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Wed, 1 Jun 2022 14:48:52 +0000 (GMT) Received: from localhost (unknown [9.41.178.126]) by b03ledav002.gho.boulder.ibm.com (Postfix) with ESMTP; Wed, 1 Jun 2022 14:48:52 +0000 (GMT) Date: Wed, 1 Jun 2022 09:48:52 -0500 From: Scott Cheloha To: Alexey Kardashevskiy Cc: linux-watchdog@vger.kernel.org, linux@roeck-us.net, tzungbi@kernel.org, brking@linux.ibm.com, nathanl@linux.ibm.com, npiggin@gmail.com, vaishnavi@linux.ibm.com, wvoigt@us.ibm.com, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v1 4/4] watchdog/pseries-wdt: initial support for PAPR H_WATCHDOG timers Message-ID: References: <20220520183552.33426-1-cheloha@linux.ibm.com> <20220520183552.33426-5-cheloha@linux.ibm.com> <74498c4b-7b6a-3864-1ae8-57e848a1254c@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <74498c4b-7b6a-3864-1ae8-57e848a1254c@ozlabs.ru> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 7GeDLk9yEyhqV6j96bGMQf43WRd-IiNX X-Proofpoint-ORIG-GUID: TLEunO7JxnPww2PPAzyBwR9REWXkaJUt X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-01_04,2022-06-01_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 mlxscore=0 adultscore=0 spamscore=0 lowpriorityscore=0 clxscore=1015 bulkscore=0 priorityscore=1501 mlxlogscore=999 phishscore=0 malwarescore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2204290000 definitions=main-2206010067 Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org On Wed, May 25, 2022 at 04:35:11PM +1000, Alexey Kardashevskiy wrote: > > On 5/21/22 04:35, 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. > > This one should go before 4/4 in the series for bisectability. > > What is platform_device_register_simple("pseries-wdt",...) going to do > without the driver? This is a chicken-and-egg problem without an obvious solution. A device without a driver is a body without a soul. A driver without a device is a ghost without a machine. ... or something like that, don't quote me :) Absent some very compelling reasoning, I would like to keep the current order. It feels logical to me to keep the powerpc/pseries patches adjacent and prior to the watchdog driver patch. > > Signed-off-by: Scott Cheloha > > --- > > .../watchdog/watchdog-parameters.rst | 12 + > > drivers/watchdog/Kconfig | 8 + > > drivers/watchdog/Makefile | 1 + > > drivers/watchdog/pseries-wdt.c | 337 ++++++++++++++++++ > > 4 files changed, 358 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..4ffe725e796c 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: 1 (power off), 2 (restart), > > + 3 (dump and restart). (default=2) > > + 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..f41bc4d3b7a2 > > --- /dev/null > > +++ b/drivers/watchdog/pseries-wdt.c > > @@ -0,0 +1,337 @@ > > +// SPDX-License-Identifier: GPL-2.0-or-later > > +/* > > + * Copyright (c) 2022 International Business Machines, Inc. > > + */ > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > + > > +#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)) > > + > > +/* > > + * H_WATCHDOG Hypercall Input > > + * > > + * R4: "flags": > > + * > > + * A 64-bit value structured as follows: > > + * > > + * Bits 0-46: Reserved (must be zero). > > + */ > > +#define PSERIES_WDTF_RESERVED PPC_BITMASK(0, 46) > > + > > +/* > > + * Bit 47: "leaveOtherWatchdogsRunningOnTimeout" > > + * > > + * 0 Stop outstanding watchdogs on timeout. > > + * 1 Leave outstanding watchdogs running on timeout. > > + */ > > +#define PSERIES_WDTF_LEAVE_OTHER PPC_BIT(47) > > + > > +/* > > + * Bits 48-55: "operation" > > + * > > + * 0x01 Start Watchdog > > + * 0x02 Stop Watchdog > > + * 0x03 Query Watchdog Capabilities > > + * 0x04 Query Watchdog LPM Requirement > > + */ > > +#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) > > +#define PSERIES_WDTF_OP_QUERY_LPM PSERIES_WDTF_OP(0x4) > > + > > +/* > > + * Bits 56-63: "timeoutAction" > > + * > > + * 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) > > > + > > +/* > > + * R5: "watchdogNumber": > > + * > > + * The target watchdog. Watchdog numbers are 1-based. The > > + * maximum supported