--- /dev/null
+/*
+ * sun4v watchdog timer
+ * (c) Copyright 2016 Oracle Corporation
+ *
+ * Implement a simple watchdog driver using the built-in sun4v hypervisor
+ * watchdog support. If time expires, the hypervisor stops or bounces
+ * the guest domain.
+ *
+ * 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/watchdog.h>
+#include <asm/hypervisor.h>
+#include <asm/mdesc.h>
+
+#define WDT_TIMEOUT 60
+#define WDT_MAX_TIMEOUT 31536000
+#define WDT_MIN_TIMEOUT 1
+#define WDT_DEFAULT_RESOLUTION_MS 1000 /* 1 second */
+
+static unsigned int timeout;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
+ __MODULE_STRING(WDT_TIMEOUT) ")");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, S_IRUGO);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static int sun4v_wdt_stop(struct watchdog_device *wdd)
+{
+ sun4v_mach_set_watchdog(0, NULL);
+
+ return 0;
+}
+
+static int sun4v_wdt_ping(struct watchdog_device *wdd)
+{
+ int hverr;
+
+ /*
+ * HV watchdog timer will round up the timeout
+ * passed in to the nearest multiple of the
+ * watchdog resolution in milliseconds.
+ */
+ hverr = sun4v_mach_set_watchdog(wdd->timeout * 1000, NULL);
+ if (hverr == HV_EINVAL)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int sun4v_wdt_set_timeout(struct watchdog_device *wdd,
+ unsigned int timeout)
+{
+ wdd->timeout = timeout;
+
+ return 0;
+}
+
+static const struct watchdog_info sun4v_wdt_ident = {
+ .options = WDIOF_SETTIMEOUT |
+ WDIOF_MAGICCLOSE |
+ WDIOF_KEEPALIVEPING,
+ .identity = "sun4v hypervisor watchdog",
+ .firmware_version = 0,
+};
+
+static struct watchdog_ops sun4v_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = sun4v_wdt_ping,
+ .stop = sun4v_wdt_stop,
+ .ping = sun4v_wdt_ping,
+ .set_timeout = sun4v_wdt_set_timeout,
+};
+
+static struct watchdog_device wdd = {
+ .info = &sun4v_wdt_ident,
+ .ops = &sun4v_wdt_ops,
+ .min_timeout = WDT_MIN_TIMEOUT,
+ .max_timeout = WDT_MAX_TIMEOUT,
+ .timeout = WDT_TIMEOUT,
+};
+
+static int __init sun4v_wdt_init(void)
+{
+ struct mdesc_handle *handle;
+ u64 node;
+ const u64 *value;
+ int err = 0;
+ unsigned long major = 1, minor = 1;
+
+ /*
+ * There are 2 properties that can be set from the control
+ * domain for the watchdog.
+ * watchdog-resolution
+ * watchdog-max-timeout
+ *
+ * We can expect a handle to be returned otherwise something
+ * serious is wrong. Correct to return -ENODEV here.
+ */
+
+ handle = mdesc_grab();
+ if (!handle)
+ return -ENODEV;
+
+ node = mdesc_node_by_name(handle, MDESC_NODE_NULL, "platform");
+ err = -ENODEV;
+ if (node == MDESC_NODE_NULL)
+ goto out_release;
+
+ /*
+ * This is a safe way to validate if we are on the right
+ * platform.
+ */
+ if (sun4v_hvapi_register(HV_GRP_CORE, major, &minor))
+ goto out_hv_unreg;
+
+ /* Allow value of watchdog-resolution up to 1s (default) */
+ value = mdesc_get_property(handle, node, "watchdog-resolution", NULL);
+ err = -EINVAL;
+ if (value) {
+ if (*value == 0 ||
+ *value > WDT_DEFAULT_RESOLUTION_MS)
+ goto out_hv_unreg;
+ }
+
+ value = mdesc_get_property(handle, node, "watchdog-max-timeout", NULL);
+ if (value) {
+ /*
+ * If the property value (in ms) is smaller than
+ * min_timeout, return -EINVAL.
+ */
+ if (*value < wdd.min_timeout * 1000)
+ goto out_hv_unreg;
+
+ /*
+ * If the property value is smaller than
+ * default max_timeout then set watchdog max_timeout to
+ * the value of the property in seconds.
+ */
+ if (*value < wdd.max_timeout * 1000)
+ wdd.max_timeout = *value / 1000;
+ }
+
+ watchdog_init_timeout(&wdd, timeout, NULL);
+
+ watchdog_set_nowayout(&wdd, nowayout);
+
+ err = watchdog_register_device(&wdd);
+ if (err)
+ goto out_hv_unreg;
+
+ pr_info("initialized (timeout=%ds, nowayout=%d)\n",
+ wdd.timeout, nowayout);
+
+ mdesc_release(handle);
+
+ return 0;
+
+out_hv_unreg:
+ sun4v_hvapi_unregister(HV_GRP_CORE);
+
+out_release:
+ mdesc_release(handle);
+ return err;
+}
+
+static void __exit sun4v_wdt_exit(void)
+{
+ sun4v_hvapi_unregister(HV_GRP_CORE);
+ watchdog_unregister_device(&wdd);
+}
+
+module_init(sun4v_wdt_init);
+module_exit(sun4v_wdt_exit);
+
+MODULE_AUTHOR("Wim Coekaerts <wim.coekaerts@oracle.com>");
+MODULE_DESCRIPTION("sun4v watchdog driver");
+MODULE_LICENSE("GPL");
projects / deliverable / linux.git / commitdiff
