[PATCH v3] watchdog: Add driver for Altera Watchdog Timer
Tobias Klauser
tklauser at distanz.ch
Wed Feb 9 18:19:12 EST 2011
This driver adds support for the Altera Timer in the Watchdog Timer
configuration. This component is usually found on SOPC (System on
Programmable Chip) for Altera FPGAs.
Signed-off-by: Tobias Klauser <tklauser at distanz.ch>
Reviewed-by: Jamie Iles <jamie at jamieiles.com>
---
Thanks a lot to Jamie Iles and Walter Goossens for their feedback on v2.
changes for v3:
- Make altera_wdt_setup static void (as suggested by Jamie)
- Use const __be32 * for devicetree properties (as suggested by Walter)
changes for v2:
- Get driver properties from devicetree (and document them), thus the
driver depends on OF
- Do not select WATCHDOG_NOWAYOUT, but instead implement a software
timer resetting the watchdog timer when the device is not open
- Only support a single instance of the watchdog, so the private data
can be kept in static data
- Use devm_* functions in altera_wdt_probe to simplify cleanup and
error handling
- Remove empty altera_wdt_shutdown function
- Add MODULE_LICENSE (GPL)
.../devicetree/bindings/watchdog/altera_wdt.txt | 7 +
drivers/watchdog/Kconfig | 8 +
drivers/watchdog/Makefile | 1 +
drivers/watchdog/altera_wdt.c | 309 ++++++++++++++++++++
4 files changed, 325 insertions(+), 0 deletions(-)
create mode 100644 Documentation/devicetree/bindings/watchdog/altera_wdt.txt
create mode 100644 drivers/watchdog/altera_wdt.c
diff --git a/Documentation/devicetree/bindings/watchdog/altera_wdt.txt b/Documentation/devicetree/bindings/watchdog/altera_wdt.txt
new file mode 100644
index 0000000..16ac949
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/altera_wdt.txt
@@ -0,0 +1,7 @@
+Altera Watchdog Timer
+
+Required properties:
+- compatible : should be "ALTR,wdt-1.0"
+- clock-frequency : frequency of the clock input
+- timeout : load value of the timer (number of clock ticks until watchdog
+ resets)
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index bd6a33d..ebcafb0 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -69,6 +69,14 @@ config WM8350_WATCHDOG
Support for the watchdog in the WM8350 AudioPlus PMIC. When
the watchdog triggers the system will be reset.
+config ALTERA_WDT
+ tristate "Altera Watchdog Timer"
+ depends on OF
+ help
+ Support for the Altera Timer in the Watchdog Timer configuration. This
+ component is found on SOPC (System on Programmable Chip) for Altera
+ FPGAs.
+
# ALPHA Architecture
# ARM Architecture
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index fd9c8c0..48a2167 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -153,4 +153,5 @@ obj-$(CONFIG_WATCHDOG_CP1XXX) += cpwd.o
obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
+obj-$(CONFIG_ALTERA_WDT) += altera_wdt.o
obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
diff --git a/drivers/watchdog/altera_wdt.c b/drivers/watchdog/altera_wdt.c
new file mode 100644
index 0000000..2a7f14a
--- /dev/null
+++ b/drivers/watchdog/altera_wdt.c
@@ -0,0 +1,309 @@
+/*
+ * Driver for the Altera Watchdog Timer
+ *
+ * Copyright (C) 2011 Tobias Klauser <tklauser at distanz.ch>
+ * Copyright (C) 2005 Walter Goossens
+ *
+ * Originally based on wdt.c which is
+ *
+ * Copyright (C) 1995-1997 Alan Cox <alan at lxorguk.ukuu.org.uk>
+ *
+ * Software timeout heartbeat code based on pika_wdt.c which is
+ *
+ * Copyright (c) 2008 PIKA Technologies
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/timer.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <linux/of_platform.h>
+
+#define WATCHDOG_NAME "altera_wdt"
+
+/* Register offsets */
+#define ALTERA_WDT_STATUS 0x00
+#define ALTERA_WDT_CONTROL 0x04
+#define ALTERA_WDT_PERIODL 0x08
+#define ALTERA_WDT_PERIODH 0x0C
+
+#define ALTERA_WDT_RUN_BIT 0x04
+
+/* User land timeout */
+#define WDT_HEARTBEAT 15
+static int heartbeat = WDT_HEARTBEAT;
+module_param(heartbeat, int, 0);
+MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
+ "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
+ "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static struct {
+ void __iomem *base;
+ unsigned long wdt_timeout; /* timeout of the hardware timer */
+
+ unsigned long next_heartbeat; /* the next_heartbeat for the timer */
+ unsigned long is_open;
+ char expect_close;
+ struct timer_list timer; /* software timer that pings the watchdog */
+} altera_wdt_priv;
+
+/*
+ * Start the watchdog. Once it has been started, it cannot be stopped anymore.
