arch/risc-v: Fix Espressif timer registering ID

[tmedicci]

Summary

• arch/risc-v: Fix Espressif timer registering ID
  • Fix Espressif timer registering ID. Espressif's general purpose timers are grouped in different Timer Groups, which may contain more than one general purpose timer. The current implementation is related to the timer groups (timer0 refers to Timer Group 0, for instance), but previous registering method was referring to the timer inside each group, which caused it to fail when more than one timer group was being selected because only the first timer on each group is being actually registered.

Impact

Impact on user: Yes. Enable registering two general purpose timers at a time.

Impact on build: No.

Impact on hardware: RISC-V-based Espressif SoCs.

Impact on documentation: No.

Impact on security: No.

Impact on compatibility: No.

Testing

Before applying this patch, only one general purpose was being properly registered at /dev/timer0 (no /dev/timer1)

Building

Check it by building the same firmware before and after applying this patch. For esp32p4-function-ev-board:timers:

make -j distclean && ./tools/configure.sh -S esp32p4-function-ev-board:timers && kconfig-tweak -d ONESHOT && kconfig-tweak -d EXAMPLES_ONESHOT && make flash ESPTOOL_PORT=/dev/ttyACM0 -s -j$(nproc) && picocom -b 115200 /dev/ttyUSB1

Running

Check timers registered at /dev/.

Results

Before this patch

Only /dev/timer0 is registered:

nsh> ls /dev/
/dev:
 console
 null
 random
 timer0
 ttyS0
 zero

After this patch

Both /dev/timer0 and /dev/timer1 are registered:

nsh> ls /dev/
/dev:
 console
 null
 random
 timer0
 timer1
 ttyS0
 zero