Message-ID: <B256D81BAE5131468A838E5D7A243641C9F86B81@penmbx01>
Date:	Wed, 5 Aug 2015 08:45:50 +0000
From:	"Yang, Wenyou" <Wenyou.Yang@...el.com>
To:	Guenter Roeck <linux@...ck-us.net>,
	"wim@...ana.be" <wim@...ana.be>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"pawel.moll@....com" <pawel.moll@....com>,
	"mark.rutland@....com" <mark.rutland@....com>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	"galak@...eaurora.org" <galak@...eaurora.org>
CC:	"sylvain.rochet@...secur.com" <sylvain.rochet@...secur.com>,
	"Ferre, Nicolas" <Nicolas.FERRE@...el.com>,
	"boris.brezillon@...e-electrons.com" 
	<boris.brezillon@...e-electrons.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v2 1/2] drivers: watchdog: add a driver to support
 SAMA5D4 watchdog timer

Hi Guenter,

Thank you very much for your review.

I will send a new version to resolve them.

> -----Original Message-----
> From: Guenter Roeck [mailto:linux@...ck-us.net]
> Sent: 2015年8月5日 14:14
> To: Yang, Wenyou; wim@...ana.be; robh+dt@...nel.org; pawel.moll@....com;
> mark.rutland@....com; ijc+devicetree@...lion.org.uk; galak@...eaurora.org
> Cc: sylvain.rochet@...secur.com; Ferre, Nicolas; boris.brezillon@...e-
> electrons.com; devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; linux-
> watchdog@...r.kernel.org; linux-arm-kernel@...ts.infradead.org
> Subject: Re: [PATCH v2 1/2] drivers: watchdog: add a driver to support SAMA5D4
> watchdog timer
> 
> On 08/04/2015 07:35 PM, Wenyou Yang wrote:
> >>From SAMA5D4, the watchdog timer is upgrated with a new feature,
> > which is describled as in the datasheet, "WDT_MR can be written until
> > a LOCKMR command is issued in WDT_CR".
> > That is to say, as long as the bootstrap and u-boot don't issue a
> > LOCKMR command, WDT_MR can be written more than once in the driver.
> >
> > So the SAMA5D4 watchdog driver's implementation is different from the
> > previous: the user application open the device file to enable
> 
> Which previous ? Please let the reader know which one you refer to.
> 
> > the watchdog timer hardware, and close to disable it, and set the
> > watchdog timer timeout by seting WDV and WDD fields of WDT_MR
> > register, and ping the watchdog by issuing WDRSTT command to WDT_CR
> > register with hard-coded key.
> >
> > Signed-off-by: Wenyou Yang <wenyou.yang@...el.com>
> > ---
> >   drivers/watchdog/Kconfig        |    9 ++
> >   drivers/watchdog/Makefile       |    1 +
> >   drivers/watchdog/at91sam9_wdt.h |    4 +
> >   drivers/watchdog/atmel_wdt.c    |  290
> +++++++++++++++++++++++++++++++++++++++
> >   4 files changed, 304 insertions(+)
> >   create mode 100644 drivers/watchdog/atmel_wdt.c
> >
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index
> > e5e7c55..4425813 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -152,6 +152,15 @@ config ARM_SP805_WATCHDOG
> >   	  ARM Primecell SP805 Watchdog timer. This will reboot your system
> when
> >   	  the timeout is reached.
> >
> > +config ATMEL_WATCHDOG
> > +	tristate "Atmel SAMA5D4 Watchdog Timer"
> > +	depends on ARCH_AT91
> > +	select WATCHDOG_CORE
> > +	help
> > +	  Atmel watchdog timer embedded into SAMA5D4 chips. Its Watchdog
> Timer
> > +	  Mode Register(WDT_MR) can be written more than once.
> > +	  This will reboot your system when the timeout is reached.
> > +
> 
> ATMEL is highly generic. Can you find a more specific name ?
> If this is part of the AT91 family, it could be something like AT91SAMAD54, for
> example.
> 
> Same goes for the driver name.