+ */
+static void altera_wdt_setup(void)
+{
+ u32 control = readl(altera_wdt_priv.base + ALTERA_WDT_CONTROL);
+
+ writel(control | ALTERA_WDT_RUN_BIT, altera_wdt_priv.base + ALTERA_WDT_CONTROL);
+}
+
+/*
+ * Tickle the watchdog (reset the watchdog timer)
+ */
+static void altera_wdt_reset(void)
+{
+ /* It doesn't matter what value we write */
+ writel(1, altera_wdt_priv.base + ALTERA_WDT_PERIODL);
+}
+
+/*
+ * Software timer tick
+ */
+static void altera_wdt_ping(unsigned long data)
+{
+ if (time_before(jiffies, altera_wdt_priv.next_heartbeat) ||
+ (!nowayout && !altera_wdt_priv.is_open)) {
+ altera_wdt_reset();
+ mod_timer(&altera_wdt_priv.timer, jiffies + altera_wdt_priv.wdt_timeout);
+ } else
+ pr_crit(WATCHDOG_NAME ": I will reset your machine!\n");
+}
+
+static void altera_wdt_keepalive(void)
+{
+ altera_wdt_priv.next_heartbeat = jiffies + heartbeat * HZ;
+}
+
+static void altera_wdt_start(void)
+{
+ altera_wdt_keepalive();
+ mod_timer(&altera_wdt_priv.timer, jiffies + altera_wdt_priv.wdt_timeout);
+}
+
+static int altera_wdt_open(struct inode *inode, struct file *file)
+{
+ /* /dev/watchdog can only be opened once */
+ if (test_and_set_bit(0, &altera_wdt_priv.is_open))
+ return -EBUSY;
+
+ altera_wdt_start();
+
+ return nonseekable_open(inode, file);
+}
+
+static int altera_wdt_release(struct inode *inode, struct file *file)
+{
+ /* stop internal ping */
+ if (!altera_wdt_priv.expect_close)
+ del_timer(&altera_wdt_priv.timer);
+
+ clear_bit(0, &altera_wdt_priv.is_open);
+ altera_wdt_priv.expect_close = 0;
+
+ return 0;
+}
+
+static ssize_t altera_wdt_write(struct file *file, const char __user *data,
+ size_t len, loff_t *ppos)
+{
+ if (!len)
+ return 0;
+
+ /* Scan for magic character */
+ if (!nowayout) {
+ size_t i;
+
+ altera_wdt_priv.expect_close = 0;
+
+ for (i = 0; i < len; i++) {
+ char c;
+ if (get_user(c, data + i))
+ return -EFAULT;
+ if (c == 'V') {
+ altera_wdt_priv.expect_close = 42;
+ break;
+ }
+ }
+ }
+
+ altera_wdt_keepalive();
+
+ return len;
+}
+
+static const struct watchdog_info altera_wdt_info = {
+ .identity = "Altera Watchdog",
+ .options = WDIOF_SETTIMEOUT |
+ WDIOF_KEEPALIVEPING |
+ WDIOF_MAGICCLOSE,
+ .firmware_version = 1,
+};
+
+static long altera_wdt_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ void __user *argp = (void __user *) arg;
+ int __user *p = argp;
+ int new_value;
+
+ switch (cmd) {
+ case WDIOC_GETSUPPORT:
+ return copy_to_user(argp, &altera_wdt_info, sizeof(altera_wdt_info));
+
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ return put_user(0, p);
+
+ case WDIOC_KEEPALIVE:
+ altera_wdt_keepalive();
+ return 0;
+
+ case WDIOC_SETTIMEOUT:
+ if (get_user(new_value, p))
+ return -EFAULT;
+
+ heartbeat = new_value;
+ altera_wdt_keepalive();
+
+ return put_user(new_value, p); /* return current value */
+
+ case WDIOC_GETTIMEOUT:
+ return put_user(heartbeat, p);
+
+ default:
+ return -ENOTTY;
