RE: [PATCH RESEND V2 2/4] watchdog: imx_sc: Add i.MX system controller watchdog support

[Anson Huang <anson.huang@nxp.com>]

Hi, Guenter

Best Regards!
Anson Huang

> -----Original Message-----
> From: Guenter Roeck [mailto:groeck7@gmail.com] On Behalf Of Guenter
> Roeck
> Sent: 2019年2月24日 11:29
> To: Anson Huang <anson.huang@nxp.com>; robh+dt@kernel.org;
> mark.rutland@arm.com; shawnguo@kernel.org; s.hauer@pengutronix.de;
> kernel@pengutronix.de; festevam@gmail.com; catalin.marinas@arm.com;
> will.deacon@arm.com; wim@linux-watchdog.org; Aisheng Dong
> <aisheng.dong@nxp.com>; ulf.hansson@linaro.org; Daniel Baluta
> <daniel.baluta@nxp.com>; Andy Gross <andy.gross@linaro.org>;
> horms+renesas@verge.net.au; heiko@sntech.de; arnd@arndb.de;
> bjorn.andersson@linaro.org; jagan@amarulasolutions.com;
> enric.balletbo@collabora.com; marc.w.gonzalez@free.fr; olof@lixom.net;
> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; linux-watchdog@vger.kernel.org
> Cc: dl-linux-imx <linux-imx@nxp.com>
> Subject: Re: [PATCH RESEND V2 2/4] watchdog: imx_sc: Add i.MX system
> controller watchdog support
> 
> On 2/17/19 10:53 PM, Anson Huang wrote:
> > i.MX8QXP is an ARMv8 SoC which has a Cortex-M4 system controller
> > inside, the system controller is in charge of controlling power, clock
> > and watchdog etc..
> >
> > This patch adds i.MX system controller watchdog driver support,
> > watchdog operation needs to be done in secure EL3 mode via
> > ARM-Trusted-Firmware, using SMC call, CPU will trap into
> > ARM-Trusted-Firmware and then it will request system controller to do
> > watchdog operation via IPC.
> >
> > Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> 
> Sorry, but I have to take back my Reviewed-by: Comments below.
> Sorry, I completely missed that earlier.
> 
> > ---
> > Changes since V1:
> >          - use watchdog_active() instead of comparing watchdog status directly;
> >          - use devm_kzalloc instead of using static variable;
> >          - remove unnecessary wdog set driver data in .probe;
> >          - use watchdog_stop_on_unregister() instead of .remove callback;
> >          - use watchdog_stop_on_reboot() instead of .shutdown callback;
> >          - use SIMPLE_DEV_PM_OPS() to simply the PM code.
> > ---
> >   drivers/watchdog/Kconfig      |  13 +++
> >   drivers/watchdog/Makefile     |   1 +
> >   drivers/watchdog/imx_sc_wdt.c | 185
> ++++++++++++++++++++++++++++++++++++++++++
> >   3 files changed, 199 insertions(+)
> >   create mode 100644 drivers/watchdog/imx_sc_wdt.c
> >
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index
> > 65c3c42..5c5b8ba 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -625,6 +625,19 @@ config IMX2_WDT
> >   	  To compile this driver as a module, choose M here: the
> >   	  module will be called imx2_wdt.
> >
> > +config IMX_SC_WDT
> > +	tristate "IMX SC Watchdog"
> > +	depends on ARCH_MXC || COMPILE_TEST
> > +	select WATCHDOG_CORE
> > +	help
> > +	  This is the driver for the system controller watchdog
> > +	  on the NXP i.MX SoCs with system controller inside.
> > +	  If you have one of these processors and wish to have
> > +	  watchdog support enabled, say Y, otherwise say N.
> > +
> > +	  To compile this driver as a module, choose M here: the
> > +	  module will be called imx_sc_wdt.
> > +
> >   config UX500_WATCHDOG
> >   	tristate "ST-Ericsson Ux500 watchdog"
> >   	depends on MFD_DB8500_PRCMU
> > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> > index 4e78a8c..0c9da63 100644
> > --- a/drivers/watchdog/Makefile
> > +++ b/drivers/watchdog/Makefile
> > @@ -68,6 +68,7 @@ obj-$(CONFIG_NUC900_WATCHDOG) +=
> nuc900_wdt.o
> >   obj-$(CONFIG_TS4800_WATCHDOG) += ts4800_wdt.o
> >   obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
> >   obj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
> > +obj-$(CONFIG_IMX_SC_WDT) += imx_sc_wdt.o
> >   obj-$(CONFIG_UX500_WATCHDOG) += ux500_wdt.o
> >   obj-$(CONFIG_RETU_WATCHDOG) += retu_wdt.o
> >   obj-$(CONFIG_BCM2835_WDT) += bcm2835_wdt.o diff --git
> > a/drivers/watchdog/imx_sc_wdt.c b/drivers/watchdog/imx_sc_wdt.c new
> > file mode 100644 index 0000000..a234a0c
> > --- /dev/null
> > +++ b/drivers/watchdog/imx_sc_wdt.c
> > @@ -0,0 +1,185 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright 2018-2019 NXP.
> > + */
> > +
> > +#include <linux/arm-smccc.h>
> > +#include <linux/io.h>
> > +#include <linux/init.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/moduleparam.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/reboot.h>
> > +#include <linux/watchdog.h>
> > +
> > +#define DEFAULT_TIMEOUT 60
> > +/*
> > + * Software timer tick implemented in scfw side, support 10ms to
> > +0xffffffff ms
> > + * in theory, but for normal case, 1s~128s is enough, you can change
> > +this max
> > + * value in case it's not enough.
> > + */
> > +#define MAX_TIMEOUT 128
> > +
> > +#define IMX_SIP_TIMER			0xC2000002
> > +#define IMX_SIP_TIMER_START_WDOG		0x01
> > +#define IMX_SIP_TIMER_STOP_WDOG		0x02
> > +#define IMX_SIP_TIMER_SET_WDOG_ACT	0x03
> > +#define IMX_SIP_TIMER_PING_WDOG		0x04
> > +#define IMX_SIP_TIMER_SET_TIMEOUT_WDOG	0x05
> > +#define IMX_SIP_TIMER_GET_WDOG_STAT	0x06
> > +#define IMX_SIP_TIMER_SET_PRETIME_WDOG	0x07
> > +
> > +#define SC_TIMER_WDOG_ACTION_PARTITION	0
> > +
> > +static bool nowayout = WATCHDOG_NOWAYOUT;
> module_param(nowayout,
> > +bool, 0000); MODULE_PARM_DESC(nowayout, "Watchdog cannot be
> stopped
> > +once started (default="
> > +		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> > +
> > +static unsigned int timeout = DEFAULT_TIMEOUT;
> 
> Should not be initialized.
> 
> > +module_param(timeout, uint, 0000);
> > +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
> > +		 __MODULE_STRING(DEFAULT_TIMEOUT) ")");
> > +
> 
> This suggests that you want to use that timeout. But that isn't the case.

