From: Keerthy <j-keerthy@ti.com>
To: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: Sekhar Nori <nsekhar@ti.com>, <linux-rtc@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
Linux OMAP List <linux-omap@vger.kernel.org>
Subject: Re: [PATCH] rtc: omap: Support scratch registers
Date: Wed, 8 Nov 2017 14:02:31 +0530 [thread overview]
Message-ID: <c24e76cc-ba52-3d26-7dce-5c9ed7e68db1@ti.com> (raw)
In-Reply-To: <79f52c27-1c6a-c4ec-9635-d05eec635661@ti.com>
On Wednesday 08 November 2017 02:01 PM, Keerthy wrote:
>
>
> On Wednesday 08 November 2017 01:51 PM, Alexandre Belloni wrote:
>> On 08/11/2017 at 13:36:15 +0530, Keerthy wrote:
>>>
>>>
>>> On Wednesday 08 November 2017 12:46 PM, Alexandre Belloni wrote:
>>>> On 08/11/2017 at 12:38:05 +0530, Keerthy wrote:
>>>>>
>>>>>
>>>>> 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.
>>>>>
>>>>
>>>> If needed, you can define nvmem cells (and I guess that is what you
>>>> want):
>>>> http://elixir.free-electrons.com/linux/latest/source/Documentation/devicetree/bindings/nvmem/nvmem.txt
>>>
>>> With this patch we cannot still use nvmem_device_write and
>>> nvmem_device_read as the nvmem_device is still not registered.
>>>
>>> How can a driver write to scratch pad registers? Should we be calling
>>> nvmem_register in the probe?
>>
>> It is not needed, it is registered by rtc_nvmem_register().
>
> Let me go through the chain:
>
> rtc_register_device -> __rtc_register_device --> rtc_nvmem_register ->
> rtc_nvram_register
>
> I am seeing that for rtc-omap driver there is rtc_register_device call
I mean there NO rtc_register_device call.
> and i see that rtc_nvmem_register is not getting called.
>
> Should we add rtc_register_device in probe of rtc-omap?
>
>>
>> nvmem_device_read/write are working because that is what I'm using to
>> implement the old sysfs ABI with rtc_nvram_read/write.
>>
next prev parent reply other threads:[~2017-11-08 8:32 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-31 16:27 [PATCH] rtc: omap: Support scratch registers Alexandre Belloni
2017-11-06 6:55 ` Sekhar Nori
2017-11-06 6:59 ` Keerthy
2017-11-06 7:02 ` Sekhar Nori
2017-11-08 6:00 ` Keerthy
2017-11-08 6:27 ` Alexandre Belloni
2017-11-08 7:08 ` Keerthy
2017-11-08 7:16 ` Alexandre Belloni
2017-11-08 8:06 ` Keerthy
2017-11-08 8:21 ` Alexandre Belloni
2017-11-08 8:31 ` Keerthy
2017-11-08 8:32 ` Keerthy [this message]
2017-11-08 8:35 ` Alexandre Belloni
2017-11-08 8:48 ` Keerthy
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