The old scheme doesn't allow sending hart0 self-IPI as the
corresponding bit on pending register is hardwired to 0, this
could lead to unhandle IPIs on SMP systems, esp. on single-core.
Furthermore, the limitation of old scheme is 8-core, instead of
reserving source hart information, we assign bit (x + 1) as the
enable and pending bit of hartx, this also expands the bootable
hart number.
The following diagram shows the enable bits of the new scheme
on 32-core Andes platform.
Pending regs: 0x1000 x---0---0---0---0------0---0
Pending hart ID: 0 1 2 3 ... 30 31
Interrupt ID: 0 1 2 3 4 ... 31 32
| | | | | | |
Enable regs: 0x2000 x---1---0---0---0-...--0---0---> hart0
| | | | | | |
0x2080 x---0---1---0---0-...--0---0---> hart1
| | | | | | |
0x2100 x---0---0---1---0-...--0---0---> hart2
| | | | | | |
0x2180 x---0---0---0---1-...--0---0---> hart3
. . . . . . .
. . . . . . .
. . . . . . .
0x2f00 x---0---0---0---0-...--1---0---> hart30
| | | | | | |
0x2f80 x---0---0---0---0-...--0---1---> hart31
<-------- word 0 -------><--- word 1 --->
To send IPI to hart0, for example, another hart (including hart0
itself) will set bit 1 of first word on the pending register.
We also fix indentation in andes_plicsw.h along with this patch.
Fixes: ce7c490719 ("lib: utils/ipi: Add Andes fdt ipi driver support")
Signed-off-by: Leo Yu-Chi Liang <ycliang@andestech.com>
Reviewed-by: Yu Chien Peter Lin <peterlin@andestech.com>
Reviewed-by: Randolph <randolph@andestech.com>
Reported-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lists.infradead.org/pipermail/opensbi/2023-October/005665.html
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Move Andes PLICSW ipi device to fdt ipi framework, this patch is based
on Leo's modified IPI scheme on PLICSW.
Current IPI scheme uses bit 0 of pending reigster on PLICSW to send IPI
from hart 0 to hart 7, but bit 0 needs to be hardwired to 0 according
to spec. After some investigation, self-IPI seems to be seldom or never
used, so we re-order the IPI scheme to support 8 core platforms.
dts example (Quad-core AX45MP):
plicsw: interrupt-controller@e6400000 {
compatible = "andestech,plicsw";
reg = <0x00000000 0xe6400000 0x00000000 0x00400000>;
interrupts-extended = <&CPU0_intc 3
&CPU1_intc 3
&CPU2_intc 3
&CPU3_intc 3>;
interrupt-controller;
#address-cells = <2>;
#interrupt-cells = <2>;
};
Signed-off-by: Yu Chien Peter Lin <peterlin@andestech.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
