iio: proximity: vl53l0x-i2c: claim direct mode for raw readsgrafted

vl53l0x_read_raw() starts a single-shot ranging measurement and reads
back the result. Once the triggered buffer is enabled the sensor runs in
continuous mode and its data-ready interrupt is routed to the trigger,
so a concurrent in_distance_raw read disturbs the streaming setup and
never gets its completion, returning -ETIMEDOUT.

The original submission claimed direct mode here, but it was dropped
during review because the driver had no buffer support at the time [1].
Continuous (buffered) mode was later added without restoring the
claim [2], reintroducing the conflict.

Reject direct reads while buffered capture is active by claiming direct
mode around the measurement, as the vl53l1x sibling already does.

Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support")
Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1]
Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2]
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 132 insertions, 0 deletions

diff --git a/Documentation/usb/acm.rst b/Documentation/usb/acm.rst
new file mode 100644
index 000000000..e8bda98e9
--- /dev/null
+++ b/Documentation/usb/acm.rst
@@ -0,0 +1,132 @@
+======================
+Linux ACM driver v0.16
+======================
+
+Copyright (c) 1999 Vojtech Pavlik <vojtech@suse.cz>
+
+Sponsored by SuSE
+
+0. Disclaimer
+~~~~~~~~~~~~~
+This program is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 2 of the License, or (at your option)
+any later version.
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc., 59
+Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+Should you need to contact me, the author, you can do so either by e-mail -
+mail your message to <vojtech@suse.cz>, or by paper mail: Vojtech Pavlik,
+Ucitelska 1576, Prague 8, 182 00 Czech Republic
+
+For your convenience, the GNU General Public License version 2 is included
+in the package: See the file COPYING.
+
+1. Usage
+~~~~~~~~
+The drivers/usb/class/cdc-acm.c drivers works with USB modems and USB ISDN terminal
+adapters that conform to the Universal Serial Bus Communication Device Class
+Abstract Control Model (USB CDC ACM) specification.
+
+Many modems do, here is a list of those I know of:
+
+	- 3Com OfficeConnect 56k
+	- 3Com Voice FaxModem Pro
+	- 3Com Sportster
+	- MultiTech MultiModem 56k
+	- Zoom 2986L FaxModem
+	- Compaq 56k FaxModem
+	- ELSA Microlink 56k
+
+I know of one ISDN TA that does work with the acm driver:
+
+	- 3Com USR ISDN Pro TA
+
+Some cell phones also connect via USB. I know the following phones work:
+
+	- SonyEricsson K800i
+
+Unfortunately many modems and most ISDN TAs use proprietary interfaces and
+thus won't work with this drivers. Check for ACM compliance before buying.
+
+To use the modems you need these modules loaded::
+
+	usbcore.ko
+	uhci-hcd.ko ohci-hcd.ko or ehci-hcd.ko
+	cdc-acm.ko
+
+After that, the modem[s] should be accessible. You should be able to use
+minicom, ppp and mgetty with them.
+
+2. Verifying that it works
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The first step would be to check /sys/kernel/debug/usb/devices, it should look
+like this::
+
+  T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12  MxCh= 2
+  B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0
+  D:  Ver= 1.00 Cls=09(hub  ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
+  P:  Vendor=0000 ProdID=0000 Rev= 0.00
+  S:  Product=USB UHCI Root Hub
+  S:  SerialNumber=6800
+  C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr=  0mA
+  I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
+  E:  Ad=81(I) Atr=03(Int.) MxPS=   8 Ivl=255ms
+  T:  Bus=01 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#=  2 Spd=12  MxCh= 0
+  D:  Ver= 1.00 Cls=02(comm.) Sub=00 Prot=00 MxPS= 8 #Cfgs=  2
+  P:  Vendor=04c1 ProdID=008f Rev= 2.07
+  S:  Manufacturer=3Com Inc.
+  S:  Product=3Com U.S. Robotics Pro ISDN TA
+  S:  SerialNumber=UFT53A49BVT7
+  C:  #Ifs= 1 Cfg#= 1 Atr=60 MxPwr=  0mA
+  I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=acm
+  E:  Ad=85(I) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
+  E:  Ad=04(O) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
+  E:  Ad=81(I) Atr=03(Int.) MxPS=  16 Ivl=128ms
+  C:* #Ifs= 2 Cfg#= 2 Atr=60 MxPwr=  0mA
+  I:  If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=acm
+  E:  Ad=81(I) Atr=03(Int.) MxPS=  16 Ivl=128ms
+  I:  If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=acm
+  E:  Ad=85(I) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
+  E:  Ad=04(O) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
+
+The presence of these three lines (and the Cls= 'comm' and 'data' classes)
+is important, it means it's an ACM device. The Driver=acm means the acm
+driver is used for the device. If you see only Cls=ff(vend.) then you're out
+of luck, you have a device with vendor specific-interface::
+
+  D:  Ver= 1.00 Cls=02(comm.) Sub=00 Prot=00 MxPS= 8 #Cfgs=  2
+  I:  If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=acm
+  I:  If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=acm
+
+In the system log you should see::
+
+  usb.c: USB new device connect, assigned device number 2
+  usb.c: kmalloc IF c7691fa0, numif 1
+  usb.c: kmalloc IF c7b5f3e0, numif 2
+  usb.c: skipped 4 class/vendor specific interface descriptors
+  usb.c: new device strings: Mfr=1, Product=2, SerialNumber=3
+  usb.c: USB device number 2 default language ID 0x409
+  Manufacturer: 3Com Inc.
+  Product: 3Com U.S. Robotics Pro ISDN TA
+  SerialNumber: UFT53A49BVT7
+  acm.c: probing config 1
+  acm.c: probing config 2
+  ttyACM0: USB ACM device
+  acm.c: acm_control_msg: rq: 0x22 val: 0x0 len: 0x0 result: 0
+  acm.c: acm_control_msg: rq: 0x20 val: 0x0 len: 0x7 result: 7
+  usb.c: acm driver claimed interface c7b5f3e0
+  usb.c: acm driver claimed interface c7b5f3f8
+  usb.c: acm driver claimed interface c7691fa0
+
+If all this seems to be OK, fire up minicom and set it to talk to the ttyACM
+device and try typing 'at'. If it responds with 'OK', then everything is
+working.