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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * ARM Secure Monitor Call watchdog driver4 *5 * Copyright 2020 Google LLC.6 * Julius Werner <jwerner@chromium.org>7 * Based on mtk_wdt.c8 */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 23enum 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 31static bool nowayout = WATCHDOG_NOWAYOUT;32static unsigned int timeout;33 34static 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 54static int smcwd_ping(struct watchdog_device *wdd)55{56 return smcwd_call(wdd, SMCWD_PET, 0, NULL);57}58 59static 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 69static 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 79static int smcwd_stop(struct watchdog_device *wdd)80{81 return smcwd_call(wdd, SMCWD_ENABLE, 0, NULL);82}83 84static int smcwd_start(struct watchdog_device *wdd)85{86 return smcwd_call(wdd, SMCWD_ENABLE, 1, NULL);87}88 89static const struct watchdog_info smcwd_info = {90 .identity = DRV_NAME,91 .options = WDIOF_SETTIMEOUT |92 WDIOF_KEEPALIVEPING |93 WDIOF_MAGICCLOSE,94};95 96static 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 103static 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 111static 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 else137 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 162static const struct of_device_id smcwd_dt_ids[] = {163 { .compatible = "arm,smc-wdt" },164 {}165};166MODULE_DEVICE_TABLE(of, smcwd_dt_ids);167 168static 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 176module_platform_driver(smcwd_driver);177 178module_param(timeout, uint, 0);179MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");180 181module_param(nowayout, bool, 0);182MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="183 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");184 185MODULE_LICENSE("GPL");186MODULE_AUTHOR("Julius Werner <jwerner@chromium.org>");187MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver");188MODULE_VERSION(DRV_VERSION);189