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Sender: Guenter Roeck <groeck7@gmail.com>
Subject: Re: [PATCH] watchdog: iTCO: Drop vendor support
To:     Wim Van Sebroeck <wim@linux-watchdog.org>
Cc:     linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20211008152637.141673-1-linux@roeck-us.net>
From:   Guenter Roeck <linux@roeck-us.net>
Message-ID: <ad2d002c-1593-62c3-934c-4c41c465fd41@roeck-us.net>
Date:   Tue, 26 Oct 2021 09:37:56 -0700
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On 10/8/21 8:26 AM, Guenter Roeck wrote:
> iTCO vendor support was introduced in 2006 to support SuperMicro boards
> with Pentium 3 CPUs. It was extended in 2009 to support motherbords
> with broken BIOS (specifically Intel DG33TL). The code is long since
> obsolete, so let's drop support for it.
> 
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Wim - this patch is buggy. Please don't apply it.

Guenter

> ---
>   .../watchdog/watchdog-parameters.rst          |   7 -
>   drivers/watchdog/Kconfig                      |   8 -
>   drivers/watchdog/Makefile                     |   3 -
>   drivers/watchdog/iTCO_vendor.h                |  14 --
>   drivers/watchdog/iTCO_vendor_support.c        | 216 ------------------
>   drivers/watchdog/iTCO_wdt.c                   |  17 --
>   6 files changed, 265 deletions(-)
>   delete mode 100644 drivers/watchdog/iTCO_vendor.h
>   delete mode 100644 drivers/watchdog/iTCO_vendor_support.c
> 
> diff --git a/Documentation/watchdog/watchdog-parameters.rst b/Documentation/watchdog/watchdog-parameters.rst
> index 223c99361a30..60ecbd53e6aa 100644
> --- a/Documentation/watchdog/watchdog-parameters.rst
> +++ b/Documentation/watchdog/watchdog-parameters.rst
> @@ -219,13 +219,6 @@ iTCO_wdt:
>   
>   -------------------------------------------------
>   
> -iTCO_vendor_support:
> -    vendorsupport:
> -	iTCO vendor specific support mode, default=0 (none),
> -	1=SuperMicro Pent3, 2=SuperMicro Pent4+, 911=Broken SMI BIOS
> -
> --------------------------------------------------
> -
>   ib700wdt:
>       timeout:
>   	Watchdog timeout in seconds. 0<= timeout <=30, default=30.
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index bf59faeb3de1..3fae89be0e27 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1233,14 +1233,6 @@ config ITCO_WDT
>   	  To compile this driver as a module, choose M here: the
>   	  module will be called iTCO_wdt.
>   
> -config ITCO_VENDOR_SUPPORT
> -	bool "Intel TCO Timer/Watchdog Specific Vendor Support"
> -	depends on ITCO_WDT
> -	help
> -	  Add vendor specific support to the intel TCO timer based watchdog
> -	  devices. At this moment we only have additional support for some
> -	  SuperMicro Inc. motherboards.
