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Subject: Re: [PATCH v12 1/1] Add support for IPMB driver
To:     Asmaa Mnebhi <Asmaa@mellanox.com>,
        "minyard@acm.org" <minyard@acm.org>,
        "wsa@the-dreams.de" <wsa@the-dreams.de>,
        Vadim Pasternak <vadimp@mellanox.com>,
        Michael Shych <michaelsh@mellanox.com>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>
References: <cover.1560192707.git.Asmaa@mellanox.com>
 <319690553a0da2a1e80b400941341081b383e5f1.1560192707.git.Asmaa@mellanox.com>
 <54f3c0e0-7aaa-9078-5328-50e8f709ebae@infradead.org>
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From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <6488312d-eb9a-381a-a529-c7cfa6f04ce6@infradead.org>
Date:   Tue, 11 Jun 2019 09:13:56 -0700
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On 6/11/19 6:28 AM, Asmaa Mnebhi wrote:
> Hello Randy,
> 
> Please refer to the slave-interface linux documentation:
> https://www.kernel.org/doc/Documentation/i2c/slave-interface

OK, thanks.

> Thanks.
> Asmaa
> 
> -----Original Message-----
> From: Randy Dunlap <rdunlap@infradead.org> 
> Sent: Monday, June 10, 2019 5:56 PM
> To: Asmaa Mnebhi <Asmaa@mellanox.com>; minyard@acm.org; wsa@the-dreams.de; Vadim Pasternak <vadimp@mellanox.com>; Michael Shych <michaelsh@mellanox.com>
> Cc: linux-kernel@vger.kernel.org; linux-i2c@vger.kernel.org
> Subject: Re: [PATCH v12 1/1] Add support for IPMB driver
> 
> On 6/10/19 11:57 AM, Asmaa Mnebhi wrote:
>> Support receiving IPMB requests on a Satellite MC from the BMC.
>> Once a response is ready, this driver will send back a response to the 
>> BMC via the IPMB channel.
>>
>> Signed-off-by: Asmaa Mnebhi <Asmaa@mellanox.com>
>> Acked-by: vadimp@mellanox.com
>> ---
>>  Documentation/IPMB.txt           | 103 +++++++++++
>>  drivers/char/ipmi/Kconfig        |   8 +
>>  drivers/char/ipmi/Makefile       |   1 +
>>  drivers/char/ipmi/ipmb_dev_int.c | 364 
>> +++++++++++++++++++++++++++++++++++++++
>>  4 files changed, 476 insertions(+)
>>  create mode 100644 Documentation/IPMB.txt  create mode 100644 
>> drivers/char/ipmi/ipmb_dev_int.c
>>
>> diff --git a/Documentation/IPMB.txt b/Documentation/IPMB.txt new file 
>> mode 100644 index 0000000..7160d53
>> --- /dev/null
>> +++ b/Documentation/IPMB.txt
>> @@ -0,0 +1,103 @@
> 
> [...]
> 
>> +Instantiate the device
>> +----------------------
>> +
>> +After loading the driver, you can instantiate the device as described 
>> +in 'Documentation/i2c/instantiating-devices'.
>> +If you have multiple BMCs, each connected to your Satellite MC via a 
>> +different I2C bus, you can instantiate a device for each of those 
>> +BMCs.
>> +The name of the instantiated device contains the I2C bus number 
>> +associated with it as follows:
>> +
>> +BMC1 ------ IPMB/I2C bus 1 ---------|   /dev/ipmb-1
>> +				Satellite MC
>> +BMC1 ------ IPMB/I2C bus 2 ---------|   /dev/ipmb-2
>> +
>> +For instance, you can instantiate the ipmb-dev-int device from user 
>> +space at the 7 bit address 0x10 on bus 2:
>> +
>> +  # echo ipmb-dev 0x1010 > /sys/bus/i2c/devices/i2c-2/new_device
> 
> This is confusing.
> 
> Can you clarify how the 7-bit address is extracted from that hex number?
> Is the 7-bit address repeated (duplicated)?
> Is the 7-bit address the low order (low bits) 0x10 or the 0x10 at bits
> 15-8 (or 14-8)?
> 
>> +This will create the device file /dev/ipmb-2, which can be accessed 
>> +by the user space program. The device needs to be instantiated before 
>> +running the user space program.
> 
> thanks.
> --
> ~Randy
> 


-- 
~Randy