drivers/watchdog/pseries-wdt.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Copyright (c) 2022 International Business Machines, Inc.
0004  */
0005
0006 #include <linux/bitops.h>
0007 #include <linux/kernel.h>
0008 #include <linux/limits.h>
0009 #include <linux/math.h>
0010 #include <linux/mod_devicetable.h>
0011 #include <linux/module.h>
0012 #include <linux/moduleparam.h>
0013 #include <linux/platform_device.h>
0014 #include <linux/time64.h>
0015 #include <linux/watchdog.h>
0016
0017 #define DRV_NAME "pseries-wdt"
0018
0019 /*
0020  * H_WATCHDOG Input
0021  *
0022  * R4: "flags":
0023  *
0024  *         Bits 48-55: "operation"
0025  */
0026 #define PSERIES_WDTF_OP_START   0x100UL     /* start timer */
0027 #define PSERIES_WDTF_OP_STOP    0x200UL     /* stop timer */
0028 #define PSERIES_WDTF_OP_QUERY   0x300UL     /* query timer capabilities */
0029
0030 /*
0031  *         Bits 56-63: "timeoutAction" (for "Start Watchdog" only)
0032  */
0033 #define PSERIES_WDTF_ACTION_HARD_POWEROFF   0x1UL   /* poweroff */
0034 #define PSERIES_WDTF_ACTION_HARD_RESTART    0x2UL   /* restart */
0035 #define PSERIES_WDTF_ACTION_DUMP_RESTART    0x3UL   /* dump + restart */
0036
0037 /*
0038  * H_WATCHDOG Output
0039  *
0040  * R3: Return code
0041  *
0042  *     H_SUCCESS    The operation completed.
0043  *
0044  *     H_BUSY       The hypervisor is too busy; retry the operation.
0045  *
0046  *     H_PARAMETER  The given "flags" are somehow invalid.  Either the
0047  *                  "operation" or "timeoutAction" is invalid, or a
0048  *                  reserved bit is set.
0049  *
0050  *     H_P2         The given "watchdogNumber" is zero or exceeds the
0051  *                  supported maximum value.
0052  *
0053  *     H_P3         The given "timeoutInMs" is below the supported
0054  *                  minimum value.
0055  *
0056  *     H_NOOP       The given "watchdogNumber" is already stopped.
0057  *
0058  *     H_HARDWARE   The operation failed for ineffable reasons.
0059  *
0060  *     H_FUNCTION   The H_WATCHDOG hypercall is not supported by this
0061  *                  hypervisor.
0062  *
0063  * R4:
0064  *
0065  * - For the "Query Watchdog Capabilities" operation, a 64-bit
0066  *   structure:
0067  */
0068 #define PSERIES_WDTQ_MIN_TIMEOUT(cap)   (((cap) >> 48) & 0xffff)
0069 #define PSERIES_WDTQ_MAX_NUMBER(cap)    (((cap) >> 32) & 0xffff)
0070
0071 static const unsigned long pseries_wdt_action[] = {
0072     [0] = PSERIES_WDTF_ACTION_HARD_POWEROFF,
0073     [1] = PSERIES_WDTF_ACTION_HARD_RESTART,
0074     [2] = PSERIES_WDTF_ACTION_DUMP_RESTART,
0075 };
0076
0077 #define WATCHDOG_ACTION 1
0078 static unsigned int action = WATCHDOG_ACTION;
0079 module_param(action, uint, 0444);
0080 MODULE_PARM_DESC(action, "Action taken when watchdog expires (default="
0081          __MODULE_STRING(WATCHDOG_ACTION) ")");
0082
0083 static bool nowayout = WATCHDOG_NOWAYOUT;
0084 module_param(nowayout, bool, 0444);
0085 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
0086          __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
0087
0088 #define WATCHDOG_TIMEOUT 60
0089 static unsigned int timeout = WATCHDOG_TIMEOUT;
0090 module_param(timeout, uint, 0444);
0091 MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds (default="
0092          __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
0093
0094 struct pseries_wdt {
0095     struct watchdog_device wd;
0096     unsigned long action;
0097     unsigned long num;      /* Watchdog numbers are 1-based */
0098 };
0099
0100 static int pseries_wdt_start(struct watchdog_device *wdd)
0101 {
0102     struct pseries_wdt *pw = watchdog_get_drvdata(wdd);
0103     struct device *dev = wdd->parent;
0104     unsigned long flags, msecs;
0105     long rc;
0106
0107     flags = pw->action | PSERIES_WDTF_OP_START;
0108     msecs = wdd->timeout * MSEC_PER_SEC;
0109     rc = plpar_hcall_norets(H_WATCHDOG, flags, pw->num, msecs);
0110     if (rc != H_SUCCESS) {
0111         dev_crit(dev, "H_WATCHDOG: %ld: failed to start timer %lu",
