i2c: qup: reorganization of driver code to remove polling for qup v2

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Following are the major issues in current driver code

1. The current driver simply assumes the transfer completion
   whenever its gets any non-error interrupts and then simply do the
   polling of available/free bytes in FIFO.
2. The block mode is not working properly since no handling in
   being done for OUT_BLOCK_WRITE_REQ and IN_BLOCK_READ_READ.
3. An i2c transfer can contain multiple message and QUP v2
   supports reconfiguration during run in which the mode should be same
   for all the sub transfer. Currently the mode is being programmed
   before every sub transfer which is functionally wrong. If one message
   is less than FIFO length and other message is greater than FIFO
   length, then transfers will fail.

Because of above, i2c v2 transfers of size greater than 64 are failing
with following error message

	i2c_qup 78b6000.i2c: timeout for fifo out full

To make block mode working properly and move to use the interrupts
instead of polling, major code reorganization is required. Following
are the major changes done in this patch

1. Remove the polling of TX FIFO free space and RX FIFO available
   bytes and move to interrupts completely. QUP has QUP_MX_OUTPUT_DONE,
   QUP_MX_INPUT_DONE, OUT_BLOCK_WRITE_REQ and IN_BLOCK_READ_REQ
   interrupts to handle FIFO’s properly so check all these interrupts.
2. Determine the mode for transfer before starting by checking
   all the tx/rx data length in each message. The complete message can be
   transferred either in DMA mode or Programmed IO by FIFO/Block mode.
   in DMA mode, both tx and rx uses same mode but in PIO mode, the TX and
   RX can be in different mode.
3. During write, For FIFO mode, TX FIFO can be directly written
   without checking for FIFO space. For block mode, the QUP will generate
   OUT_BLOCK_WRITE_REQ interrupt whenever it has block size of available
   space.
4. During read, both TX and RX FIFO will be used. TX will be used
   for writing tags and RX will be used for receiving the data. In QUP,
   TX and RX can operate in separate mode so configure modes accordingly.
5. For read FIFO mode, wait for QUP_MX_INPUT_DONE interrupt which
   will be generated after all the bytes have been copied in RX FIFO. For
   read Block mode, QUP will generate IN_BLOCK_READ_REQ interrupts
   whenever it has block size of available data.
6. Split the transfer in chunk of one QUP block size(256 bytes)
   and schedule each block separately. QUP v2 supports reconfiguration
   during run in which QUP can transfer multiple blocks without issuing a
   stop events.
7. Port the SMBus block read support for new code changes.

Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
Reviewed-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

...

This commit is contained in:

Abhishek Sahu 2018-03-12 18:45:02 +05:30 committed by Wolfram Sang

parent fbfab1ab06

commit 7545c7dba1

1 changed files with 516 additions and 386 deletions

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drivers/i2c/busses/i2c-qup.c

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