| Message ID | 20190222092522.4913-1-ludovic.desroches@microchip.com |
|---|---|
| Headers | show |
| Series | i2c: at91: slave mode support | expand |
On Fri, Feb 22, 2019 at 10:25:19AM +0100, Ludovic Desroches wrote: > [Ludovic Desroches: see Changes section] > > Based on the discussion we had on the i2c-linux list [1], I wrote a patch for > AT91 hardware and tried to fulfill the Linux I2C slave interface description > [2] as good as possible. This enables aforementioned hardware to act as an I2C > slave that can be accessed by a remote I2C master. > > I have tested this patchset successfully on an ATSAMA5D27. > > ^ 3.3V ^ 3.3V > +-----------------------+ | | +-----------------------+ > | Slave: ATSAMA5D27 | +-+ +-+ | Master: ATSAMA5D35 | > | with i2c-slave-eeprom | | | 100k | | 100k | with i2cset | > +-------------------+-+-+ +-+ +-+ +-+-+-------------------+ > | | | | | | > | +------+---------|---(SDA)---+ | > +------------------+---(SCL)-----+ > > Schematic: Connection of slave and master with 100kOhm pullup resistors. > > On the master the following BASH script has been used to stress the slave. > > root@emblinux:~# cat ./stress.sh > #!/bin/bash Not everybody has bash in their environments. See below, how easily to switch to regular shell. #!/bin/sh > I=0 > while true > do > if i2cset -y -r 1 0x64 0 $I w | grep mismatch > then > echo "$(date): Error in transmission ${I}" > fi > ((I++)) I=$(($I+1)) > if [ $I -eq 65536 ] > then > I=0 > echo "$(date): Sent 65536 transmissions" > fi This one can be optimized to for I in $(seq 65536); do ... done > done > > After running the script for some time I had the following output. To me this > looks promising :) > > root@emblinux:~# ./stress.sh > Thu Nov 9 13:58:45 CTE 2017: Sent 65536 transmissions > Thu Nov 9 14:35:20 CTE 2017: Sent 65536 transmissions > Thu Nov 9 15:12:11 CTE 2017: Sent 65536 transmissions > Thu Nov 9 15:49:04 CTE 2017: Sent 65536 transmissions > Thu Nov 9 16:26:00 CTE 2017: Sent 65536 transmissions > Thu Nov 9 17:03:07 UTC 2017: Sent 65536 transmissions > Thu Nov 9 17:40:15 UTC 2017: Sent 65536 transmissions > > If you have some hardware with an at91-i2c interface included at hand, I really > would appreciate if you can run the test script on your hardware and test this > driver. > Thu Nov 9 17:40:15 UTC 2017: Sent 65536 transmissions > > If you have some hardware with an at91-i2c interface included at hand, I really > would appreciate if you can run the test script on your hardware and test this > driver.
On Fri, Feb 22, 2019 at 10:25:19AM +0100, Ludovic Desroches wrote: > [Ludovic Desroches: see Changes section] > > Based on the discussion we had on the i2c-linux list [1], I wrote a patch for > AT91 hardware and tried to fulfill the Linux I2C slave interface description > [2] as good as possible. This enables aforementioned hardware to act as an I2C > slave that can be accessed by a remote I2C master. After this was successfully checked by buildbot in a seperate branch: Applied to for-next, thanks!
[Ludovic Desroches: see Changes section] Based on the discussion we had on the i2c-linux list [1], I wrote a patch for AT91 hardware and tried to fulfill the Linux I2C slave interface description [2] as good as possible. This enables aforementioned hardware to act as an I2C slave that can be accessed by a remote I2C master. I have tested this patchset successfully on an ATSAMA5D27. ^ 3.3V ^ 3.3V +-----------------------+ | | +-----------------------+ | Slave: ATSAMA5D27 | +-+ +-+ | Master: ATSAMA5D35 | | with i2c-slave-eeprom | | | 100k | | 100k | with i2cset | +-------------------+-+-+ +-+ +-+ +-+-+-------------------+ | | | | | | | +------+---------|---(SDA)---+ | +------------------+---(SCL)-----+ Schematic: Connection of slave and master with 100kOhm pullup resistors. On the master the following BASH script has been used to stress the slave. root@emblinux:~# cat ./stress.sh #!/bin/bash I=0 while true do if i2cset -y -r 1 0x64 0 $I w | grep mismatch then echo "$(date): Error in transmission ${I}" fi ((I++)) if [ $I -eq 65536 ] then I=0 echo "$(date): Sent 65536 transmissions" fi done After running the script for some time I had the following output. To me this looks promising :) root@emblinux:~# ./stress.sh Thu Nov 9 13:58:45 CTE 2017: Sent 65536 transmissions Thu Nov 9 14:35:20 CTE 2017: Sent 65536 transmissions Thu Nov 9 15:12:11 CTE 2017: Sent 65536 transmissions Thu Nov 9 15:49:04 CTE 2017: Sent 65536 transmissions Thu Nov 9 16:26:00 CTE 2017: Sent 65536 transmissions Thu Nov 9 17:03:07 UTC 2017: Sent 65536 transmissions Thu Nov 9 17:40:15 UTC 2017: Sent 65536 transmissions If you have some hardware with an at91-i2c interface included at hand, I really would appreciate if you can run the test script on your hardware and test this driver. Thu Nov 9 17:40:15 UTC 2017: Sent 65536 transmissions If you have some hardware with an at91-i2c interface included at hand, I really would appreciate if you can run the test script on your hardware and test this driver. Best regards Juergen [Ludovic Desroches] Changes in v5: - use SPDX for licence - replace IF_ENABLED par defined to solve compilation issue when selected as module. Changes in v4: - rebased on next-20181224 - update Kconfig part to state that this feature is experimental. - tested quickly on a single board, SAMA5D2 Xplained, i2c-gpio as master, OK. Changes in v3: - rebase (cherry-pick was enough) - fix checkpatch errors - tests: - hangs with a SAMA5D4 (master and slave on different busses) after about 100 transfers. It's the first time I do this test. - some mismatches with a SAMA5D4 as slave and a SAMA5D2 as master I don't know if it's a regression. I don't remember having seen this behavior previously. I think it's worth taking those patches even if there are some possible bugs. It'll allow to get more people using it and so to consolidate the slave mode support. Changes in v2: - Implemented all suggestions made by Ludovic. (Thank you!) - Reworked the IRQ handler completely. Have a look in patch 3 fort further details. [1] https://marc.info/?t=150824004800001&r=1&w=1 [2] https://www.kernel.org/doc/Documentation/i2c/slave-interface Juergen Fitschen (3): i2c: at91: segregate master mode specific code from probe and init func i2c: at91: split driver into core and master file i2c: at91: added slave mode support MAINTAINERS | 3 +- drivers/i2c/busses/Kconfig | 13 + drivers/i2c/busses/Makefile | 4 + drivers/i2c/busses/i2c-at91-core.c | 376 ++++++++++++++ .../busses/{i2c-at91.c => i2c-at91-master.c} | 459 +----------------- drivers/i2c/busses/i2c-at91-slave.c | 143 ++++++ drivers/i2c/busses/i2c-at91.h | 175 +++++++ 7 files changed, 721 insertions(+), 452 deletions(-) create mode 100644 drivers/i2c/busses/i2c-at91-core.c rename drivers/i2c/busses/{i2c-at91.c => i2c-at91-master.c} (66%) create mode 100644 drivers/i2c/busses/i2c-at91-slave.c create mode 100644 drivers/i2c/busses/i2c-at91.h