RE: [EXT] Re: [PATCH 2/2] Watchdog: octeontx2: Add Pseudo-NMI GTI watchdog driver

[Bharat Bhushan]

Please see inline

> -----Original Message-----
> From: Guenter Roeck <groeck7@xxxxxxxxx> On Behalf Of Guenter Roeck
> Sent: Saturday, March 25, 2023 3:33 AM
> To: Bharat Bhushan <bbhushan2@xxxxxxxxxxx>
> Cc: wim@xxxxxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx;
> krzysztof.kozlowski+dt@xxxxxxxxxx; linux-watchdog@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: [EXT] Re: [PATCH 2/2] Watchdog: octeontx2: Add Pseudo-NMI GTI
> watchdog driver
> 
> External Email
> 
> ----------------------------------------------------------------------
> On Fri, Mar 24, 2023 at 08:26:52PM +0530, Bharat Bhushan wrote:
> > GTI hardware supports per-core watchdog timer which are programmed in
> > "interrupt + del3t + reset mode" and del3t traps are not enabled.
> > This driver uses ARM64 pseudo-nmi interrupt support.
> > GTI watchdog exception flow is:
> >  - 1st timer expiration generates pseudo-nmi interrupt.
> >    NMI exception handler dumps register/context state on all cpu's.
> >  - 2nd timer expiration is ignored
> >
> >  - On 3rd timer expiration will trigger a system-wide core reset.
> >
> > Signed-off-by: Bharat Bhushan <bbhushan2@xxxxxxxxxxx>
> > ---
> >  drivers/watchdog/Kconfig                  |   9 +
> >  drivers/watchdog/Makefile                 |   1 +
> >  drivers/watchdog/octeontx2_gti_watchdog.c | 352
> > ++++++++++++++++++++++
> >  3 files changed, 362 insertions(+)
> >  create mode 100644 drivers/watchdog/octeontx2_gti_watchdog.c
> >
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index
> > f0872970daf9..9607d36645f6 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -2212,4 +2212,13 @@ config KEEMBAY_WATCHDOG
> >  	  To compile this driver as a module, choose M here: the
> >  	  module will be called keembay_wdt.
> >
> > +config OCTEON_GTI_WATCHDOG
> > +	tristate "OCTEONTX2 GTI Watchdog driver"
> > +	depends on ARM64
> > +	help
> > +	 OCTEONTX2 GTI hardware supports per-core watchdog timer which
> > +	 are programmed in "interrupt + del3t + reset mode" and del3t
> > +	 traps are not enabled.
> > +	 This driver uses ARM64 pseudo-nmi interrupt support.
> > +
> >  endif # WATCHDOG
> > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> > index 9cbf6580f16c..11af3db62fec 100644
> > --- a/drivers/watchdog/Makefile
> > +++ b/drivers/watchdog/Makefile
> > @@ -230,3 +230,4 @@ obj-$(CONFIG_MENZ069_WATCHDOG) +=
> menz69_wdt.o
> >  obj-$(CONFIG_RAVE_SP_WATCHDOG) += rave-sp-wdt.o
> >  obj-$(CONFIG_STPMIC1_WATCHDOG) += stpmic1_wdt.o
> >  obj-$(CONFIG_SL28CPLD_WATCHDOG) += sl28cpld_wdt.o
> > +obj-$(CONFIG_OCTEON_GTI_WATCHDOG) += octeontx2_gti_watchdog.o
> > diff --git a/drivers/watchdog/octeontx2_gti_watchdog.c
> > b/drivers/watchdog/octeontx2_gti_watchdog.c
> > new file mode 100644
> > index 000000000000..766b7d41defe
> > --- /dev/null
> > +++ b/drivers/watchdog/octeontx2_gti_watchdog.c
> > @@ -0,0 +1,352 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Marvell GTI Watchdog driver
> > + *
> > + * Copyright (C) 2023 Marvell International Ltd.
> > + *
> > + * This program is free software; you can redistribute it and/or
> > +modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/cpu.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/watchdog.h>
> > +#include <linux/sched/debug.h>
> > +
> > +#include <asm/arch_timer.h>
> > +
> > +/* GTI CWD Watchdog Registers */
> > +#define GTI_CWD_WDOG(cpu)		(0x8 * cpu)
> > +#define GTI_CWD_WDOG_MODE_INT_DEL3T_RST	(0x3)
> > +#define GTI_CWD_WDOG_MODE_MASK		(0x3)
> > +#define GTI_CWD_WDOG_LEN_SHIFT		(4)
> > +#define GTI_CWD_WDOG_CNT_SHIFT		(20)
> > +
> > +/* GTI Per-core Watchdog Interrupt Register */
