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Message-ID: <20190301183141.GA26332@roeck-us.net>
Date: Fri, 1 Mar 2019 10:31:41 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Anson Huang <anson.huang@....com>
Cc: "catalin.marinas@....com" <catalin.marinas@....com>,
"will.deacon@....com" <will.deacon@....com>,
"wim@...ux-watchdog.org" <wim@...ux-watchdog.org>,
"shawnguo@...nel.org" <shawnguo@...nel.org>,
"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
"kernel@...gutronix.de" <kernel@...gutronix.de>,
"festevam@...il.com" <festevam@...il.com>,
Andy Gross <andy.gross@...aro.org>,
"heiko@...ech.de" <heiko@...ech.de>,
"horms+renesas@...ge.net.au" <horms+renesas@...ge.net.au>,
"arnd@...db.de" <arnd@...db.de>, "olof@...om.net" <olof@...om.net>,
"bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
"jagan@...rulasolutions.com" <jagan@...rulasolutions.com>,
"enric.balletbo@...labora.com" <enric.balletbo@...labora.com>,
"marc.w.gonzalez@...e.fr" <marc.w.gonzalez@...e.fr>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
dl-linux-imx <linux-imx@....com>
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@....com>
> ---
> 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.
> +#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.
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.
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@....com>");
> +MODULE_DESCRIPTION("NXP i.MX system controller watchdog driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.7.4
>
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