> -
>   config IT8712F_WDT
>   	tristate "IT8712F (Smart Guardian) Watchdog Timer"
>   	depends on X86
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 1bd2d6f37c53..b05a7e611308 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -113,9 +113,6 @@ obj-$(CONFIG_WAFER_WDT) += wafer5823wdt.o
>   obj-$(CONFIG_I6300ESB_WDT) += i6300esb.o
>   obj-$(CONFIG_IE6XX_WDT) += ie6xx_wdt.o
>   obj-$(CONFIG_ITCO_WDT) += iTCO_wdt.o
> -ifeq ($(CONFIG_ITCO_VENDOR_SUPPORT),y)
> -obj-$(CONFIG_ITCO_WDT) += iTCO_vendor_support.o
> -endif
>   obj-$(CONFIG_IT8712F_WDT) += it8712f_wdt.o
>   obj-$(CONFIG_IT87_WDT) += it87_wdt.o
>   obj-$(CONFIG_HP_WATCHDOG) += hpwdt.o
> diff --git a/drivers/watchdog/iTCO_vendor.h b/drivers/watchdog/iTCO_vendor.h
> deleted file mode 100644
> index 69e92e692ae0..000000000000
> --- a/drivers/watchdog/iTCO_vendor.h
> +++ /dev/null
> @@ -1,14 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0 */
> -/* iTCO Vendor Specific Support hooks */
> -#ifdef CONFIG_ITCO_VENDOR_SUPPORT
> -extern int iTCO_vendorsupport;
> -extern void iTCO_vendor_pre_start(struct resource *, unsigned int);
> -extern void iTCO_vendor_pre_stop(struct resource *);
> -extern int iTCO_vendor_check_noreboot_on(void);
> -#else
> -#define iTCO_vendorsupport				0
> -#define iTCO_vendor_pre_start(acpibase, heartbeat)	{}
> -#define iTCO_vendor_pre_stop(acpibase)			{}
> -#define iTCO_vendor_check_noreboot_on()			1
> -				/* 1=check noreboot; 0=don't check */
> -#endif
> diff --git a/drivers/watchdog/iTCO_vendor_support.c b/drivers/watchdog/iTCO_vendor_support.c
> deleted file mode 100644
> index cf0eaa04b064..000000000000
> --- a/drivers/watchdog/iTCO_vendor_support.c
> +++ /dev/null
> @@ -1,216 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0+
> -/*
> - *	intel TCO vendor specific watchdog driver support
> - *
> - *	(c) Copyright 2006-2009 Wim Van Sebroeck <wim@iguana.be>.
> - *
> - *	Neither Wim Van Sebroeck nor Iguana vzw. admit liability nor
> - *	provide warranty for any of this software. This material is
> - *	provided "AS-IS" and at no charge.
> - */
> -
> -/*
> - *	Includes, defines, variables, module parameters, ...
> - */
> -
> -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> -
> -/* Module and version information */
> -#define DRV_NAME	"iTCO_vendor_support"
> -#define DRV_VERSION	"1.04"
> -
> -/* Includes */
> -#include <linux/module.h>		/* For module specific items */
> -#include <linux/moduleparam.h>		/* For new moduleparam's */
> -#include <linux/types.h>		/* For standard types (like size_t) */
> -#include <linux/errno.h>		/* For the -ENODEV/... values */
> -#include <linux/kernel.h>		/* For printk/panic/... */
> -#include <linux/init.h>			/* For __init/__exit/... */
> -#include <linux/ioport.h>		/* For io-port access */
> -#include <linux/io.h>			/* For inb/outb/... */
> -
> -#include "iTCO_vendor.h"
> -
> -/* List of vendor support modes */
> -/* SuperMicro Pentium 3 Era 370SSE+-OEM1/P3TSSE */
> -#define SUPERMICRO_OLD_BOARD	1
> -/* SuperMicro Pentium 4 / Xeon 4 / EMT64T Era Systems - no longer supported */
> -#define SUPERMICRO_NEW_BOARD	2
> -/* Broken BIOS */
> -#define BROKEN_BIOS		911
> -
> -int iTCO_vendorsupport;
> -EXPORT_SYMBOL(iTCO_vendorsupport);
> -
> -module_param_named(vendorsupport, iTCO_vendorsupport, int, 0);
> -MODULE_PARM_DESC(vendorsupport, "iTCO vendor specific support mode, default="
> -			"0 (none), 1=SuperMicro Pent3, 911=Broken SMI BIOS");
> -
> -/*
> - *	Vendor Specific Support
> - */
> -
> -/*
> - *	Vendor Support: 1
> - *	Board: Super Micro Computer Inc. 370SSE+-OEM1/P3TSSE
> - *	iTCO chipset: ICH2
> - *
> - *	Code contributed by: R. Seretny <lkpatches@paypc.com>
> - *	Documentation obtained by R. Seretny from SuperMicro Technical Support
> - *
> - *	To enable Watchdog function:
> - *	    BIOS setup -> Power -> TCO Logic SMI Enable -> Within5Minutes
> - *	    This setting enables SMI to clear the watchdog expired flag.
> - *	    If BIOS or CPU fail which may cause SMI hang, then system will
> - *	    reboot. When application starts to use watchdog function,
> - *	    application has to take over the control from SMI.
> - *
> - *	    For P3TSSE, J36 jumper needs to be removed to enable the Watchdog
> - *	    function.
> - *
> - *	    Note: The system will reboot when Expire Flag is set TWICE.
