On Mon, Oct 27, 2025 at 8:12 PM Michael Levit <[email protected]> wrote:
>
> From: Michael <[email protected]>
>
> Introduce NEORV32 RV32 CPU type under target/riscv, wire NEORV32 vendor ID,
> and add a vendor CSR (CSR_MXISA) guarded by mvendorid match, plus meson glue.

Looks good. There are a bunch of whitespace errors though, can you run
your patches through checkpatch.pl

Alistair

>
> Signed-off-by: Michael Levit <[email protected]>
>
> diff --git a/target/riscv/cpu-qom.h b/target/riscv/cpu-qom.h
> index 75f4e43408..a39bf853cc 100644
> --- a/target/riscv/cpu-qom.h
> +++ b/target/riscv/cpu-qom.h
> @@ -57,6 +57,8 @@
>  #define TYPE_RISCV_CPU_XIANGSHAN_NANHU  
> RISCV_CPU_TYPE_NAME("xiangshan-nanhu")
>  #define TYPE_RISCV_CPU_XIANGSHAN_KMH    
> RISCV_CPU_TYPE_NAME("xiangshan-kunminghu")
>  #define TYPE_RISCV_CPU_HOST             RISCV_CPU_TYPE_NAME("host")
> +#define TYPE_RISCV_CPU_NEORV32          RISCV_CPU_TYPE_NAME("neorv32")
> +
>
>  OBJECT_DECLARE_CPU_TYPE(RISCVCPU, RISCVCPUClass, RISCV_CPU)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 73d4280d7c..7bcf93c66c 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -245,6 +245,7 @@ const RISCVIsaExtData isa_edata_arr[] = {
>      ISA_EXT_DATA_ENTRY(xtheadmempair, PRIV_VERSION_1_11_0, 
> ext_xtheadmempair),
>      ISA_EXT_DATA_ENTRY(xtheadsync, PRIV_VERSION_1_11_0, ext_xtheadsync),
>      ISA_EXT_DATA_ENTRY(xventanacondops, PRIV_VERSION_1_12_0, 
> ext_XVentanaCondOps),
> +    ISA_EXT_DATA_ENTRY(xneorv32xisa,PRIV_VERSION_1_10_0,ext_xneorv32xisa),
>
>      { },
>  };
> @@ -1366,6 +1367,7 @@ const RISCVCPUMultiExtConfig riscv_cpu_vendor_exts[] = {
>      MULTI_EXT_CFG_BOOL("xtheadmempair", ext_xtheadmempair, false),
>      MULTI_EXT_CFG_BOOL("xtheadsync", ext_xtheadsync, false),
>      MULTI_EXT_CFG_BOOL("xventanacondops", ext_XVentanaCondOps, false),
> +       MULTI_EXT_CFG_BOOL("xneorv32xisa", ext_xneorv32xisa, false),
>
>      { },
>  };
> @@ -3032,6 +3034,7 @@ static const TypeInfo riscv_cpu_type_infos[] = {
>          .cfg.pmp_regions = 8
>      ),
>
> +
>  #if defined(TARGET_RISCV32) || \
>      (defined(TARGET_RISCV64) && !defined(CONFIG_USER_ONLY))
>      DEFINE_RISCV_CPU(TYPE_RISCV_CPU_BASE32, TYPE_RISCV_DYNAMIC_CPU,
> @@ -3075,6 +3078,21 @@ static const TypeInfo riscv_cpu_type_infos[] = {
>          .misa_mxl_max = MXL_RV32,
>          .misa_ext = RVE
>      ),
> +       DEFINE_RISCV_CPU(TYPE_RISCV_CPU_NEORV32, TYPE_RISCV_VENDOR_CPU,
> +               .misa_mxl_max = MXL_RV32,
> +        .misa_ext = RVI | RVM | RVA | RVC | RVU,
> +        .priv_spec = PRIV_VERSION_1_10_0,
> +
> +        .cfg.max_satp_mode = VM_1_10_MBARE,
> +        .cfg.ext_zifencei = true,
> +        .cfg.ext_zicsr = true,
> +        .cfg.pmp = true,
> +        .cfg.pmp_regions = 16,
> +               .cfg.mvendorid = NEORV32_VENDOR_ID,
> +#ifndef CONFIG_USER_ONLY
> +        .custom_csrs = neorv32_csr_list
> +#endif
> +    ),
>  #endif
>
>  #if (defined(TARGET_RISCV64) && !defined(CONFIG_USER_ONLY))
>
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 36e7f10037..6a9918a25a 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -985,5 +985,8 @@ const char *satp_mode_str(uint8_t satp_mode, bool 
> is_32_bit);
