Create WATCHDOG_MAX_TIMEOUT define and explain its magic number
  - Use platform_set_drvdata to match later call to platform_get_drvdata
  - Use MODULE_NAME as argument for the platform_device_alloc call
  - Remove duplicate return statement for the init function

 MAINTAINERS                     |   6 ++
 drivers/watchdog/Kconfig        |   9 ++
 drivers/watchdog/Makefile       |   1 +
 drivers/watchdog/ebc-c384_wdt.c | 187 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 203 insertions(+)
 create mode 100644 drivers/watchdog/ebc-c384_wdt.c

diff --git a/MAINTAINERS b/MAINTAINERS
index b1e3da7..c058abf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11629,6 +11629,12 @@ M:	David Härdeman <david@xxxxxxxxxxx>
 S:	Maintained
 F:	drivers/media/rc/winbond-cir.c
 
+WINSYSTEMS EBC-C384 WATCHDOG DRIVER
+M:	William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
+L:	linux-watchdog@xxxxxxxxxxxxxxx
+S:	Maintained
+F:	drivers/watchdog/ebc-c384_wdt.c
+
 WIMAX STACK
 M:	Inaky Perez-Gonzalez <inaky.perez-gonzalez@xxxxxxxxx>
 M:	linux-wimax@xxxxxxxxx
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 4f0e7be..b5b1353 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -711,6 +711,15 @@ config ALIM7101_WDT
 
 	  Most people will say N.
 