watchdog number may be obtained via the > > + * "Query Watchdog Capabilities" operation. > > + * > > + * This input is ignored for the "Query Watchdog Capabilities" > > + * operation. > > + * > > + * R6: "timeoutInMs": > > + * > > + * The timeout in milliseconds. The minimum supported timeout may > > + * be obtained via the "Query Watchdog Capabilities" operation. > > + * > > + * This input is ignored for the "Stop Watchdog", "Query Watchdog > > + * Capabilities", and "Query Watchdog LPM Requirement" operations. > > + */ > > + > > +/* > > + * H_WATCHDOG Hypercall 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) > > +#define PSERIES_WDTQ_RESERVED PPC_BITMASK(32, 63) > > PSERIES_WDTQ_RESERVED is not needed as there is a comment above. The *_RESERVED macros are from your draft patch. I will remove them, though, we aren't actually using them. I will trim up the big comment for v2, too. It's just going to rot otherwise. You need to read the PAPR to review the hypercalls, anyway. > > + > > +/* > > + * - For the "Query Watchdog LPM Requirement" operation: > > + * > > + * 1 The given "watchdogNumber" must be stopped prior to > > + * suspending. > > + * > > + * 2 The given "watchdogNumber" does not have to be stopped > > + * prior to suspending. > > + */ > > +#define PSERIES_WDTQL_MUST_STOP 1 > > +#define PSERIES_WDTQL_NEED_NOT_STOP 2 > > + > > +static unsigned long action = PSERIES_WDTF_ACTION_HARD_RESTART; > > + > > +static int action_get(char *buf, const struct kernel_param *kp) > > +{ > > + int val; > > + > > + switch (action) { > > + case PSERIES_WDTF_ACTION_HARD_POWEROFF: > > + val = 1; > > + break; > > + case PSERIES_WDTF_ACTION_HARD_RESTART: > > + val = 2; > > + break; > > + case PSERIES_WDTF_ACTION_DUMP_RESTART: > > + val = 3; > > + break; > > + default: > > + return -EINVAL; > > + } > > + return sprintf(buf, "%d\n", val); > > +} > > + > > +static int action_set(const char *val, const struct kernel_param *kp) > > +{ > > + int choice; > > + > > + if (kstrtoint(val, 10, &choice)) > > + return -EINVAL; > > + switch (choice) { > > + case 1: > > + action = PSERIES_WDTF_ACTION_HARD_POWEROFF; > > + return 0; > > + case 2: > > + action = PSERIES_WDTF_ACTION_HARD_RESTART; > > + return 0; > > + case 3: > > + action = PSERIES_WDTF_ACTION_DUMP_RESTART; > > + return 0; > > + } > > + return -EINVAL; > > +} > > + > > +static const struct kernel_param_ops action_ops = { > > + .get = action_get, > > + .set = action_set, > > +}; > > +module_param_cb(action, &action_ops, NULL, 0444); > > 0644 here and below? I do not want these changing at runtime. 0444 is the right thing. > > +MODULE_PARM_DESC(action, "Action taken when watchdog expires (default=2)"); > > + > > +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 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 = 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, min_timeout_ms; > > + long rc; > > + struct pseries_wdt *pw; > > + int err; > > + > > + rc = plpar_hcall(H_WATCHDOG, ret, PSERIES_WDTF_OP_QUERY); > > + if (rc != H_SUCCESS) > > + return rc == H_FUNCTION ? -ENODEV : -EIO; > > Nit: > > if (rc == H_FUNCTION) > return -ENODEV; > if (rc != H_SUCCESS) > return -EIO; > > ? Sure, changed in v2. > > + 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; > > + > > + pw->wd.parent = &pdev->dev; > > + pw->wd.info = &pseries_wdt_info; > > + pw->wd.ops = &pseries_wdt_ops; > > + min_timeout_ms = PSERIES_WDTQ_MIN_TIMEOUT(cap); > > + pw->wd.min_timeout = roundup(min_timeout_ms, 1000) / 1000; > > + pw->wd.max_timeout = UINT_MAX; > > + watchdog_init_timeout(&pw->wd, timeout, NULL); > > > If PSERIES_WDTF_OP_QUERY returns 2min and this driver's default is 1min, > watchdog_init_timeout() returns an error, don't we want to handle it here? Fixed in v2. -Scott From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 798DACCA473 for ; Wed, 1 Jun 2022 14:49:49 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4LCsW005VZz3bsF for ; Thu, 2 Jun 2022 00:49:48 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=nCuhzWWl; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=cheloha@linux.ibm.com; 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Wed, 1 Jun 2022 14:48:53 GMT Received: from b03ledav002.