watchdog: Add watchdog timer support for the WinSystems EBC-C384

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 granularity, while the rest have a 1
minute granularity.

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@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 188 insertions, 0 deletions

diff --git a/drivers/watchdog/ebc-c384_wdt.c b/drivers/watchdog/ebc-c384_wdt.c
new file mode 100644
index 000000000000..77fda0b4b90e
--- /dev/null
+++ b/drivers/watchdog/ebc-c384_wdt.c
@@ -0,0 +1,188 @@
+/*
+ * 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/kernel.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
+/*
+ * 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 = DIV_ROUND_UP(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) {
+		/* round second resolution up to minute granularity */
+		wdev->timeout = roundup(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@gmail.com>");
+MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" MODULE_NAME);