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? Anson. > > Guenter > > > Thanks, > > Anson. > > > > RTC: > > 68 static int imx_sc_rtc_probe(struct platform_device *pdev) > > 69 { > > 70 int ret; > > 71 > > 72 ret = imx_scu_get_handle(&rtc_ipc_handle); > > 73 if (ret) > > 74 return ret; > > > > SCU: > > 92 int imx_scu_get_handle(struct imx_sc_ipc **ipc) > > 93 { > > 94 if (!imx_sc_ipc_handle) > > 95 return -EPROBE_DEFER; > > 96 > > 97 *ipc = imx_sc_ipc_handle; > > 98 return 0; > > 99 } > > 100 EXPORT_SYMBOL(imx_scu_get_handle); > > > >> > >> Guenter > >> > >>> + > >>> + return 0; > >>> +} > >>> +module_init(imx_sc_wdt_init); > >>> + > >>> +static void __exit imx_sc_wdt_exit(void) { > >>> + platform_driver_unregister(&imx_sc_wdt_driver); > >>> + platform_device_unregister(imx_sc_wdt_pdev); > >>> +} > >>> +module_exit(imx_sc_wdt_exit); > >>> + > >>> +MODULE_AUTHOR("Robin Gong <yibin.gong@xxxxxxx>"); > >>> +MODULE_DESCRIPTION("NXP i.MX system controller watchdog driver"); > >>> +MODULE_LICENSE("GPL v2"); > >>> -- > >>> 2.7.4 > >>>
