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Message-ID: <2e633e46-ac59-495d-9ecd-46c34d2d3242@oss.nxp.com>
Date: Wed, 12 Feb 2025 10:11:35 +0200
From: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>
To: Frank Li <Frank.li@....com>
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>,
Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, Catalin Marinas
<catalin.marinas@....com>, Will Deacon <will@...nel.org>,
linux-rtc@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
NXP S32 Linux <s32@....com>, imx@...ts.linux.dev,
Christophe Lizzi <clizzi@...hat.com>, Alberto Ruiz <aruizrui@...hat.com>,
Enric Balletbo <eballetb@...hat.com>, Bogdan Hamciuc
<bogdan.hamciuc@....com>, Ghennadi Procopciuc <Ghennadi.Procopciuc@....com>
Subject: Re: [PATCH v7 2/4] rtc: s32g: add NXP S32G2/S32G3 SoC support
On 2/11/2025 7:07 PM, Frank Li wrote:
> On Tue, Feb 11, 2025 at 01:25:38PM +0200, Ciprian Marian Costea wrote:
>> On 2/7/2025 10:16 PM, Frank Li wrote:
>>> On Fri, Feb 07, 2025 at 06:38:06PM +0200, Ciprian Costea wrote:
>>>> From: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>
>>>>
>>>> Add a RTC driver for NXP S32G2/S32G3 SoCs.
>>>>
>>>> RTC tracks clock time during system suspend. It can be a wakeup source
>>>> for the S32G2/S32G3 SoC based boards.
>>>>
>>>> The RTC module from S32G2/S32G3 is not battery-powered and it is not kept
>>>> alive during system reset.
>>>>
>>>> Co-developed-by: Bogdan Hamciuc <bogdan.hamciuc@....com>
>>>> Signed-off-by: Bogdan Hamciuc <bogdan.hamciuc@....com>
>>>> Co-developed-by: Ghennadi Procopciuc <Ghennadi.Procopciuc@....com>
>>>> Signed-off-by: Ghennadi Procopciuc <Ghennadi.Procopciuc@....com>
>>>> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>
>>>> ---
>>>> drivers/rtc/Kconfig | 11 ++
>>>> drivers/rtc/Makefile | 1 +
>>>> drivers/rtc/rtc-s32g.c | 383 +++++++++++++++++++++++++++++++++++++++++
>>>> 3 files changed, 395 insertions(+)
>>>> create mode 100644 drivers/rtc/rtc-s32g.c
>>>>
>>>> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
>>>> index 0bbbf778ecfa..510dc2db745d 100644
>>>> --- a/drivers/rtc/Kconfig
>>>> +++ b/drivers/rtc/Kconfig
>>>> @@ -2103,4 +2103,15 @@ config RTC_DRV_AMLOGIC_A4
>>>> This driver can also be built as a module. If so, the module
>>>> will be called "rtc-amlogic-a4".
>>>>
>>>> +config RTC_DRV_S32G
>>>> + tristate "RTC driver for S32G2/S32G3 SoCs"
>>>> + depends on ARCH_S32 || COMPILE_TEST
>>>> + depends on COMMON_CLK
>>>> + help
>>>> + Say yes to enable RTC driver for platforms based on the
>>>> + S32G2/S32G3 SoC family.
>>>> +
>>>> + This RTC module can be used as a wakeup source.
>>>> + Please note that it is not battery-powered.
