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Message-ID: <7397f6db-1dc8-3abd-41ff-2e47323c7ffa@roeck-us.net>
Date: Sun, 20 Oct 2019 09:56:29 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Xingyu Chen <xingyu.chen@...ogic.com>,
Wim Van Sebroeck <wim@...ux-watchdog.org>,
Kevin Hilman <khilman@...libre.com>,
Neil Armstrong <narmstrong@...libre.com>
Cc: Rob Herring <robh+dt@...nel.org>,
Jerome Brunet <jbrunet@...libre.com>,
Qianggui Song <qianggui.song@...ogic.com>,
Jianxin Pan <jianxin.pan@...ogic.com>,
Jian Hu <jian.hu@...ogic.com>, linux-watchdog@...r.kernel.org,
linux-amlogic@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] watchdog: add meson secure watchdog driver
On 10/18/19 1:33 AM, Xingyu Chen wrote:
> The watchdog controller on the Meson-A/C series SoCs is moved to secure
> world, watchdog operation needs to be done in secure EL3 mode via ATF,
> Non-secure world can call SMC instruction to trap to AFT for watchdog
> operation.
>
> Signed-off-by: Xingyu Chen <xingyu.chen@...ogic.com>
> ---
> drivers/watchdog/Kconfig | 17 ++++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/meson_sec_wdt.c | 187 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 205 insertions(+)
> create mode 100644 drivers/watchdog/meson_sec_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 58e7c10..e84be42 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -826,6 +826,23 @@ config MESON_GXBB_WATCHDOG
> To compile this driver as a module, choose M here: the
> module will be called meson_gxbb_wdt.
>
> +config MESON_SEC_WATCHDOG
> + tristate "Amlogic Meson Secure watchdog support"
> + depends on MESON_SM
> + depends on ARCH_MESON || COMPILE_TEST
This dependency is pointless. MESON_SM already depends on ARCH_MESON,
thus specifying "COMPILE_TEST" here adds no value but only
creates confusion.
> + select WATCHDOG_CORE
> + help
> + The watchdog controller on the Meson-A/C series SoCs is moved to
> + secure world, watchdog operation needs to be done in secure EL3
> + mode via ATF, non-secure world can call SMC instruction to trap
> + to ATF for the watchdog operation.
> +
> + Say Y here if watchdog controller on Meson SoCs is located in
> + secure world.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called meson_sec_wdt.
> +
> config MESON_WATCHDOG
> tristate "Amlogic Meson SoCs watchdog support"
> depends on ARCH_MESON || COMPILE_TEST
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 2ee352b..5e6b73d 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -78,6 +78,7 @@ obj-$(CONFIG_QCOM_WDT) += qcom-wdt.o
> obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
> obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
> obj-$(CONFIG_MESON_GXBB_WATCHDOG) += meson_gxbb_wdt.o
> +obj-$(CONFIG_MESON_SEC_WATCHDOG) += meson_sec_wdt.o
> obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
> obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
> obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
> diff --git a/drivers/watchdog/meson_sec_wdt.c b/drivers/watchdog/meson_sec_wdt.c
> new file mode 100644
> index 00000000..86bd87c
> --- /dev/null
> +++ b/drivers/watchdog/meson_sec_wdt.c
> @@ -0,0 +1,187 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Copyright (c) 2019 Amlogic, Inc. All rights reserved.
> + * Author: Xingyu Chen <xingyu.chen@...ogic.com>
> + *
> + */
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/types.h>
> +#include <linux/watchdog.h>
> +#include <linux/firmware/meson/meson_sm.h>
> +
> +#define MESON_SIP_WDT_DISABLE 0x1
> +#define MESON_SIP_WDT_ENABLE 0x2
> +#define MESON_SIP_WDT_PING 0x3
> +#define MESON_SIP_WDT_INIT 0x4
> +#define MESON_SIP_WDT_RESETNOW 0x5
> +#define MESON_SIP_WDT_SETTIMEOUT 0x6
> +#define MESON_SIP_WDT_GETTIMELEFT 0x7
> +
> +#define DEFAULT_TIMEOUT 30 /* seconds */
> +
> +/*
> + * Watchdog timer tick is set to 1ms in secfw side, and tick count is
> + * stored in the bit[16-31] of WATCHDOG_CNT register, so the maximum
> + * timeout value is 0xffff ms.
