diff options
Diffstat (limited to 'Documentation/networking/caif')
| -rw-r--r-- | Documentation/networking/caif/caif.rst (renamed from Documentation/networking/caif/README) | 88 |
1 files changed, 60 insertions, 28 deletions
diff --git a/Documentation/networking/caif/README b/Documentation/networking/caif/caif.rst index 757ccfaa1385..07afc8063d4d 100644 --- a/Documentation/networking/caif/README +++ b/Documentation/networking/caif/caif.rst @@ -1,18 +1,31 @@ -Copyright (C) ST-Ericsson AB 2010 -Author: Sjur Brendeland/ sjur.brandeland@stericsson.com -License terms: GNU General Public License (GPL) version 2 ---------------------------------------------------------- +:orphan: -=== Start === -If you have compiled CAIF for modules do: +.. SPDX-License-Identifier: GPL-2.0 +.. include:: <isonum.txt> -$modprobe crc_ccitt -$modprobe caif -$modprobe caif_socket -$modprobe chnl_net +================ +Using Linux CAIF +================ -=== Preparing the setup with a STE modem === + +:Copyright: |copy| ST-Ericsson AB 2010 + +:Author: Sjur Brendeland/ sjur.brandeland@stericsson.com + +Start +===== + +If you have compiled CAIF for modules do:: + + $modprobe crc_ccitt + $modprobe caif + $modprobe caif_socket + $modprobe chnl_net + + +Preparing the setup with a STE modem +==================================== If you are working on integration of CAIF you should make sure that the kernel is built with module support. @@ -32,24 +45,30 @@ module parameter "ser_use_stx". Normally Frame Checksum is always used on UART, but this is also provided as a module parameter "ser_use_fcs". -$ modprobe caif_serial ser_ttyname=/dev/ttyS0 ser_use_stx=yes -$ ifconfig caif_ttyS0 up +:: + + $ modprobe caif_serial ser_ttyname=/dev/ttyS0 ser_use_stx=yes + $ ifconfig caif_ttyS0 up -PLEASE NOTE: There is a limitation in Android shell. +PLEASE NOTE: + There is a limitation in Android shell. It only accepts one argument to insmod/modprobe! -=== Trouble shooting === +Trouble shooting +================ There are debugfs parameters provided for serial communication. /sys/kernel/debug/caif_serial/<tty-name>/ * ser_state: Prints the bit-mask status where + - 0x02 means SENDING, this is a transient state. - 0x10 means FLOW_OFF_SENT, i.e. the previous frame has not been sent - and is blocking further send operation. Flow OFF has been propagated - to all CAIF Channels using this TTY. + and is blocking further send operation. Flow OFF has been propagated + to all CAIF Channels using this TTY. * tty_status: Prints the bit-mask tty status information + - 0x01 - tty->warned is on. - 0x02 - tty->low_latency is on. - 0x04 - tty->packed is on. @@ -58,13 +77,17 @@ There are debugfs parameters provided for serial communication. - 0x20 - tty->stopped is on. * last_tx_msg: Binary blob Prints the last transmitted frame. - This can be printed with + + This can be printed with:: + $od --format=x1 /sys/kernel/debug/caif_serial/<tty>/last_rx_msg. - The first two tx messages sent look like this. Note: The initial - byte 02 is start of frame extension (STX) used for re-syncing - upon errors. - - Enumeration: + The first two tx messages sent look like this. Note: The initial + byte 02 is start of frame extension (STX) used for re-syncing + upon errors. + + - Enumeration:: + 0000000 02 05 00 00 03 01 d2 02 | | | | | | STX(1) | | | | @@ -73,7 +96,9 @@ There are debugfs parameters provided for serial communication. Command:Enumeration(1) Link-ID(1) Checksum(2) - - Channel Setup: + + - Channel Setup:: + 0000000 02 07 00 00 00 21 a1 00 48 df | | | | | | | | STX(1) | | | | | | @@ -86,13 +111,18 @@ There are debugfs parameters provided for serial communication. Checksum(2) * last_rx_msg: Prints the last transmitted frame. - The RX messages for LinkSetup look almost identical but they have the - bit 0x20 set in the command bit, and Channel Setup has added one byte - before Checksum containing Channel ID. - NOTE: Several CAIF Messages might be concatenated. The maximum debug + + The RX messages for LinkSetup look almost identical but they have the + bit 0x20 set in the command bit, and Channel Setup has added one byte + before Checksum containing Channel ID. + + NOTE: + Several CAIF Messages might be concatenated. The maximum debug buffer size is 128 bytes. -== Error Scenarios: +Error Scenarios +=============== + - last_tx_msg contains channel setup message and last_rx_msg is empty -> The host seems to be able to send over the UART, at least the CAIF ldisc get notified that sending is completed. @@ -103,7 +133,9 @@ There are debugfs parameters provided for serial communication. - if /sys/kernel/debug/caif_serial/<tty>/tty_status is non-zero there might be problems transmitting over UART. + E.g. host and modem wiring is not correct you will typically see tty_status = 0x10 (hw_stopped) and ser_state = 0x10 (FLOW_OFF_SENT). + You will probably see the enumeration message in last_tx_message and empty last_rx_message. |