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

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Message-ID: <775d3cfc-95ca-1dff-d146-64efbdd71e1f@ti.com>
Date:   Wed, 8 Nov 2017 12:38:05 +0530
From:   Keerthy <j-keerthy@...com>
To:     Alexandre Belloni <alexandre.belloni@...e-electrons.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



On Wednesday 08 November 2017 11:57 AM, Alexandre Belloni wrote:
> 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

Okay Alexandre. Thanks for clarifying. Looks good to me.
I have tested on AM437X-GP-EVM.

Regards,
Keerthy

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