Message-ID: <6dea4d95-17bc-66fc-590d-3f1351fbe363@wanadoo.fr>
Date:   Sun, 2 Jan 2022 17:14:42 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Guenter Roeck <linux@...ck-us.net>, Xiantao Hu <xt.hu@...lus1.com>
Cc:     wim@...ux-watchdog.org, p.zabel@...gutronix.de,
        linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
        robh+dt@...nel.org, devicetree@...r.kernel.org,
        wells.lu@...plus.com, qinjian@...lus1.com
Subject: Re: [PATCH v4 2/2] watchdog: Add watchdog driver for Sunplus SP7021

Le 02/01/2022 à 16:00, Guenter Roeck a écrit :
> On Wed, Dec 29, 2021 at 01:43:08PM +0800, Xiantao Hu wrote:
>> Sunplus SP7021 requires watchdog timer support.
>> Add watchdog driver to enable this.
>>
>> Signed-off-by: Xiantao Hu <xt.hu@...lus1.com>
>> ---
>> Changes in v4
>>   - Drop the unused varible struct resource *wdt_res.
>>   - Drop the operations related to address 0x9c000274.
>>     Put it in bootloader before entry kernel boot in v3.
>>
>>   MAINTAINERS                    |   1 +
>>   drivers/watchdog/Kconfig       |  11 ++
>>   drivers/watchdog/Makefile      |   1 +
>>   drivers/watchdog/sunplus_wdt.c | 278 +++++++++++++++++++++++++++++++++
>>   4 files changed, 291 insertions(+)
>>   create mode 100644 drivers/watchdog/sunplus_wdt.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index fe6cc971c..a1b3d76e2 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -18247,6 +18247,7 @@ M:	Xiantao Hu <xt.hu@...lus1.com>
>>   L:	linux-watchdog@...r.kernel.org
>>   S:	Maintained
>>   F:	Documentation/devicetree/bindings/watchdog/sunplus,sp7021-wdt.yaml
>> +F:	drivers/watchdog/sunplus_wdt.c
>>   
>>   SUPERH
>>   M:	Yoshinori Sato <ysato@...rs.sourceforge.jp>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index 9d222ba17..d3dbe8695 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -976,6 +976,17 @@ config MSC313E_WATCHDOG
>>   	  To compile this driver as a module, choose M here: the
>>   	  module will be called msc313e_wdt.
>>   
>> +config SUNPLUS_WATCHDOG
>> +	tristate "Sunplus watchdog support"
>> +	depends on ARCH_SUNPLUS || COMPILE_TEST
>> +	select WATCHDOG_CORE
>> +	help
>> +	  Say Y here to include support for the watchdog timer
>> +	  in Sunplus SoCs.
>> +
>> +	  To compile this driver as a module, choose M here: the
>> +	  module will be called sunplus_wdt.
>> +
>>   # X86 (i386 + ia64 + x86_64) Architecture
>>   
>>   config ACQUIRE_WDT
>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> index 2ee970641..0fa548ee6 100644
>> --- a/drivers/watchdog/Makefile
>> +++ b/drivers/watchdog/Makefile
>> @@ -93,6 +93,7 @@ obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o
>>   obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o
>>   obj-$(CONFIG_VISCONTI_WATCHDOG) += visconti_wdt.o
>>   obj-$(CONFIG_MSC313E_WATCHDOG) += msc313e_wdt.o
>> +obj-$(CONFIG_SUNPLUS_WATCHDOG) += sunplus_wdt.o
>>   
>>   # X86 (i386 + ia64 + x86_64) Architecture
>>   obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o
>> diff --git a/drivers/watchdog/sunplus_wdt.c b/drivers/watchdog/sunplus_wdt.c
>> new file mode 100644
>> index 000000000..9fae7a14b
>> --- /dev/null
>> +++ b/drivers/watchdog/sunplus_wdt.c
>> @@ -0,0 +1,278 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * sunplus Watchdog Driver
>> + *
>> + * Copyright (C) 2021 Sunplus Technology Co., Ltd.
>> + *
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reset.h>
>> +#include <linux/watchdog.h>
>> +
>> +#define WDT_CTRL                0x00
>> +#define WDT_CNT                 0x04
>> +
>> +#define WDT_STOP				0x3877
>> +#define WDT_RESUME				0x4A4B
>> +#define WDT_CLRIRQ				0x7482
>> +#define WDT_UNLOCK				0xAB00
>> +#define WDT_LOCK				0xAB01
>> +#define WDT_CONMAX				0xDEAF
>> +
>> +#define SP_WDT_MAX_TIMEOUT		11U
>> +#define SP_WDT_DEFAULT_TIMEOUT	10
>> +
>> +#define STC_CLK				90000
>> +
>> +#define DEVICE_NAME		"sunplus-wdt"
>> +
>> +static unsigned int timeout;
>> +module_param(timeout, int, 0);
>> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
>> +
>> +static bool nowayout = WATCHDOG_NOWAYOUT;
>> +module_param(nowayout, bool, 0);
>> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
