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// SPDX-License-Identifier: GPL-2.0-only
/*
* ARM Secure Monitor Call watchdog driver
*
* Copyright 2020 Google LLC.
* Julius Werner <jwerner@chromium.org>
* Based on mtk_wdt.c
*/
#include <linux/arm-smccc.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <uapi/linux/psci.h>
#define DRV_NAME "arm_smc_wdt"
#define DRV_VERSION "1.0"
enum smcwd_call {
SMCWD_INIT = 0,
SMCWD_SET_TIMEOUT = 1,
SMCWD_ENABLE = 2,
SMCWD_PET = 3,
SMCWD_GET_TIMELEFT = 4,
};
static bool nowayout = WATCHDOG_NOWAYOUT;
static unsigned int timeout;
static int smcwd_call(struct watchdog_device *wdd, enum smcwd_call call,
unsigned long arg, struct arm_smccc_res *res)
{
struct arm_smccc_res local_res;
if (!res)
res = &local_res;
arm_smccc_smc((u32)(uintptr_t)watchdog_get_drvdata(wdd), call, arg, 0,
0, 0, 0, 0, res);
if (res->a0 == PSCI_RET_NOT_SUPPORTED)
return -ENODEV;
if (res->a0 == PSCI_RET_INVALID_PARAMS)
return -EINVAL;
if (res->a0 != PSCI_RET_SUCCESS)
return -EIO;
return 0;
}
static int smcwd_ping(struct watchdog_device *wdd)
{
return smcwd_call(wdd, SMCWD_PET, 0, NULL);
}
static unsigned int smcwd_get_timeleft(struct watchdog_device *wdd)
{
struct arm_smccc_res res;
smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, &res);
if (res.a0)
return 0;
return res.a1;
}
static int smcwd_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
{
int res;
res = smcwd_call(wdd, SMCWD_SET_TIMEOUT, timeout, NULL);
if (!res)
wdd->timeout = timeout;
return res;
}
static int smcwd_stop(struct watchdog_device *wdd)
{
return smcwd_call(wdd, SMCWD_ENABLE, 0, NULL);
}
static int smcwd_start(struct watchdog_device *wdd)
{
return smcwd_call(wdd, SMCWD_ENABLE, 1, NULL);
}
static const struct watchdog_info smcwd_info = {
.identity = DRV_NAME,
.options = WDIOF_SETTIMEOUT |
WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE,
};
static const struct watchdog_ops smcwd_ops = {
.start = smcwd_start,
.stop = smcwd_stop,
.ping = smcwd_ping,
.set_timeout = smcwd_set_timeout,
};
static const struct watchdog_ops smcwd_timeleft_ops = {
.start = smcwd_start,
.stop = smcwd_stop,
.ping = smcwd_ping,
.set_timeout = smcwd_set_timeout,
.get_timeleft = smcwd_get_timeleft,
};
static int smcwd_probe(struct platform_device *pdev)
{
struct watchdog_device *wdd;
int err;
struct arm_smccc_res res;
u32 smc_func_id;
wdd = devm_kzalloc(&pdev->dev, sizeof(*wdd), GFP_KERNEL);
if (!wdd)
return -ENOMEM;
platform_set_drvdata(pdev, wdd);
if (of_property_read_u32(pdev->dev.of_node, "arm,smc-id",
&smc_func_id))
smc_func_id = 0x82003D06;
watchdog_set_drvdata(wdd, (void *)(uintptr_t)smc_func_id);
err = smcwd_call(wdd, SMCWD_INIT, 0, &res);
if (err < 0)
return err;
wdd->info = &smcwd_info;
/* get_timeleft is optional */
if (smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, NULL))
wdd->ops = &smcwd_ops;
else
wdd->ops = &smcwd_timeleft_ops;
wdd->timeout = res.a2;
wdd->max_timeout = res.a2;
wdd->min_timeout = res.a1;
wdd->parent = &pdev->dev;
watchdog_stop_on_reboot(wdd);
watchdog_stop_on_unregister(wdd);
watchdog_set_nowayout(wdd, nowayout);
watchdog_init_timeout(wdd, timeout, &pdev->dev);
err = smcwd_set_timeout(wdd, wdd->timeout);
if (err)
return err;
err = devm_watchdog_register_device(&pdev->dev, wdd);
if (err)
return err;
dev_info(&pdev->dev,
"Watchdog registered (timeout=%d sec, nowayout=%d)\n",
wdd->timeout, nowayout);
return 0;
}
static const struct of_device_id smcwd_dt_ids[] = {
{ .compatible = "arm,smc-wdt" },
{}
};
MODULE_DEVICE_TABLE(of, smcwd_dt_ids);
static struct platform_driver smcwd_driver = {
.probe = smcwd_probe,
.driver = {
.name = DRV_NAME,
.of_match_table = smcwd_dt_ids,
},
};
module_platform_driver(smcwd_driver);
module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Julius Werner <jwerner@chromium.org>");
MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver");
MODULE_VERSION(DRV_VERSION);
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