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authorMingkai Hu <Mingkai.hu@freescale.com>2010-10-12 18:18:32 +0800
committerGrant Likely <grant.likely@secretlab.ca>2010-10-12 21:38:12 -0600
commit8b60d6c25b2a2d3525d5322de856c3ca408e5783 (patch)
tree2dd4c2c98f9facd87e052795ea79be0c734ec400 /Documentation/powerpc
parentb36ece832512c1a0afa54ff0a56d63492a1caf08 (diff)
spi/fsl_spi: add eSPI controller support
Add eSPI controller support based on the library code spi_fsl_lib.c. The eSPI controller is newer controller 85xx/Pxxx devices supported. There're some differences comparing to the SPI controller: 1. Has different register map and different bit definition So leave the code operated the register to the driver code, not the common code. 2. Support 4 dedicated chip selects The software can't controll the chip selects directly, The SPCOM[CS] field is used to select which chip selects is used, and the SPCOM[TRANLEN] field is set to tell the controller how long the CS signal need to be asserted. So the driver doesn't need the chipselect related function when transfering data, just set corresponding register fields to controll the chipseclect. 3. Different Transmit/Receive FIFO access register behavior For SPI controller, the Tx/Rx FIFO access register can hold only one character regardless of the character length, but for eSPI controller, the register can hold 4 or 2 characters according to the character lengths. Access the Tx/Rx FIFO access register of the eSPI controller will shift out/in 4/2 characters one time. For SPI subsystem, the command and data are put into different transfers, so we need to combine all the transfers to one transfer in order to pass the transfer to eSPI controller. 4. The max transaction length limitation The max transaction length one time is limitted by the SPCOM[TRANSLEN] field which is 0xFFFF. When used mkfs.ext2 command to create ext2 filesystem on the flash, the read length will exceed the max value of the SPCOM[TRANSLEN] field. Signed-off-by: Mingkai Hu <Mingkai.hu@freescale.com> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
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