> 
> >   config AT91RM9200_WATCHDOG
> >   	tristate "AT91RM9200 watchdog"
> >   	depends on SOC_AT91RM9200 && MFD_SYSCON diff --git
> > a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile index
> > 5c19294..c24a8fc 100644
> > --- a/drivers/watchdog/Makefile
> > +++ b/drivers/watchdog/Makefile
> > @@ -30,6 +30,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
> >
> >   # ARM Architecture
> >   obj-$(CONFIG_ARM_SP805_WATCHDOG) += sp805_wdt.o
> > +obj-$(CONFIG_ATMEL_WATCHDOG) += atmel_wdt.o
> >   obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
> >   obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
> >   obj-$(CONFIG_CADENCE_WATCHDOG) += cadence_wdt.o diff --git
> > a/drivers/watchdog/at91sam9_wdt.h b/drivers/watchdog/at91sam9_wdt.h
> > index c6fbb2e6..79add4f 100644
> > --- a/drivers/watchdog/at91sam9_wdt.h
> > +++ b/drivers/watchdog/at91sam9_wdt.h
> > @@ -22,11 +22,15 @@
> >
> >   #define AT91_WDT_MR		0x04			/* Watchdog
> Mode Register */
> >   #define		AT91_WDT_WDV		(0xfff << 0)		/*
> Counter Value */
> > +#define			AT91_WDT_WDV_MSK	(0xfff)
> 
> The ( ) is not necessary. AT91_WDT_WDV is already used as mask.
> You should not need a second one.
> 
> > +#define			AT91_WDT_WDV_(x)	(((x) &
> AT91_WDT_WDV_MSK) << 0)
> 
> Please no '_' at the end of the macro name; find another name that isn't as close to
> AT91_WDT_WDV.
> 
> >   #define		AT91_WDT_WDFIEN		(1     << 12)		/*
> Fault Interrupt Enable */
> >   #define		AT91_WDT_WDRSTEN	(1     << 13)		/*
> Reset Processor */
> >   #define		AT91_WDT_WDRPROC	(1     << 14)		/*
> Timer Restart */
> >   #define		AT91_WDT_WDDIS		(1     << 15)		/*
> Watchdog Disable */
> >   #define		AT91_WDT_WDD		(0xfff << 16)		/*
> Delta Value */
> > +#define			AT91_WDT_WDD_MSK	(0xfff)
> 
> ( ) is unnecessary. Also, AT91_WDT_WDD is already used as mask.
> No need to specify a second one.
> 
> > +#define			AT91_WDT_WDD_(x)	(((x) &
> AT91_WDT_WDD_MSK) << 16)
> 
> Again, please no '_' at the end of the macro name.
> 
> >   #define		AT91_WDT_WDDBGHLT	(1     << 28)		/*
> Debug Halt */
> >   #define		AT91_WDT_WDIDLEHLT	(1     << 29)		/*
> Idle Halt */
> >
> > diff --git a/drivers/watchdog/atmel_wdt.c
> > b/drivers/watchdog/atmel_wdt.c new file mode 100644 index
> > 0000000..e1cdc84
> > --- /dev/null
> > +++ b/drivers/watchdog/atmel_wdt.c
> > @@ -0,0 +1,290 @@
> > +/*
> > + * Driver for Atmel SAMA5D4 Watchdog Timer
> > + *
> > + * Copyright (C) 2015 Atmel Corporation
> > + *
> > + * Licensed under GPLv2.
> > + */
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/of.h>
> > +#include <linux/of_irq.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/watchdog.h>
> > +#include <linux/reboot.h>
> 
> Please use alphabetic order for include files. That makes it easier to find files, and
> simplifies later additions.
