From: Xingyu Chen <xingyu.chen@amlogic.com>
To: Guenter Roeck <linux@roeck-us.net>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
Kevin Hilman <khilman@baylibre.com>,
Neil Armstrong <narmstrong@baylibre.com>
Cc: Qianggui Song <qianggui.song@amlogic.com>,
linux-watchdog@vger.kernel.org,
Jianxin Pan <jianxin.pan@amlogic.com>,
linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
Jian Hu <jian.hu@amlogic.com>,
linux-amlogic@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
Jerome Brunet <jbrunet@baylibre.com>
Subject: Re: [PATCH 3/4] watchdog: add meson secure watchdog driver
Date: Tue, 15 Oct 2019 13:45:47 +0800 [thread overview]
Message-ID: <753ce57b-f271-2d21-7d55-b0014f21b39c@amlogic.com> (raw)
In-Reply-To: <1c2ac5b1-4ba4-b4e9-8775-b1597d9aae99@roeck-us.net>
Hi, Guenter
On 2019/10/14 21:49, Guenter Roeck wrote:
> On 10/14/19 4:42 AM, Xingyu Chen wrote:
>> Hi, Guenter
>> Thanks for your review.
>>
>> On 2019/10/12 22:29, Guenter Roeck wrote:
>>> On 10/12/19 3:05 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@amlogic.com>
>>>> ---
>>>> drivers/watchdog/Kconfig | 16 +++
>>>> drivers/watchdog/Makefile | 1 +
>>>> drivers/watchdog/meson_sec_wdt.c | 205
>>>> +++++++++++++++++++++++++++++++++++++++
>>>> 3 files changed, 222 insertions(+)
>>>> create mode 100644 drivers/watchdog/meson_sec_wdt.c
>>>>
>>>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>>>> index 58e7c10..e6b0707 100644
>>>> --- a/drivers/watchdog/Kconfig
>>>> +++ b/drivers/watchdog/Kconfig
>>>> @@ -826,6 +826,22 @@ 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 ARCH_MESON || COMPILE_TEST
>>>
>>> Did you try COMPILE_TEST (eg allmodconfig) on, say x86_64 ?
>>> AFAICS the meson sm calls are only available if MESON_SM is
>>> enabled, and that depends on both ARCH_MESON and ARM64_4K_PAGES.
>>> This dependency is not expressed here, and neither is enabled
>>> with COMPILE_TEST.Sorry, I have't done this kind of test before for
>>> this patchset. There
>> is a kernel build error which related to the current driver when i try
>> to use allmodconfig with x86. I will fix it by adding "depends on
>> MESON_SM" in next version.
>>>
>>>> + 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..2b5357c
>>>> --- /dev/null
>>>> +++ b/drivers/watchdog/meson_sec_wdt.c
>>>> @@ -0,0 +1,205 @@
>>>> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
>>>> +/*
>>>> + * Copyright (c) 2019 Amlogic, Inc. All rights reserved.
>>>> + * Author: Xingyu Chen <xingyu.chen@amlogic.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)
>>>> +{
>>>> + int ret;
>>>> + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>>>> +
>>>> + ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
>>>> + MESON_SIP_WDT_ENABLE, 0, 0, 0, 0); > + if (ret)
>>>> + return ret;
>>>> +
>>>> + return 0;
>>>
>>> This is equivalent to
>>> return ret;
>>> or even
>>> return meson_sm_call(...);
>>> I will fix it in next version.
>>>> +}
>>>> +
>>>> +static int meson_sec_wdt_stop(struct watchdog_device *wdt_dev)
>>>> +{
>>>> + int ret;
>>>> + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>>>> +
>>>> + ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
>>>> + MESON_SIP_WDT_DISABLE, 0, 0, 0, 0);
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + return 0;
>>>
>>> Same as above.
>> I will fix it in next version.
>>>
>>>> +}
>>>> +
>>>> +static int meson_sec_wdt_ping(struct watchdog_device *wdt_dev)
>>>> +{
>>>> + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>>>> +
>>>> + meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
>>>> + MESON_SIP_WDT_PING, 0, 0, 0, 0);
>>>> +
>>>> + return 0;
>>>
>>> Why ignore errors ?
>> I will fix it as above.
