[PATCH] sim-qmi: load operator identifier and name from NAS home network

[Aleksander Morgado]

On Fri, Oct 23, 2015 at 1:14 PM, Aleksander Morgado
<aleksander at aleksander.es> wrote:
> On Fri, Oct 23, 2015 at 12:13 AM, Dan Williams <dcbw at redhat.com> wrote:
>> On Thu, 2015-10-22 at 23:30 +0200, Aleksander Morgado wrote:
>>> On Thu, Oct 22, 2015 at 10:45 PM, Dan Williams <dcbw at redhat.com> wrote:
>>> >> Being NAS commands, are these available also when not registered
>>> >> anywhere? E.g. when in low-power mode?
>>> >> I've seen people using these commands to retrieve SIM MCCMNC, but was
>>> >> never sure about them as they were NAS and not DMS.
>>> >
>>> > Tried Gobi 1k and UML290; they both still return the home network when
>>> > in low-power mode.  Also, the Gobi 1k didn't have any antennas connected
>>> > and it still returned the right home network...
>>>
>>> Ah! good then.
>>>
>>> The issue with the MNC length (whether 2 or 3 digits) still affects
>>> this implementation though. Actually, the implementation would not be
>>> ok even for 2 digits, as it's not appending a leading 0 for
>>> single-digit MNCs (e.g. "2141" instead of "21401"):
>>>     operator_id = g_strdup_printf ("%" G_GUINT16_FORMAT "%"
>>> G_GUINT16_FORMAT, mcc, mnc);
>>> It should append leading 0s to the MNC based on whether the MNC is 2
>>> or 3 digit long.
>>
>> Ah, good point.  I'd copied that from qmicli code and I guess it's wrong
>> there, and I didn't catch it here either.
>>
>>> Now, there's a TLV 0x12 "3GPP Home Network MNC" in Get Home Network
>>> that we didn't add yet to libqmi as far as I can tell. It consists of
>>> a sequence of 2 bytes that are read as booleans:
>>>   * 1st byte: whether the network is 3GPP.
>>>   * 2nd byte: if 1st byte is true (net is 3GPP), whether the MNC is 3
>>> digits long.
>>>
>>> Based on this, we could do:
>>>   * If TLV 0x12 is available,  we already got told the MNC length and
>>> we know how many 0s we need to prepend.
>>>   * If TLV 0x12 is not available, we only print 3 digits if MNC is >99
>>> and otherwise 2 digits always.
>>> This logic is already what we do when building MCCMNC from current
>>> serving system, as in common_process_serving_system_3gpp().
>>
>> Works for me, would you mind taking a stab at this?  I have to move on
>> to other stuff tomorrow and early next week...
>
> Sure, I'll try to do it myself during the weekend.

All changes in git master already.

MM now requires libqmi 1.13.5, which is the version bump I did to flag
the availability of the new optional TLV in "Get Home Network". Let me
know if you got any issue with the changes.

Not backported to 1.12.x as we require a libqmi version bump here.
Maybe we should backport your change plus this one?
http://cgit.freedesktop.org/ModemManager/ModemManager/commit/?id=77b6b02fd37cd8d89961dc32814b186639d1bafa

My MC7304 does report this optional TLV, but in my case it doesn't
request 3 digits for MNC:

25 oct 2015, 14:56:40] [Debug] [/dev/cdc-wdm6] Received message (translated)...
>>>>>> QMUX:
>>>>>>   length  = 42
>>>>>>   flags   = 0x80
>>>>>>   service = "nas"
>>>>>>   client  = 3
>>>>>> QMI:
>>>>>>   flags       = "response"
>>>>>>   transaction = 1
>>>>>>   tlv_length  = 30
>>>>>>   message     = "Get Home Network" (0x0025)
>>>>>> TLV:
>>>>>>   type       = "Result" (0x02)
>>>>>>   length     = 4
>>>>>>   value      = 00:00:00:00
>>>>>>   translated = SUCCESS
>>>>>> TLV:
>>>>>>   type       = "Home Network" (0x01)
>>>>>>   length     = 15
>>>>>>   value      = D6:00:01:00:0A:76:6F:64:61:66:6F:6E:65:20:45
>>>>>>   translated = [ mcc = '214' mnc = '1' description = 'vodafone E' ]
>>>>>> TLV:
>>>>>>   type       = "Home Network 3GPP MNC" (0x12)
>>>>>>   length     = 2
>>>>>>   value      = 01:00
>>>>>>   translated = [ is_3gpp = 'yes' includes_pcs_digit = 'no' ]

[/dev/cdc-wdm6] Successfully got home network:
Home network:
MCC: '214'
MNC: '1'
Description: 'vodafone E'

Cheers!

-- 
Aleksander
https://aleksander.es