PCI: endpoint: Return error if EPC is started/stopped multiple times

When the EPC is started or stopped multiple times from configfs, just
return -EALREADY. There is no need to call the EPC start/stop functions
in those cases.

Link: https://lore.kernel.org/r/20230602114756.36586-4-manivannan.sadhasivam@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kishon Vijay Abraham I <kishon@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

PCI: endpoint: Improve pci_epf_type_add_cfs()

pci_epf_type_add_cfs() should not be called with an unbound EPF device,
that is, an epf device with epf->driver not set. For such case, replace the
NULL return in pci_epf_type_add_cfs() with a clear ERR_PTR(-ENODEV) pointer
error return.

Link: https://lore.kernel.org/r/20230515074348.595704-2-dlemoal@kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivami <manivannan.sadhasivam@linaro.org>

PCI: endpoint: Move pci_epf_type_add_cfs() code

pci_epf_type_add_cfs() is called only from pci_ep_cfs_add_type_group() in
drivers/pci/endpoint/pci-ep-cfs.c, so there is no need to export this
function. Move its code from pci-epf-core.c to pci-ep-cfs.c as a static
function.

Link: https://lore.kernel.org/r/20230415023542.77601-3-dlemoal@kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>

PCI: endpoint: Automatically create a function specific attributes group

A PCI endpoint function driver can define function specific attributes
under its function configfs directory using the add_cfs() endpoint driver
operation. This is done by tying up the mkdir operation for the function
configfs directory to a call to the add_cfs() operation. However, there
are no checks preventing the user from repeatedly creating function
specific attribute directories with different names, resulting in the same
endpoint specific attributes group being added multiple times, which also
result in an invalid reference counting for the attribute groups. E.g.,
using the pci-epf-ntb function driver as an example, the user creates the
function as follows:

$ modprobe pci-epf-ntb
$ cd /sys/kernel/config/pci_ep/functions/pci_epf_ntb
$ mkdir func0
$ tree func0
func0/
|-- baseclass_code
|-- cache_line_size
|-- ...
`-- vendorid

$ mkdir func0/attrs
$ tree func0
func0/
|-- attrs
| |-- db_count
| |-- mw1
| |-- mw2
| |-- mw3
| |-- mw4
| |-- num_mws
| `-- spad_count
|-- baseclass_code
|-- cache_line_size
|-- ...
`-- vendorid

At this point, the function can be started by linking the EP controller.
However, if the user mistakenly creates again a directory:

$ mkdir func0/attrs2
$ tree func0
func0/
|-- attrs
| |-- db_count
| |-- mw1
| |-- mw2
| |-- mw3
| |-- mw4
| |-- num_mws
| `-- spad_count
|-- attrs2
| |-- db_count
| |-- mw1
| |-- mw2
| |-- mw3
| |-- mw4
| |-- num_mws
| `-- spad_count
|-- baseclass_code
|-- cache_line_size
|-- ...
`-- vendorid

The endpoint function specific attributes are duplicated and cause a crash
when the endpoint function device is torn down:

refcount_t: addition on 0; use-after-free.
WARNING: CPU: 2 PID: 834 at lib/refcount.c:25 refcount_warn_saturate+0xc8/0x144
CPU: 2 PID: 834 Comm: rmdir Not tainted 6.3.0-rc1 #1
Hardware name: Pine64 RockPro64 v2.1 (DT)
pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
...
Call trace:
refcount_warn_saturate+0xc8/0x144
config_item_get+0x7c/0x80
configfs_rmdir+0x17c/0x30c
vfs_rmdir+0x8c/0x204
do_rmdir+0x158/0x184
__arm64_sys_unlinkat+0x64/0x80
invoke_syscall+0x48/0x114
...

Fix this by modifying pci_epf_cfs_work() to execute the new function
pci_ep_cfs_add_type_group() which itself calls pci_epf_type_add_cfs() to
obtain the function specific attribute group and the group name (directory
name) from the endpoint function driver. If the function driver defines an
attribute group, pci_ep_cfs_add_type_group() then proceeds to register this
group using configfs_register_group(), thus automatically exposing the
function type specific configfs attributes to the user. E.g.:

$ modprobe pci-epf-ntb
$ cd /sys/kernel/config/pci_ep/functions/pci_epf_ntb
$ mkdir func0
$ tree func0
func0/
|-- baseclass_code
|-- cache_line_size
|-- ...
|-- pci_epf_ntb.0
| |-- db_count
| |-- mw1
| |-- mw2
| |-- mw3
| |-- mw4
| |-- num_mws
| `-- spad_count
|-- primary
|-- ...
`-- vendorid

With this change, there is no need for the user to create or delete
directories in the endpoint function attributes directory. The
pci_epf_type_group_ops group operations are thus removed.

