Re: [PATCH 05/26] hw/riscv: pfsoc: Couple L2CC to L2-LIM

On Thu, Jul 23, 2026 at 11:18:32PM +0800, Bin Meng wrote:
> Instantiate the L2CC in the PolarFire SoC machine and connect its
> WayEnable register to the L2-LIM MemoryRegion. Back the complete 2 MiB
> aperture and shrink it by 128 KiB for each cache way enabled.
> 
> Keep L2 Zero at its fixed aperture because it represents a cache
> allocation window rather than the remaining L2-LIM capacity.
> 
> Signed-off-by: Bin Meng <[email protected]>
Reviewed-by: Chao Liu <[email protected]>

Thanks,
Chao

> ---
> 
>  include/hw/misc/mchp_pfsoc_l2cc.h  |  1 +
>  include/hw/riscv/microchip_pfsoc.h |  2 ++
>  hw/misc/mchp_pfsoc_l2cc.c          | 50 ++++++++++++++++++++++++++++++
>  hw/riscv/microchip_pfsoc.c         | 23 +++++++-------
>  hw/riscv/Kconfig                   |  1 +
>  5 files changed, 66 insertions(+), 11 deletions(-)
> 
> diff --git a/include/hw/misc/mchp_pfsoc_l2cc.h b/include/hw/misc/mchp_pfsoc_l2cc.h
> index 1b5b3888d5..3a175a6340 100644
> --- a/include/hw/misc/mchp_pfsoc_l2cc.h
> +++ b/include/hw/misc/mchp_pfsoc_l2cc.h
> @@ -22,6 +22,7 @@ typedef struct MchpPfSoCL2ccState {
>      SysBusDevice parent;
>      uint64_t regs[MCHP_PFSOC_L2CC_REG_NUM];
>      RegisterInfo regs_info[MCHP_PFSOC_L2CC_REG_NUM];
> +    MemoryRegion *l2lim;
>  } MchpPfSoCL2ccState;
>  
>  #define TYPE_MCHP_PFSOC_L2CC "mchp.pfsoc.l2cc"
> diff --git a/include/hw/riscv/microchip_pfsoc.h b/include/hw/riscv/microchip_pfsoc.h
> index 612fd2b69c..0aeccedf77 100644
> --- a/include/hw/riscv/microchip_pfsoc.h
> +++ b/include/hw/riscv/microchip_pfsoc.h
> @@ -27,6 +27,7 @@
>  #include "hw/cpu/cluster.h"
>  #include "hw/dma/sifive_pdma.h"
>  #include "hw/misc/mchp_pfsoc_dmc.h"
> +#include "hw/misc/mchp_pfsoc_l2cc.h"
>  #include "hw/misc/mchp_pfsoc_ioscb.h"
>  #include "hw/misc/mchp_pfsoc_sysreg.h"
>  #include "hw/net/cadence_gem.h"
> @@ -43,6 +44,7 @@ typedef struct MicrochipPFSoCState {
>      RISCVHartArrayState e_cpus;
>      RISCVHartArrayState u_cpus;
>      DeviceState *plic;
> +    MchpPfSoCL2ccState l2cc;
>      MchpPfSoCDdrSgmiiPhyState ddr_sgmii_phy;
>      MchpPfSoCDdrCfgState ddr_cfg;
>      MchpPfSoCIoscbState ioscb;
> diff --git a/hw/misc/mchp_pfsoc_l2cc.c b/hw/misc/mchp_pfsoc_l2cc.c
> index b320356572..7f3c2672c3 100644
> --- a/hw/misc/mchp_pfsoc_l2cc.c
> +++ b/hw/misc/mchp_pfsoc_l2cc.c
> @@ -11,6 +11,9 @@
>  
>  #include "qemu/osdep.h"
>  #include "qemu/log.h"
> +#include "qemu/units.h"
> +#include "qapi/error.h"
> +#include "hw/core/qdev-properties.h"
>  #include "hw/core/register.h"
>  #include "hw/core/registerfields.h"
>  #include "hw/misc/mchp_pfsoc_l2cc.h"
> @@ -39,6 +42,25 @@ REG64(L2_WAY_MASK_HART4_DCACHE, 0x868)
>  REG64(L2_WAY_MASK_HART4_ICACHE, 0x870)
>  
>  #define L2_CONFIG_RESET         0x06091004
> +#define L2_LIM_WAY_COUNT        15