+config EBC_C386_WDT
+	tristate "WinSystems EBC-C384 Watchdog Timer"
+	depends on X86
+	select WATCHDOG_CORE
+	help
+	  Enables watchdog timer support for the watchdog timer on the
+	  WinSystems EBC-C384 motherboard. The timeout may be configured via
+	  the timeout module parameter.
+
 config F71808E_WDT
 	tristate "Fintek F71808E, F71862FG, F71869, F71882FG and F71889FG Watchdog"
 	depends on X86
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index f566753..1522316 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -88,6 +88,7 @@ obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o
 obj-$(CONFIG_ADVANTECH_WDT) += advantechwdt.o
 obj-$(CONFIG_ALIM1535_WDT) += alim1535_wdt.o
 obj-$(CONFIG_ALIM7101_WDT) += alim7101_wdt.o
+obj-$(CONFIG_EBC_C386_WDT) += ebc-c384_wdt.o
 obj-$(CONFIG_F71808E_WDT) += f71808e_wdt.o
 obj-$(CONFIG_SP5100_TCO) += sp5100_tco.o
 obj-$(CONFIG_GEODE_WDT) += geodewdt.o
diff --git a/drivers/watchdog/ebc-c384_wdt.c b/drivers/watchdog/ebc-c384_wdt.c
new file mode 100644
index 0000000..9166b02
--- /dev/null
+++ b/drivers/watchdog/ebc-c384_wdt.c
@@ -0,0 +1,187 @@
+/*
+ * Watchdog timer driver for the WinSystems EBC-C384
+ * Copyright (C) 2016 William Breathitt Gray
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/device.h>
+#include <linux/dmi.h>
+#include <linux/errno.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+#define MODULE_NAME "ebc-c384_wdt"
+#define WATCHDOG_TIMEOUT 60
+/* Since the timeout value in minutes must fit in a single byte when sent to the
+ * watchdog timer, the maximum timeout possible is 15300 (255 * 60) seconds
+ */
+#define WATCHDOG_MAX_TIMEOUT 15300
+#define BASE_ADDR 0x564
+#define ADDR_EXTENT 5
+#define CFG_ADDR (BASE_ADDR + 1)
+#define PET_ADDR (BASE_ADDR + 2)
+
+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 timeout;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
+	__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+static int ebc_c384_wdt_start(struct watchdog_device *wdev)
+{
+	unsigned t = wdev->timeout;
+
+	/* resolution is in minutes for timeouts greater than 255 seconds */
+	if (t > 255)
+		t /= 60;
+
+	outb(t, PET_ADDR);
+
+	return 0;
+}
+
+static int ebc_c384_wdt_stop(struct watchdog_device *wdev)
+{
+	outb(0x00, PET_ADDR);
+
+	return 0;
+}
+
+static int ebc_c384_wdt_set_timeout(struct watchdog_device *wdev, unsigned t)
+{
+	/* resolution is in minutes for timeouts greater than 255 seconds */
+	if (t > 255) {
+		/* truncate second resolution to minute resolution */
+		t /= 60;
+		wdev->timeout = t * 60;
+
+		/* set watchdog timer for minutes */
+		outb(0x00, CFG_ADDR);
+	} else {
+		wdev->timeout = t;
+
+		/* set watchdog timer for seconds */
+		outb(0x80, CFG_ADDR);
+	}
+
+	return 0;
+}
+
+static const struct watchdog_ops ebc_c384_wdt_ops = {
+	.start = ebc_c384_wdt_start,
+	.stop = ebc_c384_wdt_stop,
+	.set_timeout = ebc_c384_wdt_set_timeout
+};
+
+static const struct watchdog_info ebc_c384_wdt_info = {
+	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT,
+	.identity = MODULE_NAME
+};
+
+static int __init ebc_c384_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *wdd;
+
+	if (!devm_request_region(dev, BASE_ADDR, ADDR_EXTENT, dev_name(dev))) {
+		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
+			BASE_ADDR, BASE_ADDR + ADDR_EXTENT);
+		return -EBUSY;
+	}
+
+	wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
+	if (!wdd)
+		return -ENOMEM;
+
+	wdd->info = &ebc_c384_wdt_info;
+	wdd->ops = &ebc_c384_wdt_ops;
+	wdd->timeout = WATCHDOG_TIMEOUT;
+	wdd->min_timeout = 1;
+	wdd->max_timeout = WATCHDOG_MAX_TIMEOUT;
+
+	watchdog_set_nowayout(wdd, nowayout);
+
+	if (watchdog_init_timeout(wdd, timeout, dev))
+		dev_warn(dev, "Invalid timeout (%u seconds), using default (%u seconds)\n",
+			timeout, WATCHDOG_TIMEOUT);
+
+	platform_set_drvdata(pdev, wdd);
+
+	return watchdog_register_device(wdd);
+}
+
+static int ebc_c384_wdt_remove(struct platform_device *pdev)
+{
+	struct watchdog_device *wdd = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(wdd);
+
+	return 0;
+}
+
+static struct platform_driver ebc_c384_wdt_driver = {
+	.driver = {
+		.name = MODULE_NAME
+	},
+	.remove = ebc_c384_wdt_remove
+};
+
+static struct platform_device *ebc_c384_wdt_device;
+
+static int __init ebc_c384_wdt_init(void)
+{
+	int err;
+
+	if (!dmi_match(DMI_BOARD_NAME, "EBC-C384 SBC"))
+		return -ENODEV;
+
+	ebc_c384_wdt_device = platform_device_alloc(MODULE_NAME, -1);
+	if (!ebc_c384_wdt_device)
+		return -ENOMEM;
+
+	err = platform_device_add(ebc_c384_wdt_device);
+	if (err)
+		goto err_platform_device;
+
+	err = platform_driver_probe(&ebc_c384_wdt_driver, ebc_c384_wdt_probe);
+	if (err)
+		goto err_platform_driver;
+
+	return 0;
+
+err_platform_driver:
+	platform_device_del(ebc_c384_wdt_device);
+err_platform_device:
+	platform_device_put(ebc_c384_wdt_device);
+	return err;
+}
+
+static void __exit ebc_c384_wdt_exit(void)
+{
+	platform_device_unregister(ebc_c384_wdt_device);
+	platform_driver_unregister(&ebc_c384_wdt_driver);
+}
+
+module_init(ebc_c384_wdt_init);
+module_exit(ebc_c384_wdt_exit);
+
+MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@xxxxxxxxx>");
+MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" MODULE_NAME);
-- 
2.4.10