On Wed Jan 29, 2025 at 8:55 AM AEST, Paul Mackerras wrote:
> This adds support for Microwatt systems with more than one core, and
> updates the device tree for a 2-core version. (This does not prevent
> the kernel from running on a single-core system.)
>
> Signed-off-by: Paul Mackerras <pau...@ozlabs.org>
Well, I'm impressed you added SMP :)
What happens with a 1 CPU system? Do we time out waiting for secondaries
and continue, or is there something more graceful?
> ---
> arch/powerpc/boot/dts/microwatt.dts | 34 ++++++++++++++++++--
> arch/powerpc/platforms/microwatt/Kconfig | 2 +-
> arch/powerpc/platforms/microwatt/Makefile | 1 +
> arch/powerpc/platforms/microwatt/microwatt.h | 1 +
> arch/powerpc/platforms/microwatt/setup.c | 10 ++++++
> 5 files changed, 45 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/boot/dts/microwatt.dts
> b/arch/powerpc/boot/dts/microwatt.dts
> index 6e575e841a7b..89281dc975b3 100644
> --- a/arch/powerpc/boot/dts/microwatt.dts
> +++ b/arch/powerpc/boot/dts/microwatt.dts
> @@ -142,6 +142,36 @@ PowerPC,Microwatt@0 {
> ibm,mmu-lpid-bits = <12>;
> ibm,mmu-pid-bits = <20>;
> };
> +
> + PowerPC,Microwatt@1 {
> + i-cache-sets = <2>;
> + ibm,dec-bits = <64>;
> + reservation-granule-size = <64>;
> + clock-frequency = <100000000>;
> + timebase-frequency = <100000000>;
> + i-tlb-sets = <1>;
> + ibm,ppc-interrupt-server#s = <1>;
> + i-cache-block-size = <64>;
> + d-cache-block-size = <64>;
> + d-cache-sets = <2>;
> + i-tlb-size = <64>;
> + cpu-version = <0x990000>;
> + status = "okay";
> + i-cache-size = <0x1000>;
> + ibm,processor-radix-AP-encodings = <0x0c 0xa0000010
> 0x20000015 0x4000001e>;
> + tlb-size = <0>;
> + tlb-sets = <0>;
> + device_type = "cpu";
> + d-tlb-size = <128>;
> + d-tlb-sets = <2>;
> + reg = <1>;
> + general-purpose;
> + 64-bit;
> + d-cache-size = <0x1000>;
> + ibm,chip-id = <0>;
> + ibm,mmu-lpid-bits = <12>;
> + ibm,mmu-pid-bits = <20>;
> + };
> };
>
> soc@c0000000 {
> @@ -154,8 +184,8 @@ soc@c0000000 {
>
> interrupt-controller@4000 {
> compatible = "openpower,xics-presentation",
> "ibm,ppc-xicp";
> - ibm,interrupt-server-ranges = <0x0 0x1>;
> - reg = <0x4000 0x100>;
> + ibm,interrupt-server-ranges = <0x0 0x2>;
> + reg = <0x4000 0x10 0x4010 0x10>;
> };
>
> ICS: interrupt-controller@5000 {
> diff --git a/arch/powerpc/platforms/microwatt/Kconfig
> b/arch/powerpc/platforms/microwatt/Kconfig
> index 1d5cc1ae3636..8911ea7cf12e 100644
> --- a/arch/powerpc/platforms/microwatt/Kconfig
> +++ b/arch/powerpc/platforms/microwatt/Kconfig
> @@ -1,6 +1,6 @@
> # SPDX-License-Identifier: GPL-2.0
> config PPC_MICROWATT
> - depends on PPC_BOOK3S_64 && !SMP
> + depends on PPC_BOOK3S_64
> bool "Microwatt SoC platform"
> select PPC_XICS
> select PPC_ICS_NATIVE
> diff --git a/arch/powerpc/platforms/microwatt/Makefile
> b/arch/powerpc/platforms/microwatt/Makefile
> index 116d6d3ad3f0..d973b2ab4042 100644
> --- a/arch/powerpc/platforms/microwatt/Makefile
> +++ b/arch/powerpc/platforms/microwatt/Makefile
> @@ -1 +1,2 @@
> obj-y += setup.o rng.o
> +obj-$(CONFIG_SMP) += smp.o
Hmm.... `git add arch/powerpc/platforms/microwatt/smp.c` ?
> diff --git a/arch/powerpc/platforms/microwatt/microwatt.h
> b/arch/powerpc/platforms/microwatt/microwatt.h
> index 335417e95e66..891aa2800768 100644
> --- a/arch/powerpc/platforms/microwatt/microwatt.h
> +++ b/arch/powerpc/platforms/microwatt/microwatt.h
> @@ -3,5 +3,6 @@
> #define _MICROWATT_H
>
> void microwatt_rng_init(void);
> +void microwatt_init_smp(void);
>
> #endif /* _MICROWATT_H */
> diff --git a/arch/powerpc/platforms/microwatt/setup.c
> b/arch/powerpc/platforms/microwatt/setup.c
> index 97828a99780d..d966bf1f57f7 100644
> --- a/arch/powerpc/platforms/microwatt/setup.c
> +++ b/arch/powerpc/platforms/microwatt/setup.c
> @@ -29,6 +29,15 @@ static int __init microwatt_populate(void)
> }
> machine_arch_initcall(microwatt, microwatt_populate);
>
> +static int __init microwatt_probe(void)
> +{
> + /* Main reason for having this is to start the other CPU(s) */
> +#ifdef CONFIG_SMP
> + microwatt_init_smp();
> +#endif
Could use
if (IS_ENABLED(CONFIG_SMP))
microwatt_init_smp();
Thanks,
Nick
> + return 1;
> +}
> +
> static void __init microwatt_setup_arch(void)
> {
> microwatt_rng_init();
> @@ -45,6 +54,7 @@ static void microwatt_idle(void)
> define_machine(microwatt) {
> .name = "microwatt",
> .compatible = "microwatt-soc",
> + .probe = microwatt_probe,
> .init_IRQ = microwatt_init_IRQ,
> .setup_arch = microwatt_setup_arch,
> .progress = udbg_progress,
