// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (c) 2022 International Business Machines, Inc.
*/
#include <linux/bitops.h>
#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/math.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/time64.h>
#include <linux/watchdog.h>
#define DRV_NAME "pseries-wdt"
/*
* H_WATCHDOG Input
*
* R4: "flags":
*
* Bits 48-55: "operation"
*/
#define PSERIES_WDTF_OP_START 0x100UL /* start timer */
#define PSERIES_WDTF_OP_STOP 0x200UL /* stop timer */
#define PSERIES_WDTF_OP_QUERY 0x300UL /* query timer capabilities */
/*
* Bits 56-63: "timeoutAction" (for "Start Watchdog" only)
*/
#define PSERIES_WDTF_ACTION_HARD_POWEROFF 0x1UL /* poweroff */
#define PSERIES_WDTF_ACTION_HARD_RESTART 0x2UL /* restart */
#define PSERIES_WDTF_ACTION_DUMP_RESTART 0x3UL /* dump + restart */
/*
* H_WATCHDOG Output
*
* R3: Return code
*
* H_SUCCESS The operation completed.
*
* H_BUSY The hypervisor is too busy; retry the operation.
*
* H_PARAMETER The given "flags" are somehow invalid. Either the
* "operation" or "timeoutAction" is invalid, or a
* reserved bit is set.
*
* H_P2 The given "watchdogNumber" is zero or exceeds the
* supported maximum value.
*
* H_P3 The given "timeoutInMs" is below the supported
* minimum value.
*
* H_NOOP The given "watchdogNumber" is already stopped.
*
* H_HARDWARE The operation failed for ineffable reasons.
*
* H_FUNCTION The H_WATCHDOG hypercall is not supported by this
* hypervisor.
*
* R4:
*
* - For the "Query Watchdog Capabilities" operation, a 64-bit
* structure:
*/
#define PSERIES_WDTQ_MIN_TIMEOUT(cap) (((cap) >> 48) & 0xffff)
#define PSERIES_WDTQ_MAX_NUMBER(cap) (((cap) >> 32) & 0xffff)
static const unsigned long pseries_wdt_action[] = {
[0] = PSERIES_WDTF_ACTION_HARD_POWEROFF,
[1] = PSERIES_WDTF_ACTION_HARD_RESTART,
[2] = PSERIES_WDTF_ACTION_DUMP_RESTART,
};
#define WATCHDOG_ACTION 1
static unsigned int action = WATCHDOG_ACTION;
module_param(action, uint, 0444);
MODULE_PARM_DESC(action, "Action taken when watchdog expires (default="
__MODULE_STRING(WATCHDOG_ACTION) ")");
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0444);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
#define WATCHDOG_TIMEOUT 60
static unsigned int timeout = WATCHDOG_TIMEOUT;
module_param(timeout, uint, 0444);
MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds (default="
__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
struct pseries_wdt {
struct watchdog_device wd;
unsigned long action;
unsigned long num; /* Watchdog numbers are 1-based */
};
static int pseries_wdt_start(struct watchdog_device *wdd)
{
struct pseries_wdt *pw = watchdog_get_drvdata(wdd);
struct device *dev = wdd->parent;
unsigned long flags, msecs;
long rc;
flags = pw->action | PSERIES_WDTF_OP_START;
msecs = wdd->timeout * MSEC_PER_SEC;
rc = plpar_hcall_norets(H_WATCHDOG, flags, pw->num, msecs);
if (rc != H_SUCCESS) {
dev_crit(dev, "H_WATCHDOG: %ld: failed to start timer %lu",
rc, pw->num);
return -EIO;
}
return 0;