+ }
+}
+
+static const struct file_operations altera_wdt_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .open = altera_wdt_open,
+ .release = altera_wdt_release,
+ .write = altera_wdt_write,
+ .unlocked_ioctl = altera_wdt_ioctl,
+};
+
+static struct miscdevice altera_wdt_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &altera_wdt_fops,
+};
+
+static int __devinit altera_wdt_probe(struct platform_device *pdev)
+{
+ struct resource *res, *mem;
+ const __be32 *freq_prop, *timeout_prop;
+ unsigned long timeout;
+ int ret;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENOENT;
+
+ mem = devm_request_mem_region(&pdev->dev, res->start,
+ resource_size(res), pdev->name);
+ if (!mem)
+ return -EBUSY;
+
+ altera_wdt_priv.base = devm_ioremap_nocache(&pdev->dev, mem->start,
+ resource_size(mem));
+ if (!altera_wdt_priv.base)
+ return -ENOMEM;
+
+ freq_prop = of_get_property(pdev->dev.of_node, "clock-frequency", NULL);
+ if (!freq_prop)
+ return -ENODEV;
+
+ timeout_prop = of_get_property(pdev->dev.of_node, "timeout", NULL);
+ if (!timeout_prop)
+ return -ENODEV;
+
+ /* Add 1 as the timeout property actually holds the load value */
+ timeout = be32_to_cpup(timeout_prop) + 1;
+ /* Convert timeout to msecs */
+ timeout = timeout / (be32_to_cpup(freq_prop) / MSEC_PER_SEC);
+ /* Tickle the watchdog twice per timeout period */
+ altera_wdt_priv.wdt_timeout = msecs_to_jiffies(timeout / 2);
+
+ ret = misc_register(&altera_wdt_miscdev);
+ if (ret)
+ return ret;
+
+ altera_wdt_setup();
+ altera_wdt_priv.next_heartbeat = jiffies + heartbeat * HZ;
+ setup_timer(&altera_wdt_priv.timer, altera_wdt_ping, 0);
+ mod_timer(&altera_wdt_priv.timer, jiffies + altera_wdt_priv.wdt_timeout);
+
+ pr_info(WATCHDOG_NAME " enabled (heartbeat=%d sec, nowayout=%d)\n",
+ heartbeat, nowayout);
+
+ return 0;
+}
+
+static int __devexit altera_wdt_remove(struct platform_device *pdev)
+{
+ misc_deregister(&altera_wdt_miscdev);
+ return 0;
+}
+
+static struct of_device_id altera_wdt_match[] = {
+ { .compatible = "altr,wdt-1.0", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, altera_wdt_match);
+
+static struct platform_driver altera_wdt_driver = {
+ .probe = altera_wdt_probe,
+ .remove = __devexit_p(altera_wdt_remove),
+ .driver = {
+ .owner = THIS_MODULE,
+ .name = WATCHDOG_NAME,
+ .of_match_table = altera_wdt_match,
+ },
+};
+
+static int __init altera_wdt_init(void)
+{
+ return platform_driver_register(&altera_wdt_driver);
+}
+
+static void __exit altera_wdt_exit(void)
+{
+ platform_driver_unregister(&altera_wdt_driver);
+}
+
+module_init(altera_wdt_init);
+module_exit(altera_wdt_exit);
+
+MODULE_AUTHOR("Walter Goossens, Tobias Klauser <tklauser at distanz.ch>");
+MODULE_DESCRIPTION("Driver for Altera Watchdog Timer");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
+MODULE_ALIAS("platform:" WATCHDOG_NAME);
--
1.7.0.4
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