Message-ID: <558A7EBE.5030108@i2se.com>
Date: Wed, 24 Jun 2015 11:56:14 +0200
From: Stefan Wahren <stefan.wahren@i2se.com>
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To: maitysanchayan@gmail.com
CC: srinivas.kandagatla@linaro.org, maxime.ripard@free-electrons.com,
        linux-arm-kernel@lists.infradead.org, stefan@agner.ch,
        kernel@pengutronix.de, linux-kernel@vger.kernel.org,
        shawn.guo@linaro.org, arnd@arndb.de
Subject: Re: [RFC PATCH v6 2/2] nvmem: Add Vybrid OCOTP and OCROM support
References: <cover.1435066190.git.maitysanchayan@gmail.com> <b4a52f6c229bdabbfe9d21c03cb04593dde33ec4.1435066190.git.maitysanchayan@gmail.com> <1037424954.250728.1435087901102.JavaMail.open-xchange@oxbsltgw00.schlund.de> <20150624051903.GA11753@Sanchayan-Arch.toradex.int>
In-Reply-To: <20150624051903.GA11753@Sanchayan-Arch.toradex.int>
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Hi Sanchayan,

Am 24.06.2015 um 07:19 schrieb maitysanchayan@gmail.com:
> On 15-06-23 21:31:41, Stefan Wahren wrote:
>> Hi Sanchayan,
>>
>>> Sanchayan Maity <maitysanchayan@gmail.com> hat am 23. Juni 2015 um 15:44
>>> geschrieben:
>>>
>>>
>>> The patch adds support for the On Chip One Time Programmable Peripheral
>>> (OCOTP) and On Chip ROM (OCROM) support.
>>>
>>> On Vybrid OCOTP contain data like SoC ID, MAC address and OCROM has the
>>> revision ID.
>>>
>>> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
>>> ---
>>> drivers/nvmem/Kconfig | 11 +++++++++
>>> drivers/nvmem/Makefile | 2 ++
>>> drivers/nvmem/vf610-ocotp.c | 60 +++++++++++++++++++++++++++++++++++++++++++++
>>> 3 files changed, 73 insertions(+)
>>> create mode 100644 drivers/nvmem/vf610-ocotp.c
>>>
>>> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
>>> index 17f1a57..557c1e0 100644
>>> --- a/drivers/nvmem/Kconfig
>>> +++ b/drivers/nvmem/Kconfig
>>> @@ -33,4 +33,15 @@ config NVMEM_SUNXI_SID
>>> This driver can also be built as a module. If so, the module
>>> will be called eeprom-sunxi-sid.
>>>
>>> +config NVMEM_VF610_OCOTP
>>> + tristate "VF610 SoCs OCOTP support"
>>> + depends on SOC_VF610
>>> + select REGMAP_MMIO
>> how do you come to the conclusion that Vybrid On-Chip OTP is accessable via
>> MMIO?
> Frankly speaking I just changed the naming conventions and followed the qfrom
> and sunxi sid examples in Srinivas's patches.
>
> I just tested it without the "select REGMAP_MMIO" and it works just fine.
>
> - Sanchayan.

sorry for the confusion. My question refers to the whole driver
implementation not only to the REGMAP_MMIO.

According to

Vybrid Reference Manual F-Series
Document Number: VYBRIDRM
Rev 7, 06/2014

35.5 OCOTP memory map/register definition

the memory region is organized in control and shadow registers. I'm very
sceptical that using REGMAP_MMIO is the right way for accessing the OCOTP.

It possible that it works in your case. But in the case the lock bits
are set the driver won't work correctly.

Stefan
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