--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2022 International Business Machines, Inc.
+ */
+
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/limits.h>
+#include <linux/math.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/time64.h>
+#include <linux/watchdog.h>
+
+#define DRV_NAME "pseries-wdt"
+
+/*
+ * H_WATCHDOG Input
+ *
+ * R4: "flags":
+ *
+ * Bits 48-55: "operation"
+ */
+#define PSERIES_WDTF_OP_START 0x100UL /* start timer */
+#define PSERIES_WDTF_OP_STOP 0x200UL /* stop timer */
+#define PSERIES_WDTF_OP_QUERY 0x300UL /* query timer capabilities */
+
+/*
+ * Bits 56-63: "timeoutAction" (for "Start Watchdog" only)
+ */
+#define PSERIES_WDTF_ACTION_HARD_POWEROFF 0x1UL /* poweroff */
+#define PSERIES_WDTF_ACTION_HARD_RESTART 0x2UL /* restart */
+#define PSERIES_WDTF_ACTION_DUMP_RESTART 0x3UL /* dump + restart */
+
+/*
+ * H_WATCHDOG Output
+ *
+ * R3: Return code
+ *
+ * H_SUCCESS The operation completed.
+ *
+ * H_BUSY The hypervisor is too busy; retry the operation.
+ *
+ * H_PARAMETER The given "flags" are somehow invalid. Either the
+ * "operation" or "timeoutAction" is invalid, or a
+ * reserved bit is set.
+ *
+ * H_P2 The given "watchdogNumber" is zero or exceeds the
+ * supported maximum value.
+ *
+ * H_P3 The given "timeoutInMs" is below the supported
+ * minimum value.
+ *
+ * H_NOOP The given "watchdogNumber" is already stopped.
+ *
+ * H_HARDWARE The operation failed for ineffable reasons.
+ *
+ * H_FUNCTION The H_WATCHDOG hypercall is not supported by this
+ * hypervisor.
+ *
+ * R4:
+ *
+ * - For the "Query Watchdog Capabilities" operation, a 64-bit
+ * structure:
+ */
+#define PSERIES_WDTQ_MIN_TIMEOUT(cap) (((cap) >> 48) & 0xffff)
+#define PSERIES_WDTQ_MAX_NUMBER(cap) (((cap) >> 32) & 0xffff)
+
+static const unsigned long pseries_wdt_action[] = {
+ [0] = PSERIES_WDTF_ACTION_HARD_POWEROFF,
+ [1] = PSERIES_WDTF_ACTION_HARD_RESTART,
+ [2] = PSERIES_WDTF_ACTION_DUMP_RESTART,
+};
+
+#define WATCHDOG_ACTION 1
+static unsigned int action = WATCHDOG_ACTION;
+module_param(action, uint, 0444);
+MODULE_PARM_DESC(action, "Action taken when watchdog expires (default="
+ __MODULE_STRING(WATCHDOG_ACTION) ")");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0444);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+#define WATCHDOG_TIMEOUT 60
+static unsigned int timeout = WATCHDOG_TIMEOUT;
+module_param(timeout, uint, 0444);
+MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds (default="
+ __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+struct pseries_wdt {
+ struct watchdog_device wd;
+ unsigned long action;
+ unsigned long num; /* Watchdog numbers are 1-based */
+};
+
+static int pseries_wdt_start(struct watchdog_device *wdd)
+{
+ struct pseries_wdt *pw = watchdog_get_drvdata(wdd);
+ struct device *dev = wdd->parent;
+ unsigned long flags, msecs;
+ long rc;
+
+ flags = pw->action | PSERIES_WDTF_OP_START;
+ msecs = wdd->timeout * MSEC_PER_SEC;
+ rc = plpar_hcall_norets(H_WATCHDOG, flags, pw->num, msecs);
+ if (rc != H_SUCCESS) {
+ dev_crit(dev, "H_WATCHDOG: %ld: failed to start timer %lu",
+ rc, pw->num);
+ return -EIO;
+ }
+ return 0;
+}
+
+static int pseries_wdt_stop(struct watchdog_device *wdd)
