linux/drivers/fsi
Andrew Jeffery 5e50229956 fsi: aspeed: Fix OPB0 byte order register values
The data byte order selection registers in the APB2OPB primarily expose some
internal plumbing necessary to get correct write accesses onto the OPB.
OPB write cycles require "data mirroring" across the 32-bit data bus to
support variable data width slaves that don't implement "byte enables".
For slaves that do implement byte enables the master can signal which
bytes on the data bus the slave should consider valid.

The data mirroring behaviour is specified by the following table:

    +-----------------+----------+-----------------------------------+
    |                 |          |          32-bit Data Bus          |
    +---------+-------+----------+---------+---------+-------+-------+
    |         |       |          |         |         |       |       |
    |   ABus  | Mn_BE |  Request |   Dbus  |   Dbus  |  Dbus |  Dbus |
    | (30:31) | (0:3) | Transfer |   0:7   |   8:15  | 16:23 | 24:31 |
    |         |       |   Size   |  byte0  |  byte1  | byte2 | byte3 |
    +---------+-------+----------+---------+---------+-------+-------+
    |    00   |  1111 | fullword |  byte0  |  byte1  | byte2 | byte3 |
    +---------+-------+----------+---------+---------+-------+-------+
    |    00   |  1110 | halfword |  byte0  |  byte1  | byte2 |       |
    +---------+-------+----------+---------+---------+-------+-------+
    |    01   |  0111 |   byte   | _byte1_ |  byte1  | byte2 | byte3 |
    +---------+-------+----------+---------+---------+-------+-------+
    |    00   |  1100 | halfword |  byte0  |  byte1  |       |       |
    +---------+-------+----------+---------+---------+-------+-------+
    |    01   |  0110 |   byte   | _byte1_ |  byte1  | byte2 |       |
    +---------+-------+----------+---------+---------+-------+-------+
    |    10   |  0011 | halfword | _byte2_ | _byte3_ | byte2 | byte3 |
    +---------+-------+----------+---------+---------+-------+-------+
    |    00   |  1000 |   byte   |  byte0  |         |       |       |
    +---------+-------+----------+---------+---------+-------+-------+
    |    01   |  0100 |   byte   | _byte1_ |  byte1  |       |       |
    +---------+-------+----------+---------+---------+-------+-------+
    |    10   |  0010 |   byte   | _byte2_ |         | byte2 |       |
    +---------+-------+----------+---------+---------+-------+-------+
    |    11   |  0001 |   byte   | _byte3_ | _byte3_ |       | byte3 |
    +---------+-------+----------+---------+---------+-------+-------+

Mirrored data values are highlighted by underscores in the Dbus columns.
The values in the ABus and Request Transfer Size columns correspond to
values in the field names listed in the write data order select register
descriptions.

Similar configuration registers are exposed for reads which enables the
secondary purpose of configuring hardware endian conversions. It appears the
data bus byte order is switched around in hardware so set the registers such
that we can access the correct values for all widths. The values were
determined by experimentation on hardware against fixed CFAM register
values to configure the read data order, then in combination with the
table above and the register layout documentation in the AST2600
datasheet performing write/read cycles to configure the write data order
registers.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Acked-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20191108051945.7109-12-joel@jms.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-11-08 11:28:21 +01:00
..
Kconfig fsi: Add ast2600 master driver 2019-11-08 11:28:20 +01:00
Makefile fsi: Add ast2600 master driver 2019-11-08 11:28:20 +01:00
cf-fsi-fw.h fsi: cf-fsi-fw: Use the correct style for SPDX License Identifier 2019-06-19 19:35:51 +02:00
fsi-core.c fsi: fsi_master_class can be static 2019-11-08 11:23:40 +01:00
fsi-master-aspeed.c fsi: aspeed: Fix OPB0 byte order register values 2019-11-08 11:28:21 +01:00
fsi-master-ast-cf.c fsi: master-ast-cf: Rename dump_trace() to avoid name collision 2018-07-26 14:49:50 +10:00
fsi-master-gpio.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
fsi-master-hub.c fsi: Move defines to common header 2019-11-08 11:23:40 +01:00
fsi-master.h fsi: Move defines to common header 2019-11-08 11:23:40 +01:00
fsi-occ.c OCC: FSI and hwmon: Add sequence numbering 2019-07-03 10:41:22 +09:30
fsi-sbefifo.c fsi: sbefifo: Don't fail operations when in SBE IPL state 2019-07-03 21:17:11 +02:00
fsi-scom.c fsi: scom: Don't abort operations for minor errors 2019-08-28 22:59:18 +02:00