Hi Bin,
On Tue, 2018-12-11 at 23:11 -0800, Bin Meng wrote:
> This updates supports_extension() implementation to use the desc
> string from the cpu driver whenever possible, which avoids the
> reading of misa CSR for S-mode U-Boot.
>
> Signed-off-by: Bin Meng <bmeng...@gmail.com>
>
> ---
>
> Changes in v4:
> - print warnings for S-mode without CONFIG_CPU
>
> Changes in v3:
> - new patch to update supports_extension() to use desc from cpu
> driver
>
> Changes in v2: None
>
> arch/riscv/cpu/cpu.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/arch/riscv/cpu/cpu.c b/arch/riscv/cpu/cpu.c
> index d3c59da..a2ebaf3 100644
> --- a/arch/riscv/cpu/cpu.c
> +++ b/arch/riscv/cpu/cpu.c
> @@ -5,8 +5,10 @@
>
> #include <common.h>
> #include <cpu.h>
> +#include <dm.h>
> #include <log.h>
> #include <asm/csr.h>
> +#include <dm/uclass-internal.h>
>
> /*
> * prior_stage_fdt_address must be stored in the data section since
> it is used
> @@ -16,7 +18,27 @@ phys_addr_t prior_stage_fdt_address
> __attribute__((section(".data")));
>
> static inline bool supports_extension(char ext)
> {
> +#ifdef CONFIG_CPU
> + struct udevice *dev;
> + char desc[32];
> +
> + uclass_find_first_device(UCLASS_CPU, &dev);
Sorry, I missed this before. Can you add error handling here to catch
uclass_find_first_device returning an error or not finding a device? It
would probably also make sense to print a warning message to the user
in this case.
Other than that, this patch and the series look good!
Reviewed-by: Lukas Auer <lukas.a...@aisec.fraunhofer.de>
Thanks,
Lukas
> + if (!cpu_get_desc(dev, desc, sizeof(desc))) {
> + /* skip the first 4 characters (rv32|rv64) */
> + if (strchr(desc + 4, ext))
> + return true;
> + }
> +
> + return false;
> +#else /* !CONFIG_CPU */
> +#ifdef CONFIG_RISCV_MMODE
> return csr_read(misa) & (1 << (ext - 'a'));
> +#else /* !CONFIG_RISCV_MMODE */
> +#warning "There is no way to determine the available extensions in
> S-mode."
> +#warning "Please convert your board to use the RISC-V CPU driver."
> + return false;
> +#endif /* CONFIG_RISCV_MMODE */
> +#endif /* CONFIG_CPU */
> }
>
> static int riscv_cpu_probe(void)
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