[PATCH v2 4/4] watchdog/pseries-wdt: initial support for H_WATCHDOG-based watchdog timers
Alexey Kardashevskiy
aik at ozlabs.ru
Mon Jun 20 16:09:06 AEST 2022
On 6/3/22 03:53, Scott Cheloha wrote:
> 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: Scott Cheloha <cheloha at linux.ibm.com>
Besides the patch ordering and 0444 vs. 0644 (which is up to the PPC
maintainer to decide anyway :) ), looks good to me.
Reviewed-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> ---
> .../watchdog/watchdog-parameters.rst | 12 +
> drivers/watchdog/Kconfig | 8 +
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/pseries-wdt.c | 264 ++++++++++++++++++
> 4 files changed, 285 insertions(+)
> create mode 100644 drivers/watchdog/pseries-wdt.c
>
> diff --git a/Documentation/watchdog/watchdog-parameters.rst b/Documentation/watchdog/watchdog-parameters.rst
> index 223c99361a30..29153eed6689 100644
> --- a/Documentation/watchdog/watchdog-parameters.rst
> +++ b/Documentation/watchdog/watchdog-parameters.rst
> @@ -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)
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index c4e82a8d863f..06b412603f3e 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1932,6 +1932,14 @@ 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
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index f7da867e8782..f35660409f17 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -184,6 +184,7 @@ 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
> diff --git a/drivers/watchdog/pseries-wdt.c b/drivers/watchdog/pseries-wdt.c
> new file mode 100644
> index 000000000000..cfe53587457d
> --- /dev/null
> +++ b/drivers/watchdog/pseries-wdt.c
> @@ -0,0 +1,264 @@
> +// 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/watchdog.h>
> +
> +#define DRV_NAME "pseries-wdt"
> +
> +/*
> + * The PAPR's MSB->LSB bit ordering is 0->63. These macros simplify
> + * defining bitfields as described in the PAPR without needing to
> + * transpose values to the more C-like 63->0 ordering.
> + */
> +#define SETFIELD(_v, _b, _e) \
> + (((unsigned long)(_v) << PPC_BITLSHIFT(_e)) & PPC_BITMASK((_b), (_e)))
> +#define GETFIELD(_v, _b, _e) \
> + (((unsigned long)(_v) & PPC_BITMASK((_b), (_e))) >> PPC_BITLSHIFT(_e))
> +
> +/*
> + * The H_WATCHDOG hypercall first appears in PAPR v2.12 and is
> + * described fully in sections 14.5 and 14.15.6.
> + *
> + *
> + * H_WATCHDOG Input
> + *
> + * R4: "flags":
> + *
> + * Bits 48-55: "operation"
> + *
> + * 0x01 Start Watchdog
> + * 0x02 Stop Watchdog
> + * 0x03 Query Watchdog Capabilities
> + */
> +#define PSERIES_WDTF_OP(op) SETFIELD((op), 48, 55)
> +#define PSERIES_WDTF_OP_START PSERIES_WDTF_OP(0x1)
> +#define PSERIES_WDTF_OP_STOP PSERIES_WDTF_OP(0x2)
> +#define PSERIES_WDTF_OP_QUERY PSERIES_WDTF_OP(0x3)
> +
> +/*
> + * Bits 56-63: "timeoutAction" (for "Start Watchdog" only)
> + *
> + * 0x01 Hard poweroff
> + * 0x02 Hard restart
> + * 0x03 Dump restart
> + */
> +#define PSERIES_WDTF_ACTION(ac) SETFIELD(ac, 56, 63)
> +#define PSERIES_WDTF_ACTION_HARD_POWEROFF PSERIES_WDTF_ACTION(0x1)
> +#define PSERIES_WDTF_ACTION_HARD_RESTART PSERIES_WDTF_ACTION(0x2)
> +#define PSERIES_WDTF_ACTION_DUMP_RESTART PSERIES_WDTF_ACTION(0x3)
> +
> +/*
> + * 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
> + * value structured as follows:
> + *
> + * Bits 0-15: The minimum supported timeout in milliseconds.
> + * Bits 16-31: The number of watchdogs supported.
> + * Bits 32-63: Reserved.
> + */
> +#define PSERIES_WDTQ_MIN_TIMEOUT(cap) GETFIELD((cap), 0, 15)
> +#define PSERIES_WDTQ_MAX_NUMBER(cap) GETFIELD((cap), 16, 31)
> +
> +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 device *dev = wdd->parent;
> + struct pseries_wdt *pw = watchdog_get_drvdata(wdd);
> + unsigned long flags, msecs;
> + long rc;
> +
> + flags = pw->action | PSERIES_WDTF_OP_START;
> + msecs = wdd->timeout * 1000UL;
> + 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 device *dev = wdd->parent;
> + struct pseries_wdt *pw = watchdog_get_drvdata(wdd);
> + 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 };
> + unsigned long cap;
> + long rc;
> + struct pseries_wdt *pw;
> + 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 (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;
> + pw->wd.min_timeout = DIV_ROUND_UP(PSERIES_WDTQ_MIN_TIMEOUT(cap), 1000);
> + pw->wd.max_timeout = UINT_MAX / 1000;
> + 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,
> + .owner = THIS_MODULE,
> + },
> + .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 <aik at ozlabs.ru>");
> +MODULE_AUTHOR("Scott Cheloha <cheloha at linux.ibm.com>");
> +MODULE_DESCRIPTION("POWER Architecture Platform Watchdog Driver");
> +MODULE_LICENSE("GPL");
--
Alexey
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