Also update the documentation for the pci-epf-ntb and pci-epf-vntb function
drivers to reflect this change, removing the explanations showing the need
to manually create the sub-directory for the function specific attributes.

Link: https://lore.kernel.org/r/20230415023542.77601-2-dlemoal@kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>

PCI: Remove MODULE_LICENSE so boolean drivers don't look like modules

Since 8b41fc4454e3 ("kbuild: create modules.builtin without
Makefile.modbuiltin or tristate.conf"), MODULE_LICENSE declarations are
used to identify modules. As a consequence, MODULE_LICENSE in non-modules
causes modprobe to misidentify the object file as a module when it is not,
and modprobe might succeed rather than failing with a suitable error
message.

For tristate modules that can be either built-in or loaded at runtime,
modprobe succeeds in both cases:

# modprobe ext4
[exit status zero if CONFIG_EXT4_FS=y or =m]

For boolean modules like the Standard Hot Plug Controller driver (shpchp)
that cannot be loaded at runtime, modprobe should always fail like this:

# modprobe shpchp
modprobe: FATAL: Module shpchp not found in directory /lib/modules/...
[exit status non-zero regardless of CONFIG_HOTPLUG_PCI_SHPC]

but prior to this commit, shpchp_core.c contained MODULE_LICENSE, so
"modprobe shpchp" silently succeeded when it should have failed.

Remove MODULE_LICENSE in files that cannot be built as modules.

[bhelgaas: commit log, squash]
Suggested-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20230216152410.4312-1-nick.alcock@oracle.com/
Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Hitomi Hasegawa <hasegawa-hitomi@fujitsu.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>

PCI: endpoint: Use sysfs_emit() in "show" functions

Convert sprintf() in sysfs "show" functions to sysfs_emit() in order to
check for buffer overruns in sysfs outputs.

Link: https://lore.kernel.org/r/1630472957-26857-1-git-send-email-hayashi.kunihiko@socionext.com
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Krzysztof Wilczyński <kw@linux.com>

PCI/sysfs: Return -EINVAL consistently from "store" functions

Most of the "store" functions that handle userspace input via sysfs return
-EINVAL should the value fail validation and/or type conversion. This
error code is a clear message to userspace that the value is not a valid
input.

However, some of the "show" functions return input parsing error codes
as-is, which may be either -EINVAL or -ERANGE. The former would often be
from kstrtobool(), and the latter typically from other kstr*() functions
such as kstrtou8(), kstrtou32(), kstrtoint(), etc.

-EINVAL is commonly returned as the error code to indicate that the value
provided is invalid, but -ERANGE is not very useful in userspace.

Therefore, normalize the return error code to be -EINVAL for when the
validation and/or type conversion fails.

Link: https://lore.kernel.org/r/20210915230127.2495723-2-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI: endpoint: Add support to link a physical function to a virtual function

While the physical function has to be linked to endpoint controller, the
virtual function has to be linked to a physical function. Add support to
link a physical function to a virtual function in pci-ep-cfs.

Link: https://lore.kernel.org/r/20210819123343.1951-4-kishon@ti.com
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

PCI: endpoint: Allow user to create sub-directory of 'EPF Device' directory

Documentation/PCI/endpoint/pci-endpoint-cfs.rst explains how a user has to
create a directory in-order to create a 'EPF Device' that can be
configured/probed by 'EPF Driver'.

Allow user to create a sub-directory of 'EPF Device' directory for any
function specific attributes that has to be exposed to the user.

Link: https://lore.kernel.org/r/20210201195809.7342-11-kishon@ti.com
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI: endpoint: Add support in configfs to associate two EPCs with EPF

Now that PCI endpoint core supports to add secondary endpoint controller
(EPC) with endpoint function (EPF), Add support in configfs to associate
two EPCs with EPF. This creates "primary" and "secondary" directory inside
the directory created by users for EPF device. Users have to add a symlink
of endpoint controller (pci_ep/controllers/) to "primary" or "secondary"
directory to bind EPF to primary and secondary EPF interfaces respectively.
Existing method of linking directory representing EPF device to directory
representing EPC device to associate a single EPC device with a EPF device
will continue to work.