> > +#define GTI_CWD_INT			0x200
> > +
> > +/* GTI Per-core Watchdog Interrupt Enable Clear Register */
> > +#define GTI_CWD_INT_ENA_CLR		0x210
> > +
> > +/* GTI Per-core Watchdog Interrupt Enable Set Register */
> > +#define GTI_CWD_INT_ENA_SET		0x218
> > +
> > +/* GTI Per-core Watchdog Poke Registers */
> > +#define GTI_CWD_POKE(cpu)		(0x10000 + 0x8 * cpu)
> > +
> > +struct octeontx2_gti_wdt_percpu_priv {
> > +	struct watchdog_device wdev;
> > +	int irq;
> > +};
> > +
> > +struct octeontx2_gti_wdt_priv {
> > +	void __iomem *base;
> > +	u64 clock_freq;
> > +	int is_nmi;
> > +	struct octeontx2_gti_wdt_percpu_priv __percpu *percpu_priv; };
> > +
> > +static int octeontx2_gti_wdt_get_cpuid(struct watchdog_device *wdev)
> > +{
> > +	struct octeontx2_gti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +	struct octeontx2_gti_wdt_percpu_priv *percpu_priv;
> > +	int cpu;
> > +
> > +	for_each_online_cpu(cpu) {
> > +		percpu_priv = per_cpu_ptr(priv->percpu_priv, cpu);
> > +		if (&percpu_priv->wdev == wdev)
> > +			return cpu;
> > +	}
> > +
> > +	return -1;
> > +}
> > +
> > +void octeontx2_gti_wdt_callback_other_cpus(void *unused) {
> > +	struct pt_regs *regs = get_irq_regs();
> > +
> > +	pr_emerg("GTI Watchdog CPU:%d\n", raw_smp_processor_id());
> > +
> > +	if (regs)
> > +		show_regs(regs);
> > +	else
> > +		dump_stack();
> > +}
> > +
> > +static irqreturn_t octeontx2_gti_wdt_interrupt(int irq, void *data) {
> > +	struct octeontx2_gti_wdt_priv *priv = (struct octeontx2_gti_wdt_priv
> *)data;
> > +	int cpu = smp_processor_id();
> > +
> > +	/* Clear interrupt to fire again if delayed poke happens */
> > +	writeq(1 << cpu, priv->base + GTI_CWD_INT);
> > +	dump_stack();
> > +
> > +	for_each_online_cpu(cpu) {
> > +		if (cpu == raw_smp_processor_id())
> > +			continue;
> > +
> > +		smp_call_function_single(cpu,
> > +
> octeontx2_gti_wdt_callback_other_cpus,
> > +					 NULL, 1);
> > +	}
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int octeontx2_gti_wdt_ping(struct watchdog_device *wdev) {
> > +	struct octeontx2_gti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +	int cpu = octeontx2_gti_wdt_get_cpuid(wdev);
> > +
> > +	if (cpu < 0)
> > +		return -EINVAL;
> > +
> > +	writeq(1, priv->base + GTI_CWD_POKE(cpu));
> > +	return 0;
> > +}
> > +
> > +static int octeontx2_gti_wdt_start(struct watchdog_device *wdev) {
> > +	struct octeontx2_gti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +	int cpu = octeontx2_gti_wdt_get_cpuid(wdev);
> > +	u64 regval;
> > +
> > +	if (cpu < 0)
> > +		return -EINVAL;
> > +
> > +	set_bit(WDOG_HW_RUNNING, &wdev->status);
> > +
> > +	/* Clear any pending interrupt */
> > +	writeq(1 << cpu, priv->base + GTI_CWD_INT);
> > +
> > +	/* Enable Interrupt */
> > +	writeq(1 << cpu, priv->base + GTI_CWD_INT_ENA_SET);
> > +
> > +	/* Set (Interrupt + SCP interrupt (DEL3T) + core domain reset) Mode */
> > +	regval = readq(priv->base + GTI_CWD_WDOG(cpu));
> > +	regval |= GTI_CWD_WDOG_MODE_INT_DEL3T_RST;
> > +	writeq(regval, priv->base + GTI_CWD_WDOG(cpu));
> > +
> > +	return 0;
> > +}
> > +
> > +static int octeontx2_gti_wdt_stop(struct watchdog_device *wdev) {
> > +	struct octeontx2_gti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +	u64 regval;
> > +	int cpu = octeontx2_gti_wdt_get_cpuid(wdev);
> > +
> > +	if (cpu < 0)
> > +		return -EINVAL;
> > +
> > +	/* Disable Interrupt */
> > +	writeq(1 << cpu, priv->base + GTI_CWD_INT_ENA_CLR);
> > +
> > +	/* Set GTI_CWD_WDOG.Mode = 0 to stop the timer */
> > +	regval = readq(priv->base + GTI_CWD_WDOG(cpu));
> > +	regval &= ~GTI_CWD_WDOG_MODE_MASK;
> > +	writeq(regval, priv->base + GTI_CWD_WDOG(cpu));
> > +
> > +	return 0;
> > +}
> > +
> > +static int octeontx2_gti_wdt_settimeout(struct watchdog_device *wdev,
