treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

scsi: cxlflash: Isolate external module dependencies

Depending on the underlying transport, cxlflash has a dependency on either
the CXL or OCXL drivers, which are enabled via their Kconfig option.
Instead of having a module wide dependency on these config options, it is
better to isolate the object modules that are dependent on the CXL and OCXL
drivers and adjust the module dependencies accordingly.

This commit isolates the object files that are dependent on CXL and/or
OCXL. The cxl/ocxl fops used in the core driver are tucked under an ifdef to
avoid compilation errors.

Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: cxlflash: Introduce OCXL backend

Add initial infrastructure to support a new cxlflash transport, OCXL.

Claim a dependency on OCXL and add a new file, ocxl_hw.c, which will host the
backend routines that are specific to OCXL.

Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: cxlflash: Select IRQ_POLL

The driver now uses IRQ_POLL and needs to select it to avoid the
following build error.

ERROR: ".irq_poll_complete" [drivers/scsi/cxlflash/cxlflash.ko] undefined!
ERROR: ".irq_poll_sched" [drivers/scsi/cxlflash/cxlflash.ko] undefined!
ERROR: ".irq_poll_disable" [drivers/scsi/cxlflash/cxlflash.ko] undefined!
ERROR: ".irq_poll_init" [drivers/scsi/cxlflash/cxlflash.ko] undefined!

Fixes: cba06e6de403 ("scsi: cxlflash: Implement IRQ polling for RRQ processing")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

cxlflash: Base error recovery support

Introduce support for enhanced I/O error handling.

A device state is added to track 3 possible states of the device:

Normal - the device is operating normally and is fully operational

Limbo - the device is in a reset/recovery scenario and its operational
status is paused

Failed/terminating - the device has either failed to be reset/recovered
or is being terminated (removed); it is no longer
operational

All operations are allowed when the device is operating normally. When the
device transitions to limbo state, I/O must be paused. To help accomplish
this, a wait queue is introduced where existing and new threads can wait
until the device is no longer in limbo. When coming out of limbo, threads
need to check the state and error out gracefully when encountering the
failed state. When the device transitions to the failed/terminating state,
normal operations are no longer allowed. Only specially designated
operations related to graceful cleanup are permitted.

Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Reviewed-by: Wen Xiong <wenxiong@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

cxlflash: Base support for IBM CXL Flash Adapter

SCSI device driver to support filesystem access on the IBM CXL Flash adapter.

Supported-by: Stephen Bates <stephen.bates@pmcs.com>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>