[PATCH v2 5/8] lib: utils: Add detection of Smepmp from ISA string in FDT

[Anup Patel]

On Thu, Jul 6, 2023 at 4:19 PM Himanshu Chauhan
<hchauhan at ventanamicro.com> wrote:
>
> - Add function to parse ISA string in FDT.
> - Set Smepmp feature bit in extensions if "smepmp" string is found in ISA string.
>
> Signed-off-by: Himanshu Chauhan <hchauhan at ventanamicro.com>

Looks good to me.

Reviewed-by: Anup Patel <anup at brainfault.org>

Regards,
Anup

> ---
>  include/sbi_utils/fdt/fdt_helper.h |   3 +
>  lib/utils/fdt/fdt_helper.c         | 111 +++++++++++++++++++++++++++++
>  platform/generic/platform.c        |   9 +++
>  3 files changed, 123 insertions(+)
>
> diff --git a/include/sbi_utils/fdt/fdt_helper.h b/include/sbi_utils/fdt/fdt_helper.h
> index 39d7f3a..5c928ff 100644
> --- a/include/sbi_utils/fdt/fdt_helper.h
> +++ b/include/sbi_utils/fdt/fdt_helper.h
> @@ -56,6 +56,9 @@ int fdt_parse_max_enabled_hart_id(void *fdt, u32 *max_hartid);
>
>  int fdt_parse_timebase_frequency(void *fdt, unsigned long *freq);
>
> +int fdt_parse_isa_extensions(void *fdt, unsigned int hard_id,
> +                            unsigned long *extensions);
> +
>  int fdt_parse_gaisler_uart_node(void *fdt, int nodeoffset,
>                                 struct platform_uart_data *uart);
>
> diff --git a/lib/utils/fdt/fdt_helper.c b/lib/utils/fdt/fdt_helper.c
> index a88a4ba..61a4100 100644
> --- a/lib/utils/fdt/fdt_helper.c
> +++ b/lib/utils/fdt/fdt_helper.c
> @@ -12,6 +12,7 @@
>  #include <sbi/sbi_hartmask.h>
>  #include <sbi/sbi_platform.h>
>  #include <sbi/sbi_scratch.h>
> +#include <sbi/sbi_hart.h>
>  #include <sbi_utils/fdt/fdt_helper.h>
>  #include <sbi_utils/irqchip/aplic.h>
>  #include <sbi_utils/irqchip/imsic.h>
> @@ -313,6 +314,116 @@ int fdt_parse_timebase_frequency(void *fdt, unsigned long *freq)
>         return 0;
>  }
>
> +static int fdt_get_isa_string(void *fdt, unsigned int hartid,
> +                       const char **isa_string)
> +{
> +       int err, cpu_offset, cpus_offset, len;
> +       u32 c_hartid;
> +       const fdt32_t *val;
> +
> +       if (!fdt)
> +               return SBI_EINVAL;
> +
> +       cpus_offset = fdt_path_offset(fdt, "/cpus");
> +       if (cpus_offset < 0)
> +               return cpus_offset;
> +
> +       fdt_for_each_subnode(cpu_offset, fdt, cpus_offset) {
> +               err = fdt_parse_hart_id(fdt, cpu_offset, &c_hartid);
> +               if (err)
> +                       continue;
> +
> +               if (!fdt_node_is_enabled(fdt, cpu_offset))
> +                       continue;
> +
> +               if (c_hartid == hartid) {
> +                       val = fdt_getprop(fdt, cpu_offset, "riscv,isa", &len);
> +                       if (val && len > 0) {
> +                               *isa_string = (const char *)val;
> +                               return 0;
> +                       }
> +               }
> +       }
> +
> +       return SBI_EINVAL;
> +}
> +
> +#define RISCV_ISA_EXT_NAME_LEN_MAX     32
> +
> +int fdt_parse_isa_extensions(void *fdt, unsigned int hartid,
> +                       unsigned long *extensions)
> +{
> +       size_t i, j, isa_len;
> +       char mstr[RISCV_ISA_EXT_NAME_LEN_MAX];
> +       const char *isa = NULL;
> +
> +       if (fdt_get_isa_string(fdt, hartid, &isa))
> +               return SBI_EINVAL;
> +
> +       if (!isa)
> +               return SBI_EINVAL;
> +
> +       i = 0;
> +       isa_len = strlen(isa);
> +
> +       if (isa[i] == 'r' || isa[i] == 'R')
> +               i++;
> +       else
> +               return SBI_EINVAL;
> +
> +       if (isa[i] == 'v' || isa[i] == 'V')
> +               i++;
> +       else
> +               return SBI_EINVAL;
> +
> +       if (isa[i] == '3' || isa[i+1] == '2')
> +               i += 2;
> +       else if (isa[i] == '6' || isa[i+1] == '4')
> +               i += 2;
> +       else
> +               return SBI_EINVAL;
> +
> +       /* Skip base ISA extensions */
> +       for (; i < isa_len; i++) {
> +               if (isa[i] == '_')
> +                       break;
> +       }
> +
> +       while (i < isa_len) {
> +               if (isa[i] != '_') {
> +                       i++;
> +                       continue;
> +               }
> +
> +               /* Skip the '_' character */
> +               i++;
> +
> +               /* Extract the multi-letter extension name */
> +               j = 0;
> +               while ((i < isa_len) && (isa[i] != '_') &&
> +                      (j < (sizeof(mstr) - 1)))
> +                       mstr[j++] = isa[i++];
> +               mstr[j] = '\0';
> +
> +               /* Skip empty multi-letter extension name */
> +               if (!j)
> +                       continue;
> +
> +#define SET_ISA_EXT_MAP(name, bit)                             \
> +               do {                                            \
> +                       if (!strcmp(mstr, name)) {              \
> +                               __set_bit(bit, extensions);     \
> +                               continue;                       \
> +                       }                                       \
> +               } while (false)                                 \
> +
> +               SET_ISA_EXT_MAP("smepmp", SBI_HART_EXT_SMEPMP);
> +#undef SET_ISA_EXT_MAP
> +       }
> +
> +       return 0;
> +}
> +
>  static int fdt_parse_uart_node_common(void *fdt, int nodeoffset,
>                                       struct platform_uart_data *uart,
>                                       unsigned long default_freq,
> diff --git a/platform/generic/platform.c b/platform/generic/platform.c
> index 86811e6..34b87f7 100644
> --- a/platform/generic/platform.c
> +++ b/platform/generic/platform.c
> @@ -211,6 +211,15 @@ static void generic_final_exit(void)
>
>  static int generic_extensions_init(struct sbi_hart_features *hfeatures)
>  {
> +       int rc;
> +
> +       /* Parse the ISA string from FDT and enable the listed extensions */
> +       rc = fdt_parse_isa_extensions(fdt_get_address(), current_hartid(),
> +                                     &hfeatures->extensions);
> +
> +       if (rc)
> +               return rc;
> +
>         if (generic_plat && generic_plat->extensions_init)
>                 return generic_plat->extensions_init(generic_plat_match,
>                                                      hfeatures);
> --
> 2.34.1
>
>
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