Message-ID: <832d7830-be98-243c-ebf7-c23ae51e4ccc@linaro.org>
Date:   Fri, 14 Apr 2023 13:27:46 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Bharat Bhushan <bbhushan2@...vell.com>, wim@...ux-watchdog.org,
        linux@...ck-us.net, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-watchdog@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] Watchdog: Add octeontx2 GTI watchdog driver

On 14/04/2023 12:23, Bharat Bhushan wrote:
> GTI watchdog timer are programmed in "interrupt + del3t + reset mode"
> and del3t traps are not enabled.
> GTI watchdog exception flow is:
>  - 1st timer expiration generates watchdog interrupt.
>  - 2nd timer expiration is ignored
>  - On 3rd timer expiration will trigger a system-wide core reset.
> 
> Signed-off-by: Bharat Bhushan <bbhushan2@...vell.com>
> ---
>  drivers/watchdog/Kconfig         |   9 ++
>  drivers/watchdog/Makefile        |   1 +
>  drivers/watchdog/octeontx2_wdt.c | 238 +++++++++++++++++++++++++++++++
>  3 files changed, 248 insertions(+)
>  create mode 100644 drivers/watchdog/octeontx2_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index f0872970daf9..31ff282c62ad 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 OCTEONTX2_WATCHDOG
> +	tristate "OCTEONTX2 Watchdog driver"
> +	depends on ARCH_THUNDER || (COMPILE_TEST && 64BIT)

Why it cannot be compile tested on 32-bit?

> +	help
> +	 OCTEONTX2 GTI hardware supports watchdog timer. This watchdog timer are
> +	 programmed in "interrupt + del3t + reset" mode. On first expiry it will
> +	 generate interrupt. Second expiry (del3t) is ignored and system will reset
> +	 on final timer expiry.
> +
>  endif # WATCHDOG
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 9cbf6580f16c..aa1b813ad1f9 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_OCTEONTX2_WATCHDOG) += octeontx2_wdt.o

Please tell me that you added it in some reasonable place, not just at
the end... The same in Kconfig.

> diff --git a/drivers/watchdog/octeontx2_wdt.c b/drivers/watchdog/octeontx2_wdt.c
> new file mode 100644
> index 000000000000..7b78a092e83f
> --- /dev/null
> +++ b/drivers/watchdog/octeontx2_wdt.c
> @@ -0,0 +1,238 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Marvell Octeontx2 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.

Drop boilerplate.

> + */
> +
> +#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_GLOBAL_WDOG_IDX		63
> +#define GTI_CWD_WDOG			(0x8 * GTI_CWD_GLOBAL_WDOG_IDX)
> +#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
> +#define GTI_CWD_INT_PENDING_STATUS	(1ULL << GTI_CWD_GLOBAL_WDOG_IDX)
> +
> +/* GTI Per-core Watchdog Interrupt Enable Clear Register */
> +#define GTI_CWD_INT_ENA_CLR		0x210
> +#define GTI_CWD_INT_ENA_CLR_VAL		(1ULL << GTI_CWD_GLOBAL_WDOG_IDX)
> +
> +/* GTI Per-core Watchdog Interrupt Enable Set Register */
> +#define GTI_CWD_INT_ENA_SET		0x218
> +#define GTI_CWD_INT_ENA_SET_VAL		(1ULL << GTI_CWD_GLOBAL_WDOG_IDX)
> +
> +/* GTI Per-core Watchdog Poke Registers */
> +#define GTI_CWD_POKE		(0x10000 + 0x8 * GTI_CWD_GLOBAL_WDOG_IDX)
> +#define GTI_CWD_POKE_VAL	(1ULL << GTI_CWD_GLOBAL_WDOG_IDX)
> +
> +struct octeontx2_wdt_priv {
> +	struct watchdog_device wdev;
> +	void __iomem *base;
> +	u64 clock_freq;
> +	int irq;
> +};
> +
> +static irqreturn_t octeontx2_wdt_interrupt(int irq, void *data)
> +{
> +	panic("Kernel Watchdog");
> +	return IRQ_HANDLED;
> +}
> +
> +static int octeontx2_wdt_ping(struct watchdog_device *wdev)
> +{
> +	struct octeontx2_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +	writeq(GTI_CWD_POKE_VAL, priv->base + GTI_CWD_POKE);
> +	return 0;
> +}
> +
> +static int octeontx2_wdt_start(struct watchdog_device *wdev)
> +{
> +	struct octeontx2_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +	u64 regval;
> +
> +	set_bit(WDOG_HW_RUNNING, &wdev->status);
> +
> +	/* Clear any pending interrupt */
> +	writeq(GTI_CWD_INT_PENDING_STATUS, priv->base + GTI_CWD_INT);
> +
> +	/* Enable Interrupt */
> +	writeq(GTI_CWD_INT_ENA_SET_VAL, priv->base + GTI_CWD_INT_ENA_SET);
> +
> +	/* Set (Interrupt + SCP interrupt (DEL3T) + core domain reset) Mode */
> +	regval = readq(priv->base + GTI_CWD_WDOG);
> +	regval |= GTI_CWD_WDOG_MODE_INT_DEL3T_RST;
> +	writeq(regval, priv->base + GTI_CWD_WDOG);
> +
> +	return 0;
> +}
> +
> +static int octeontx2_wdt_stop(struct watchdog_device *wdev)
> +{
> +	struct octeontx2_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +	u64 regval;
> +
> +	/* Disable Interrupt */
> +	writeq(GTI_CWD_INT_ENA_CLR_VAL, priv->base + GTI_CWD_INT_ENA_CLR);
> +
> +	/* Set GTI_CWD_WDOG.Mode = 0 to stop the timer */
> +	regval = readq(priv->base + GTI_CWD_WDOG);
> +	regval &= ~GTI_CWD_WDOG_MODE_MASK;
> +	writeq(regval, priv->base + GTI_CWD_WDOG);
> +
> +	return 0;
> +}
> +
> +static int octeontx2_wdt_settimeout(struct watchdog_device *wdev,
> +					unsigned int timeout)
> +{
> +	struct octeontx2_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +	u64 timeout_wdog, regval;
> +
> +	/* 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);
> +	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);
> +	return 0;
> +}
> +
> +static const struct watchdog_info octeontx2_wdt_ident = {
> +	.identity = "OcteonTX2 watchdog",
> +	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE |
> +			  WDIOF_CARDRESET,

