From: "H. Nikolaus Schaller" <hns@goldelico.com>
To: Rob Herring <robh+dt@kernel.org>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
"Benoît Cousson" <bcousson@baylibre.com>,
"Tony Lindgren" <tony@atomide.com>,
"Russell King" <linux@armlinux.org.uk>,
"Thierry Reding" <treding@nvidia.com>,
"Jonathan Cameron" <jic23@kernel.org>,
"Maxime Ripard" <maxime.ripard@free-electrons.com>,
"Jarkko Sakkinen" <jarkko.sakkinen@linux.intel.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-omap <linux-omap@vger.kernel.org>,
"Discussions about the Letux Kernel"
<letux-kernel@openphoenux.org>,
kernel@pyra-handheld.com, "Marcel Holtmann" <marcel@holtmann.org>
Subject: Re: [RFC 0/3] misc: new serdev based drivers for w2sg00x4 GPS module and w2cbw003 wifi/bluetooth
Date: Tue, 23 May 2017 15:49:17 +0200 [thread overview]
Message-ID: <889E8F7F-FC0F-490E-B924-D04D9F4D3402@goldelico.com> (raw)
In-Reply-To: <CAL_JsqK5NxL+rHU2enW0Lo+e+HThp-iK3hpW-UxeFREbivRZOw@mail.gmail.com>
Hi Rob,
> Am 23.05.2017 um 15:10 schrieb Rob Herring <robh+dt@kernel.org>:
>
> +Marcel
Good!
>
> On Tue, May 23, 2017 at 7:48 AM, H. Nikolaus Schaller <hns@goldelico.com> wrote:
>> Hi Rob,
>>
>>> Am 23.05.2017 um 14:28 schrieb Rob Herring <robh+dt@kernel.org>:
>>>
>>> On Tue, May 23, 2017 at 12:43 AM, H. Nikolaus Schaller
>>> <hns@goldelico.com> wrote:
>>>> Hi Rob,
>>>>
>>>>> Am 23.05.2017 um 04:26 schrieb Rob Herring <robh+dt@kernel.org>:
>>>>>
>>>>> On Sun, May 21, 2017 at 5:44 AM, H. Nikolaus Schaller <hns@goldelico.com> wrote:
>>>>>> Since our proposed API was not acceptable and the new serdev API has arrived in 4.11 kernels,
>>>>>> we finally took the challenge to update the w2sg and w2cbw drivers to use the serdev API.
>>>>>>
>>>>>> The approach is to write a "man in the middle" driver which is on one side a serdev client
>>>>>> which directly controls the UART where the device is connected to and on the other side
>>>>>> presents a new tty port so that user-space software can talk to the chips as if they would
>>>>>> directly talk to the UART of the SoC (e.g. ttyO1). This is similar to connecting to a remote
>>>>>> serial device e.g. through USB (ttyACM) or Bluetooth UART profiles.
>>>>>>
>>>>>> For example gpsd or hciattach expect a /dev/tty they can control (flow control, baud rate
>>>>>> etc.).
>>>>>
>>>>> I understand from the prior discussion why you want to pass the data
>>>>> thru for gps, but why do you need to do that for BT?
>>>>
>>>> Because we otherwise can't turn on power when /dev/ttyBT0 is opened and turn off when it
>>>> is closed. I.e. it should not be powered unless someone does a hciattach /dev/ttyBT0. And it
>>>> should be turned off by a killall hciattach.
>>>
>>> Still, you can do power control within BT HCI drivers.
>>
>> We do not use any driver for bluetooth. We just start hciattach on demand.
>> And afaik there is no plugin mechanism for adding power control to hciattach.
>
> You don't need hciattach. All userspace has to do for kernel BT
> drivers is "hciconfig hci0 up|down".
Hm. Well:
root@letux:~# hciconfig hci0 up
Can't get device info: No such device
root@letux:~#
I wonder how I can tell hciconfig about the UART port if not by running hciattach /dev/ttyBT0?
>
>> Or do you have a link to what you think about?
>
> Look at the nokia BT or TI (HCI_LL) BT drivers. Those both have f/w
> downloading and some GPIO controls. Given that this module is based on
> Marvell chipset, I'd expect you need to add serdev support to
> hci_mrvl.c.
The w2cb003 has a Marvell WiFi (libertas) but a CSR Bluetooth side.
It has built-in firmware and already talks serial HCI over simple UART right
after power-on. This is why our serdev driver has no firmware download.
>
>>> You wouldn't be
>>> limited to just open/close, but can handle suspend/resume as well.
>>
>> Well, it does not look as if we need more than open/close since suspend/resume
>> is already handled by the regulator driver. We just need to keep it powered off
>> if there is no user-space client.
>
> Okay.
>
> Rob
BR,
Nikolaus
next prev parent reply other threads:[~2017-05-23 13:49 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-21 10:44 [RFC 0/3] misc: new serdev based drivers for w2sg00x4 GPS module and w2cbw003 wifi/bluetooth H. Nikolaus Schaller
2017-05-21 10:44 ` [RFC 1/3] DTS: gta04: add serdev nodes for w2sg00x4, w2cbw etc H. Nikolaus Schaller
2017-05-21 10:44 ` [RFC 2/3] misc: Add w2sg0004 (gps receiver) power control driver H. Nikolaus Schaller
2017-05-21 10:48 ` H. Nikolaus Schaller
2017-05-30 23:09 ` Rob Herring
2017-06-06 18:50 ` H. Nikolaus Schaller
2017-06-07 7:34 ` Ladislav Michl
2017-06-07 10:08 ` H. Nikolaus Schaller
2017-05-21 10:44 ` [RFC 3/3] misc: Add w2cbw003 (wifi/bluetooth) " H. Nikolaus Schaller
2017-05-23 2:26 ` [RFC 0/3] misc: new serdev based drivers for w2sg00x4 GPS module and w2cbw003 wifi/bluetooth Rob Herring
2017-05-23 5:43 ` H. Nikolaus Schaller
2017-05-23 12:28 ` Rob Herring
2017-05-23 12:48 ` H. Nikolaus Schaller
2017-05-23 13:10 ` Rob Herring
2017-05-23 13:49 ` H. Nikolaus Schaller [this message]
2017-05-25 12:48 ` Rob Herring
2017-06-06 18:50 ` H. Nikolaus Schaller
2017-05-25 17:05 ` Pavel Machek
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