>> +			__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>> +
>> +struct sp_wdt_priv {
>> +	struct watchdog_device wdev;
>> +	void __iomem *base;
>> +	struct clk *clk;
>> +	struct reset_control *rstc;
>> +};
>> +
>> +static int sp_wdt_restart(struct watchdog_device *wdev,
>> +			  unsigned long action, void *data)
>> +{
>> +	struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
>> +	void __iomem *base = priv->base;
>> +
>> +	writel(WDT_STOP, base + WDT_CTRL);
>> +	writel(WDT_UNLOCK, base + WDT_CTRL);
>> +	writel(0x0001, base + WDT_CNT);
>> +	writel(WDT_LOCK, base + WDT_CTRL);
>> +	writel(WDT_RESUME, base + WDT_CTRL);
>> +
>> +	return 0;
>> +}
>> +
>> +/* TIMEOUT_MAX = ffff0/90kHz =11.65,so longer than 11 seconds will time out */
>> +static int sp_wdt_ping(struct watchdog_device *wdev)
>> +{
>> +	struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
>> +	void __iomem *base = priv->base;
>> +	u32 count;
>> +	u32 actual;
>> +
>> +	actual = min(wdev->timeout, SP_WDT_MAX_TIMEOUT);
>> +
>> +	if (actual > SP_WDT_MAX_TIMEOUT) {
>> +		writel(WDT_CONMAX, base + WDT_CTRL);
>> +	} else {
>> +		writel(WDT_UNLOCK, base + WDT_CTRL);
>> +		/* tiemrw_cnt[3:0]can't be write,only [19:4] can be write. */
>> +		count = (actual * STC_CLK) >> 4;
>> +		writel(count, base + WDT_CNT);
>> +		writel(WDT_LOCK, base + WDT_CTRL);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int sp_wdt_set_timeout(struct watchdog_device *wdev,
>> +			      unsigned int timeout)
>> +{
>> +	wdev->timeout = timeout;
>> +	sp_wdt_ping(wdev);
> 
> This is exactly what the calling code does if there is no set_timeout
> function, so you can just drop this function,
> 
>> +
>> +	return 0;
>> +}
>> +
>> +static int sp_wdt_stop(struct watchdog_device *wdev)
>> +{
>> +	struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
>> +	void __iomem *base = priv->base;
>> +
>> +	writel(WDT_STOP, base + WDT_CTRL);
>> +
>> +	return 0;
>> +}
>> +
>> +static int sp_wdt_start(struct watchdog_device *wdev)
>> +{
>> +	struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
>> +	void __iomem *base = priv->base;
>> +
>> +	writel(WDT_RESUME, base + WDT_CTRL);
>> +
>> +	return 0;
>> +}
>> +
>> +static unsigned int sp_wdt_get_timeleft(struct watchdog_device *wdev)
>> +{
>> +	struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
>> +	void __iomem *base = priv->base;
>> +	u32 val;
>> +
>> +	val = readl(base + WDT_CNT);
>> +	val &= 0xffff;
>> +	val = val << 4;
>> +
>> +	return val;
>> +}
>> +
>> +static const struct watchdog_info sp_wdt_info = {
>> +	.identity	= DEVICE_NAME,
>> +	.options	= WDIOF_SETTIMEOUT |
>> +			  WDIOF_MAGICCLOSE |
>> +			  WDIOF_KEEPALIVEPING,
>> +};
>> +
>> +static const struct watchdog_ops sp_wdt_ops = {
>> +	.owner		= THIS_MODULE,
>> +	.start		= sp_wdt_start,
>> +	.stop		= sp_wdt_stop,
>> +	.ping		= sp_wdt_ping,
>> +	.set_timeout	= sp_wdt_set_timeout,
>> +	.get_timeleft	= sp_wdt_get_timeleft,
>> +	.restart	= sp_wdt_restart,
>> +};
>> +
>> +static void sp_clk_disable_unprepare(void *data)
>> +{
>> +	clk_disable_unprepare(data);
>> +}
>> +
>> +static void sp_reset_control_assert(void *data)
>> +{
>> +	reset_control_assert(data);
>> +}
>> +
>> +static int sp_wdt_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct sp_wdt_priv *priv;
>> +	int err;
>> +
>> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> +	if (!priv)
>> +		return -ENOMEM;
>> +
>> +	priv->clk = devm_clk_get(dev, NULL);
>> +	if (IS_ERR(priv->clk)) {
>> +		dev_err(dev, "Can't find clock source\n");
>> +		return PTR_ERR(priv->clk);
>> +	}
>> +
>> +	err = clk_prepare_enable(priv->clk);
>> +	if (err) {
>> +		dev_err(dev, "Clock can't be enabled correctly\n");
>> +		return err;
>> +	}
>> +
>> +	/* The timer and watchdog shared the STC reset */
>> +	priv->rstc = devm_reset_control_get_shared(dev, NULL);
>> +	if (!IS_ERR(priv->rstc))
>> +		reset_control_deassert(priv->rstc);
>> +
>> +	err = devm_add_action_or_reset(dev, sp_reset_control_assert,
>> +				       priv->rstc);
>> +	if (err)
>> +		return err;
>> +
> 
> devm_add_action_or_reset() above should only be called if
> devm_reset_control_get_shared succeeds.

