[v7] target/riscv: Add isa extenstion strings to the device tree

The Linux kernel parses the ISA extensions from "riscv,isa" DT
property. It used to parse only the single letter base extensions
until now. A generic ISA extension parsing framework was proposed[1]
recently that can parse multi-letter ISA extensions as well.

Generate the extended ISA string by appending the available ISA extensions
to the "riscv,isa" string if it is enabled so that kernel can process it.

[1] https://lkml.org/lkml/2022/2/15/263

Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Suggested-by: Heiko Stubner <heiko@sntech.de>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
---

Changes from v6->v7:
1. Fixed indentation and typo.
2. Added Reviewed-by tags.

Changes from v5->v6:
1. Improved commit message.
2. Fixed a typo for Zfh.

Changes from v4->v5:
1. Fixed the order of Zxx extensions.
2. Added a comment clearly describing the rules of extension order.

Changes from v3->v4:
1. Fixed the order of the extension names.
2. Added all the available ISA extensions in Qemu.

Changes from v2->v3:
1. Used g_strconcat to replace snprintf & a max isa string length as
suggested by Anup.
2. I have not included the Tested-by Tag from Heiko because the
implementation changed from v2 to v3.

Changes from v1->v2:
1. Improved the code redability by using arrays instead of individual check
---
 target/riscv/cpu.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

On Wed, Mar 30, 2022 at 5:59 AM Atish Patra <atishp@rivosinc.com> wrote:
>
> The Linux kernel parses the ISA extensions from "riscv,isa" DT
> property. It used to parse only the single letter base extensions
> until now. A generic ISA extension parsing framework was proposed[1]
> recently that can parse multi-letter ISA extensions as well.
>
> Generate the extended ISA string by appending the available ISA extensions
> to the "riscv,isa" string if it is enabled so that kernel can process it.
>
> [1] https://lkml.org/lkml/2022/2/15/263
>
> Reviewed-by: Anup Patel <anup@brainfault.org>
> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> Reviewed-by: Frank Chang <frank.chang@sifive.com>
> Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
> Tested-by: Bin Meng <bmeng.cn@gmail.com>
> Suggested-by: Heiko Stubner <heiko@sntech.de>
> Signed-off-by: Atish Patra <atishp@rivosinc.com>

Thanks!

Applied to riscv-to-apply.next

Alistair

> ---
>
> Changes from v6->v7:
> 1. Fixed indentation and typo.
> 2. Added Reviewed-by tags.
>
> Changes from v5->v6:
> 1. Improved commit message.
> 2. Fixed a typo for Zfh.
>
> Changes from v4->v5:
> 1. Fixed the order of Zxx extensions.
> 2. Added a comment clearly describing the rules of extension order.
>
> Changes from v3->v4:
> 1. Fixed the order of the extension names.
> 2. Added all the available ISA extensions in Qemu.
>
> Changes from v2->v3:
> 1. Used g_strconcat to replace snprintf & a max isa string length as
> suggested by Anup.
> 2. I have not included the Tested-by Tag from Heiko because the
> implementation changed from v2 to v3.
>
> Changes from v1->v2:
> 1. Improved the code redability by using arrays instead of individual check
> ---
>  target/riscv/cpu.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 60 insertions(+)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 198274fb34e5..86e48ff54dd1 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -34,6 +34,11 @@
>
>  /* RISC-V CPU definitions */
>
> +struct isa_ext_data {
> +    const char *name;
> +    bool enabled;
> +};
> +
>  static const char riscv_exts[26] = "IEMAFDQCLBJTPVNSUHKORWXYZG";
>
>  const char * const riscv_int_regnames[] = {
> @@ -920,6 +925,60 @@ static void riscv_cpu_class_init(ObjectClass *c, void *data)
>      device_class_set_props(dc, riscv_cpu_properties);
>  }
>
> +#define ISA_EDATA_ENTRY(name, prop) {#name, cpu->cfg.prop}
> +
> +static void riscv_isa_string_ext(RISCVCPU *cpu, char **isa_str, int max_str_len)
> +{
> +    char *old = *isa_str;
> +    char *new = *isa_str;
> +    int i;
> +
> +    /**
> +     * Here are the ordering rules of extension naming defined by RISC-V
> +     * specification :
> +     * 1. All extensions should be separated from other multi-letter extensions
> +     *    by an underscore.
> +     * 2. The first letter following the 'Z' conventionally indicates the most
> +     *    closely related alphabetical extension category, IMAFDQLCBKJTPVH.
> +     *    If multiple 'Z' extensions are named, they should be ordered first
> +     *    by category, then alphabetically within a category.
> +     * 3. Standard supervisor-level extensions (starts with 'S') should be
> +     *    listed after standard unprivileged extensions.  If multiple
> +     *    supervisor-level extensions are listed, they should be ordered
> +     *    alphabetically.
> +     * 4. Non-standard extensions (starts with 'X') must be listed after all
> +     *    standard extensions. They must be separated from other multi-letter
> +     *    extensions by an underscore.
> +     */
> +    struct isa_ext_data isa_edata_arr[] = {
> +        ISA_EDATA_ENTRY(zfh, ext_zfh),
> +        ISA_EDATA_ENTRY(zfhmin, ext_zfhmin),
> +        ISA_EDATA_ENTRY(zfinx, ext_zfinx),
> +        ISA_EDATA_ENTRY(zhinx, ext_zhinx),
> +        ISA_EDATA_ENTRY(zhinxmin, ext_zhinxmin),
> +        ISA_EDATA_ENTRY(zdinx, ext_zdinx),
> +        ISA_EDATA_ENTRY(zba, ext_zba),
> +        ISA_EDATA_ENTRY(zbb, ext_zbb),
> +        ISA_EDATA_ENTRY(zbc, ext_zbc),
> +        ISA_EDATA_ENTRY(zbs, ext_zbs),
> +        ISA_EDATA_ENTRY(zve32f, ext_zve32f),
> +        ISA_EDATA_ENTRY(zve64f, ext_zve64f),
> +        ISA_EDATA_ENTRY(svinval, ext_svinval),
> +        ISA_EDATA_ENTRY(svnapot, ext_svnapot),
> +        ISA_EDATA_ENTRY(svpbmt, ext_svpbmt),
> +    };
> +
> +    for (i = 0; i < ARRAY_SIZE(isa_edata_arr); i++) {
> +        if (isa_edata_arr[i].enabled) {
> +            new = g_strconcat(old, "_", isa_edata_arr[i].name, NULL);
> +            g_free(old);
> +            old = new;
> +        }
> +    }
> +
> +    *isa_str = new;
> +}
> +
>  char *riscv_isa_string(RISCVCPU *cpu)
>  {
>      int i;
> @@ -932,6 +991,7 @@ char *riscv_isa_string(RISCVCPU *cpu)
>          }
>      }
>      *p = '\0';
> +    riscv_isa_string_ext(cpu, &isa_str, maxlen);
>      return isa_str;
>  }
>
> --
> 2.25.1
>
>