Re: [PATCH v1 3/3] board: qemu-riscv: Override enable_caches

[Heinrich Schuchardt <heinrich.schuchardt@canonical.com>]

On 20.08.24 11:37, Mayuresh Chitale wrote:
> Define enable_caches function for the qemu-riscv board which probes for
> the cbom-block-size dt property when RISCV_ISA_ZICBOM is enabled. Also
> add flush_dcache_range and invalidate_dcache_range functions which use
> the corresponding CBO ops.
> 
> Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
> ---
>   board/emulation/qemu-riscv/qemu-riscv.c | 16 ++++++++++++++++
>   1 file changed, 16 insertions(+)
> 
> diff --git a/board/emulation/qemu-riscv/qemu-riscv.c b/board/emulation/qemu-riscv/qemu-riscv.c
> index e5193e31e3..1795d2f831 100644
> --- a/board/emulation/qemu-riscv/qemu-riscv.c
> +++ b/board/emulation/qemu-riscv/qemu-riscv.c
> @@ -14,6 +14,7 @@
>   #include <usb.h>
>   #include <virtio_types.h>
>   #include <virtio.h>
> +#include <asm/cache.h>
>   
>   DECLARE_GLOBAL_DATA_PTR;
>   
> @@ -70,3 +71,18 @@ void *board_fdt_blob_setup(int *err)
>   	/* Stored the DTB address there during our init */
>   	return (void *)(ulong)gd->arch.firmware_fdt_addr;
>   }
> +
> +void enable_caches(void)
> +{
> +	riscv_zicbom_init();
> +}

Enable caches may be called multiple times. But riscv_zicbom_init() only 
needs to be called once.

> +
> +void flush_dcache_range(unsigned long start, unsigned long end)
> +{
> +	cbo_flush(start, end);
> +}
> +
> +void invalidate_dcache_range(unsigned long start, unsigned long end)
> +{
> +	cbo_inval(start, end);
> +}

The ZICBOM extension is not specific to a single board. We should not 
add this code to board files but into the central place for cache 
operations, i.e. arch/riscv/lib/cache.c.

E.g.

static int get_zicbom_block_size()
{
	if (!CONFIG_IS_ENABLED(RISCV_ISA_ZICBOM))
		return 0;
	if (zicbom_block_size)
		return zicbom_block_size;

	uclass_first_device(UCLASS_CPU, &dev);
	if (!dev) {
		log_err("Failed to get CPU device!\n");
		return 0;
	}

	if (dev_read_u32(dev, "riscv,cbom-block-size", &zicbom_block_size))
		return 0;
	
	return zicbom_block_size
}

__weak void invalidate_icache_range(unsigned long start, unsigned long end)
{
	if (CONFIG_IS_ENABLED(RISCV_ISA_ZICBOM) && get_zicbom_block_size())
		cbo_inval(start, end);
	else		
	        invalidate_icache_all();
}

Cc: Rick as one of the RISC-V maintainers.

Best regards

Heinrich