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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Copyright (c) 2022 International Business Machines, Inc.4 */5 6#include <linux/bitops.h>7#include <linux/kernel.h>8#include <linux/limits.h>9#include <linux/math.h>10#include <linux/mod_devicetable.h>11#include <linux/module.h>12#include <linux/moduleparam.h>13#include <linux/platform_device.h>14#include <linux/time64.h>15#include <linux/watchdog.h>16 17#define DRV_NAME "pseries-wdt"18 19/*20 * H_WATCHDOG Input21 *22 * R4: "flags":23 *24 * Bits 48-55: "operation"25 */26#define PSERIES_WDTF_OP_START 0x100UL /* start timer */27#define PSERIES_WDTF_OP_STOP 0x200UL /* stop timer */28#define PSERIES_WDTF_OP_QUERY 0x300UL /* query timer capabilities */29 30/*31 * Bits 56-63: "timeoutAction" (for "Start Watchdog" only)32 */33#define PSERIES_WDTF_ACTION_HARD_POWEROFF 0x1UL /* poweroff */34#define PSERIES_WDTF_ACTION_HARD_RESTART 0x2UL /* restart */35#define PSERIES_WDTF_ACTION_DUMP_RESTART 0x3UL /* dump + restart */36 37/*38 * H_WATCHDOG Output39 *40 * R3: Return code41 *42 * H_SUCCESS The operation completed.43 *44 * H_BUSY The hypervisor is too busy; retry the operation.45 *46 * H_PARAMETER The given "flags" are somehow invalid. Either the47 * "operation" or "timeoutAction" is invalid, or a48 * reserved bit is set.49 *50 * H_P2 The given "watchdogNumber" is zero or exceeds the51 * supported maximum value.52 *53 * H_P3 The given "timeoutInMs" is below the supported54 * minimum value.55 *56 * H_NOOP The given "watchdogNumber" is already stopped.57 *58 * H_HARDWARE The operation failed for ineffable reasons.59 *60 * H_FUNCTION The H_WATCHDOG hypercall is not supported by this61 * hypervisor.62 *63 * R4:64 *65 * - For the "Query Watchdog Capabilities" operation, a 64-bit66 * structure:67 */68#define PSERIES_WDTQ_MIN_TIMEOUT(cap) (((cap) >> 48) & 0xffff)69#define PSERIES_WDTQ_MAX_NUMBER(cap) (((cap) >> 32) & 0xffff)70 71static const unsigned long pseries_wdt_action[] = {72 [0] = PSERIES_WDTF_ACTION_HARD_POWEROFF,73 [1] = PSERIES_WDTF_ACTION_HARD_RESTART,74 [2] = PSERIES_WDTF_ACTION_DUMP_RESTART,75};76 77#define WATCHDOG_ACTION 178static unsigned int action = WATCHDOG_ACTION;79module_param(action, uint, 0444);80MODULE_PARM_DESC(action, "Action taken when watchdog expires (default="81 __MODULE_STRING(WATCHDOG_ACTION) ")");82 83static bool nowayout = WATCHDOG_NOWAYOUT;84module_param(nowayout, bool, 0444);85MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="86 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");87 88#define WATCHDOG_TIMEOUT 6089static unsigned int timeout = WATCHDOG_TIMEOUT;90module_param(timeout, uint, 0444);91MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds (default="92 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");93 94struct pseries_wdt {95 struct watchdog_device wd;96 unsigned long action;97 unsigned long num; /* Watchdog numbers are 1-based */98};99 100static int pseries_wdt_start(struct watchdog_device *wdd)101{102 struct pseries_wdt *pw = watchdog_get_drvdata(wdd);103 struct device *dev = wdd->parent;104 unsigned long flags, msecs;105 long rc;106 107 flags = pw->action | PSERIES_WDTF_OP_START;108 msecs = wdd->timeout * MSEC_PER_SEC;109 rc = plpar_hcall_norets(H_WATCHDOG, flags, pw->num, msecs);110 if (rc != H_SUCCESS) {111 dev_crit(dev, "H_WATCHDOG: %ld: failed to start timer %lu",112 