> > +					unsigned int timeout)
> > +{
> > +	struct octeontx2_gti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +	int cpu = octeontx2_gti_wdt_get_cpuid(wdev);
> > +	u64 timeout_wdog, regval;
> > +
> > +	if (cpu < 0)
> > +		return -EINVAL;
> > +
> > +	/* Update new timeout */
> > +	wdev->timeout = timeout;
> > +
> > +	/* Get clock cycles from timeout in second */
> > +	timeout_wdog = (u64)timeout * priv->clock_freq;
> > +
> > +	/* Watchdog counts in 1024 cycle steps */
> > +	timeout_wdog = timeout_wdog >> 10;
> > +
> > +	/*
> > +	 * Hardware allows programming of upper 16-bits of 24-bits cycles
> > +	 * Round up and use upper 16-bits only.
> > +	 * Set max if timeout more than h/w supported
> > +	 */
> > +	timeout_wdog = (timeout_wdog + 0xff) >> 8;
> > +	if (timeout_wdog >= 0x10000)
> > +		timeout_wdog = 0xffff;
> > +
> > +	/*
> > +	 * GTI_CWD_WDOG.LEN have only upper 16-bits of 24-bits
> > +	 * GTI_CWD_WDOG.CNT, need addition shift of 8.
> > +	 */
> > +	regval = readq(priv->base + GTI_CWD_WDOG(cpu));
> > +	regval &= GTI_CWD_WDOG_MODE_MASK;
> > +	regval |= ((timeout_wdog) << (GTI_CWD_WDOG_CNT_SHIFT + 8)) |
> > +		   (timeout_wdog << GTI_CWD_WDOG_LEN_SHIFT);
> > +	writeq(regval, priv->base + GTI_CWD_WDOG(cpu));
> > +	return 0;
> > +}
> > +
> > +static const struct watchdog_info octeontx2_gti_wdt_ident = {
> > +	.identity = "OcteonTX2 GTI watchdog",
> > +	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
> WDIOF_MAGICCLOSE |
> > +			  WDIOF_CARDRESET,
> > +};
> > +
> > +static const struct watchdog_ops octeontx2_gti_wdt_ops = {
> > +	.owner = THIS_MODULE,
> > +	.start = octeontx2_gti_wdt_start,
> > +	.stop = octeontx2_gti_wdt_stop,
> > +	.ping = octeontx2_gti_wdt_ping,
> > +	.set_timeout = octeontx2_gti_wdt_settimeout, };
> > +
> > +static void octeontx2_gti_wdt_free_irqs(struct octeontx2_gti_wdt_priv
> > +*priv) {
> > +	struct octeontx2_gti_wdt_percpu_priv *percpu_priv;
> > +	int irq, cpu = 0;
> > +
> > +	for_each_online_cpu(cpu) {
> > +		percpu_priv = per_cpu_ptr(priv->percpu_priv, cpu);
> > +		irq = percpu_priv->irq;
> > +		if (irq) {
> > +			if (priv->is_nmi) {
> > +				disable_nmi_nosync(irq);
> > +				free_nmi(irq, priv);
> > +			} else {
> > +				disable_irq_nosync(irq);
> > +				free_irq(irq, priv);
> > +			}
> > +
> > +			percpu_priv->irq = 0;
> > +		}
> > +	}
> > +}
> > +
> > +static int octeontx2_gti_wdt_probe(struct platform_device *pdev) {
> > +	struct octeontx2_gti_wdt_percpu_priv *percpu_priv;
> > +	struct octeontx2_gti_wdt_priv *priv;
> > +	struct device *dev = &pdev->dev;
> > +	struct watchdog_device *wdog_dev;
> > +	unsigned long irq_flags;
> > +	int irq, cpu, num_irqs;
> > +	int err;
> > +
> > +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> > +	if (!priv)
> > +		return -ENOMEM;
> > +
> > +	priv->percpu_priv = devm_alloc_percpu(&pdev->dev, *priv-
> >percpu_priv);
> > +	if (!priv->percpu_priv)
> > +		return -ENOMEM;
> > +
> > +	priv->base = devm_platform_ioremap_resource(pdev, 0);
> > +	if (IS_ERR(priv->base))
> > +		return dev_err_probe(&pdev->dev, PTR_ERR(priv->base),
> > +			      "reg property not valid/found\n");
> > +
> > +	num_irqs = platform_irq_count(pdev);
> > +	if (num_irqs < 0)
> > +		return dev_err_probe(dev, num_irqs, "GTI CWD no IRQs\n");
> > +
> > +	if (num_irqs < num_online_cpus())
> > +		return dev_err_probe(dev, -EINVAL, "IRQs (%d) < CPUs (%d)\n",
> > +				     num_irqs, num_online_cpus());
> > +
> > +	priv->clock_freq = arch_timer_get_cntfrq();
> > +
> > +	for_each_online_cpu(cpu) {
> 
> Watchdogs are supposed to be per system, not per CPU. The Linux kernel has
> other means to detect hung CPUs, and the watchdog subsystem should be
> (ab)used to bypass or replace those methods.

