mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
To: krzk@kernel.org
Cc: abd.masalkhi@gmail.com, arnd@arndb.de, conor+dt@kernel.org,
	devicetree@vger.kernel.org, gregkh@linuxfoundation.org,
	krzk+dt@kernel.org, linux-kernel@vger.kernel.org,
	robh@kernel.org
Subject: Re: [PATCH v2 1/3] dt-bindings: Add Device Tree binding for ST M24LR control interface
Date: Mon,  2 Jun 2025 17:23:27 +0000	[thread overview]
Message-ID: <20250602172327.2029611-1-abd.masalkhi@gmail.com> (raw)
In-Reply-To: <3c49628c-00b0-488d-a660-4b904febca1e@kernel.org>

Hi Krzysztof,

Thank you again for yourfeedback, it's been very helpful in
understanding how best to write the binding file represent
this device.

>> A Brief Overview of the Device:
>> 
>> The M24LR series is a dual-interface EEPROM with both I2C and ISO/IEC 15693
>> RF support. While it is technically an EEPROM, it also exposes a control
>> interface over I2C via a second address, which is used to manage features
>> such as password protection, energy harvesting configuration, and UID access.
>> This secondary interface is not memory-mapped like traditional EEPROMs, which
>> is why I initially considered separating the control aspect in the software.
>> 
>> How to Access the EEPROM and the System Parameter Sector?
>> 
>> According to the datasheet for the M24LR04E-R, the E2 bit must be set
>> appropriately in the I2C device select code to distinguish between EEPROM
>> access and control access.
>> 
>> What is E2?
>> E2 is a bit in the I2C device select code. It determines which internal
>> function of the chip is being accessed.
>> 
>> Device Select Code Format:
>> Bit:                b7  b6  b5  b4  b3  b2  b1  b0
>> Value:              1   0   1   0   E2  1   1   R/W
>> 
>> To access the EEPROM memory, E2 (b3) should be 0:
>> 
>> Device Select Code Format:
>> Bit:                b7  b6  b5  b4  b3  b2  b1  b0
>> Value:              1   0   1   0   0  1   1   R/W
>> 
>> To access the system control interface, E2 (b3) should be 1:
>
> So these are just two different addresses. I already commented on this.
> This is not I2C mux but a device with two addresses.

I'd like to clarify one point before proceeding further, If I remove
the i2c-mux usage from the binding file, as your recommendation, does
this also imply that I should stop using the i2c-mux API in my driver
implementation itself? and treat this as a multi-function device, or
Is it acceptable to keep the current driver logic as-is, while limiting
the change to just fixing the binding and device tree representation?

and if only the binding file, should i represent it as the following:

  eeprom-ctl@57 {
  #address-cells = <1>;
  #size-cells = <0>;
  compatible = "st,m24lr04e-r";
  reg = <0x57>;

  }

Best regards,
Abd-Alrhman Masalkhi

  reply	other threads:[~2025-06-02 17:23 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-01 15:30 [PATCH v2 0/3] Add control driver for ST M24LR RFID/NFC EEPROM chips Abd-Alrhman Masalkhi
2025-06-01 15:30 ` [PATCH v2 1/3] dt-bindings: eeprom: Add ST M24LR control interface Abd-Alrhman Masalkhi
2025-06-01 15:42   ` Krzysztof Kozlowski
2025-06-02  3:48     ` [PATCH v2 1/3] dt-bindings: Add Device Tree binding for " Abd-Alrhman Masalkhi
2025-06-02  6:28       ` Krzysztof Kozlowski
2025-06-02 17:23         ` Abd-Alrhman Masalkhi [this message]
2025-06-02 18:11           ` Krzysztof Kozlowski
2025-06-02 17:47             ` Abd-Alrhman Masalkhi
2025-06-01 16:33   ` [PATCH v2 1/3] dt-bindings: eeprom: Add " Rob Herring (Arm)
2025-06-03  5:40     ` Abd-Alrhman Masalkhi
2025-06-03  6:56       ` Krzysztof Kozlowski
2025-06-01 15:30 ` [PATCH v2 2/3] misc: add sysfs control driver for ST M24LR series RFID/NFC chips Abd-Alrhman Masalkhi
2025-06-01 15:30 ` [PATCH v2 3/3] ABI: sysfs: document control attributes for ST M24LR Abd-Alrhman Masalkhi
2025-06-01 15:50 ` [PATCH v2 0/3] Add control driver for ST M24LR RFID/NFC EEPROM chips Greg KH
  -- strict thread matches above, loose matches on Subject: below --
2025-05-31 13:37 [PATCH 1/3] dt-bindings: misc: Add binding for ST M24LR control interface Krzysztof Kozlowski
2025-06-01  7:31 ` [PATCH v2 1/3] dt-bindings: Add Device Tree " Abd-Alrhman Masalkhi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20250602172327.2029611-1-abd.masalkhi@gmail.com \
    --to=abd.masalkhi@gmail.com \
    --cc=arnd@arndb.de \
    --cc=conor+dt@kernel.org \
    --cc=devicetree@vger.kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=krzk+dt@kernel.org \
    --cc=krzk@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=robh@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox

all inboxes | Powered by JetHome®