rc, pw->num);113 return -EIO;114 }115 return 0;116}117 118static int pseries_wdt_stop(struct watchdog_device *wdd)119{120 struct pseries_wdt *pw = watchdog_get_drvdata(wdd);121 struct device *dev = wdd->parent;122 long rc;123 124 rc = plpar_hcall_norets(H_WATCHDOG, PSERIES_WDTF_OP_STOP, pw->num);125 if (rc != H_SUCCESS && rc != H_NOOP) {126 dev_crit(dev, "H_WATCHDOG: %ld: failed to stop timer %lu",127 rc, pw->num);128 return -EIO;129 }130 return 0;131}132 133static struct watchdog_info pseries_wdt_info = {134 .identity = DRV_NAME,135 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT136 | WDIOF_PRETIMEOUT,137};138 139static const struct watchdog_ops pseries_wdt_ops = {140 .owner = THIS_MODULE,141 .start = pseries_wdt_start,142 .stop = pseries_wdt_stop,143};144 145static int pseries_wdt_probe(struct platform_device *pdev)146{147 unsigned long ret[PLPAR_HCALL_BUFSIZE] = { 0 };148 struct pseries_wdt *pw;149 unsigned long cap;150 long msecs, rc;151 int err;152 153 rc = plpar_hcall(H_WATCHDOG, ret, PSERIES_WDTF_OP_QUERY);154 if (rc == H_FUNCTION)155 return -ENODEV;156 if (rc != H_SUCCESS)157 return -EIO;158 cap = ret[0];159 160 pw = devm_kzalloc(&pdev->dev, sizeof(*pw), GFP_KERNEL);161 if (!pw)162 return -ENOMEM;163 164 /*165 * Assume watchdogNumber 1 for now. If we ever support166 * multiple timers we will need to devise a way to choose a167 * distinct watchdogNumber for each platform device at device168 * registration time.169 */170 pw->num = 1;171 if (PSERIES_WDTQ_MAX_NUMBER(cap) < pw->num)172 return -ENODEV;173 174 if (action >= ARRAY_SIZE(pseries_wdt_action))175 return -EINVAL;176 pw->action = pseries_wdt_action[action];177 178 pw->wd.parent = &pdev->dev;179 pw->wd.info = &pseries_wdt_info;180 pw->wd.ops = &pseries_wdt_ops;181 msecs = PSERIES_WDTQ_MIN_TIMEOUT(cap);182 pw->wd.min_timeout = DIV_ROUND_UP(msecs, MSEC_PER_SEC);183 pw->wd.max_timeout = UINT_MAX / 1000; /* from linux/watchdog.h */184 pw->wd.timeout = timeout;185 if (watchdog_init_timeout(&pw->wd, 0, NULL))186 return -EINVAL;187 watchdog_set_nowayout(&pw->wd, nowayout);188 watchdog_stop_on_reboot(&pw->wd);189 watchdog_stop_on_unregister(&pw->wd);190 watchdog_set_drvdata(&pw->wd, pw);191 192 err = devm_watchdog_register_device(&pdev->dev, &pw->wd);193 if (err)194 return err;195 196 platform_set_drvdata(pdev, &pw->wd);197 198 return 0;199}200 201static int pseries_wdt_suspend(struct platform_device *pdev, pm_message_t state)202{203 struct watchdog_device *wd = platform_get_drvdata(pdev);204 205 if (watchdog_active(wd))206 return pseries_wdt_stop(wd);207 return 0;208}209 210static int pseries_wdt_resume(struct platform_device *pdev)211{212 struct watchdog_device *wd = platform_get_drvdata(pdev);213 214 if (watchdog_active(wd))215 return pseries_wdt_start(wd);216 return 0;217}218 219static const struct platform_device_id pseries_wdt_id[] = {220 { .name = "pseries-wdt" },221 {}222};223MODULE_DEVICE_TABLE(platform, pseries_wdt_id);224 225static struct platform_driver pseries_wdt_driver = {226 .driver = {227 .name = DRV_NAME,228 },229 .id_table = pseries_wdt_id,230 .probe = pseries_wdt_probe,231 .resume = pseries_wdt_resume,232 .suspend = pseries_wdt_suspend,233};234module_platform_driver(pseries_wdt_driver);235 236MODULE_AUTHOR("Alexey Kardashevskiy");237MODULE_AUTHOR("Scott Cheloha");238MODULE_DESCRIPTION("POWER Architecture Platform Watchdog Driver");239MODULE_LICENSE("GPL");240