linux-kernel - Re: [PATCH] rtc: omap: Support scratch registers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20171108062738.cml7qaek324rvc4e@piout.net>
Date:   Wed, 8 Nov 2017 07:27:38 +0100
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     Keerthy <j-keerthy@...com>
Cc:     Sekhar Nori <nsekhar@...com>, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Linux OMAP List <linux-omap@...r.kernel.org>
Subject: Re: [PATCH] rtc: omap: Support scratch registers

Hi,

On 08/11/2017 at 11:30:45 +0530, Keerthy wrote:
> >>> +static int omap_rtc_scratch_read(void *priv, unsigned int offset, void *_val,
> >>> +				 size_t bytes)
> >>> +{
> >>> +	struct omap_rtc	*rtc = priv;
> >>> +	u32 *val = _val;
> >>> +	int i;
> >>> +
> >>> +	for (i = 0; i < bytes / 4; i++)
> >>> +		val[i] = rtc_readl(rtc,
> >>> +				   OMAP_RTC_SCRATCH0_REG + offset + (i * 4));
> 
> Can the offset be the Scratch register number instead of bytes offset?
> More intuitive to me.
> 
> So that one can request using offset as 0, 1, 2 instead of 0, 4, 8?
> 

Well, the offset is coming from the nvmem core, itself getting it from
the Linux file API (and it is in bytes). However, you have the guarantee
that it will be aligned on a word, see:
http://elixir.free-electrons.com/linux/latest/source/drivers/nvmem/core.c#L88

> The above can be:
> rtc_readl(rtc, OMAP_RTC_SCRATCH0_REG + (offset + i) * 4), val[i]);
> 
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com