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Date:   Sat, 14 May 2022 14:56:32 +0200
From:   Alexandre Belloni <alexandre.belloni@bootlin.com>
To:     Huacai Chen <chenhuacai@loongson.cn>
Cc:     Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Airlie <airlied@linux.ie>,
        Jonathan Corbet <corbet@lwn.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-arch@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
        Yanteng Si <siyanteng@loongson.cn>,
        Huacai Chen <chenhuacai@gmail.com>,
        Guo Ren <guoren@kernel.org>, Xuerui Wang <kernel@xen0n.name>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [PATCH V10 16/22] LoongArch: Add misc common routines
Message-ID: <Yn+nAFCA/+Wm+rC/@mail.local>
References: <20220514080402.2650181-1-chenhuacai@loongson.cn>
 <20220514080402.2650181-17-chenhuacai@loongson.cn>
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In-Reply-To: <20220514080402.2650181-17-chenhuacai@loongson.cn>
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Hi,

On 14/05/2022 16:03:56+0800, Huacai Chen wrote:
> diff --git a/arch/loongarch/kernel/rtc.c b/arch/loongarch/kernel/rtc.c
> new file mode 100644
> index 000000000000..d7568385219f
> --- /dev/null
> +++ b/arch/loongarch/kernel/rtc.c
> @@ -0,0 +1,36 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <asm/loongson.h>
> +
> +#define RTC_TOYREAD0    0x2C
> +#define RTC_YEAR        0x30
> +
> +unsigned long loongson_get_rtc_time(void)
> +{
> +	unsigned int year, mon, day, hour, min, sec;
> +	unsigned int value;
> +
> +	value = ls7a_readl(LS7A_RTC_REG_BASE + RTC_TOYREAD0);
> +	sec = (value >> 4) & 0x3f;
> +	min = (value >> 10) & 0x3f;
> +	hour = (value >> 16) & 0x1f;
> +	day = (value >> 21) & 0x1f;
> +	mon = (value >> 26) & 0x3f;
> +	year = ls7a_readl(LS7A_RTC_REG_BASE + RTC_YEAR);
> +
> +	year = 1900 + year;
> +
> +	return mktime64(year, mon, day, hour, min, sec);
> +}
> +
> +void read_persistent_clock64(struct timespec64 *ts)
> +{

This should rather be implemented in a proper rtc driver and then have
userspace set the system time or use hctosys.

> +	ts->tv_sec = loongson_get_rtc_time();
> +	ts->tv_nsec = 0;
> +}
> -- 
> 2.27.0
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com