drm/panthor: Don't return NULL from panthor_vm_get_heap_pool()

The kernel doc says this function returns either a valid pointer
or an ERR_PTR(), but in practice this function can return NULL if
create=false. Fix the function to match the doc (return
ERR_PTR(-ENOENT) instead of NULL) and adjust all call-sites
accordingly.

Fixes: 4bdca1150792 ("drm/panthor: Add the driver frontend block")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240402141412.1707949-1-harshit.m.mogalapalli@oracle.com

drm/panthor: Fix NULL vs IS_ERR() bug in panthor_probe()

The devm_drm_dev_alloc() function returns error pointers.
Update the error handling to check for error pointers instead of NULL.

Fixes: 4bdca1150792 ("drm/panthor: Add the driver frontend block")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240402104041.1689951-1-harshit.m.mogalapalli@oracle.com

drm/panthor: Fix IO-page mmap() for 32-bit userspace on 64-bit kernel

When mapping an IO region, the pseudo-file offset is dependent on the
userspace architecture. panthor_device_mmio_offset() abstracts that
away for us by turning a userspace MMIO offset into its kernel
equivalent, but we were not updating vm_area_struct::vm_pgoff
accordingly, leading us to attach the MMIO region to the wrong file
offset.

This has implications when we start mixing 64 bit and 32 bit apps, but
that's only really a problem when we start having more that 2^43 bytes of
memory allocated, which is very unlikely to happen.

What's more problematic is the fact this turns our
unmap_mapping_range(DRM_PANTHOR_USER_MMIO_OFFSET) calls, which are
supposed to kill the MMIO mapping when entering suspend, into NOPs.
Which means we either keep the dummy flush_id mapping active at all
times, or we risk a BUS_FAULT if the MMIO region was mapped, and the
GPU is suspended after that.

Solve that by patching vm_pgoff early in panthor_mmap(). With
this in place, we no longer need the panthor_device_mmio_offset()
helper.

v3:
- No changes

v2:
- Kill panthor_device_mmio_offset()

Fixes: 5fe909cae118 ("drm/panthor: Add the device logical block")
Reported-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Reported-by: Lukas F. Hartmann <lukas@mntmn.com>
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10835
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240326111205.510019-1-boris.brezillon@collabora.com

drm/panthor: Fix the CONFIG_PM=n case

Putting a hard dependency on CONFIG_PM is not possible because of a
circular dependency issue, and it's actually not desirable either. In
order to support this use case, we forcibly resume at init time, and
suspend at unplug time.

v2:
- Drop the #ifdef CONFIG_PM section around panthor_pm_ops's definition

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202403031944.EOimQ8WK-lkp@intel.com/
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240318153117.1321544-1-boris.brezillon@collabora.com

drm/panthor: Add the driver frontend block

This is the last piece missing to expose the driver to the outside
world.

This is basically a wrapper between the ioctls and the other logical
blocks.

v6:
- Add Maxime's and Heiko's acks
- Return a page-aligned BO size to userspace
- Keep header inclusion alphabetically ordered

v5:
- Account for the drm_exec_init() prototype change
- Include platform_device.h

v4:
- Add an ioctl to let the UMD query the VM state
- Fix kernel doc
- Let panthor_device_init() call panthor_device_init()
- Fix cleanup ordering in the panthor_init() error path
- Add Steve's and Liviu's R-b

v3:
- Add acks for the MIT/GPL2 relicensing
- Fix 32-bit support
- Account for panthor_vm and panthor_sched changes
- Simplify the resv preparation/update logic
- Use a linked list rather than xarray for list of signals.
- Simplify panthor_get_uobj_array by returning the newly allocated
array.
- Drop the "DOC" for job submission helpers and move the relevant
comments to panthor_ioctl_group_submit().
- Add helpers sync_op_is_signal()/sync_op_is_wait().
- Simplify return type of panthor_submit_ctx_add_sync_signal() and
panthor_submit_ctx_get_sync_signal().
- Drop WARN_ON from panthor_submit_ctx_add_job().
- Fix typos in comments.

Co-developed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Steven Price <steven.price@arm.com> # MIT+GPL2 relicensing,Arm
Acked-by: Grant Likely <grant.likely@linaro.org> # MIT+GPL2 relicensing,Linaro
Acked-by: Boris Brezillon <boris.brezillon@collabora.com> # MIT+GPL2 relicensing,Collabora
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240229162230.2634044-12-boris.brezillon@collabora.com