> +#define L2_WAY_SIZE             (128 * KiB)
> +
> +static void mchp_pfsoc_l2cc_update_l2lim(MchpPfSoCL2ccState *s,
> +                                         uint64_t way_enable)
> +{
> +    uint64_t l2lim_size;
> +
> +    if (way_enable >= L2_LIM_WAY_COUNT) {
> +        l2lim_size = 0;
> +    } else {
> +        l2lim_size = (L2_LIM_WAY_COUNT - way_enable) * L2_WAY_SIZE;
> +    }
> +
> +    memory_region_transaction_begin();
> +    memory_region_set_size(s->l2lim, l2lim_size);
> +    memory_region_set_enabled(s->l2lim, l2lim_size != 0);
> +    memory_region_transaction_commit();
> +}
>  
>  static uint64_t mchp_pfsoc_l2cc_way_enable_pre_write(RegisterInfo *reg,
>                                                       uint64_t value)
> @@ -48,6 +70,14 @@ static uint64_t mchp_pfsoc_l2cc_way_enable_pre_write(RegisterInfo *reg,
>      return MAX(current, value);
>  }
>  
> +static void mchp_pfsoc_l2cc_way_enable_post_write(RegisterInfo *reg,
> +                                                  uint64_t value)
> +{
> +    MchpPfSoCL2ccState *s = MCHP_PFSOC_L2CC(reg->opaque);
> +
> +    mchp_pfsoc_l2cc_update_l2lim(s, value);
> +}
> +
>  #define WAY_MASK_REGISTER(_name)                \
>      {                                           \
>          .name = "WAY_MASK_" #_name,             \
> @@ -66,6 +96,7 @@ static const RegisterAccessInfo mchp_pfsoc_l2cc_regs_info[] = {
>          .addr = A_L2_WAY_ENABLE,
>          .rsvd = ~R_L2_WAY_ENABLE_VALUE_MASK,
>          .pre_write = mchp_pfsoc_l2cc_way_enable_pre_write,
> +        .post_write = mchp_pfsoc_l2cc_way_enable_post_write,
>      },
>      WAY_MASK_REGISTER(DMA),
>      WAY_MASK_REGISTER(AXI4_PORT_0),
> @@ -157,11 +188,30 @@ static void mchp_pfsoc_l2cc_init(Object *obj)
>      sysbus_init_mmio(SYS_BUS_DEVICE(obj), &reg_array->mem);
>  }
>  
> +static void mchp_pfsoc_l2cc_realize(DeviceState *dev, Error **errp)
> +{
> +    MchpPfSoCL2ccState *s = MCHP_PFSOC_L2CC(dev);
> +
> +    if (!s->l2lim) {
> +        error_setg(errp, TYPE_MCHP_PFSOC_L2CC ": 'l2-lim' link not set");
> +        return;
> +    }
> +
> +    mchp_pfsoc_l2cc_update_l2lim(s, s->regs[R_L2_WAY_ENABLE]);
> +}
> +
> +static const Property mchp_pfsoc_l2cc_properties[] = {
> +    DEFINE_PROP_LINK("l2-lim", MchpPfSoCL2ccState, l2lim,
> +                     TYPE_MEMORY_REGION, MemoryRegion *),
> +};
> +
>  static void mchp_pfsoc_l2cc_class_init(ObjectClass *klass, const void *data)
>  {
>      DeviceClass *dc = DEVICE_CLASS(klass);
>  
>      device_class_set_legacy_reset(dc, mchp_pfsoc_l2cc_reset);
> +    device_class_set_props(dc, mchp_pfsoc_l2cc_properties);
> +    dc->realize = mchp_pfsoc_l2cc_realize;
>  }
>  
>  static const TypeInfo mchp_pfsoc_l2cc_info = {
> diff --git a/hw/riscv/microchip_pfsoc.c b/hw/riscv/microchip_pfsoc.c
> index fd28ee75fe..248de4d022 100644
