[PATCH v3 01/12] lib: utils: Add cache flush library

[Anup Patel]

On Tue, Jul 8, 2025 at 1:19 PM Nick Hu <nick.hu at sifive.com> wrote:
>
> The current RISC-V CMO only defines how to flush a cache block. However,
> certain use cases, such as power management, may require flushing the
> entire cache. Therefore, a framework is being introduced to allow vendors
> to flush the entire cache using their own methods.
>
> Signed-off-by: Nick Hu <nick.hu at sifive.com>
> Reviewed-by: Samuel Holland <samuel.holland at sifive.com>

LGTM.

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

Regards,
Anup



> ---
>  include/sbi_utils/cache/cache.h | 69 +++++++++++++++++++++++++++++++++
>  lib/utils/Kconfig               |  2 +
>  lib/utils/cache/Kconfig         |  9 +++++
>  lib/utils/cache/cache.c         | 46 ++++++++++++++++++++++
>  lib/utils/cache/objects.mk      |  7 ++++
>  5 files changed, 133 insertions(+)
>  create mode 100644 include/sbi_utils/cache/cache.h
>  create mode 100644 lib/utils/cache/Kconfig
>  create mode 100644 lib/utils/cache/cache.c
>  create mode 100644 lib/utils/cache/objects.mk
>
> diff --git a/include/sbi_utils/cache/cache.h b/include/sbi_utils/cache/cache.h
> new file mode 100644
> index 00000000..70d9286f
> --- /dev/null
> +++ b/include/sbi_utils/cache/cache.h
> @@ -0,0 +1,69 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2025 SiFive Inc.
> + */
> +
> +#ifndef __CACHE_H__
> +#define __CACHE_H__
> +
> +#include <sbi/sbi_list.h>
> +#include <sbi/sbi_types.h>
> +
> +#define CACHE_NAME_LEN 32
> +
> +struct cache_device;
> +
> +struct cache_ops {
> +       /** Warm init **/
> +       int (*warm_init)(struct cache_device *dev);
> +       /** Flush entire cache **/
> +       int (*cache_flush_all)(struct cache_device *dev);
> +};
> +
> +struct cache_device {
> +       /** Name of the device **/
> +       char name[CACHE_NAME_LEN];
> +       /** List node for search **/
> +       struct sbi_dlist node;
> +       /** Point to the next level cache **/
> +       struct cache_device *next;
> +       /** Cache Management Operations **/
> +       struct cache_ops *ops;
> +       /** CPU private cache **/
> +       bool cpu_private;
> +       /** The unique id of this cache device **/
> +       u32 id;
> +};
> +
> +/**
> + * Find a registered cache device
> + *
> + * @param id unique ID of the cache device
> + *
> + * @return the cache device or NULL
> + */
> +struct cache_device *cache_find(u32 id);
> +
> +/**
> + * Register a cache device
> + *
> + * cache_device->id must be initialized already and must not change during the life
> + * of the cache_device object.
> + *
> + * @param dev the cache device to register
> + *
> + * @return 0 on success, or a negative error code on failure
> + */
> +int cache_add(struct cache_device *dev);
> +
> +/**
> + * Flush the entire cache
> + *
> + * @param dev the cache to flush
> + *
> + * @return 0 on success, or a negative error code on failure
> + */
> +int cache_flush_all(struct cache_device *dev);
> +
> +#endif
> diff --git a/lib/utils/Kconfig b/lib/utils/Kconfig
> index 901ba564..5a5b3b1e 100644
> --- a/lib/utils/Kconfig
> +++ b/lib/utils/Kconfig
> @@ -2,6 +2,8 @@
>
>  menu "Utils and Drivers Support"
>
> +source "$(OPENSBI_SRC_DIR)/lib/utils/cache/Kconfig"
> +
>  source "$(OPENSBI_SRC_DIR)/lib/utils/cppc/Kconfig"
>
>  source "$(OPENSBI_SRC_DIR)/lib/utils/fdt/Kconfig"
> diff --git a/lib/utils/cache/Kconfig b/lib/utils/cache/Kconfig
> new file mode 100644
> index 00000000..24aa41bc
> --- /dev/null
> +++ b/lib/utils/cache/Kconfig
> @@ -0,0 +1,9 @@
> +# SPDX-License-Identifier: BSD-2-Clause
> +
> +menu "Cache Support"
> +
> +config CACHE
> +       bool "Cache support"
> +       default n
> +
> +endmenu
> diff --git a/lib/utils/cache/cache.c b/lib/utils/cache/cache.c
> new file mode 100644
> index 00000000..6bc3d10e
> --- /dev/null
> +++ b/lib/utils/cache/cache.c
> @@ -0,0 +1,46 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2025 SiFive Inc.
> + */
> +
> +#include <sbi/sbi_error.h>
> +#include <sbi_utils/cache/cache.h>
> +
> +static SBI_LIST_HEAD(cache_list);
> +
> +struct cache_device *cache_find(u32 id)
> +{
> +       struct cache_device *dev;
> +
> +       sbi_list_for_each_entry(dev, &cache_list, node) {
> +               if (dev->id == id)
> +                       return dev;
> +       }
> +
> +       return NULL;
> +}
> +
> +int cache_add(struct cache_device *dev)
> +{
> +       if (!dev)
> +               return SBI_ENODEV;
> +
> +       if (cache_find(dev->id))
> +               return SBI_EALREADY;
> +
> +       sbi_list_add(&dev->node, &cache_list);
> +
> +       return SBI_OK;
> +}
> +
> +int cache_flush_all(struct cache_device *dev)
> +{
> +       if (!dev)
> +               return SBI_ENODEV;
> +
> +       if (!dev->ops || !dev->ops->cache_flush_all)
> +               return SBI_ENOTSUPP;
> +
> +       return dev->ops->cache_flush_all(dev);
> +}
> diff --git a/lib/utils/cache/objects.mk b/lib/utils/cache/objects.mk
> new file mode 100644
> index 00000000..21d30ce8
> --- /dev/null
> +++ b/lib/utils/cache/objects.mk
> @@ -0,0 +1,7 @@
> +#
> +# SPDX-License-Identifier: BSD-2-Clause
> +#
> +# Copyright (c) 2025 SiFive
> +#
> +
> +libsbiutils-objs-$(CONFIG_CACHE) += cache/cache.o
> --
> 2.17.1
>