Sorry for late reply, just returned from vacation.

Okay, will remove the per core watchdog and submit next patch for global watchdog.

Thanks
-Bharat

> 
> I am not inclined to accept this patch.
> 
> Guenter
> 
> > +		percpu_priv = per_cpu_ptr(priv->percpu_priv, cpu);
> > +		wdog_dev = &percpu_priv->wdev;
> > +		wdog_dev->info = &octeontx2_gti_wdt_ident,
> > +		wdog_dev->ops = &octeontx2_gti_wdt_ops,
> > +		wdog_dev->parent = dev;
> > +		wdog_dev->min_timeout = 1;
> > +		wdog_dev->max_timeout = 16;
> > +		wdog_dev->max_hw_heartbeat_ms = 16000;
> > +		wdog_dev->timeout = 8;
> > +
> > +		irq = platform_get_irq(pdev, cpu);
> > +		if (irq < 0) {
> > +			dev_err(&pdev->dev, "IRQ resource not found\n");
> > +			err = -ENODEV;
> > +			goto out;
> > +		}
> > +
> > +		err = irq_force_affinity(irq, cpumask_of(cpu));
> > +		if (err) {
> > +			pr_warn("unable to set irq affinity (irq=%d, cpu=%u)\n",
> irq, cpu);
> > +			goto out;
> > +		}
> > +
> > +		irq_flags = IRQF_PERCPU | IRQF_NOBALANCING |
> IRQF_NO_AUTOEN |
> > +			    IRQF_NO_THREAD;
> > +		err = request_nmi(irq, octeontx2_gti_wdt_interrupt, irq_flags,
> > +				  pdev->name, priv);
> > +		if (err) {
> > +			err = request_irq(irq, octeontx2_gti_wdt_interrupt,
> irq_flags,
> > +					  pdev->name, priv);
> > +			if (err) {
> > +				dev_err(dev, "cannot register interrupt handler
> %d\n", err);
> > +				goto out;
> > +			}
> > +			enable_irq(irq);
> > +		} else {
> > +			priv->is_nmi = 1;
> > +			enable_nmi(irq);
> > +		}
> > +
> > +		percpu_priv->irq = irq;
> > +		watchdog_set_drvdata(wdog_dev, priv);
> > +		platform_set_drvdata(pdev, priv);
> > +		watchdog_init_timeout(wdog_dev, wdog_dev->timeout, dev);
> > +		octeontx2_gti_wdt_settimeout(wdog_dev, wdog_dev-
> >timeout);
> > +		watchdog_stop_on_reboot(wdog_dev);
> > +		watchdog_stop_on_unregister(wdog_dev);
> > +
> > +		err = devm_watchdog_register_device(dev, wdog_dev);
> > +		if (unlikely(err))
> > +			goto out;
> > +		dev_info(dev, "Watchdog enabled (timeout=%d sec)",
> wdog_dev->timeout);
> > +	}
> > +	return 0;
> > +
> > +out:
> > +	octeontx2_gti_wdt_free_irqs(priv);
> > +	return err;
> > +}
> > +
> > +static int octeontx2_gti_wdt_remove(struct platform_device *pdev) {
> > +	struct octeontx2_gti_wdt_priv *priv = platform_get_drvdata(pdev);
> > +
> > +	octeontx2_gti_wdt_free_irqs(priv);
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id octeontx2_gti_wdt_of_match[] = {
> > +	{ .compatible = "mrvl,octeontx2-gti-wdt", },
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, octeontx2_gti_wdt_of_match);
> > +
> > +static struct platform_driver octeontx2_gti_wdt_driver = {
> > +	.driver = {
> > +		.name = "octeontx2-gti-wdt",
> > +		.of_match_table = octeontx2_gti_wdt_of_match,
> > +	},
> > +	.probe = octeontx2_gti_wdt_probe,
> > +	.remove = octeontx2_gti_wdt_remove,
> > +};
> > +module_platform_driver(octeontx2_gti_wdt_driver);
> > +
> > +MODULE_AUTHOR("Bharat Bhushan <bbhushan2@xxxxxxxxxxx>");
> > +MODULE_DESCRIPTION("OcteonTX2 GTI per cpu watchdog driver");
> > --
> > 2.17.1
> >