Commit 69472ffa authored by Scott Cheloha's avatar Scott Cheloha Committed by Michael Ellerman
Browse files

watchdog/pseries-wdt: initial support for H_WATCHDOG-based watchdog timers 



PAPR v2.12 defines a new hypercall, H_WATCHDOG.  The hypercall permits
guest control of one or more virtual watchdog timers.  The timers have
millisecond granularity.  The guest is terminated when a timer
expires.

This patch adds a watchdog driver for these timers, "pseries-wdt".

pseries_wdt_probe() currently assumes the existence of only one
platform device and always assigns it watchdogNumber 1.  If we ever
expose more than one timer to userspace we will need to devise a way
to assign a distinct watchdogNumber to each platform device at device
registration time.

Signed-off-by: default avatarScott Cheloha <cheloha@linux.ibm.com>
Acked-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220713202335.1217647-5-cheloha@linux.ibm.com
parent 578030bf

Documentation/watchdog/watchdog-parameters.rst

+12 −0
Original line number Diff line number Diff line
@@ -425,6 +425,18 @@ pnx833x_wdt: 


-------------------------------------------------



pseries-wdt:

    action:

	Action taken when watchdog expires: 0 (power off), 1 (restart),

	2 (dump and restart). (default=1)

    timeout:

	Initial watchdog timeout in seconds. (default=60)

    nowayout:

	Watchdog cannot be stopped once started.

	(default=kernel config parameter)



-------------------------------------------------



rc32434_wdt:

    timeout:

	Watchdog timeout value, in seconds (default=20)

drivers/watchdog/Kconfig

+8 −0
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@@ -1962,6 +1962,14 @@ config MEN_A21_WDT 


# PPC64 Architecture



config PSERIES_WDT

	tristate "POWER Architecture Platform Watchdog Timer"

	depends on PPC_PSERIES

	select WATCHDOG_CORE

	help

	  Driver for virtual watchdog timers provided by PAPR

	  hypervisors (e.g. PowerVM, KVM).



config WATCHDOG_RTAS

	tristate "RTAS watchdog"

	depends on PPC_RTAS

drivers/watchdog/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -187,6 +187,7 @@ obj-$(CONFIG_BOOKE_WDT) += booke_wdt.o 
obj-$(CONFIG_MEN_A21_WDT) += mena21_wdt.o



# PPC64 Architecture

obj-$(CONFIG_PSERIES_WDT) += pseries-wdt.o

obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o



# S390 Architecture

drivers/watchdog/pseries-wdt.c

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+239 −0
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// 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");