wb_reg_link: add generics for instantiating wb adapters, since wb_reg_link works correctly only when used with pipelined wb interfaces

Apologies for the double renaming, but it occured to me that the constant names were too generic and could cause conflicts.

This is introduced to better match the OHWR VHDL coding style [1].

Old names are preserved for backward compatibility.

[1]: https://www.ohwr.org/projects/vhdl-style

For the few peripherals where it was being used (eg. uart, spi, etc) the output port
has been renamed to "int_o".

The only peripheral that was not touched is "wb_eic.vhd", because this one is being used
by wbgen, and it would require users to update their wbgen tool as well. So, until a new
tool is introduced, wbgen-generated interrupt controllers will have an output port called
wb_int_o".

This reverts commit 49afba43.

This change was introduced in the masterFIP branch, but it can break many existing designs, so it is reverted.

the wishbone package

In wishbone_pkg.vhd, the new g_sdb_name generic was added to
xwb_crossbar instead of xwb_sdb_crossbar. Fixed

Piotr Miedzik authored 7 years ago and Dimitris Lampridis committed 7 years ago

- sdb_rom: add parameter g_sdb_name
- xwb_sdb_crossbar: add parameter g_sdb_name
- wishbone_pkg: f_string_fix_len add parameter justify_right
- wishbone_pkg: f_sdb_auto_device add parameter name
- wishbone_pkg: f_sdb_auto_bridge add parameter name

This was due to a bug in the f_string2bits() which took the commit ID as a string argument, assuming that the character array of the string is (32 downto 1), while in fact the commit_id is a string(1 to 32).

f_string2bits() is now  more resilient, it works with both "up" and "downto" string arguments, by checking the "ascending" attribute of the string type.

The subrange type might not be known in this context.
Fixes:
  wishbone_pkg.vhd:1379:26: object subtype is not locally static

Variable lengths might change; standard forbids length in a loop.
Fixes:
  wishbone_pkg.vhd:1576:18: universal integer bound must be numeric literal or attribute
  wishbone_pkg.vhd:1613:18: universal integer bound must be numeric literal or attribute
  wishbone_pkg.vhd:1734:30: universal integer bound must be numeric literal or attribute
  wishbone_pkg.vhd:1771:16: universal integer bound must be numeric literal or attribute
  wishbone_pkg.vhd:1806:16: universal integer bound must be numeric literal or attribute
  wishbone_pkg.vhd:1817:16: universal integer bound must be numeric literal or attribute

Sometimes a master needs to stop the flow of acks.

Now wb_spi has generic parameters to configure registers length and number of
spi slaves. Reason for that is to keep default configuration in the repository
but also allow to adjust settings for WR Switch synthesis (and save resources).

The values used in WR Switch software fit in 8-bit registers so using 16-bits
in HDL was waste of resources.

Commit adds new WB register(IFS) that selects to which I2C interface master
should talk to. All other interfaces are then hold in idle state. IFS contains
also BUSY bit that is written only by host and marks that I2C Master is
currently in use and cannot be switched to another I2C interface. Host must
clear BUSY flag after the interaction with I2C interface is finished.

This is done to better reflect the interface of the module (structured Wishbone).
The documentation of the module is also changed in this respect.