You are correct, I should have used this module parameter when setting timeout;

> 
> 
> 
> 
> > +static int imx_sc_wdt_ping(struct watchdog_device *wdog) {
> > +	struct arm_smccc_res res;
> > +
> > +	arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_PING_WDOG,
> > +		      0, 0, 0, 0, 0, 0, &res);
> > +
> > +	return res.a0;
> > +}
> > +
> > +static int imx_sc_wdt_start(struct watchdog_device *wdog) {
> > +	struct arm_smccc_res res;
> > +
> > +	arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_START_WDOG,
> > +		      0, 0, 0, 0, 0, 0, &res);
> > +	if (res.a0)
> > +		return res.a0;
> > +
> > +	arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_SET_WDOG_ACT,
> > +		      SC_TIMER_WDOG_ACTION_PARTITION,
> > +		      0, 0, 0, 0, 0, &res);
> > +	return res.a0;
> > +}
> > +
> > +static int imx_sc_wdt_stop(struct watchdog_device *wdog) {
> > +	struct arm_smccc_res res;
> > +
> > +	arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_STOP_WDOG,
> > +		      0, 0, 0, 0, 0, 0, &res);
> > +
> > +	return res.a0;
> > +}
> > +
> > +static int imx_sc_wdt_set_timeout(struct watchdog_device *wdog,
> > +				unsigned int timeout)
> > +{
> > +	struct arm_smccc_res res;
> > +
> > +	wdog->timeout = timeout;
> > +	arm_smccc_smc(IMX_SIP_TIMER,
> IMX_SIP_TIMER_SET_TIMEOUT_WDOG,
> > +		      timeout * 1000, 0, 0, 0, 0, 0, &res);
> > +
> > +	return res.a0;
> > +}
> > +
> > +static const struct watchdog_ops imx_sc_wdt_ops = {
> > +	.owner = THIS_MODULE,
> > +	.start = imx_sc_wdt_start,
> > +	.stop  = imx_sc_wdt_stop,
> > +	.ping  = imx_sc_wdt_ping,
> > +	.set_timeout = imx_sc_wdt_set_timeout, };
> > +
> > +static const struct watchdog_info imx_sc_wdt_info = {
> > +	.identity	= "i.MX SC watchdog timer",
> > +	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
> > +			  WDIOF_MAGICCLOSE | WDIOF_PRETIMEOUT, };
> > +
> > +static int imx_sc_wdt_probe(struct platform_device *pdev) {
> > +	struct watchdog_device *imx_sc_wdd;
> > +	int ret;
> > +
> > +	imx_sc_wdd = devm_kzalloc(&pdev->dev, sizeof(*imx_sc_wdd),
> GFP_KERNEL);
> > +	if (!imx_sc_wdd)
> > +		return -ENOMEM;
> > +
> > +	platform_set_drvdata(pdev, imx_sc_wdd);
> > +
> > +	imx_sc_wdd->info = &imx_sc_wdt_info;
> > +	imx_sc_wdd->ops = &imx_sc_wdt_ops;
> > +	imx_sc_wdd->min_timeout = 1;
> > +	imx_sc_wdd->max_timeout = MAX_TIMEOUT;
> > +	imx_sc_wdd->parent = &pdev->dev;
> 
> 	imx_sc_wdd->timeout = DEFAULT_TIMEOUT;
> 
> > +
> > +	ret = watchdog_init_timeout(imx_sc_wdd, DEFAULT_TIMEOUT,
> > +&pdev->dev);
> 
> As written this doesn't make sense: It will set the timeout to the default,
> which is always valid, making the error check unnecessary. I assume you
> meant the above plus
> 	ret = watchdog_init_timeout(imx_sc_wdd, timeout, &pdev->dev);
> 
> By not pre=initializing 'timeout', the watchdog core will try to read the
> configured timeout from devicetree. If it is not specified, it will keep the
> default timeout which should be set explicitly as suggested above.
> 
> With that, the error check makes some sense, though it is unusual to bail out
> if an out-of-range timeout was specified. But that is your call.
> 
> Again, sorry for not noticing this earlier.