> + */
> +#define MAX_TIMEOUT_MS 0xFFFF
> +
> +struct meson_sec_wdt {
> + struct watchdog_device wdt_dev;
> + struct meson_sm_firmware *fw;
> +};
> +
> +static int meson_sec_wdt_start(struct watchdog_device *wdt_dev)
> +{
> + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> + return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
> + MESON_SIP_WDT_ENABLE, 0, 0, 0, 0);
> +}
> +
> +static int meson_sec_wdt_stop(struct watchdog_device *wdt_dev)
> +{
> + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> + return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
> + MESON_SIP_WDT_DISABLE, 0, 0, 0, 0);
> +}
> +
> +static int meson_sec_wdt_ping(struct watchdog_device *wdt_dev)
> +{
> + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> + return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
> + MESON_SIP_WDT_PING, 0, 0, 0, 0);
> +}
> +
> +static int meson_sec_wdt_set_timeout(struct watchdog_device *wdt_dev,
> + unsigned int timeout)
> +{
> + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> + wdt_dev->timeout = timeout;
> +
> + return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
> + MESON_SIP_WDT_SETTIMEOUT,
> + wdt_dev->timeout, 0, 0, 0);
> +}
> +
> +static unsigned int meson_sec_wdt_get_timeleft(struct watchdog_device *wdt_dev)
> +{
> + int ret;
> + unsigned int timeleft;
> + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> + ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, &timeleft,
> + MESON_SIP_WDT_GETTIMELEFT, 0, 0, 0, 0);
> +
> + if (ret)
> + return ret;
Meh, that doesn't work. I just realized that the return type is unsigned,
so returning a negative error code is pointless. Guess we'll have to
live with returning 0 in this case after all. I wonder if we should
fix the API and return an integer (with negative error code), but that
is a different question.
Sorry for the confusion - I should have noticed that before.
> +
> + return timeleft;
> +}
> +
> +static const struct watchdog_ops meson_sec_wdt_ops = {
> + .start = meson_sec_wdt_start,
> + .stop = meson_sec_wdt_stop,
> + .ping = meson_sec_wdt_ping,
> + .set_timeout = meson_sec_wdt_set_timeout,
> + .get_timeleft = meson_sec_wdt_get_timeleft,
> +};
> +
> +static const struct watchdog_info meson_sec_wdt_info = {
> + .identity = "Meson Secure Watchdog Timer",
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> +};
> +
> +static int __maybe_unused meson_sec_wdt_resume(struct device *dev)
> +{
> + struct meson_sec_wdt *data = dev_get_drvdata(dev);
> +
> + if (watchdog_active(&data->wdt_dev))
> + return meson_sec_wdt_start(&data->wdt_dev);
> +
> + return 0;
> +}
> +
> +static int __maybe_unused meson_sec_wdt_suspend(struct device *dev)
> +{
> + struct meson_sec_wdt *data = dev_get_drvdata(dev);
> +
> + if (watchdog_active(&data->wdt_dev))
> + return meson_sec_wdt_stop(&data->wdt_dev);
> +
> + return 0;
> +}
> +
> +static const struct dev_pm_ops meson_sec_wdt_pm_ops = {
> + SET_SYSTEM_SLEEP_PM_OPS(meson_sec_wdt_suspend, meson_sec_wdt_resume)
> +};
> +
> +static const struct of_device_id meson_sec_wdt_dt_ids[] = {
> + { .compatible = "amlogic,meson-sec-wdt", },
> + { /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, meson_sec_wdt_dt_ids);
> +
> +static int meson_sec_wdt_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct meson_sec_wdt *data;
> + struct device_node *sm_np;
> + int ret;
> +
> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + sm_np = of_parse_phandle(pdev->dev.of_node, "secure-monitor", 0);
> + if (!sm_np) {
> + dev_err(&pdev->dev, "no secure-monitor node\n");
> + return -EINVAL;
> + }
> +
> + data->fw = meson_sm_get(sm_np);
> + of_node_put(sm_np);
> + if (!data->fw)
> + return -EPROBE_DEFER;
> +
> + platform_set_drvdata(pdev, data);
> +
> + data->wdt_dev.parent = dev;
> + data->wdt_dev.info = &meson_sec_wdt_info;
> + data->wdt_dev.ops = &meson_sec_wdt_ops;
> + data->wdt_dev.max_hw_heartbeat_ms = MAX_TIMEOUT_MS;
> + data->wdt_dev.min_timeout = 1;
> + data->wdt_dev.timeout = DEFAULT_TIMEOUT;
> + watchdog_set_drvdata(&data->wdt_dev, data);
> +
> + ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
> + MESON_SIP_WDT_INIT,
> + data->wdt_dev.timeout, 0, 0, 0);
> + if (ret)
> + return ret;
> +
> + watchdog_stop_on_reboot(&data->wdt_dev);
> +
> + return devm_watchdog_register_device(dev, &data->wdt_dev);
> +}
> +
> +static struct platform_driver meson_sec_wdt_driver = {
> + .probe = meson_sec_wdt_probe,
> + .driver = {
> + .name = "meson-sec-wdt",
> + .pm = &meson_sec_wdt_pm_ops,
> + .of_match_table = meson_sec_wdt_dt_ids,
> + },
> +};
> +
> +module_platform_driver(meson_sec_wdt_driver);
> +
> +MODULE_AUTHOR("Xingyu Chen <xingyu.chen@...ogic.com>");
> +MODULE_DESCRIPTION("Amlogic Secure Watchdog Timer Driver");
> +MODULE_LICENSE("Dual MIT/GPL");
>
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