Qualcomm Kernel¶

Random notes about the Qualcomm Kernel as used on the MDM9615

diag¶

diag forwarding¶

drivers/char/diag/diagfwd.[ch]
drivers/usb/gadget/f_diag.[ch]
drivers/usb/misc/diag_bridge.c

• the usb diag gadget handles diag packet read/write over usb
• issues events like USB_DIAG_READ_DONE
• picked up by diagfwd.c
  • can forward diag requests via SMD shared memory to other processors

diag char¶

drivers/char/diag/diagchar_core.c

• ioctl()s for diag configuration
• supports several concurrent diag clients
• diag logging can be directed to USB/HSIC, character device and more
  • {USB,CALLBACK,MEMORY_DEVICE,UART,NO_LOGGING}_MODE

driver/schar/diag/diag_dci.c

• DCI table is a routing table where pid/sockets can register for a
  given DCI. socket close/cleanup code releases all DCI routes for
  that socket.

SMD (shared memory)¶

• SMD sub-systems:
  • Modem (assumed to be hexagon with modem firmware?)
  • Q6 (formerly known as LPASS == Low Power Audio SubSystem)
  • DSPS
  • WCNSS (Wireless Connectivity Sub System) aka 'riva'
  • RPM (Resource Power Manager)
• inter-processor-interrupts for various 'edges'

core driver¶

• arch/arm/mach-msm/smd.c

api

• smd_open()
• smd_close()
• smd_write*()
• smd_read*()
• smsm_*()

MSM IPC socket¶

• arch/arm/mach-msm/ipc_socket.c
• AF_MSM_IPC

packet ports¶

• Some kind of packet oriented interface towards the SMD
• msm_smd_pkt.c contains driver
  • smdpkt0..7+smd22 devices, 2048 byte buffer
  • open/release/read/write/poll syscalls implemented