>>>> +
>>>> endif # RTC_CLASS
>>>> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
>>>> index 489b4ab07068..e4b616ecd5ce 100644
>>>> --- a/drivers/rtc/Makefile
>>>> +++ b/drivers/rtc/Makefile
>>>> @@ -161,6 +161,7 @@ obj-$(CONFIG_RTC_DRV_RX8111) += rtc-rx8111.o
>>>> obj-$(CONFIG_RTC_DRV_RX8581) += rtc-rx8581.o
>>>> obj-$(CONFIG_RTC_DRV_RZN1) += rtc-rzn1.o
>>>> obj-$(CONFIG_RTC_DRV_RENESAS_RTCA3) += rtc-renesas-rtca3.o
>>>> +obj-$(CONFIG_RTC_DRV_S32G) += rtc-s32g.o
>>>> obj-$(CONFIG_RTC_DRV_S35390A) += rtc-s35390a.o
>>>> obj-$(CONFIG_RTC_DRV_S3C) += rtc-s3c.o
>>>> obj-$(CONFIG_RTC_DRV_S5M) += rtc-s5m.o
>>>> diff --git a/drivers/rtc/rtc-s32g.c b/drivers/rtc/rtc-s32g.c
>>>> new file mode 100644
>>>> index 000000000000..3244b23c533e
>>>> --- /dev/null
>>>> +++ b/drivers/rtc/rtc-s32g.c
>>>
>>> ...
>>>
>>>> +
>>>> +static int s32g_rtc_suspend(struct device *dev)
>>>> +{
>>>> + struct rtc_priv *priv = dev_get_drvdata(dev);
>>>> + u32 apival = readl(priv->rtc_base + APIVAL_OFFSET);
>>>> +
>>>> + /* RTC registers are being reset in suspend.
>>>> + * Thus store standby time.
>>>> + */
>>>> + if (check_add_overflow(priv->sleep_sec, div64_u64(apival, priv->rtc_hz),
>>>> + &priv->sleep_sec)) {
>>>> + dev_warn(dev, "Overflow on sleep cycles occurred. Resetting to 0.\n");
>>>> + priv->sleep_sec = 0;
>>>> + }
>>>
>>> Strange. If RTC register are reset in suspend. How do it wake up system?
>>>
>>> Frank
>>>
>>
>> Hello Frank,
>>
>> I believe the transition between resume to run is a reset event. This would
>> lead to the RTC registers being reset after resume from suspend (triggered
>> via Suspend to RAM).
>
> It is weird design. I suppose it should be design error. (any errata for
> it).
>
> Frank
>
Unfortunately I could not find any such errata. But this behaviour (RTC
registers being reset) is what I see when resuming from Suspend to RAM
operations.
Regards,
Ciprian
>>
>> On the other hand, the RTC is kept on during suspend for as long as its been
>> set up (for example via rtcwake -s), thus waking up the sistem via an API
>> interrupt.
>>
>> Regards,
>> Ciprian
>>
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int s32g_rtc_resume(struct device *dev)
>>>> +{
>>>> + struct rtc_priv *priv = dev_get_drvdata(dev);
>>>> +
>>>> + return rtc_clk_src_setup(priv);
>>>> +}
>>>> +
>>>> +static const struct of_device_id rtc_dt_ids[] = {
>>>> + { .compatible = "nxp,s32g2-rtc", .data = &rtc_s32g2_data},
>>>> + { /* sentinel */ },
>>>> +};
>>>> +
>>>> +static DEFINE_SIMPLE_DEV_PM_OPS(s32g_rtc_pm_ops,
>>>> + s32g_rtc_suspend, s32g_rtc_resume);
>>>> +
>>>> +static struct platform_driver s32g_rtc_driver = {
>>>> + .driver = {
>>>> + .name = "s32g-rtc",
>>>> + .pm = pm_sleep_ptr(&s32g_rtc_pm_ops),
>>>> + .of_match_table = rtc_dt_ids,
>>>> + },
>>>> + .probe = s32g_rtc_probe,
>>>> +};
>>>> +module_platform_driver(s32g_rtc_driver);
>>>> +
>>>> +MODULE_AUTHOR("NXP");
>>>> +MODULE_DESCRIPTION("NXP RTC driver for S32G2/S32G3");
>>>> +MODULE_LICENSE("GPL");
>>>> --
>>>> 2.45.2
>>>>
>>
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