> --- a/hw/riscv/microchip_pfsoc.c
> +++ b/hw/riscv/microchip_pfsoc.c
> @@ -175,6 +175,9 @@ static void microchip_pfsoc_soc_instance_init(Object *obj)
>      object_initialize_child(obj, "dma-controller", &s->dma,
>                              TYPE_SIFIVE_PDMA);
>  
> +    object_initialize_child(obj, "l2-cache-controller", &s->l2cc,
> +                            TYPE_MCHP_PFSOC_L2CC);
> +
>      object_initialize_child(obj, "sysreg", &s->sysreg,
>                              TYPE_MCHP_PFSOC_SYSREG);
>  
> @@ -260,18 +263,9 @@ static void microchip_pfsoc_soc_realize(DeviceState *dev, Error **errp)
>          RISCV_ACLINT_DEFAULT_MTIMECMP, RISCV_ACLINT_DEFAULT_MTIME,
>          iks->clint_timebase_freq, false);
>  
> -    /* L2 cache controller */
> -    create_unimplemented_device("microchip.pfsoc.l2cc",
> -        memmap[MICROCHIP_PFSOC_L2CC].base, memmap[MICROCHIP_PFSOC_L2CC].size);
> -
>      /*
> -     * Add L2-LIM at reset size.
> -     * This should be reduced in size as the L2 Cache Controller WayEnable
> -     * register is incremented. Unfortunately I don't see a nice (or any) way
> -     * to handle reducing or blocking out the L2 LIM while still allowing it
> -     * be re returned to all enabled after a reset. For the time being, just
> -     * leave it enabled all the time. This won't break anything, but will be
> -     * too generous to misbehaving guests.
> +     * Back the complete L2-LIM aperture. The L2 cache controller resizes
> +     * this MemoryRegion to 128 KiB for every way assigned to L2-LIM.
>       */
>      memory_region_init_ram(l2lim_mem, NULL, "microchip.pfsoc.l2lim",
>                             memmap[MICROCHIP_PFSOC_L2LIM].size, &error_fatal);
> @@ -279,6 +273,13 @@ static void microchip_pfsoc_soc_realize(DeviceState *dev, Error **errp)
>                                  memmap[MICROCHIP_PFSOC_L2LIM].base,
>                                  l2lim_mem);
>  
> +    /* L2 cache controller */
> +    object_property_set_link(OBJECT(&s->l2cc), "l2-lim",
> +                             OBJECT(l2lim_mem), &error_abort);
> +    sysbus_realize(SYS_BUS_DEVICE(&s->l2cc), errp);
> +    sysbus_mmio_map(SYS_BUS_DEVICE(&s->l2cc), 0,
> +                    memmap[MICROCHIP_PFSOC_L2CC].base);
> +
>      /*
>       * HSS decompresses into the L2 zero-device window and executes there.
>       * Model it as RAM because QEMU does not model the backing L2 cache.
> diff --git a/hw/riscv/Kconfig b/hw/riscv/Kconfig
> index de37c08cae..22619481e4 100644
> --- a/hw/riscv/Kconfig
> +++ b/hw/riscv/Kconfig
> @@ -18,6 +18,7 @@ config MICROCHIP_PFSOC
>      select DEVICE_TREE
>      select MCHP_PFSOC_DMC
>      select MCHP_PFSOC_IOSCB
> +    select MCHP_PFSOC_L2CC
>      select MCHP_PFSOC_MMUART
>      select MCHP_PFSOC_SYSREG
>      select RISCV_ACLINT
> -- 
> 2.34.1
>