Hi, Guenter Best Regards! Anson Huang > -----Original Message----- > From: Guenter Roeck [mailto:groeck7@xxxxxxxxx] On Behalf Of Guenter > Roeck > Sent: 2019年3月4日 21:53 > To: Anson Huang <anson.huang@xxxxxxx> > Cc: catalin.marinas@xxxxxxx; will.deacon@xxxxxxx; wim@linux- > watchdog.org; shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; > kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; Andy Gross > <andy.gross@xxxxxxxxxx>; heiko@xxxxxxxxx; horms+renesas@xxxxxxxxxxxx; > arnd@xxxxxxxx; olof@xxxxxxxxx; bjorn.andersson@xxxxxxxxxx; > jagan@xxxxxxxxxxxxxxxxxxxx; enric.balletbo@xxxxxxxxxxxxx; > marc.w.gonzalez@xxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; linux-watchdog@xxxxxxxxxxxxxxx; dl-linux-imx > <linux-imx@xxxxxxx> > Subject: Re: [PATCH V5 1/2] watchdog: imx_sc: Add i.MX system controller > watchdog support > > On 3/3/19 7:22 PM, Anson Huang wrote: > > Hi, Guenter > > > > Best Regards! > > Anson Huang > > > >> -----Original Message----- > >> From: Guenter Roeck [mailto:groeck7@xxxxxxxxx] On Behalf Of Guenter > >> Roeck > >> Sent: 2019年3月4日 10:46 > >> To: Anson Huang <anson.huang@xxxxxxx> > >> Cc: catalin.marinas@xxxxxxx; will.deacon@xxxxxxx; wim@linux- > >> watchdog.org; shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; > >> kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; Andy Gross > >> <andy.gross@xxxxxxxxxx>; heiko@xxxxxxxxx; > horms+renesas@xxxxxxxxxxxx; > >> arnd@xxxxxxxx; olof@xxxxxxxxx; bjorn.andersson@xxxxxxxxxx; > >> jagan@xxxxxxxxxxxxxxxxxxxx; enric.balletbo@xxxxxxxxxxxxx; > >> marc.w.gonzalez@xxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux- > >> kernel@xxxxxxxxxxxxxxx; linux-watchdog@xxxxxxxxxxxxxxx; dl-linux-imx > >> <linux-imx@xxxxxxx> > >> Subject: Re: [PATCH V5 1/2] watchdog: imx_sc: Add i.MX system > >> controller watchdog support > >> > >> On 3/3/19 5:32 PM, Anson Huang wrote: > >>> Hi, Guenter > >>> > >>> Best Regards! > >>> Anson Huang > >>> > >>>> -----Original Message----- > >>>> From: Guenter Roeck [mailto:groeck7@xxxxxxxxx] On Behalf Of > Guenter > >>>> Roeck > >>>> Sent: 2019年3月2日 2:32 > >>>> To: Anson Huang <anson.huang@xxxxxxx> > >>>> Cc: catalin.marinas@xxxxxxx; will.deacon@xxxxxxx; wim@linux- > >>>> watchdog.org; shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; > >>>> kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; Andy Gross > >>>> <andy.gross@xxxxxxxxxx>; heiko@xxxxxxxxx; > >> horms+renesas@xxxxxxxxxxxx; > >>>> arnd@xxxxxxxx; olof@xxxxxxxxx; bjorn.andersson@xxxxxxxxxx; > >>>> jagan@xxxxxxxxxxxxxxxxxxxx; enric.balletbo@xxxxxxxxxxxxx; > >>>> marc.w.gonzalez@xxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > >>>> linux- kernel@xxxxxxxxxxxxxxx; linux-watchdog@xxxxxxxxxxxxxxx; > >>>> dl-linux-imx <linux-imx@xxxxxxx> > >>>> Subject: Re: [PATCH V5 1/2] watchdog: imx_sc: Add i.MX system > >>>> controller watchdog support > >>>> > >>>> On Fri, Mar 01, 2019 at 06:35:31AM +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@xxxxxxx> > >>>>> --- > >>>>> Changes since V4: > >>>>> - change the module build dependency as depends on IMX_SCU and > >>>> HAVE_ARM_SMCCC, as this > >>>>> driver is ONLY for i.MX SoC with SCU inside and it uses ARM SMC call. > >>>>> --- > >>>>> drivers/watchdog/Kconfig | 14 +++ > >>>>> drivers/watchdog/Makefile | 1 + > >>>>> drivers/watchdog/imx_sc_wdt.c | 201 > >>>>> ++++++++++++++++++++++++++++++++++++++++++ > >>>>> 3 files changed, 216 insertions(+) > >>>>> create mode 100644 drivers/watchdog/imx_sc_wdt.c > >>>>> > >>>>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig > >>>>> index > >>>>> 65c3c42..a6bfa54 100644 > >>>>> --- a/drivers/watchdog/Kconfig > >>>>> +++ b/drivers/watchdog/Kconfig > >>>>> @@ -625,6 +625,20 @@ 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 IMX_SCU > >>>>> + 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. > >>>>> + 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..50b49b2 > >>>>> --- /dev/null > >>>>> +++ b/drivers/watchdog/imx_sc_wdt.c > >>>>> @@ -0,0 +1,201 @@ > >>>>> +// 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> > >>>> > >>>> Should no longer be needed. > >>> > >>> Correct, I will remove it. > >>> > >>>> > >>>>> +#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; > >>>>> +module_param(timeout, uint, 0000); MODULE_PARM_DESC(timeout, > >>>>> +"Watchdog timeout in > >>>> seconds > >>>>> +(default=" > >>>>> + __MODULE_STRING(DEFAULT_TIMEOUT) ")"); > >>>>> + > >>>>> +static struct platform_device *imx_sc_wdt_pdev; > >>>>> + > >>>>> +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 struct platform_driver imx_sc_wdt_driver = { > >>>>> + .probe = imx_sc_wdt_probe, > >>>>> + .driver = { > >>>>> + .name = "imx-sc-wdt", > >>>>> + .pm = &imx_sc_wdt_pm_ops, > >>>>> + }, > >>>>> +}; > >>>>> + > >>>>> +static int __init imx_sc_wdt_init(void) { > >>>>> + int ret; > >>>>> + > >>>>> + ret = platform_driver_register(&imx_sc_wdt_driver); > >>>>> + if (ret) > >>>>> + return ret; > >>>>> + > >>>>> + imx_sc_wdt_pdev = platform_device_register_simple("imx- > sc-wdt", > >>>>> +- > >>>> 1, NULL, 0); > >>>>> + if (IS_ERR(imx_sc_wdt_pdev)) { > >>>>> + platform_driver_unregister(&imx_sc_wdt_driver); > >>>>> + return PTR_ERR(imx_sc_wdt_pdev); > >>>>> + } > >>>> > >>>> I just realized what you are doing here. So the watchdog will > >>>> always be instantiated if/when the module is loaded. I don't think > >>>> that was the idea, and it seems to be risky. What happens if > >>>> someone loads the module on a system where the watchdog is not > >>>> supported ? There maye be lots of "Access Denied" errors, or > something undefined may happen. > >>> > >>> I thought the "depends on IMX_SCU" was already added in Kconfig, > >>> that means the module will be ONLY built with IMX_SCU enabled, and > >>> watchdog will be always enabled if IMX_SCU is enabled. Is it safe enough? > >>> > >> No. The driver will be built with arm64:defconfig, meaning it will be > >> built for all arm64 systems using defconfig. Any such system will > >> have the driver installed as module, and nothing will prevent the > >> user from running modprobe. But even if it wasn't enabled with > >> defconfig, we must not instantiate the driver on an arbitrary system. > >> > >>>> > >>>> Is everyone on Cc: ok with this ? Is this how we handle > >>>> instantiations nowadays ? Or should the driver be instantiated > >>>> from > >>>> imx_scu_probe() in drivers/firmware/imx/imx-scu.c ? > >>>> > >>>> Sorry if the answer is obvious, but I am still struggling with "no > >>>> more instantiations through devicetree". > >>>> > >>>> If the driver is auto-instantiated when the module is loaded, as > >>>> currently written, there needs to be some check if it is actually > >>>> supported, possibly in > >>>> imx_sc_wdt_init() or, if that is not possible, in the probe function. > >>>> I don't like that, but it would at least prevent the module from > >>>> being loaded when the hardware is not supported. > >>> > >>> Other modules depend on the IMX_SCU IPC will have defer probe there > >>> to make sure IMX_SCU driver is ready for IPC handle, since watchdog > >>> driver ONLY uses ARM SMC but no IPC call, so I did NOT add the defer > >>> probe handle here, so if adding it can answer your question/concern, > >>> then I can add it, although I think the dependency in Kconfig should > >>> be good here. Without SCU firmware ready, the SoC does NOT boot up A > >> core with ATF/Linux at all. > >>> > >> That has nothing to do with deferred probing. My concern is that the > >> driver will be instantiated just by loading it, no matter if the > >> hardware supporting it is present or not. > >> > >> Having a devicetree node would have prevented that since it > >> instantiates the child drivers with devm_of_platform_populate() in > >> imx_scu_probe(). The equivalent is to register the platform device from > imx_scu_probe(). > >> That is the only means to prevent the driver from being instantiated > >> where it shouldn't. As mentioned before, I would have preferred the > >> devicetree method, but having it no longer available doesn't mean > >> that we should add risky code. > >> > >> Maybe you can check in the init function if the 'fsl,imx-scu' node > >> exists, and instantiate the driver if it does. I don't like that > >> either, but it would be acceptable to me - and maybe better than > >> instantiating it manually from imx_scu_probe(). > > > > OK, I can add check of "fsl,imx-scu" in init function and ONLY > > instantiate the driver if it exist, since there is no watchdog node in > > devicetree and "fsl,imx-scu" should be treated as watchdog node, so > > adding such check also makes some sense, putting it inside SCU driver is > NOT that good I think, do you agree? > > > > I dislike both. Putting it into the SCU driver probe function would be more > appropriate. Putting it into the watchdog driver is worse since it should really > only be instantiated if (and after) the parent driver is instantiated, and the > parent driver should be listed as its parent. That will get lost if you put the > check into the watchdog driver. > > I would suggest to submit the patch for the SCU driver first. If that gets > rejected by its maintainer, we'll have to do it in the watchdog driver. Thanks Guenter, I resend the V6 patch to move the watchdog platform device register to SCU driver probe, to be child of SCU device, let's wait for SCU maintainer's feedback. Anson. > > Guenter