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 02546136061; Wed, 1 Jun 2022 14:48:53 +0000 (GMT) Received: from b03ledav002.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C42FE136060; Wed, 1 Jun 2022 14:48:52 +0000 (GMT) Received: from localhost (unknown [9.41.178.126]) by b03ledav002.gho.boulder.ibm.com (Postfix) with ESMTP; Wed, 1 Jun 2022 14:48:52 +0000 (GMT) Date: Wed, 1 Jun 2022 09:48:52 -0500 From: Scott Cheloha To: Alexey Kardashevskiy Subject: Re: [PATCH v1 4/4] watchdog/pseries-wdt: initial support for PAPR H_WATCHDOG timers Message-ID: References: <20220520183552.33426-1-cheloha@linux.ibm.com> <20220520183552.33426-5-cheloha@linux.ibm.com> <74498c4b-7b6a-3864-1ae8-57e848a1254c@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <74498c4b-7b6a-3864-1ae8-57e848a1254c@ozlabs.ru> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 7GeDLk9yEyhqV6j96bGMQf43WRd-IiNX X-Proofpoint-ORIG-GUID: TLEunO7JxnPww2PPAzyBwR9REWXkaJUt X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-01_04,2022-06-01_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 mlxscore=0 adultscore=0 spamscore=0 lowpriorityscore=0 clxscore=1015 bulkscore=0 priorityscore=1501 mlxlogscore=999 phishscore=0 malwarescore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2204290000 definitions=main-2206010067 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: nathanl@linux.ibm.com, wvoigt@us.ibm.com, linux-watchdog@vger.kernel.org, vaishnavi@linux.ibm.com, npiggin@gmail.com, tzungbi@kernel.org, brking@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, linux@roeck-us.net Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, May 25, 2022 at 04:35:11PM +1000, Alexey Kardashevskiy wrote: > > On 5/21/22 04:35, 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. > > This one should go before 4/4 in the series for bisectability. > > What is platform_device_register_simple("pseries-wdt",...) going to do > without the driver? This is a chicken-and-egg problem without an obvious solution. A device without a driver is a body without a soul. A driver without a device is a ghost without a machine. ... or something like that, don't quote me :) Absent some very compelling reasoning, I would like to keep the current order. It feels logical to me to keep the powerpc/pseries patches adjacent and prior to the watchdog driver patch. > > Signed-off-by: Scott Cheloha > > --- > > .../watchdog/watchdog-parameters.rst | 12 + > > drivers/watchdog/Kconfig | 8 + > > drivers/watchdog/Makefile | 1 + > > drivers/watchdog/pseries-wdt.c | 337 ++++++++++++++++++ > > 4 files changed, 358 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..4ffe725e796c 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: 1 (power off), 2 (restart), > > + 3 (dump and restart). (default=2) > > + 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..f41bc4d3b7a2 > > --- /dev/null > > +++ b/drivers/watchdog/pseries-wdt.c > > @@ -0,0 +1,337 @@ > > +// SPDX-License-Identifier: GPL-2.0-or-later > > +/* > > + * Copyright (c) 2022 International Business Machines, Inc. > > + */ > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > + > > +#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)) > > + > > +/* > > + * H_WATCHDOG Hypercall Input > > + * > > + * R4: "flags": > > + * > > + * A 64-bit value structured as follows: > > + * > > + * Bits 0-46: Reserved (must be zero). > > + */ > > +#define PSERIES_WDTF_RESERVED PPC_BITMASK(0, 46) > > + > > +/* > > + * Bit 47: "leaveOtherWatchdogsRunningOnTimeout" > > + * > > + * 0 Stop outstanding watchdogs on timeout. > > + * 1 Leave outstanding watchdogs running on timeout. > > + */ > > +#define PSERIES_WDTF_LEAVE_OTHER PPC_BIT(47) > > + > > +/* > > + * Bits 48-55: "operation" > > + * > > + * 0x01 Start Watchdog > > + * 0x02 Stop Watchdog > > + * 0x03 Query Watchdog Capabilities > > + * 0x04 Query Watchdog LPM Requirement > > + */ > > +#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) > > +#define