Weird indentation in =

> +};
> +
> +static const struct watchdog_ops octeontx2_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = octeontx2_wdt_start,
> +	.stop = octeontx2_wdt_stop,
> +	.ping = octeontx2_wdt_ping,
> +	.set_timeout = octeontx2_wdt_settimeout,
> +};
> +
> +static int octeontx2_wdt_probe(struct platform_device *pdev)
> +{
> +	struct octeontx2_wdt_priv *priv;
> +	struct device *dev = &pdev->dev;
> +	struct watchdog_device *wdog_dev;
> +	int irq;
> +	int err;
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!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");
> +
> +	priv->clock_freq = arch_timer_get_cntfrq();
> +
> +	wdog_dev = &priv->wdev;
> +	wdog_dev->info = &octeontx2_wdt_ident,
> +	wdog_dev->ops = &octeontx2_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, 0);
> +	if (irq < 0) {
> +		dev_err(&pdev->dev, "IRQ resource not found\n");

return dev_err_probe
also in other places

> +		return -ENODEV;
> +	}
> +
> +	err = request_irq(irq, octeontx2_wdt_interrupt, 0, pdev->name, priv);
> +	if (err) {
> +		dev_err(dev, "cannot register interrupt handler %d\n", err);
> +		return err;
> +	}
> +
> +	priv->irq = irq;
> +	watchdog_set_drvdata(wdog_dev, priv);
> +	platform_set_drvdata(pdev, priv);
> +	watchdog_init_timeout(wdog_dev, wdog_dev->timeout, dev);
> +	octeontx2_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 (err) {
> +		free_irq(irq, priv);
> +		return err;
> +	}
> +
> +	dev_info(dev, "Watchdog enabled (timeout=%d sec)\n", wdog_dev->timeout);
> +	return 0;
> +}
> +
> +static int octeontx2_wdt_remove(struct platform_device *pdev)
> +{
> +	struct octeontx2_wdt_priv *priv = platform_get_drvdata(pdev);
> +
> +	if (priv->irq)

Is it possible?

> +		free_irq(priv->irq, priv);

Anyway, your order of cleanup is a bit surprising. It is expected to be
reversed from probe. In probe() you requested IRQs before watchdog, but
cleanup will be done before watchdog release? This does not look right.

> +
> +	return 0;
> +}
> +
> +static const struct of_device_id octeontx2_wdt_of_match[] = {
> +	{ .compatible = "marvell-octeontx2-wdt", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, octeontx2_wdt_of_match);

Best regards,
Krzysztof

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