drm/panthor: Reset the FW VM to NULL on unplug

This way get NULL derefs instead of use-after-free if the FW VM is
referenced after the device has been unplugged.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240502183813.1612017-4-boris.brezillon@collabora.com

drm/panthor: Keep a ref to the VM at the panthor_kernel_bo level

Avoids use-after-free situations when panthor_fw_unplug() is called
and the kernel BO was mapped to the FW VM.

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/20240502183813.1612017-3-boris.brezillon@collabora.com

drm/panthor: Fix the FW reset logic

In the post_reset function, if the fast reset didn't succeed, we
are not clearing the fast_reset flag, which prevents firmware
sections from being reloaded. While at it, use panthor_fw_stop()
instead of manually writing DISABLE to the MCU_CONTROL register.

Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240430113727.493155-1-boris.brezillon@collabora.com

drm/panthor: Fix off by one in panthor_fw_get_cs_iface()

The ->iface.streams[csg_slot][] array has MAX_CS_PER_CSG elements so
this > comparison needs to be >= to prevent an out of bounds access.

Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/62835c16-c85c-483d-a8fe-63be78d49d15@moroto.mountain

drm/panthor: Add the FW logical block

Contains everything that's FW related, that includes the code dealing
with the microcontroller unit (MCU) that's running the FW, and anything
related to allocating memory shared between the FW and the CPU.

A few global FW events are processed in the IRQ handler, the rest is
forwarded to the scheduler, since scheduling is the primary reason for
the FW existence, and also the main source of FW <-> kernel
interactions.

v6:
- Add Maxime's and Heiko's acks
- Keep header inclusion alphabetically ordered

v5:
- Fix typo in GLB_PERFCNT_SAMPLE definition
- Fix unbalanced panthor_vm_idle/active() calls
- Fallback to a slow reset when the fast reset fails
- Add extra information when reporting a FW boot failure

v4:
- Add a MODULE_FIRMWARE() entry for gen 10.8
- Fix a wrong return ERR_PTR() in panthor_fw_load_section_entry()
- Fix typos
- Add Steve's R-b

v3:
- Make the FW path more future-proof (Liviu)
- Use one waitqueue for all FW events
- Simplify propagation of FW events to the scheduler logic
- Drop the panthor_fw_mem abstraction and use panthor_kernel_bo instead
- Account for the panthor_vm changes
- Replace magic number with 0x7fffffff with ~0 to better signify that
it's the maximum permitted value.
- More accurate rounding when computing the firmware timeout.
- Add a 'sub iterator' helper function. This also adds a check that a
firmware entry doesn't overflow the firmware image.
- Drop __packed from FW structures, natural alignment is good enough.
- Other minor code improvements.

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>
Reviewed-by: Steven Price <steven.price@arm.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240229162230.2634044-9-boris.brezillon@collabora.com