}
static int pseries_wdt_stop(struct watchdog_device *wdd)
{
struct pseries_wdt *pw = watchdog_get_drvdata(wdd);
struct device *dev = wdd->parent;
long rc;
rc = plpar_hcall_norets(H_WATCHDOG, PSERIES_WDTF_OP_STOP, pw->num);
if (rc != H_SUCCESS && rc != H_NOOP) {
dev_crit(dev, "H_WATCHDOG: %ld: failed to stop timer %lu",
rc, pw->num);
return -EIO;
}
return 0;
}
static struct watchdog_info pseries_wdt_info = {
.identity = DRV_NAME,
.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT
| WDIOF_PRETIMEOUT,
};
static const struct watchdog_ops pseries_wdt_ops = {
.owner = THIS_MODULE,
.start = pseries_wdt_start,
.stop = pseries_wdt_stop,
};
static int pseries_wdt_probe(struct platform_device *pdev)
{
unsigned long ret[PLPAR_HCALL_BUFSIZE] = { 0 };
struct pseries_wdt *pw;
unsigned long cap;
long msecs, rc;
int err;
rc = plpar_hcall(H_WATCHDOG, ret, PSERIES_WDTF_OP_QUERY);
if (rc == H_FUNCTION)
return -ENODEV;
if (rc != H_SUCCESS)
return -EIO;
cap = ret[0];
pw = devm_kzalloc(&pdev->dev, sizeof(*pw), GFP_KERNEL);
if (!pw)
return -ENOMEM;
/*
* Assume watchdogNumber 1 for now. If we ever support
* multiple timers we will need to devise a way to choose a
* distinct watchdogNumber for each platform device at device
* registration time.
*/
pw->num = 1;
if (PSERIES_WDTQ_MAX_NUMBER(cap) < pw->num)
return -ENODEV;
if (action >= ARRAY_SIZE(pseries_wdt_action))
return -EINVAL;
pw->action = pseries_wdt_action[action];
pw->wd.parent = &pdev->dev;
pw->wd.info = &pseries_wdt_info;
pw->wd.ops = &pseries_wdt_ops;
msecs = PSERIES_WDTQ_MIN_TIMEOUT(cap);
pw->wd.min_timeout = DIV_ROUND_UP(msecs, MSEC_PER_SEC);
pw->wd.max_timeout = UINT_MAX / 1000; /* from linux/watchdog.h */
pw->wd.timeout = timeout;
if (watchdog_init_timeout(&pw->wd, 0, NULL))
return -EINVAL;
watchdog_set_nowayout(&pw->wd, nowayout);
watchdog_stop_on_reboot(&pw->wd);
watchdog_stop_on_unregister(&pw->wd);
watchdog_set_drvdata(&pw->wd, pw);
err = devm_watchdog_register_device(&pdev->dev, &pw->wd);
if (err)
return err;
platform_set_drvdata(pdev, &pw->wd);
return 0;
}
static int pseries_wdt_suspend(struct platform_device *pdev, pm_message_t state)
{
struct watchdog_device *wd = platform_get_drvdata(pdev);
if (watchdog_active(wd))
return pseries_wdt_stop(wd);
return 0;
}
static int pseries_wdt_resume(struct platform_device *pdev)
{
struct watchdog_device *wd = platform_get_drvdata(pdev);
if (watchdog_active(wd))
return pseries_wdt_start(wd);
return 0;
}
static const struct platform_device_id pseries_wdt_id[] = {
{ .name = "pseries-wdt" },
{}
};
MODULE_DEVICE_TABLE(platform, pseries_wdt_id);
static struct platform_driver pseries_wdt_driver = {
.driver = {
.name = DRV_NAME,
},
.id_table = pseries_wdt_id,
.probe = pseries_wdt_probe,
.resume = pseries_wdt_resume,
.suspend = pseries_wdt_suspend,
};
module_platform_driver(pseries_wdt_driver);
MODULE_AUTHOR("Alexey Kardashevskiy");
MODULE_AUTHOR("Scott Cheloha");
MODULE_DESCRIPTION("POWER Architecture Platform Watchdog Driver");
MODULE_LICENSE("GPL");