>  /* In th_csr.c */
>  extern const RISCVCSR th_csr_list[];
>
> +/* Implemented in neorv32_csr.c */
> +extern const RISCVCSR neorv32_csr_list[];
> +
>  const char *priv_spec_to_str(int priv_version);
>  #endif /* RISCV_CPU_H */
>
> diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
> index aa28dc8d7e..9ad38506e4 100644
> --- a/target/riscv/cpu_cfg.h
> +++ b/target/riscv/cpu_cfg.h
> @@ -64,5 +64,6 @@ MATERIALISE_EXT_PREDICATE(xtheadmemidx)
>  MATERIALISE_EXT_PREDICATE(xtheadmempair)
>  MATERIALISE_EXT_PREDICATE(xtheadsync)
>  MATERIALISE_EXT_PREDICATE(XVentanaCondOps)
> +MATERIALISE_EXT_PREDICATE(xneorv32xisa)
>
>  #endif
>
> diff --git a/target/riscv/cpu_cfg_fields.h.inc 
> b/target/riscv/cpu_cfg_fields.h.inc
> index a154ecdc79..b84e1bd287 100644
> --- a/target/riscv/cpu_cfg_fields.h.inc
> +++ b/target/riscv/cpu_cfg_fields.h.inc
> @@ -147,6 +147,7 @@ BOOL_FIELD(ext_xtheadmemidx)
>  BOOL_FIELD(ext_xtheadmempair)
>  BOOL_FIELD(ext_xtheadsync)
>  BOOL_FIELD(ext_XVentanaCondOps)
> +BOOL_FIELD(ext_xneorv32xisa)
>
>  BOOL_FIELD(mmu)
>  BOOL_FIELD(pmp)
>
> diff --git a/target/riscv/cpu_vendorid.h b/target/riscv/cpu_vendorid.h
> index 96b6b9c2cb..66a8f30b81 100644
> --- a/target/riscv/cpu_vendorid.h
> +++ b/target/riscv/cpu_vendorid.h
> @@ -7,4 +7,6 @@
>  #define VEYRON_V1_MIMPID        0x111
>  #define VEYRON_V1_MVENDORID     0x61f
>
> +#define NEORV32_VENDOR_ID       0xF0000001
> +
>  #endif /*  TARGET_RISCV_CPU_VENDORID_H */
>
> diff --git a/target/riscv/meson.build b/target/riscv/meson.build
> index fdefe88ccd..44e706ad3f 100644
> --- a/target/riscv/meson.build
> +++ b/target/riscv/meson.build
> @@ -40,6 +40,7 @@ riscv_system_ss.add(files(
>    'th_csr.c',
>    'time_helper.c',
>    'riscv-qmp-cmds.c',
> +  'neorv32_csr.c',
>  ))
>
>  subdir('tcg')
>
> diff --git a/target/riscv/neorv32_csr.c b/target/riscv/neorv32_csr.c
> new file mode 100644
> index 0000000000..0cb8663436
> --- /dev/null
> +++ b/target/riscv/neorv32_csr.c
> @@ -0,0 +1,54 @@
> +/*
> + * Neorv32-specific CSR.
> + *
> + * Copyright (c) 2025 Michael Levit
> + *
> + * Author:
> + *   Michael Levit <[email protected]>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2 or later, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along 
> with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "cpu.h"
> +#include "cpu_vendorid.h"
> +
> +#define    CSR_MXISA    (0xfc0)
> +
> +static RISCVException smode(CPURISCVState *env, int csrno)
> +{
> +       return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException read_neorv32_xisa(CPURISCVState *env, int csrno,
> +                                       target_ulong *val)
> +{
> +       /* We don't support any extension for now on QEMU */
> +    *val = 0x00;
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static bool test_neorv32_mvendorid(RISCVCPU *cpu)
> +{
> +    return cpu->cfg.mvendorid == NEORV32_VENDOR_ID;
> +}
> +
> +const RISCVCSR neorv32_csr_list[] = {
> +    {
> +        .csrno = CSR_MXISA,
> +        .insertion_test = test_neorv32_mvendorid,
> +        .csr_ops = { "neorv32.xisa", smode, read_neorv32_xisa }
> +    },
> +    { }
> +};
> +
> --
> 2.51.1
>

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