cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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arm_smc_wdt.c (4338B)

      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
     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	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
    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);