Thanks for your detail review, in V3 patch series, I follow the suggestion to make
the timeout value to be default first, then try to set the watchdog timeout using
module parameter, if it is invalid, common driver will try to find it from dts node,
if return value is error, it will use default value set and NOT return error during probe.

This makes the error check making sense and NOT break watchdog driver probe even
if the module parameter "timeout" is invalid. Please help review V3 patch series.

Thanks,
Anson

> 
> Guenter
> 
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Failed to init the wdog timeout:%d\n",
> > +			ret);
> > +		return ret;
> > +	}
> > +
> > +	watchdog_stop_on_reboot(imx_sc_wdd);
> > +	watchdog_stop_on_unregister(imx_sc_wdd);
> > +
> > +	ret = devm_watchdog_register_device(&pdev->dev, imx_sc_wdd);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Failed to register watchdog device\n");
> > +		return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id imx_sc_wdt_dt_ids[] = {
> > +	{ .compatible = "fsl,imx8qxp-sc-wdt", },
> > +	{ /* sentinel */ }
> > +};
> > +MODULE_DEVICE_TABLE(of, imx_sc_wdt_dt_ids);
> > +
> > +static int __maybe_unused imx_sc_wdt_suspend(struct device *dev) {
> > +	struct watchdog_device *imx_sc_wdd = dev_get_drvdata(dev);
> > +
> > +	if (watchdog_active(imx_sc_wdd))
> > +		imx_sc_wdt_stop(imx_sc_wdd);
> > +
> > +	return 0;
> > +}
> > +
> > +static int __maybe_unused imx_sc_wdt_resume(struct device *dev) {
> > +	struct watchdog_device *imx_sc_wdd = dev_get_drvdata(dev);
> > +
> > +	if (watchdog_active(imx_sc_wdd))
> > +		imx_sc_wdt_start(imx_sc_wdd);
> > +
> > +	return 0;
> > +}
> > +
> > +static SIMPLE_DEV_PM_OPS(imx_sc_wdt_pm_ops,
> > +			 imx_sc_wdt_suspend, imx_sc_wdt_resume);
> > +
> > +static struct platform_driver imx_sc_wdt_driver = {
> > +	.probe		= imx_sc_wdt_probe,
> > +	.driver		= {
> > +		.name	= "imx-sc-wdt",
> > +		.of_match_table = imx_sc_wdt_dt_ids,
> > +		.pm	= &imx_sc_wdt_pm_ops,
> > +	},
> > +};
> > +
> > +module_platform_driver(imx_sc_wdt_driver);
> > +
> > +MODULE_AUTHOR("Robin Gong <yibin.gong@nxp.com>");
> > +MODULE_DESCRIPTION("NXP i.MX system controller watchdog driver");
> > +MODULE_LICENSE("GPL v2");
> >