0112              rc, pw->num);
0113         return -EIO;
0114     }
0115     return 0;
0116 }
0117
0118 static int pseries_wdt_stop(struct watchdog_device *wdd)
0119 {
0120     struct pseries_wdt *pw = watchdog_get_drvdata(wdd);
0121     struct device *dev = wdd->parent;
0122     long rc;
0123
0124     rc = plpar_hcall_norets(H_WATCHDOG, PSERIES_WDTF_OP_STOP, pw->num);
0125     if (rc != H_SUCCESS && rc != H_NOOP) {
0126         dev_crit(dev, "H_WATCHDOG: %ld: failed to stop timer %lu",
0127              rc, pw->num);
0128         return -EIO;
0129     }
0130     return 0;
0131 }
0132
0133 static struct watchdog_info pseries_wdt_info = {
0134     .identity = DRV_NAME,
0135     .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT
0136         | WDIOF_PRETIMEOUT,
0137 };
0138
0139 static const struct watchdog_ops pseries_wdt_ops = {
0140     .owner = THIS_MODULE,
0141     .start = pseries_wdt_start,
0142     .stop = pseries_wdt_stop,
0143 };
0144
0145 static int pseries_wdt_probe(struct platform_device *pdev)
0146 {
0147     unsigned long ret[PLPAR_HCALL_BUFSIZE] = { 0 };
0148     struct pseries_wdt *pw;
0149     unsigned long cap;
0150     long msecs, rc;
0151     int err;
0152
0153     rc = plpar_hcall(H_WATCHDOG, ret, PSERIES_WDTF_OP_QUERY);
0154     if (rc == H_FUNCTION)
0155         return -ENODEV;
0156     if (rc != H_SUCCESS)
0157         return -EIO;
0158     cap = ret[0];
0159
0160     pw = devm_kzalloc(&pdev->dev, sizeof(*pw), GFP_KERNEL);
0161     if (!pw)
0162         return -ENOMEM;
0163
0164     /*
0165      * Assume watchdogNumber 1 for now.  If we ever support
0166      * multiple timers we will need to devise a way to choose a
0167      * distinct watchdogNumber for each platform device at device
0168      * registration time.
0169      */
0170     pw->num = 1;
0171     if (PSERIES_WDTQ_MAX_NUMBER(cap) < pw->num)
0172         return -ENODEV;
0173
0174     if (action >= ARRAY_SIZE(pseries_wdt_action))
0175         return -EINVAL;
0176     pw->action = pseries_wdt_action[action];
0177
0178     pw->wd.parent = &pdev->dev;
0179     pw->wd.info = &pseries_wdt_info;
0180     pw->wd.ops = &pseries_wdt_ops;
0181     msecs = PSERIES_WDTQ_MIN_TIMEOUT(cap);
0182     pw->wd.min_timeout = DIV_ROUND_UP(msecs, MSEC_PER_SEC);
0183     pw->wd.max_timeout = UINT_MAX / 1000;   /* from linux/watchdog.h */
0184     pw->wd.timeout = timeout;
0185     if (watchdog_init_timeout(&pw->wd, 0, NULL))
0186         return -EINVAL;
0187     watchdog_set_nowayout(&pw->wd, nowayout);
0188     watchdog_stop_on_reboot(&pw->wd);
0189     watchdog_stop_on_unregister(&pw->wd);
0190     watchdog_set_drvdata(&pw->wd, pw);
0191
0192     err = devm_watchdog_register_device(&pdev->dev, &pw->wd);
0193     if (err)
0194         return err;
0195
0196     platform_set_drvdata(pdev, &pw->wd);
0197
0198     return 0;
0199 }
0200
0201 static int pseries_wdt_suspend(struct platform_device *pdev, pm_message_t state)
0202 {
0203     struct watchdog_device *wd = platform_get_drvdata(pdev);
0204
0205     if (watchdog_active(wd))
0206         return pseries_wdt_stop(wd);
0207     return 0;
0208 }
0209
0210 static int pseries_wdt_resume(struct platform_device *pdev)
0211 {
0212     struct watchdog_device *wd = platform_get_drvdata(pdev);
0213
0214     if (watchdog_active(wd))
0215         return pseries_wdt_start(wd);
0216     return 0;
0217 }
0218
0219 static const struct platform_device_id pseries_wdt_id[] = {
0220     { .name = "pseries-wdt" },
0221     {}
0222 };
0223 MODULE_DEVICE_TABLE(platform, pseries_wdt_id);
0224
0225 static struct platform_driver pseries_wdt_driver = {
0226     .driver = {
0227         .name = DRV_NAME,
0228     },
0229     .id_table = pseries_wdt_id,
0230     .probe = pseries_wdt_probe,
0231     .resume = pseries_wdt_resume,
0232     .suspend = pseries_wdt_suspend,
0233 };
0234 module_platform_driver(pseries_wdt_driver);
0235
0236 MODULE_AUTHOR("Alexey Kardashevskiy");
0237 MODULE_AUTHOR("Scott Cheloha");
0238 MODULE_DESCRIPTION("POWER Architecture Platform Watchdog Driver");
0239 MODULE_LICENSE("GPL");