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? > > 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. 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 > >
