1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ARM Secure Monitor Call watchdog driver 4 * 5 * Copyright 2020 Google LLC. 6 * Julius Werner <jwerner@chromium.org> 7 * Based on mtk_wdt.c 8 */ 9 10 #include <linux/arm-smccc.h> 11 #include <linux/err.h> 12 #include <linux/module.h> 13 #include <linux/moduleparam.h> 14 #include <linux/of.h> 15 #include <linux/platform_device.h> 16 #include <linux/types.h> 17 #include <linux/watchdog.h> 18 #include <uapi/linux/psci.h> 19 20 #define DRV_NAME "arm_smc_wdt" 21 #define DRV_VERSION "1.0" 22 23 enum smcwd_call { 24 SMCWD_INIT = 0, 25 SMCWD_SET_TIMEOUT = 1, 26 SMCWD_ENABLE = 2, 27 SMCWD_PET = 3, 28 SMCWD_GET_TIMELEFT = 4, 29 }; 30 31 static bool nowayout = WATCHDOG_NOWAYOUT; 32 static unsigned int timeout; 33 34 static int smcwd_call(struct watchdog_device *wdd, enum smcwd_call call, 35 unsigned long arg, struct arm_smccc_res *res) 36 { 37 struct arm_smccc_res local_res; 38 39 if (!res) 40 res = &local_res; 41 42 arm_smccc_smc((u32)(uintptr_t)watchdog_get_drvdata(wdd), call, arg, 0, 43 0, 0, 0, 0, res); 44 45 if (res->a0 == PSCI_RET_NOT_SUPPORTED) 46 return -ENODEV; 47 if (res->a0 == PSCI_RET_INVALID_PARAMS) 48 return -EINVAL; 49 if (res->a0 == PSCI_RET_DISABLED) 50 return -ENODATA; 51 if (res->a0 != PSCI_RET_SUCCESS) 52 return -EIO; 53 return 0; 54 } 55 56 static int smcwd_ping(struct watchdog_device *wdd) 57 { 58 return smcwd_call(wdd, SMCWD_PET, 0, NULL); 59 } 60 61 static unsigned int smcwd_get_timeleft(struct watchdog_device *wdd) 62 { 63 struct arm_smccc_res res; 64 65 smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, &res); 66 if (res.a0) 67 return 0; 68 return res.a1; 69 } 70 71 static int smcwd_set_timeout(struct watchdog_device *wdd, unsigned int timeout) 72 { 73 int res; 74 75 res = smcwd_call(wdd, SMCWD_SET_TIMEOUT, timeout, NULL); 76 if (!res) 77 wdd->timeout = timeout; 78 return res; 79 } 80 81 static int smcwd_stop(struct watchdog_device *wdd) 82 { 83 return smcwd_call(wdd, SMCWD_ENABLE, 0, NULL); 84 } 85 86 static int smcwd_start(struct watchdog_device *wdd) 87 { 88 return smcwd_call(wdd, SMCWD_ENABLE, 1, NULL); 89 } 90 91 static const struct watchdog_info smcwd_info = { 92 .identity = DRV_NAME, 93 .options = WDIOF_SETTIMEOUT | 94 WDIOF_KEEPALIVEPING | 95 WDIOF_MAGICCLOSE, 96 }; 97 98 static const struct watchdog_ops smcwd_ops = { 99 .start = smcwd_start, 100 .stop = smcwd_stop, 101 .ping = smcwd_ping, 102 .set_timeout = smcwd_set_timeout, 103 }; 104 105 static const struct watchdog_ops smcwd_timeleft_ops = { 106 .start = smcwd_start, 107 .stop = smcwd_stop, 108 .ping = smcwd_ping, 109 .set_timeout = smcwd_set_timeout, 110 .get_timeleft = smcwd_get_timeleft, 111 }; 112 113 static int smcwd_probe(struct platform_device *pdev) 114 { 115 struct watchdog_device *wdd; 116 int err; 117 struct arm_smccc_res res; 118 u32 smc_func_id; 119 120 wdd = devm_kzalloc(&pdev->dev, sizeof(*wdd), GFP_KERNEL); 121 if (!wdd) 122 return -ENOMEM; 123 platform_set_drvdata(pdev, wdd); 124 125 if (of_property_read_u32(pdev->dev.of_node, "arm,smc-id", 126 &smc_func_id)) 127 smc_func_id = 0x82003D06; 128 watchdog_set_drvdata(wdd, (void *)(uintptr_t)smc_func_id); 129 130 err = smcwd_call(wdd, SMCWD_INIT, 0, &res); 131 if (err < 0) 132 return err; 133 134 wdd->info = &smcwd_info; 135 /* get_timeleft is optional */ 136 err = smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, NULL); 137 switch (err) { 138 case 0: 139 set_bit(WDOG_HW_RUNNING, &wdd->status); 140 fallthrough; 141 case -ENODATA: 142 wdd->ops = &smcwd_timeleft_ops; 143 break; 144 default: 145 wdd->ops = &smcwd_ops; 146 break; 147 } 148 149 wdd->timeout = res.a2; 150 wdd->max_timeout = res.a2; 151 wdd->min_timeout = res.a1; 152 wdd->parent = &pdev->dev; 153 154 watchdog_stop_on_reboot(wdd); 155 watchdog_stop_on_unregister(wdd); 156 watchdog_set_nowayout(wdd, nowayout); 157 watchdog_init_timeout(wdd, timeout, &pdev->dev); 158 err = smcwd_set_timeout(wdd, wdd->timeout); 159 if (err) 160 return err; 161 162 err = devm_watchdog_register_device(&pdev->dev, wdd); 163 if (err) 164 return err; 165 166 dev_info(&pdev->dev, 167 "Watchdog registered (timeout=%d sec, nowayout=%d)\n", 168 wdd->timeout, nowayout); 169 170 return 0; 171 } 172 173 static const struct of_device_id smcwd_dt_ids[] = { 174 { .compatible = "arm,smc-wdt" }, 175 {} 176 }; 177 MODULE_DEVICE_TABLE(of, smcwd_dt_ids); 178 179 static struct platform_driver smcwd_driver = { 180 .probe = smcwd_probe, 181 .driver = { 182 .name = DRV_NAME, 183 .of_match_table = smcwd_dt_ids, 184 }, 185 }; 186 187 module_platform_driver(smcwd_driver); 188 189 module_param(timeout, uint, 0); 190 MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds"); 191 192 module_param(nowayout, bool, 0); 193 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 194 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 195 196 MODULE_LICENSE("GPL"); 197 MODULE_AUTHOR("Julius Werner <jwerner@chromium.org>"); 198 MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver"); 199 MODULE_VERSION(DRV_VERSION); 200