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SubjectRe: [PATCH 2/4] watchdog: imx_sc: Add i.MX system controller watchdog support
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On 2/14/19 3:44 AM, 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>
> ---
> drivers/watchdog/Kconfig | 13 +++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/imx_sc_wdt.c | 210 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 224 insertions(+)
> create mode 100644 drivers/watchdog/imx_sc_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 65c3c42..5c5b8ba 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -625,6 +625,19 @@ 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 ARCH_MXC || COMPILE_TEST
> + 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..ae52e34
> --- /dev/null
> +++ b/drivers/watchdog/imx_sc_wdt.c
> @@ -0,0 +1,210 @@
> +// 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;
> +module_param(timeout, uint, 0000);
> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
> + __MODULE_STRING(DEFAULT_TIMEOUT) ")");
> +
> +static struct watchdog_device imx_sc_wdd;
> +
> +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 res.a0;
> +}
> +
> +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 res.a0;
> +
> + 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;
> +}
> +
> +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;
> +}
> +
> +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;
> +}
> +
> +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,
> +};
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int imx_sc_wdt_suspend(struct device *dev)
> +{
> + if (test_bit(WDOG_ACTIVE, &imx_sc_wdd.status))
> + imx_sc_wdt_stop(&imx_sc_wdd);
> +

What is wrong with watchdog_active() ? It is used below ?

> + return 0;
> +}
> +
> +static int imx_sc_wdt_resume(struct device *dev)
> +{
> + if (test_bit(WDOG_ACTIVE, &imx_sc_wdd.status))
> + imx_sc_wdt_start(&imx_sc_wdd);
> +
> + return 0;
> +}
> +
> +static const struct dev_pm_ops imx_sc_wdt_pm_ops = {
> + .suspend = imx_sc_wdt_suspend,
> + .resume = imx_sc_wdt_resume,
> +};
> +
> +#define IMX_SC_WDT_PM_OPS (&imx_sc_wdt_pm_ops)
> +
> +#else
> +
> +#define IMX_SC_WDT_PM_OPS NULL
> +
> +#endif
> +
> +static int imx_sc_wdt_probe(struct platform_device *pdev)
> +{
> + struct watchdog_device *wdt = &imx_sc_wdd;

Please use devm_kzalloc() and drop the static variable. You can use
dev_get_drvdata() to access it where needed.

> + int err;
> +
> + platform_set_drvdata(pdev, wdt);
> +
> + wdt->info = &imx_sc_wdt_info;
> + wdt->ops = &imx_sc_wdt_ops;
> + wdt->min_timeout = 1;
> + wdt->max_timeout = MAX_TIMEOUT;
> + wdt->parent = &pdev->dev;
> + watchdog_set_drvdata(wdt, NULL);
> +
This is quite pointless.

> + err = watchdog_init_timeout(wdt, DEFAULT_TIMEOUT, &pdev->dev);
> + if (err) {
> + dev_err(&pdev->dev, "Failed to init the wdog timeout:%d\n",
> + err);
> + return err;
> + }
> +
> + err = watchdog_register_device(wdt);
> + if (err) {
> + dev_err(&pdev->dev, "Failed to register watchdog device\n");
> + return err;
> + }
> +
> + return 0;
> +}
> +
> +static int imx_sc_wdt_remove(struct platform_device *pdev)
> +{
> + struct watchdog_device *wdt = platform_get_drvdata(pdev);
> +
> + imx_sc_wdt_stop(wdt);

Any reason for not using watchdog_stop_on_unregister() ?

> +
> + watchdog_unregister_device(wdt);
> +
> + return 0;
> +}
> +
> +static void imx_sc_wdt_shutdown(struct platform_device *pdev)
> +{
> + struct watchdog_device *wdt = platform_get_drvdata(pdev);
> +
> + if (watchdog_active(wdt))
> + imx_sc_wdt_stop(wdt);
> +}
> +
Any reason for not using watchdog_stop_on_reboot() ?

> +static const struct of_device_id imx_sc_wdt_dt_ids[] = {
> + { .compatible = "fsl,imx8qxp-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,
> + .remove = imx_sc_wdt_remove,
> + .shutdown = imx_sc_wdt_shutdown,
> + .driver = {
> + .name = "imx-sc-wdt",
> + .of_match_table = imx_sc_wdt_dt_ids,
> + .pm = IMX_SC_WDT_PM_OPS,

I prefer the use of SIMPLE_DEV_PM_OPS() together with
__maybe_unused for the pm functions instead of #ifdef.
This ensures that the unused code compiles even if PM_SLEEP
is not enabled.

Thanks,
Guenter

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