I also think that the same "if (!IS_ERR(priv->rstc))" should be done in 
the suspend/resume function before calling reset_control_[de]assert()
Otherwise it will WARN.

CJ

> 
>> +	err = devm_add_action_or_reset(dev, sp_clk_disable_unprepare,
>> +				       priv->clk);
> 
> This should be called immediately after clk_prepare_enable().
> 
>> +	if (err)
>> +		return err;
>> +
>> +	priv->base = devm_platform_ioremap_resource(pdev, 0);
>> +	if (IS_ERR(priv->base))
>> +		return PTR_ERR(priv->base);
>> +
>> +	priv->wdev.info = &sp_wdt_info;
>> +	priv->wdev.ops = &sp_wdt_ops;
>> +	priv->wdev.timeout = SP_WDT_DEFAULT_TIMEOUT;
>> +	priv->wdev.max_hw_heartbeat_ms = SP_WDT_MAX_TIMEOUT * 1000;
>> +	priv->wdev.min_timeout = 1;
>> +	priv->wdev.parent = dev;
>> +
>> +	watchdog_init_timeout(&priv->wdev, timeout, dev);
>> +	watchdog_set_nowayout(&priv->wdev, nowayout);
>> +	watchdog_set_restart_priority(&priv->wdev, 128);
>> +
>> +	watchdog_set_drvdata(&priv->wdev, priv);
>> +
>> +	watchdog_stop_on_reboot(&priv->wdev);
>> +	err = devm_watchdog_register_device(dev, &priv->wdev);
>> +	if (err)
>> +		return err;
>> +
>> +	platform_set_drvdata(pdev, priv);
>> +
>> +	dev_info(dev, "Watchdog enabled (timeout=%d sec%s.)\n",
>> +		 priv->wdev.timeout, nowayout ? ", nowayout" : "");
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id sp_wdt_of_match[] = {
>> +	{.compatible = "sunplus,sp7021-wdt", },
>> +	{ /* sentinel */ }
>> +};
>> +MODULE_DEVICE_TABLE(of, sp_wdt_of_match);
>> +
>> +static int __maybe_unused sp_wdt_suspend(struct device *dev)
>> +{
>> +	struct sp_wdt_priv *priv = dev_get_drvdata(dev);
>> +
>> +	if (watchdog_active(&priv->wdev))
>> +		sp_wdt_stop(&priv->wdev);
>> +
>> +	reset_control_assert(priv->rstc);
>> +	clk_disable_unprepare(priv->clk);
>> +
>> +	return 0;
>> +}
>> +
>> +static int __maybe_unused sp_wdt_resume(struct device *dev)
>> +{
>> +	int err;
>> +
>> +	struct sp_wdt_priv *priv = dev_get_drvdata(dev);
>> +
>> +	err = clk_prepare_enable(priv->clk);
>> +	if (err) {
>> +		dev_err(dev, "Clock can't be enabled correctly\n");
>> +		return err;
>> +	}
>> +
>> +	reset_control_deassert(priv->rstc);
>> +
>> +	if (watchdog_active(&priv->wdev))
>> +		sp_wdt_start(&priv->wdev);
>> +
>> +	return 0;
>> +}
>> +
>> +static SIMPLE_DEV_PM_OPS(sp_wdt_pm_ops, sp_wdt_suspend, sp_wdt_resume);
>> +
>> +static struct platform_driver sp_wdt_driver = {
>> +	.probe = sp_wdt_probe,
>> +	.driver = {
>> +		   .name = DEVICE_NAME,
>> +		   .of_match_table = sp_wdt_of_match,
>> +		   .pm = &sp_wdt_pm_ops,
>> +	},
>> +};
>> +
>> +module_platform_driver(sp_wdt_driver);
>> +
>> +MODULE_AUTHOR("Xiantao Hu <xt.hu@...lus1.com>");
>> +MODULE_DESCRIPTION("Sunplus Watchdog Timer Driver");
>> +MODULE_LICENSE("GPL v2");
>> -- 
>> 2.33.1
>>
> 

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