> - *	    So, if the watchdog timer is 20 seconds, then the maximum hang
> - *	    time is about 40 seconds, and the minimum hang time is about
> - *	    20.6 seconds.
> - */
> -
> -static void supermicro_old_pre_start(struct resource *smires)
> -{
> -	unsigned long val32;
> -
> -	/* Bit 13: TCO_EN -> 0 = Disables TCO logic generating an SMI# */
> -	val32 = inl(smires->start);
> -	val32 &= 0xffffdfff;	/* Turn off SMI clearing watchdog */
> -	outl(val32, smires->start);	/* Needed to activate watchdog */
> -}
> -
> -static void supermicro_old_pre_stop(struct resource *smires)
> -{
> -	unsigned long val32;
> -
> -	/* Bit 13: TCO_EN -> 1 = Enables the TCO logic to generate SMI# */
> -	val32 = inl(smires->start);
> -	val32 |= 0x00002000;	/* Turn on SMI clearing watchdog */
> -	outl(val32, smires->start);	/* Needed to deactivate watchdog */
> -}
> -
> -/*
> - *	Vendor Support: 911
> - *	Board: Some Intel ICHx based motherboards
> - *	iTCO chipset: ICH7+
> - *
> - *	Some Intel motherboards have a broken BIOS implementation: i.e.
> - *	the SMI handler clear's the TIMEOUT bit in the TC01_STS register
> - *	and does not reload the time. Thus the TCO watchdog does not reboot
> - *	the system.
> - *
> - *	These are the conclusions of Andriy Gapon <avg@icyb.net.ua> after
> - *	debugging: the SMI handler is quite simple - it tests value in
> - *	TCO1_CNT against 0x800, i.e. checks TCO_TMR_HLT. If the bit is set
> - *	the handler goes into an infinite loop, apparently to allow the
> - *	second timeout and reboot. Otherwise it simply clears TIMEOUT bit
> - *	in TCO1_STS and that's it.
> - *	So the logic seems to be reversed, because it is hard to see how
> - *	TIMEOUT can get set to 1 and SMI generated when TCO_TMR_HLT is set
> - *	(other than a transitional effect).
> - *
> - *	The only fix found to get the motherboard(s) to reboot is to put
> - *	the glb_smi_en bit to 0. This is a dirty hack that bypasses the
> - *	broken code by disabling Global SMI.
> - *
> - *	WARNING: globally disabling SMI could possibly lead to dramatic
> - *	problems, especially on laptops! I.e. various ACPI things where
> - *	SMI is used for communication between OS and firmware.
> - *
> - *	Don't use this fix if you don't need to!!!
> - */
> -
> -static void broken_bios_start(struct resource *smires)
> -{
> -	unsigned long val32;
> -
> -	val32 = inl(smires->start);
> -	/* Bit 13: TCO_EN     -> 0 = Disables TCO logic generating an SMI#
> -	   Bit  0: GBL_SMI_EN -> 0 = No SMI# will be generated by ICH. */
> -	val32 &= 0xffffdffe;
> -	outl(val32, smires->start);
> -}
> -
> -static void broken_bios_stop(struct resource *smires)
> -{
> -	unsigned long val32;
> -
> -	val32 = inl(smires->start);
> -	/* Bit 13: TCO_EN     -> 1 = Enables TCO logic generating an SMI#
> -	   Bit  0: GBL_SMI_EN -> 1 = Turn global SMI on again. */
> -	val32 |= 0x00002001;
> -	outl(val32, smires->start);
> -}
> -
> -/*
> - *	Generic Support Functions
> - */
> -
> -void iTCO_vendor_pre_start(struct resource *smires,
> -			   unsigned int heartbeat)
> -{
> -	switch (iTCO_vendorsupport) {
> -	case SUPERMICRO_OLD_BOARD:
> -		supermicro_old_pre_start(smires);
> -		break;
> -	case BROKEN_BIOS:
> -		broken_bios_start(smires);
> -		break;
> -	}
> -}
> -EXPORT_SYMBOL(iTCO_vendor_pre_start);