PSERIES_WDTF_OP_QUERY_LPM PSERIES_WDTF_OP(0x4) > > + > > +/* > > + * Bits 56-63: "timeoutAction" > > + * > > + * 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) > > > + > > +/* > > + * R5: "watchdogNumber": > > + * > > + * The target watchdog. Watchdog numbers are 1-based. The > > + * maximum supported watchdog number may be obtained via the > > + * "Query Watchdog Capabilities" operation. > > + * > > + * This input is ignored for the "Query Watchdog Capabilities" > > + * operation. > > + * > > + * R6: "timeoutInMs": > > + * > > + * The timeout in milliseconds. The minimum supported timeout may > > + * be obtained via the "Query Watchdog Capabilities" operation. > > + * > > + * This input is ignored for the "Stop Watchdog", "Query Watchdog > > + * Capabilities", and "Query Watchdog LPM Requirement" operations. > > + */ > > + > > +/* > > + * H_WATCHDOG Hypercall 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) > > +#define PSERIES_WDTQ_RESERVED PPC_BITMASK(32, 63) > > PSERIES_WDTQ_RESERVED is not needed as there is a comment above. The *_RESERVED macros are from your draft patch. I will remove them, though, we aren't actually using them. I will trim up the big comment for v2, too. It's just going to rot otherwise. You need to read the PAPR to review the hypercalls, anyway. > > + > > +/* > > + * - For the "Query Watchdog LPM Requirement" operation: > > + * > > + * 1 The given "watchdogNumber" must be stopped prior to > > + * suspending. > > + * > > + * 2 The given "watchdogNumber" does not have to be stopped > > + * prior to suspending. > > + */ > > +#define PSERIES_WDTQL_MUST_STOP 1 > > +#define PSERIES_WDTQL_NEED_NOT_STOP 2 > > + > > +static unsigned long action = PSERIES_WDTF_ACTION_HARD_RESTART; > > + > > +static int action_get(char *buf, const struct kernel_param *kp) > > +{ > > + int val; > > + > > + switch (action) { > > + case PSERIES_WDTF_ACTION_HARD_POWEROFF: > > + val = 1; > > + break; > > + case PSERIES_WDTF_ACTION_HARD_RESTART: > > + val = 2; > > + break; > > + case PSERIES_WDTF_ACTION_DUMP_RESTART: > > + val = 3; > > + break; > > + default: > > + return -EINVAL; > > + } > > + return sprintf(buf, "%d\n", val); > > +} > > + > > +static int action_set(const char *val, const struct kernel_param *kp) > > +{ > > + int choice; > > + > > + if (kstrtoint(val, 10, &choice)) > > + return -EINVAL; > > + switch (choice) { > > + case 1: > > + action = PSERIES_WDTF_ACTION_HARD_POWEROFF; > > + return 0; > > + case 2: > > + action = PSERIES_WDTF_ACTION_HARD_RESTART; > > + return 0; > > + case 3: > > + action = PSERIES_WDTF_ACTION_DUMP_RESTART; > > + return 0; > > + } > > + return -EINVAL; > > +} > > + > > +static const struct kernel_param_ops action_ops = { > > + .get = action_get, > > + .set = action_set, > > +}; > > +module_param_cb(action, &action_ops, NULL, 0444); > > 0644 here and below? I do not want these changing at runtime. 0444 is the right thing. > > +MODULE_PARM_DESC(action, "Action taken when watchdog expires (default=2)"); > > + > > +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 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 = 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, min_timeout_ms; > > + long rc; > > + struct pseries_wdt *pw; > > + int err; > > + > > + rc = plpar_hcall(H_WATCHDOG, ret, PSERIES_WDTF_OP_QUERY); > > + if (rc != H_SUCCESS) > > + return rc == H_FUNCTION ? -ENODEV : -EIO; > > Nit: > > if (rc == H_FUNCTION) > return -ENODEV; > if (rc != H_SUCCESS) > return -EIO; > > ? Sure, changed in v2. > > + 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; > > + > > + pw->wd.parent = &pdev->dev; > > + pw->wd.info = &pseries_wdt_info; > > + pw->wd.ops = &pseries_wdt_ops; > > + min_timeout_ms = PSERIES_WDTQ_MIN_TIMEOUT(cap); > > + pw->wd.min_timeout = roundup(min_timeout_ms, 1000) / 1000; > > + pw->wd.max_timeout = UINT_MAX; > > + watchdog_init_timeout(&pw->wd, timeout, NULL); > > > If PSERIES_WDTF_OP_QUERY returns 2min and this driver's default is 1min, > watchdog_init_timeout() returns an error, don't we want to handle it here? Fixed in v2. -Scott