> 
> > +
> > +#include "at91sam9_wdt.h"
> > +
> > +/* minimum and maximum watchdog timeout, in seconds */
> > +#define MIN_WDT_TIMEOUT		1
> > +#define MAX_WDT_TIMEOUT		16
> > +#define WDT_DEFAULT_TIMEOUT	MAX_WDT_TIMEOUT
> > +
> > +#define WDT_MAX_WDV		0xFFF
> > +
> > +#define WDT_SEC2TICKS(s)	((s) ? (((s) << 8) - 1) : 0)
> > +
> > +struct atmel_wdt {
> > +	struct watchdog_device	wdd;
> > +	void __iomem		*reg_base;
> > +	u32	config;
> > +};
> > +
> > +static int wdt_timeout = WDT_DEFAULT_TIMEOUT; static bool nowayout =
> > +WATCHDOG_NOWAYOUT;
> > +
> > +module_param(wdt_timeout, int, 0);
> > +MODULE_PARM_DESC(wdt_timeout,
> > +	"Watchdog wdt_timeout in seconds. (default = "
> > +	__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
> > +
> > +module_param(nowayout, bool, 0);
> > +MODULE_PARM_DESC(nowayout,
> > +	"Watchdog cannot be stopped once started (default="
> > +	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> > +
> > +#define wdt_read(wdt, field) \
> > +	readl_relaxed((wdt)->reg_base + (field))
> > +
> > +#define wdt_write(wtd, field, val) \
> > +	writel_relaxed((val), (wdt)->reg_base + (field))
> > +
> > +static int atmel_wdt_start(struct watchdog_device *wdd) {
> > +	struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
> > +	u32 reg;
> > +
> > +	reg = wdt_read(wdt, AT91_WDT_MR);
> > +	reg &= ~AT91_WDT_WDDIS;
> > +	wdt_write(wdt, AT91_WDT_MR, reg);
> > +
> > +	return 0;
> > +}
> > +
> > +static int atmel_wdt_stop(struct watchdog_device *wdd) {
> > +	struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
> > +	u32 reg;
> > +
> > +	reg = wdt_read(wdt, AT91_WDT_MR);
> > +	reg |= AT91_WDT_WDDIS;
> > +	wdt_write(wdt, AT91_WDT_MR, reg);
> > +
> > +	return 0;
> > +}
> > +
> > +static int atmel_wdt_ping(struct watchdog_device *wdd) {
> > +	struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
> > +
> > +	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY |
> AT91_WDT_WDRSTT);
> > +
> > +	return 0;
> > +}
> > +
> > +static int atmel_wdt_set_timeout(struct watchdog_device *wdd,
> > +				 unsigned int timeout)
> > +{
> > +	struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
> > +	u32 reg, value;
> > +
> > +	value = WDT_SEC2TICKS(timeout);
> > +	if (value > WDT_MAX_WDV)
> > +		return -EINVAL;
> > +
> Unnecessary check.
> 
> > +	reg = wdt_read(wdt, AT91_WDT_MR);
> > +	reg &= ~AT91_WDT_WDV;
> > +	reg &= ~AT91_WDT_WDD;
> > +	reg |= AT91_WDT_WDV_(value);
> > +	reg |= AT91_WDT_WDD_(value);
> > +	wdt_write(wdt, AT91_WDT_MR, reg);
> > +
> > +	wdd->timeout = timeout;
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct watchdog_info atmel_wdt_info = {
> > +	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
> WDIOF_KEEPALIVEPING,
> > +	.firmware_version = 0,
> > +	.identity = "Atmel SAMA5D4 Watchdog", };
> > +
> > +static struct watchdog_ops atmel_wdt_ops = {
> > +	.owner = THIS_MODULE,
> > +	.start = atmel_wdt_start,
> > +	.stop = atmel_wdt_stop,
> > +	.ping = atmel_wdt_ping,
> > +	.set_timeout = atmel_wdt_set_timeout, };
> > +
> > +static irqreturn_t atmel_wdt_irq_handler(int irq, void *dev_id) {
> > +	struct atmel_wdt *wdt = platform_get_drvdata(dev_id);
> > +
> > +	if (wdt_read(wdt, AT91_WDT_SR)) {
> > +		pr_crit("Atmel Watchdog Software Reset\n");
> > +		emergency_restart();
> > +		pr_crit("Reboot didn't ?????\n");
> > +	}
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int of_atmel_wdt_init(struct device_node *np, struct atmel_wdt
> > +*wdt) {
> > +	const char *tmp;
> > +
> > +	wdt->config = AT91_WDT_WDDIS;
> > +
> > +	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
> > +	    !strcmp(tmp, "software"))
> > +		wdt->config |= AT91_WDT_WDFIEN;
> > +	else
> > +		wdt->config |= AT91_WDT_WDRSTEN;
> > +
> > +	if (of_property_read_bool(np, "atmel,idle-halt"))
> > +		wdt->config |= AT91_WDT_WDIDLEHLT;
> > +
> > +	if (of_property_read_bool(np, "atmel,dbg-halt"))
> > +		wdt->config |= AT91_WDT_WDDBGHLT;
> > +
> > +	return 0;
> > +}
> > +
> > +static int atmel_wdt_init(struct atmel_wdt *wdt) {
> > +	struct watchdog_device *wdd = &wdt->wdd;
> > +	u32 value, timeout;
> > +
> > +	timeout = WDT_SEC2TICKS(wdd->timeout);
> > +	if (timeout > WDT_MAX_WDV)
> > +		return -1;
> > +
> 
> Unnecessary range check.
> 
> > +	/*
> > +	 * Because the fields WDV and WDD must not be modified when the
> WDDIS
> > +	 * bit is set, so clear the WDDIS bit before writing the WDT_MR.