> -
> -void iTCO_vendor_pre_stop(struct resource *smires)
> -{
> -	switch (iTCO_vendorsupport) {
> -	case SUPERMICRO_OLD_BOARD:
> -		supermicro_old_pre_stop(smires);
> -		break;
> -	case BROKEN_BIOS:
> -		broken_bios_stop(smires);
> -		break;
> -	}
> -}
> -EXPORT_SYMBOL(iTCO_vendor_pre_stop);
> -
> -int iTCO_vendor_check_noreboot_on(void)
> -{
> -	switch (iTCO_vendorsupport) {
> -	case SUPERMICRO_OLD_BOARD:
> -		return 0;
> -	default:
> -		return 1;
> -	}
> -}
> -EXPORT_SYMBOL(iTCO_vendor_check_noreboot_on);
> -
> -static int __init iTCO_vendor_init_module(void)
> -{
> -	if (iTCO_vendorsupport == SUPERMICRO_NEW_BOARD) {
> -		pr_warn("Option vendorsupport=%d is no longer supported, "
> -			"please use the w83627hf_wdt driver instead\n",
> -			SUPERMICRO_NEW_BOARD);
> -		return -EINVAL;
> -	}
> -	pr_info("vendor-support=%d\n", iTCO_vendorsupport);
> -	return 0;
> -}
> -
> -static void __exit iTCO_vendor_exit_module(void)
> -{
> -	pr_info("Module Unloaded\n");
> -}
> -
> -module_init(iTCO_vendor_init_module);
> -module_exit(iTCO_vendor_exit_module);
> -
> -MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>, "
> -		"R. Seretny <lkpatches@paypc.com>");
> -MODULE_DESCRIPTION("Intel TCO Vendor Specific WatchDog Timer Driver Support");
> -MODULE_VERSION(DRV_VERSION);
> -MODULE_LICENSE("GPL");
> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
> index ced2fc0deb8c..fc0ed665f7db 100644
> --- a/drivers/watchdog/iTCO_wdt.c
> +++ b/drivers/watchdog/iTCO_wdt.c
> @@ -64,8 +64,6 @@
>   #include <linux/platform_data/itco_wdt.h>
>   #include <linux/mfd/intel_pmc_bxt.h>
>   
> -#include "iTCO_vendor.h"
> -
>   /* Address definitions for the TCO */
>   /* TCO base address */
>   #define TCOBASE(p)	((p)->tco_res->start)
> @@ -272,8 +270,6 @@ static int iTCO_wdt_start(struct watchdog_device *wd_dev)
>   
>   	spin_lock(&p->io_lock);
>   
> -	iTCO_vendor_pre_start(p->smi_res, wd_dev->timeout);
> -
>   	/* disable chipset's NO_REBOOT bit */
>   	if (p->update_no_reboot_bit(p->no_reboot_priv, false)) {
>   		spin_unlock(&p->io_lock);
> @@ -307,8 +303,6 @@ static int iTCO_wdt_stop(struct watchdog_device *wd_dev)
>   
>   	spin_lock(&p->io_lock);
>   
> -	iTCO_vendor_pre_stop(p->smi_res);
> -
>   	/* Bit 11: TCO Timer Halt -> 1 = The TCO timer is disabled */
>   	val = inw(TCO1_CNT(p));
>   	val |= 0x0800;
> @@ -483,10 +477,6 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
>   			       (u64)SMI_EN(p));
>   			return -EBUSY;
>   		}
> -	} else if (iTCO_vendorsupport ||
> -		   turn_SMI_watchdog_clear_off >= p->iTCO_version) {
> -		dev_err(dev, "SMI I/O resource is missing\n");
> -		return -ENODEV;
>   	}
>   
>   	iTCO_wdt_no_reboot_bit_setup(p, pdev, pdata);
> @@ -505,13 +495,6 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
>   			return PTR_ERR(p->gcs_pmc);
>   	}
>   
> -	/* Check chipset's NO_REBOOT bit */
> -	if (p->update_no_reboot_bit(p->no_reboot_priv, false) &&
> -	    iTCO_vendor_check_noreboot_on()) {
> -		dev_info(dev, "unable to reset NO_REBOOT flag, device disabled by hardware/BIOS\n");
> -		return -ENODEV;	/* Cannot reset NO_REBOOT bit */
> -	}
> -
>   	/* Set the NO_REBOOT bit to prevent later reboots, just for sure */
>   	p->update_no_reboot_bit(p->no_reboot_priv, true);
>   
>