Link: https://lore.kernel.org/r/20210201195809.7342-8-kishon@ti.com
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI: endpoint: Add support to associate secondary EPC with EPF

In the case of standard endpoint functions, only one endpoint controller
(EPC) will be associated with an endpoint function (EPF). However for
providing NTB (non transparent bridge) functionality, two EPCs should be
associated with a single EPF. Add support to associate secondary EPC with
EPF. This is in preparation for adding NTB endpoint function driver.

Link: https://lore.kernel.org/r/20210201195809.7342-7-kishon@ti.com
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI: Fix kerneldoc warnings

Fix kerneldoc warnings, e.g.,

$ make W=1 drivers/pci/
drivers/pci/ats.c:196: warning: Function parameter or member 'pdev' not described in 'pci_enable_pri'
drivers/pci/ats.c:196: warning: Function parameter or member 'reqs' not described in 'pci_enable_pri'
...

Link: https://lore.kernel.org/r/20200729201224.26799-2-krzk@kernel.org
Link: https://lore.kernel.org/r/20200729201224.26799-3-krzk@kernel.org
Link: https://lore.kernel.org/r/20200729201224.26799-4-krzk@kernel.org
Link: https://lore.kernel.org/r/20200729201224.26799-5-krzk@kernel.org
Link: https://lore.kernel.org/r/20200729201224.26799-6-krzk@kernel.org
Link: https://lore.kernel.org/r/20200729201224.26799-7-krzk@kernel.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI: endpoint: Fix clearing start entry in configfs

After an endpoint is started through configfs, if 0 is written to the
configfs entry 'start', the controller stops but the epc_group->start
value remains 1.

A subsequent unlinking of the function from the controller would trigger
a spurious WARN_ON_ONCE() in pci_epc_epf_unlink() despite right
behavior.

Fix it by setting epc_group->start = 0 when a controller is stopped
using configfs.

Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Kishon Vijay Abraham I <kishon@ti.com>

PCI: endpoint: Assign function number for each PF in EPC core

The PCIe endpoint core relies on the drivers that invoke the
pci_epc_add_epf() API to allocate and assign a function number
to each physical function (PF). Since endpoint function device can
be created by multiple mechanisms (configfs, devicetree, etc..),
allowing each of these mechanisms to assign a function number
would result in mutliple endpoint function devices having the
same function number. In order to avoid this, let EPC core assign
a function number to the endpoint device.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

PCI: endpoint: Add MSI-X interfaces

Add PCI_EPC_IRQ_MSIX type.

Add MSI-X callbacks signatures to the ops structure.

Add sysfs interface for set/get MSI-X capability maximum number.

Update documentation accordingly.

Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>

PCI: endpoint: Fix EPF device name to support multi-function devices

Fix the pci_epf_make() function so it can now bind many EPF devices to the
same EPF driver.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@free-electrons.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

PCI: Add SPDX GPL-2.0 to replace GPL v2 boilerplate

Add SPDX GPL-2.0 to all PCI files that specified the GPL version 2 license.

Remove the boilerplate GPL version 2 language, relying on the assertion in
b24413180f56 ("License cleanup: add SPDX GPL-2.0 license identifier to
files with no license") that the SPDX identifier may be used instead of the
full boilerplate text.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

PCI: endpoint: Fix find_first_zero_bit() usage

find_first_zero_bit()'s parameter 'size' is defined in bits,
not in bytes.

Calling find_first_zero_bit() with the wrong size unit
will lead to insidious bugs.

Fix this by calling find_first_zero_bit() with size BITS_PER_LONG,
rather than sizeof() and add missing find_first_zero_bit() return
handling.

Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>

PCI: endpoint: Populate func_no before calling pci_epc_add_epf()

func_no is a member of struct pci_epf.

Since struct pci_epf is used as an argument to pci_epc_add_epf() (to
bind an endpoint function to a controller), struct pci_epf.func_no
should be populated before calling pci_epc_add_epf().

Initialize the struct pci_epf.func_no member before calling
pci_epc_add_epf(), to fix the endpoint function binding to
an endpoint controller.

Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
[lorenzo.pieralisi@arm.com: rewrote the commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Suggested-by: Kishon Vijay Abraham I <kishon@ti.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>

PCI: endpoint: make config_item_type const

Make config_item_type structures const as they are either passed to a
function having the argument as const or stored in the const "ci_type"
field of a config_item structure.

Done using Coccinelle.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

PCI: endpoint: Introduce configfs entry for configuring EP functions

Introduce a new configfs entry to configure the EP function (like
configuring the standard configuration header entries) and to bind the EP
function with EP controller.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>