> > +	 */
> > +	value = wdt_read(wdt, AT91_WDT_MR);
> > +	value &= ~AT91_WDT_WDDIS;
> > +	wdt_write(wdt, AT91_WDT_MR, value);
> > +
> > +	value = wdt->config;
> > +	value |= AT91_WDT_WDD_(timeout);
> > +	value |= AT91_WDT_WDV_(timeout);
> > +
> > +	wdt_write(wdt, AT91_WDT_MR, value);
> > +
> > +	return 0;
> > +}
> > +
> > +static int atmel_wdt_probe(struct platform_device *pdev) {
> > +	struct watchdog_device *wdd;
> > +	struct atmel_wdt *wdt;
> > +	struct resource *res;
> > +	void __iomem *regs;
> > +	int ret, irq = -1;
> > +
> > +	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> > +	if (!wdt)
> > +		return -ENOMEM;
> > +
> > +	wdd = &wdt->wdd;
> > +	wdd->timeout = wdt_timeout;
> > +	wdd->info = &atmel_wdt_info;
> > +	wdd->ops = &atmel_wdt_ops;
> > +	wdd->min_timeout = MIN_WDT_TIMEOUT;
> > +	wdd->max_timeout = MAX_WDT_TIMEOUT;
> > +
> > +	watchdog_set_drvdata(wdd, wdt);
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	regs = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(regs))
> > +		return PTR_ERR(regs);
> > +
> > +	wdt->reg_base = regs;
> > +
> > +	if (pdev->dev.of_node) {
> > +		irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
> > +		if (!irq)
> > +			dev_warn(&pdev->dev, "the IRQ NOT specify from DT\n");
> 
> "failed to get IRQ from DT" would be a better message.
> This leaves irq set to 0 in the error case, and cause the code below to request an
> interrupt.
> 
> > +
> > +		ret = of_atmel_wdt_init(pdev->dev.of_node, wdt);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	if ((wdt->config & AT91_WDT_WDFIEN) && (irq >= 0)) {
> 
> Second ( ) is unnecessary.
> 
> > +		ret = devm_request_irq(&pdev->dev, irq, atmel_wdt_irq_handler,
> > +				       0, pdev->name, pdev);
> > +		if (ret) {
> > +			dev_err(&pdev->dev,
> > +				"cannot register interrupt handler\n");
> > +			return ret;
> > +		}
> > +	}
> > +
> > +	ret = watchdog_init_timeout(wdd, wdt_timeout, &pdev->dev);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "unable to set timeout value\n");
> > +		return ret;
> 
> I would suggest to set the default timeout in this case, as done by other drivers.
> 
> > +	}
> > +
> > +	ret = atmel_wdt_init(wdt);
> > +	if (ret)
> > +		return ret;
> > +
> > +	watchdog_set_nowayout(wdd, nowayout);
> > +
> > +	ret = watchdog_register_device(wdd);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "failed to register watchdog device\n");
> > +		return ret;
> > +	}
> > +
> > +	platform_set_drvdata(pdev, wdt);
> > +
> > +	dev_info(&pdev->dev, "initialized (timeout = %d sec, nowayout = %d)\n",
> > +		 wdt_timeout, nowayout);
> > +
> > +	return 0;
> > +}
> > +
> > +static int atmel_wdt_remove(struct platform_device *pdev) {
> > +	struct atmel_wdt *wdt = platform_get_drvdata(pdev);
> > +
> > +	atmel_wdt_stop(&wdt->wdd);
> > +
> > +	watchdog_unregister_device(&wdt->wdd);
> > +
> > +	dev_info(&pdev->dev, "removed wdt\n");
> > +
> Unnecessary message.
> 
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id atmel_wdt_of_match[] = {
> > +	{ .compatible = "atmel,sama5d4-wdt", },
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, atmel_wdt_of_match);
> > +
> > +static struct platform_driver atmel_wdt_driver = {
> > +	.probe		= atmel_wdt_probe,
> > +	.remove		= atmel_wdt_remove,
> > +	.driver		= {
> > +		.name	= "atmel-wdt",
> > +		.of_match_table = atmel_wdt_of_match,
> > +	},
> > +};
> > +module_platform_driver(atmel_wdt_driver);
> > +
> > +MODULE_ALIAS("platform:atmel-wdt");
> > +MODULE_AUTHOR("Atmel Corporation");
> > +MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
> > +MODULE_LICENSE("GPL v2");
> >

Best Regards,
Wenyou Yang

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