FROMLIST: misc: fastrpc: Add cache maintenance for non-coherent platforms

[quic-anane]

Some platforms using fastrpc do not support DMA coherency on
HLOS. On such systems, explicit cache maintenance is
required to ensure data consistency for RPC argument buffers.

Add cache maintenance for argument buffers when operating on
non-coherent platforms:

• Flush input buffers before invoking RPC to ensure CPU writes are
  visible to the DSP
• Invalidate output buffers after RPC completion to ensure DSP
  writes are visible to the CPU

Introduce helper functions fastrpc_flush_args() and
fastrpc_inv_args() to perform the required dma-buf cache
operations. These are invoked only when the device is not marked
as DMA coherent.

The coherency capability is determined using the "dma-coherent"
device tree property and stored per session context.

This ensures correct data synchronization on platforms lacking
DMA coherency, while avoiding unnecessary overhead on coherent
systems.

Link: https://lore.kernel.org/all/20260604194811.2437567-1-abhinav.parihar@oss.qualcomm.com/
Signed-off-by: Abhinav Parihar abhinav.parihar@oss.qualcomm.com

[qswat-orbit-external]

Merge Check Failed: No CR Numbers Found

Error: No Change Request numbers were found.

Please add Change Request numbers to your pull request description in the format CRs-Fixed: 12345 or link GitHub issues that are associated with Change Requests.

[qcomlnxci]

Test jobs on c01da04

• Job 119210 on lemans-evk
• Job 119212 on monaco-evk
• Job 119209 on qcs615-ride
• Job 119214 on qcs6490-rb3gen2
• Job 119213 on qcs8300-ride
• Job 119215 on qcs9100-ride-r3
• Job 119211 on x1e80100-crd

[qcomlnxci]

Test Matrix

Test Case	lemans-evk	monaco-evk	qcs615-ride	qcs6490-rb3gen2	qcs8300-ride	qcs9100-ride-r3	x1e80100-crd
BT_FW_KMD_Service	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
BT_ON_OFF	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
BT_SCAN	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
CPUFreq_Validation	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
CPU_affinity	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
DSP_AudioPD	✅ Pass	◻️	⚠️ skip	✅ Pass	✅ Pass	⚠️ skip	◻️
Ethernet	⚠️ skip	◻️	⚠️ skip	⚠️ skip	⚠️ skip	⚠️ skip	◻️
Freq_Scaling	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
GIC	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
IPA	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
Interrupts	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
OpenCV	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
PCIe	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
Probe_Failure_Check	❌ Fail	◻️	❌ Fail	❌ Fail	❌ Fail	❌ Fail	◻️
RMNET	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
UFS_Validation	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
USBHost	❌ Fail	◻️	❌ Fail	❌ Fail	❌ Fail	❌ Fail	◻️
WiFi_Firmware_Driver	❌ Fail	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
WiFi_OnOff	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
adsp_remoteproc	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	❌ Fail	◻️
cdsp_remoteproc	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	❌ Fail	◻️
gpdsp_remoteproc	✅ Pass	◻️	⚠️ skip	⚠️ skip	✅ Pass	❌ Fail	◻️
hotplug	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
irq	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
kaslr	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
pinctrl	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
qcom_hwrng	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
remoteproc	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	❌ Fail	◻️
rngtest	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
shmbridge	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
smmu	❌ Fail	◻️	❌ Fail	✅ Pass	✅ Pass	❌ Fail	◻️
watchdog	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
wpss_remoteproc	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️