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_SUCCESS) 50 return -EIO; 51 return 0; 52 } 53 54 static int smcwd_ping(struct watchdog_device *wdd) 55 { 56 return smcwd_call(wdd, SMCWD_PET, 0, NULL); 57 } 58 59 static unsigned int smcwd_get_timeleft(struct watchdog_device *wdd) 60 { 61 struct arm_smccc_res res; 62 63 smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, &res); 64 if (res.a0) 65 return 0; 66 return res.a1; 67 } 68 69 static int smcwd_set_timeout(struct watchdog_device *wdd, unsigned int timeout) 70 { 71 int res; 72 73 res = smcwd_call(wdd, SMCWD_SET_TIMEOUT, timeout, NULL); 74 if (!res) 75 wdd->timeout = timeout; 76 return res; 77 } 78 79 static int smcwd_stop(struct watchdog_device *wdd) 80 { 81 return smcwd_call(wdd, SMCWD_ENABLE, 0, NULL); 82 } 83 84 static int smcwd_start(struct watchdog_device *wdd) 85 { 86 return smcwd_call(wdd, SMCWD_ENABLE, 1, NULL); 87 } 88 89 static const struct watchdog_info smcwd_info = { 90 .identity = DRV_NAME, 91 .options = WDIOF_SETTIMEOUT | 92 WDIOF_KEEPALIVEPING | 93 WDIOF_MAGICCLOSE, 94 }; 95 96 static const struct watchdog_ops smcwd_ops = { 97 .start = smcwd_start, 98 .stop = smcwd_stop, 99 .ping = smcwd_ping, 100 .set_timeout = smcwd_set_timeout, 101 }; 102 103 static const struct watchdog_ops smcwd_timeleft_ops = { 104 .start = smcwd_start, 105 .stop = smcwd_stop, 106 .ping = smcwd_ping, 107 .set_timeout = smcwd_set_timeout, 108 .get_timeleft = smcwd_get_timeleft, 109 }; 110 111 static int smcwd_probe(struct platform_device *pdev) 112 { 113 struct watchdog_device *wdd; 114 int err; 115 struct arm_smccc_res res; 116 u32 smc_func_id; 117 118 wdd = devm_kzalloc(&pdev->dev, sizeof(*wdd), GFP_KERNEL); 119 if (!wdd) 120 return -ENOMEM; 121 platform_set_drvdata(pdev, wdd); 122 123 if (of_property_read_u32(pdev->dev.of_node, "arm,smc-id", 124 &smc_func_id)) 125 smc_func_id = 0x82003D06; 126 watchdog_set_drvdata(wdd, (void *)(uintptr_t)smc_func_id); 127 128 err = smcwd_call(wdd, SMCWD_INIT, 0, &res); 129 if (err < 0) 130 return err; 131 132 wdd->info = &smcwd_info; 133 /* get_timeleft is optional */ 134 if (smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, NULL)) 135 wdd->ops = &smcwd_ops; 136 else 137 wdd->ops = &smcwd_timeleft_ops; 138 wdd->timeout = res.a2; 139 wdd->max_timeout = res.a2; 140 wdd->min_timeout = res.a1; 141 wdd->parent = &pdev->dev; 142 143 watchdog_stop_on_reboot(wdd); 144 watchdog_stop_on_unregister(wdd); 145 watchdog_set_nowayout(wdd, nowayout); 146 watchdog_init_timeout(wdd, timeout, &pdev->dev); 147 err = smcwd_set_timeout(wdd, wdd->timeout); 148 if (err) 149 return err; 150 151 err = devm_watchdog_register_device(&pdev->dev, wdd); 152 if (err) 153 return err; 154 155 dev_info(&pdev->dev, 156 "Watchdog registered (timeout=%d sec, nowayout=%d)\n", 157 wdd->timeout, nowayout); 158 159 return 0; 160 } 161 162 static const struct of_device_id smcwd_dt_ids[] = { 163 { .compatible = "arm,smc-wdt" }, 164 {} 165 }; 166 MODULE_DEVICE_TABLE(of, smcwd_dt_ids); 167 168 static struct platform_driver smcwd_driver = { 169 .probe = smcwd_probe, 170 .driver = { 171 .name = DRV_NAME, 172 .of_match_table = smcwd_dt_ids, 173 }, 174 }; 175 176 module_platform_driver(smcwd_driver); 177 178 module_param(timeout, uint, 0); 179 MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds"); 180 181 module_param(nowayout, bool, 0); 182 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 183 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 184 185 MODULE_LICENSE("GPL"); 186 MODULE_AUTHOR("Julius Werner <jwerner@chromium.org>"); 187 MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver"); 188 MODULE_VERSION(DRV_VERSION); 189