RE: [PATCH V8 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3月21日 8:32
> To: Anson Huang <anson.huang@nxp.com>
> Cc: wim@linux-watchdog.org; 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;
> Aisheng Dong <aisheng.dong@nxp.com>; Daniel Baluta
> <daniel.baluta@nxp.com>; heiko@sntech.de; horms+renesas@verge.net.au;
> Andy Gross <andy.gross@linaro.org>; maxime.ripard@bootlin.com;
> olof@lixom.net; bjorn.andersson@linaro.org; jagan@amarulasolutions.com;
> enric.balletbo@collabora.com; ezequiel@collabora.com;
> stefan.wahren@i2se.com; marc.w.gonzalez@free.fr; linux-
> watchdog@vger.kernel.org; devicetree@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; linux-kernel@vger.kernel.org; dl-linux-imx
> <linux-imx@nxp.com>
> Subject: Re: [PATCH V8 2/4] watchdog: imx_sc: Add i.MX system controller
> watchdog support
> 
> On 3/20/19 5:22 PM, Anson Huang wrote:
> > Hi, Guenter
> >
> > Best Regards!
> > Anson Huang
> >
> >> -----Original Message-----
> >> From: Guenter Roeck [mailto:groeck7@gmail.com] On Behalf Of Guenter
> >> Roeck
> >> Sent: 2019年3月20日 21:44
> >> To: Anson Huang <anson.huang@nxp.com>
> >> Cc: wim@linux-watchdog.org; 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;
> >> Aisheng Dong <aisheng.dong@nxp.com>; Daniel Baluta
> >> <daniel.baluta@nxp.com>; heiko@sntech.de;
> horms+renesas@verge.net.au;
> >> Andy Gross <andy.gross@linaro.org>; maxime.ripard@bootlin.com;
> >> olof@lixom.net; bjorn.andersson@linaro.org;
> >> jagan@amarulasolutions.com; enric.balletbo@collabora.com;
> >> ezequiel@collabora.com; stefan.wahren@i2se.com;
> >> marc.w.gonzalez@free.fr; linux- watchdog@vger.kernel.org;
> >> devicetree@vger.kernel.org; linux-arm- kernel@lists.infradead.org;
> >> linux-kernel@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>
> >> Subject: Re: [PATCH V8 2/4] watchdog: imx_sc: Add i.MX system
> >> controller watchdog support
> >>
> >> On Fri, Mar 15, 2019 at 06:17:25AM +0000, 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>
> >>
> >> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> >>
> >> Waiting for bindings approval, though. Plus a minor comment below.
> >>
> >> Guenter
> >>
> >>> ---
> >>> Changes since V7:
> >>> 	- remove the dependence of IMX_SCU as it does NOT call SCU API
> >> directly;
> >>> 	- add more detail info into the help section of how this module works;
> >>> 	- add back device id table since now we have watchdog node in DT.
> >>> ---
> >>>   drivers/watchdog/Kconfig      |  16 ++++
> >>>   drivers/watchdog/Makefile     |   1 +
> >>>   drivers/watchdog/imx_sc_wdt.c | 182
> >>> ++++++++++++++++++++++++++++++++++++++++++
> >>>   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
> >>> 242eea8..44a3158 100644
> >>> --- a/drivers/watchdog/Kconfig
> >>> +++ b/drivers/watchdog/Kconfig
> >>> @@ -641,6 +641,22 @@ 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 HAVE_ARM_SMCCC
> >>> +	select WATCHDOG_CORE
> >>> +	help
> >>> +	  This is the driver for the system controller watchdog
> >>> +	  on the NXP i.MX SoCs with system controller inside, the
> >>> +	  watchdog driver will call ARM SMC API and trap into
> >>> +	  ARM-Trusted-Firmware for operations, ARM-Trusted-Firmware
> >>> +	  will request system controller to execute the operations.
> >>> +	  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 ba930e4..136d9f0 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..c8a087a
> >>> --- /dev/null
> >>> +++ b/drivers/watchdog/imx_sc_wdt.c
> >>> @@ -0,0 +1,182 @@
> >>> +// 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;
> >>
> >> I still don't understand why you explicitly disable configuring the
> >> watchdog timeout through devicetree (unless the user explicitly
> >> provides a timeout=0 module parameter). Maybe add some comment if
> you send another version.
> >
> > I thought this watchdog will be built as module anyway, and user can
> > pass the timeout parameter when insmod this module, so I just choose the
> way of getting it from module parameter.
> 
> Even when built as module, the driver will be loaded and instantiated when
> its devicetree entry is parsed. That is what devicetree is about, after all.
> There will be no insmod.

OK, understand now, if there is new version needed, I will change it to be from
device-tree, thanks.

Anson.


> 
> Guenter
> 
> > I will add a comment if there is another version needed.
> >
> > Thanks,
> > Anson.
> >
> >>
> >>> +module_param(timeout, uint, 0000);
> >>> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds
> (default="
> >>> +		 __MODULE_STRING(DEFAULT_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 0;
> >>> +}
> >>> +
> >>> +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 -EACCES;
> >>> +
> >>> +	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 ? -EACCES : 0;
> >>> +}
> >>> +
> >>> +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 ? -EACCES : 0;
> >>> +}
> >>> +
> >>> +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 ? -EACCES : 0;
> >>> +}
> >>> +
> >>> +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, timeout, &pdev->dev);
> >>> +	if (ret)
> >>> +		dev_warn(&pdev->dev, "Failed to set timeout value, using
> >>> +default\n");
> >>> +
> >>> +	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 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 const struct of_device_id imx_sc_wdt_dt_ids[] = {
> >>> +	{ .compatible = "fsl,imx-sc-wdt", },
> >>> +	{ /* sentinel */ }
> >>> +};
> >>> +MODULE_DEVICE_TABLE(of, imx_sc_wdt_dt_ids);
> >>> +
> >>> +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");