+{
+ struct pseries_wdt *pw = watchdog_get_drvdata(wdd);
+ struct device *dev = wdd->parent;
+ long rc;
+
+ rc = plpar_hcall_norets(H_WATCHDOG, PSERIES_WDTF_OP_STOP, pw->num);
+ if (rc != H_SUCCESS && rc != H_NOOP) {
+ dev_crit(dev, "H_WATCHDOG: %ld: failed to stop timer %lu",
+ rc, pw->num);
+ return -EIO;
+ }
+ return 0;
+}
+
+static struct watchdog_info pseries_wdt_info = {
+ .identity = DRV_NAME,
+ .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT
+ | WDIOF_PRETIMEOUT,
+};
+
+static const struct watchdog_ops pseries_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = pseries_wdt_start,
+ .stop = pseries_wdt_stop,
+};
+
+static int pseries_wdt_probe(struct platform_device *pdev)
+{
+ unsigned long ret[PLPAR_HCALL_BUFSIZE] = { 0 };
+ struct pseries_wdt *pw;
+ unsigned long cap;
+ long msecs, rc;
+ int err;
+
+ rc = plpar_hcall(H_WATCHDOG, ret, PSERIES_WDTF_OP_QUERY);
+ if (rc == H_FUNCTION)
+ return -ENODEV;
+ if (rc != H_SUCCESS)
+ return -EIO;
+ cap = ret[0];
+
+ pw = devm_kzalloc(&pdev->dev, sizeof(*pw), GFP_KERNEL);
+ if (!pw)
+ return -ENOMEM;
+
+ /*
+ * Assume watchdogNumber 1 for now. If we ever support
+ * multiple timers we will need to devise a way to choose a
+ * distinct watchdogNumber for each platform device at device
+ * registration time.
+ */
+ pw->num = 1;
+ if (PSERIES_WDTQ_MAX_NUMBER(cap) < pw->num)
+ return -ENODEV;
+
+ if (action >= ARRAY_SIZE(pseries_wdt_action))
+ return -EINVAL;
+ pw->action = pseries_wdt_action[action];
+
+ pw->wd.parent = &pdev->dev;
+ pw->wd.info = &pseries_wdt_info;
+ pw->wd.ops = &pseries_wdt_ops;
+ msecs = PSERIES_WDTQ_MIN_TIMEOUT(cap);
+ pw->wd.min_timeout = DIV_ROUND_UP(msecs, MSEC_PER_SEC);
+ pw->wd.max_timeout = UINT_MAX / 1000; /* from linux/watchdog.h */
+ pw->wd.timeout = timeout;
+ if (watchdog_init_timeout(&pw->wd, 0, NULL))
+ return -EINVAL;
+ watchdog_set_nowayout(&pw->wd, nowayout);
+ watchdog_stop_on_reboot(&pw->wd);
+ watchdog_stop_on_unregister(&pw->wd);
+ watchdog_set_drvdata(&pw->wd, pw);
+
+ err = devm_watchdog_register_device(&pdev->dev, &pw->wd);
+ if (err)
+ return err;
+
+ platform_set_drvdata(pdev, &pw->wd);
+
+ return 0;
+}
+
+static int pseries_wdt_suspend(struct platform_device *pdev, pm_message_t state)
+{
+ struct watchdog_device *wd = platform_get_drvdata(pdev);
+
+ if (watchdog_active(wd))
+ return pseries_wdt_stop(wd);
+ return 0;
+}
+
+static int pseries_wdt_resume(struct platform_device *pdev)
+{
+ struct watchdog_device *wd = platform_get_drvdata(pdev);
+
+ if (watchdog_active(wd))
+ return pseries_wdt_start(wd);
+ return 0;
+}
+
+static const struct platform_device_id pseries_wdt_id[] = {
+ { .name = "pseries-wdt" },
+ {}
+};
+MODULE_DEVICE_TABLE(platform, pseries_wdt_id);
+
+static struct platform_driver pseries_wdt_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ },
+ .id_table = pseries_wdt_id,
+ .probe = pseries_wdt_probe,
+ .resume = pseries_wdt_resume,
+ .suspend = pseries_wdt_suspend,
+};
+module_platform_driver(pseries_wdt_driver);
+
+MODULE_AUTHOR("Alexey Kardashevskiy");
+MODULE_AUTHOR("Scott Cheloha");
+MODULE_DESCRIPTION("POWER Architecture Platform Watchdog Driver");
+MODULE_LICENSE("GPL");
projects / kernel.git / commitdiff