drivers/watchdog/pseries-wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   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 Input
  21  *
  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 Output
  39  *
  40  * R3: Return code
  41  *
  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 the
  47  *                  "operation" or "timeoutAction" is invalid, or a
  48  *                  reserved bit is set.
  49  *
  50  *     H_P2         The given "watchdogNumber" is zero or exceeds the
  51  *                  supported maximum value.
  52  *
  53  *     H_P3         The given "timeoutInMs" is below the supported
  54  *                  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 this
  61  *                  hypervisor.
  62  *
  63  * R4:
  64  *
  65  * - For the "Query Watchdog Capabilities" operation, a 64-bit
  66  *   structure:
  67  */
  68 #define PSERIES_WDTQ_MIN_TIMEOUT(cap)   (((cap) >> 48) & 0xffff)
  69 #define PSERIES_WDTQ_MAX_NUMBER(cap)    (((cap) >> 32) & 0xffff)
  70
  71 static 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 1
  78 static unsigned int action = WATCHDOG_ACTION;
  79 module_param(action, uint, 0444);
  80 MODULE_PARM_DESC(action, "Action taken when watchdog expires (default="
  81                  __MODULE_STRING(WATCHDOG_ACTION) ")");
  82
  83 static bool nowayout = WATCHDOG_NOWAYOUT;
  84 module_param(nowayout, bool, 0444);
  85 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  86                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  87
  88 #define WATCHDOG_TIMEOUT 60
  89 static unsigned int timeout = WATCHDOG_TIMEOUT;
  90 module_param(timeout, uint, 0444);
  91 MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds (default="
  92                  __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  93
  94 struct pseries_wdt {
  95         struct watchdog_device wd;
  96         unsigned long action;
  97         unsigned long num;              /* Watchdog numbers are 1-based */
  98 };
  99
 100 static 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
 118 static 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
 133 static struct watchdog_info pseries_wdt_info = {
 134         .identity = DRV_NAME,
 135         .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT
 136             | WDIOF_PRETIMEOUT,
 137 };
 138
 139 static const struct watchdog_ops pseries_wdt_ops = {
 140         .owner = THIS_MODULE,
 141         .start = pseries_wdt_start,
 142         .stop = pseries_wdt_stop,
 143 };
 144
 145 static 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 support
 166          * multiple timers we will need to devise a way to choose a
 167          * distinct watchdogNumber for each platform device at device
 168          * 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
 201 static 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
 210 static 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
 219 static const struct platform_device_id pseries_wdt_id[] = {
 220         { .name = "pseries-wdt" },
 221         {}
 222 };
 223 MODULE_DEVICE_TABLE(platform, pseries_wdt_id);
 224
 225 static 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 };
 234 module_platform_driver(pseries_wdt_driver);
 235
 236 MODULE_AUTHOR("Alexey Kardashevskiy");
 237 MODULE_AUTHOR("Scott Cheloha");
 238 MODULE_DESCRIPTION("POWER Architecture Platform Watchdog Driver");
 239 MODULE_LICENSE("GPL");