linux-phytec-ti

remoteproc/keystone: add support for MPM userspace loader

The Keystone remoteproc driver performs the device management of
different DSP processor subsystems present on various Keystone 2
family of SoCs. The driver currently supports loading/booting using
the remoteproc core's 'auto-boot' feature and supports advanced
features like error recovery.

This patch enhances the Keystone remoteproc driver to add support
for a TI specific userspace based loading/booting mechanism called
the Multi Proc Manager (MPM) by exposing a character device interface
to userspace per device. A new module parameter 'use_rproc_core_loader'
is introduced to configure the driver for in-kernel auto-boot mode
or the MPM non auto-boot mode, with the default configured for MPM.
The standard platform driver's bind and unbind sysfs attributes are
suppressed for MPM-based stack so that the regular sysfs approach of
booting and shutting down a Keystone DSP remote processor does not
mess up the MPM-based state-machine by unbinding the device from the
driver even when it has open usage reference counts. The standard
remoteproc sysfs interfaces for changing 'state' and 'firmware'
conflict with the MPM state-machine and are denied using the
remoteproc generic 'deny_sysfs_ops' flag.  An exception notification
is also provided through an UIO device exposed by the keystone
remoteproc driver for now.

The MPM loading/booting mechanism uses the file operations exported
by the character device. The mmap interface is used for mapping device
memory into userspace for loading and the ioctl interfaces are used
for reset and remoteproc resource table configuration and triggering
the boot and shutdown of the DSPs.

The address and size of the various DSP internal RAM memories to
be used with the mmap interface are provided through two sysfs
files 'addr' and 'size' for each region, and are created under the
respective dspX misc device for each DSP remoteproc processor. These
files are created in their own directory for each region accessible
under the /sys/class/misc/dspX/ path, where X is the DSP number
(indexed from 0). The MPM also relies on another memory mapping
character device (/dev/dspmem) to support loading images into
external DDR memory and the Multicore Shared Memory (MSM). This
sysfs logic allows the userspace-based Multi Proc Manager (MPM)
stack to not rely on procfs-based DT parsing for looking up the
memories.

The MPM supports various kinds of firmware images - images with and
without resource tables, images that have a resource table but with
or without the virtio device resource entries. The loadable regions
include images just using internal DSP memories, or images using
portions of the MSM RAM and/or external DDR. The load/boot of images
with and without resource tables are supported using separate ioctl
operations. The KEYSTONE_RPROC_IOC_SET_STATE ioctl is used to boot
and shutdown remote processors for images with resource tables, and
the KEYSTONE_RPROC_IOC_DSP_RESET/BOOT ioctls for images without a
resource table. The boot address/entry point is published during the
corresponding ioctls that trigger a boot, and is stored in a local
variable in driver instance and later picked up by remoteproc core
driver through fw_ops.

This logic is created anew using an older code from Cyril Chemparathy
as a baseline.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Sam Nelson <samnelson@ti.com>