>>>
>>>> +}
>>>> +
>>>> +static int meson_sec_wdt_set_timeout(struct watchdog_device *wdt_dev,
>>>> + unsigned int timeout)
>>>> +{
>>>> + int ret;
>>>> + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>>>> +
>>>> + wdt_dev->timeout = timeout;
>>>> + meson_sec_wdt_ping(wdt_dev);
>>>> +
>>>
>>> Unconditionally ? Also, the core does that after setting the
>>> timeoutIt is used to avoid watchdog timer expire once the timeout is
>>> updated,
>> and that the watchdog_ping from core not been invoked. If it is
>> considered useless, i will remove it.
>>
>
> As mentioned, the core sends a ping immediately after the update.
Ok, I will remove it in next version, Thanks
>
>>>
>>>> + ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
>>>> + MESON_SIP_WDT_SETTIMEOUT,
>>>> + wdt_dev->timeout, 0, 0, 0);
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + return 0;
>>>
>>> same as above.
>> I will fix it in next version.
>>>
>>>> +}
>>>> +
>>>> +static unsigned int meson_sec_wdt_get_timeleft(struct
>>>> watchdog_device *wdt_dev)
>>>> +{
>>>> + int ret;
>>>> + 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 0;
>>>
>>> Really ? Why ? 0 is most definitely incorrect here.
>> I just want to return a invalid value after I failed to get valid
>> timeleft. Could you tell me what is corrent value ?
>
> Why not return the error ?
I will return the error in next version, Thanks for your suggestion.
>
>>>
>>>> +
>>>> + 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))
>>>> + meson_sec_wdt_start(&data->wdt_dev);
>>>
>>> No error return ?
>> I will fix it in next version
>>>
>>>> +
>>>> + 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))
>>>> + meson_sec_wdt_stop(&data->wdt_dev);
>>>
>>> No error return ?
>> same as above
>>>
>>>> +
>>>> + 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 -ENODEV;
>>>
>>> ENODEV is wrong here.
>> I found some drivers use the ENODEV in this case, Eg:
>> - ./watchdog/ts4800_wdt.c -122
>> - ./nvmem/meson-efuse.c -55
>> ...
>>
>> Could you tell me which error code is more suitable in this case ?
>>
>
> Yes, I understand, with Millions of LOC to choose from, you will
> find examples for everything somewhere in the Linux kernel.
> That doesn't mean it is a good idea.
>
> The property is listed as mandatory, so EINVAL would probably be
> most appropriate, unless DT handling proposes a different error code
> in such situations.
Thanks for your help, I will replace ENODEV with EINVAL in next version.
>
>>>
>>>> + }
>>>> +
>>>> + data->fw = meson_sm_get(sm_np);
>>>> + of_node_put(sm_np);
>>>> + if (!data->fw)
>>>> + return -EPROBE_DEFER;
>>>
>>> How do you know ?
>> The fw pointer is static variable which is initialized to NULL. if it
>> is equal to NULL, and indicate the meson_sm driver is not registered,
>> then wdt driver use EPROBE_DEFER to defer probe.
>>>
>>>> +
>>>> + 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);
>>>> +
>>> No watchdog_init_timeout() ? Any special reason for not supporting
>>> to set the timeout with a devicetree property ?
>> I want to keep consistency with previous meson watchdog driver.
>> as follows:
>> - meson_gxbb_wdt.c
>> - meson_wdt.c
>>
>
> Yes, again, it is possible to find examples for pretty much everything
> in the linux kernel. But, sure, as you wish.
Thank you again.
>
> Guenter
>
> .
>
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next prev parent reply other threads:[~2019-10-15 5:46 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-12 10:05 [PATCH 0/4] add meson secure watchdog driver Xingyu Chen
2019-10-12 10:05 ` [PATCH 1/4] firmware: meson_sm: add new SMC ID support for accessing secure watchdog Xingyu Chen
2019-10-12 10:05 ` [PATCH 2/4] dt-bindings: watchdog: add new binding for meson " Xingyu Chen
2019-10-12 10:05 ` [PATCH 3/4] watchdog: add meson secure watchdog driver Xingyu Chen
2019-10-12 14:29 ` Guenter Roeck
2019-10-14 11:42 ` Xingyu Chen
2019-10-14 13:49 ` Guenter Roeck
2019-10-15 5:45 ` Xingyu Chen [this message]
2019-10-12 10:05 ` [PATCH 4/4] arm64: dts: a1: add secure watchdog controller Xingyu Chen
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