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"); 240