linux-toradex.git/include/linux/ntb.h, branch v4.19-rc5

NTB: Fix UB/bug in ntb_mw_get_align()

2018-01-29T03:17:24+00:00

Simple (1 << pidx) operation causes undefined behaviour when
pidx >= 32. It must be casted to u64 to match the actual return
value of ntb_link_is_up() method, so to have all the possible
peer indexes covered and to get rid of undefined behaviour.
Additionally there are special macros in "linux/bitops.h" to perform
the bit-set-shift operations, so it's recommended to have them used
for proper bit setting.

Signed-off-by: Serge Semin 
Reviewed-by: Logan Gunthorpe 
Signed-off-by: Jon Mason

NTB: Rename NTB messaging API methods

2018-01-29T03:17:23+00:00

There is a common methods signature form used over all the NTB API
like functions naming scheme, arguments names and order, etc.
Recently added NTB messaging API IO callbacks were named a bit
different so should be renamed to be in compliance with the rest
of the API.

Signed-off-by: Serge Semin 
Signed-off-by: Jon Mason

ntb_hw_switchtec: Add initialization code for crosslink

2018-01-29T03:17:23+00:00

Crosslink is a feature of the Switchtec switches that is similar to
the B2B mode of other NTB devices. It allows a system to be designed
that is perfectly symmetric with two identical switches that link
two hosts together.

In order for the system to be symmetric, there is an empty host-less
partition between the two switches which the host must enumerate and
assign BAR addresses to. The firmware in the switch manages this
specially so that the BAR addresses on both sides of the empty
partition will be identical despite being in the same partition with
the same address space.

The driver determines whether crosslink is enabled by a flag set in
the NTB partition info registers which are set by the switch's
configuration file.

When crosslink is enabled, a reserved LUT window is setup to point to
the peer's switch's NTB registers and the local MWs are set to forward
to the host-less partition's BARs. (Yes, this hurts my brain too.)
Once this is setup, largely the same NTB infrastructure is used to
communicate between the two hosts.

Signed-off-by: Logan Gunthorpe 
Signed-off-by: Jon Mason

NTB: switchtec_ntb: Add skeleton NTB driver

2017-11-19T01:37:12+00:00

Add a skeleton NTB driver which will be filled out in subsequent patches.

Signed-off-by: Logan Gunthorpe 
Reviewed-by: Stephen Bates 
Reviewed-by: Kurt Schwemmer 
Acked-by: Allen Hubbe 
Signed-off-by: Jon Mason

NTB: Add check and comment for link up to mw_count() and mw_get_align()

2017-11-19T01:37:11+00:00

Adds a comment and a check to ntb_mw_get_align() so that it always fails
if the function is called before the link is up.

Also adds a comment to ntb_mw_count() to note that it may return 0 if
it is called before the link is up.

This is to prevent accidental mis-use in clients that are testing
on hardware that this doesn't matter for.

Signed-off-by: Logan Gunthorpe 
Acked-by: Allen Hubbe 
Signed-off-by: Jon Mason

NTB: Add ntb.h comments

2017-07-06T15:30:07+00:00

Signed-off-by: Serge Semin 
Acked-by: Allen Hubbe 
Signed-off-by: Jon Mason

NTB: Add PCIe Gen4 link speed

2017-07-06T15:30:07+00:00

Signed-off-by: Serge Semin 
Acked-by: Allen Hubbe 
Signed-off-by: Jon Mason

NTB: Add Messaging NTB API

2017-07-06T15:30:07+00:00

Some IDT NTB-capable PCIe-switches have message registers to communicate with
peer devices. This patch adds new NTB API callback methods, which can be used
to utilize these registers functionality:
 ntb_msg_count(); - get number of message registers
 ntb_msg_inbits(); - get bitfield of inbound message registers status
 ntb_msg_outbits(); - get bitfield of outbound message registers status
 ntb_msg_read_sts(); - read the inbound and outbound message registers status
 ntb_msg_clear_sts(); - clear status bits of message registers
 ntb_msg_set_mask(); - mask interrupts raised by status bits of message
registers.
 ntb_msg_clear_mask(); - clear interrupts mask bits of message registers
 ntb_msg_read(midx, *pidx); - read message register with specified index,
additionally getting peer port index which data received from
 ntb_msg_write(midx, pidx); - write data to the specified message register
sending it to the passed peer device connected over a pidx port
 ntb_msg_event(); - notify driver context of a new message event

Of course there is hardware which doesn't support Message registers, so
this API is made optional.

Signed-off-by: Serge Semin 
Acked-by: Allen Hubbe 
Signed-off-by: Jon Mason

NTB: Alter Scratchpads API to support multi-ports devices

2017-07-06T15:30:07+00:00

Even though there is no any real NTB hardware, which would have both more
than two ports and Scratchpad registers, it is logically correct to have
Scratchpad API accepting a peer port index as well. Intel/AMD drivers utilize
Primary and Secondary topology to split Scratchpad between connected root
devices. Since port-index API introduced, Intel/AMD NTB hardware drivers can
use device port to determine which Scratchpad registers actually belong to
local and peer devices. The same approach can be used if some potential
hardware in future will be multi-port and have some set of Scratchpads.
Here are the brief of changes in the API:
 ntb_spad_count() - return number of Scratchpads per each port
 ntb_peer_spad_addr(pidx, sidx) - address of Scratchpad register of the
peer device with pidx-index
 ntb_peer_spad_read(pidx, sidx) - read specified Scratchpad register of the
peer with pidx-index
 ntb_peer_spad_write(pidx, sidx) - write data to Scratchpad register of the
peer with pidx-index

Since there is hardware which doesn't support Scratchpad registers, the
corresponding API methods are now made optional.

Signed-off-by: Serge Semin 
Acked-by: Allen Hubbe 
Signed-off-by: Jon Mason

NTB: Alter MW API to support multi-ports devices

2017-07-06T15:30:07+00:00

Multi-port NTB devices permit to share a memory between all accessible peers.
Memory Windows API is altered to correspondingly initialize and map memory
windows for such devices:
 ntb_mw_count(pidx); - number of inbound memory windows, which can be allocated
for shared buffer with specified peer device.
 ntb_mw_get_align(pidx, widx); - get alignment and size restriction parameters
to properly allocate inbound memory region.
 ntb_peer_mw_count(); - get number of outbound memory windows.
 ntb_peer_mw_get_addr(widx); - get mapping address of an outbound memory window

If hardware supports inbound translation configured on the local ntb port:
 ntb_mw_set_trans(pidx, widx); - set translation address of allocated inbound
memory window so a peer device could access it.
 ntb_mw_clear_trans(pidx, widx); - clear the translation address of an inbound
memory window.

If hardware supports outbound translation configured on the peer ntb port:
 ntb_peer_mw_set_trans(pidx, widx); - set translation address of a memory
window retrieved from a peer device
 ntb_peer_mw_clear_trans(pidx, widx); - clear the translation address of an
outbound memory window

Signed-off-by: Serge Semin 
Acked-by: Allen Hubbe 
Signed-off-by: Jon Mason