NTB: send DB event when driver is loaded or un-loaded

When the driver on the local side is loaded, it sets
SIDE_READY bit in SIDE_INFO register. Likewise, when
it is un-loaded, it clears the bit.

Also just after being loaded, the driver polls for
peer SIDE_READY bit to be set. Since that bit is set
when the peer side driver has loaded, the polling on
local side breaks as soon as this condition is met.

But the situation is different when the driver is
un-loaded. Since the polling has already been stopped
as mentioned before, if the peer side driver gets
un-loaded, the driver on the local side is not notified
implicitly.

So, we improvise using existing doorbell mechanism.
We reserve the highest order bit of the DB register to
send a notification to peer when the driver on local
side is un-loaded. This also means that now we are one
short of 16 DB events and that is taken care of in the
valid DB mask.

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

NTB: return link up status correctly for PRI and SEC

Since NTB connects two physically separate systems,
there can be scenarios where one system goes down
while the other one remains active. In case of NTB
primary, if the NTB secondary goes down, a Link-Down
event is received. For the NTB secondary, if the
NTB primary goes down, the PCIe hotplug mechanism
ensures that the driver on the secondary side is also
unloaded.

But there are other scenarios to consider as well,
when suppose the physical link remains active, but
the driver on primary or secondary side is loaded
or un-loaded.

When the driver is loaded, on either side, it sets
SIDE_READY bit(bit-1) of SIDE_INFO register. Similarly,
when the driver is un-loaded, it resets the same bit.

We consider the NTB link to be up and operational
only when the driver on both sides of link are loaded
and ready. But we also need to take account of
Link Up and Down events which signify the physical
link status. So amd_link_is_up() is modified to take
care of the above scenarios.

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

NTB: add helper functions to set and clear sideinfo

We define two new helper functions to set and clear
sideinfo registers respectively. These functions
take an additional boolean parameter which signifies
whether we want to set/clear the sideinfo register
of the peer(true) or local host(false).

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

NTB: return the side info status from amd_poll_link

Bit 1 of SIDE_INFO register is an indication that
the driver on the other side of link is ready. We
set this bit during driver initialization sequence.
So rather than having separate macros to return the
status, we can simply return the status of this bit
from amd_poll_link(). So a return of 1 or 0 from
this function will indicate to the caller whether
the driver on the other side of link is ready or not,
respectively.

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

NTB: Fix an error in get link status

The offset of PCIe Capability Header for AMD and HYGON NTB is 0x64,
but the macro which named "AMD_LINK_STATUS_OFFSET" is defined as 0x68.
It is offset of Device Capabilities Reg rather than Link Control Reg.

This code trigger an error in get link statsus:

cat /sys/kernel/debug/ntb_hw_amd/0000:43:00.1/info
LNK STA - 0x8fa1
Link Status - Up
Link Speed - PCI-E Gen 0
Link Width - x0

This patch use pcie_capability_read_dword to get link status.
After fix this issue, we can get link status accurately:

cat /sys/kernel/debug/ntb_hw_amd/0000:43:00.1/info
LNK STA - 0x11030042
Link Status - Up
Link Speed - PCI-E Gen 3
Link Width - x16

Fixes: a1b3695820aa4 ("NTB: Add support for AMD PCI-Express Non-Transparent Bridge")
Signed-off-by: Jiasen Lin <linjiasen@hygon.cn>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

ntb_hw_amd: Add memory window support for new AMD hardware

The AMD new hardware uses BAR23 and BAR45 as memory windows
as compared to previos where BAR1, BAR23 and BAR45 is used
for memory windows.

This patch add support for both AMD hardwares.

Signed-off-by: Sanjay R Mehta <sanju.mehta@amd.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

ntb_hw_amd: Add a new NTB PCI device ID

Signed-off-by: Sanjay R Mehta <sanju.mehta@amd.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

ntb_hw_amd: Style fixes: open code macros that just obfuscate code

As per a comments in [1] by Greg Kroah-Hartman, the ndev_* macros should
be cleaned up. This makes it more clear what's actually going on when
reading the code.

[1] http://www.spinics.net/lists/linux-pci/msg56904.html

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

NTB: add support for hotplug feature

AMD NTB support hotplug under B2B mode. NTB will trigger link
up/down interrupt event when doing plug add/remove, this patch
implements the two interrupt event to support B2B hotplug function.

Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Acked-by: Allen Hubbe <Allen.Hubbe@dell.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

NTB: Add support for AMD PCI-Express Non-Transparent Bridge

This adds support for AMD's PCI-Express Non-Transparent Bridge
(NTB) device on the Zeppelin platform. The driver connnects to the
standard NTB sub-system interface, with modification to add hooks
for power management in a separate patch. The AMD NTB device has 3
memory windows, 16 doorbell, 16 scratch-pad registers, and supports
up to 16 PCIe lanes running a Gen3 speeds.

Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Reviewed-by: Allen Hubbe <Allen.Hubbe@emc.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>