Re: [PATCH v2 3/6] riscv: lib: introduce cache_init interface

[Sean Anderson <seanga2@gmail.com>]

On 8/10/21 2:57 AM, Zong Li wrote:
> On Tue, Aug 10, 2021 at 12:47 PM Sean Anderson <seanga2@gmail.com> wrote:
>>
>> On 8/3/21 12:44 AM, Zong Li wrote:
>>> Add an interface for cache initialization. Each platform can overwrite
>>> this weak function by their own implementation, such as sifive_cache in
>>> this patch.
>>
>> Can we call this enable_caches instead of cache_init? This function is
>> called by initr_caches in board_r.c for ARM. There's even an
>> eight-year-old TODO on the subject.
>>
> 
> I had considered use it, The reason I finally used cache_init here is
> that it seems to me that cache_init would be more flexible for risc-v
> platforms to do not only cache enable, but also various
> platform-specific initialization of cache, even they could decide the
> time to invoke cache_init if there is particular initialization
> sequence.

Do you have some example in mind?

> If you think that cache_init is OK to you, I would prefer to
> retain cache_init. I can still use enable_caches instead of cache_init
> if you think that it is a better way. Please let me know your thoughts
> and thanks for your review.

I would like to reduce the proliferation of different cache enable
functions. Right now we have (i|d)cache_enable which are RISC-V-specific
and called very early during boot; cache_enable, which must be called
manually; enable_caches, which is implemented only for ARM; and your
proposed cache_init. I don't think there is need for yet another way to
accomplish the same thing.

--Sean

>>>
>>> Signed-off-by: Zong Li <zong.li@sifive.com>
>>> ---
>>>    arch/riscv/Kconfig             |  5 +++++
>>>    arch/riscv/include/asm/cache.h |  1 +
>>>    arch/riscv/lib/Makefile        |  1 +
>>>    arch/riscv/lib/cache.c         |  5 +++++
>>>    arch/riscv/lib/sifive_cache.c  | 27 +++++++++++++++++++++++++++
>>>    5 files changed, 39 insertions(+)
>>>    create mode 100644 arch/riscv/lib/sifive_cache.c
>>>
>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>> index 4b0c3dffa6..ec651fe0a4 100644
>>> --- a/arch/riscv/Kconfig
>>> +++ b/arch/riscv/Kconfig
>>> @@ -179,6 +179,11 @@ config SPL_SIFIVE_CLINT
>>>          The SiFive CLINT block holds memory-mapped control and status registers
>>>          associated with software and timer interrupts.
>>>
>>> +config SIFIVE_CACHE
>>> +     bool
>>> +     help
>>> +       This enables the operations to configure SiFive cache
>>> +
>>>    config ANDES_PLIC
>>>        bool
>>>        depends on RISCV_MMODE || SPL_RISCV_MMODE
>>> diff --git a/arch/riscv/include/asm/cache.h b/arch/riscv/include/asm/cache.h
>>> index ec8fe201d3..6ebb2b4329 100644
>>> --- a/arch/riscv/include/asm/cache.h
>>> +++ b/arch/riscv/include/asm/cache.h
>>> @@ -9,6 +9,7 @@
>>>
>>>    /* cache */
>>>    void        cache_flush(void);
>>> +int cache_init(void);
>>>
>>>    /*
>>>     * The current upper bound for RISCV L1 data cache line sizes is 32 bytes.
>>> diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
>>> index c4cc41434b..06020fcc2a 100644
>>> --- a/arch/riscv/lib/Makefile
>>> +++ b/arch/riscv/lib/Makefile
>>> @@ -10,6 +10,7 @@ obj-$(CONFIG_CMD_BOOTM) += bootm.o
>>>    obj-$(CONFIG_CMD_BOOTI) += bootm.o image.o
>>>    obj-$(CONFIG_CMD_GO) += boot.o
>>>    obj-y       += cache.o
>>> +obj-$(CONFIG_SIFIVE_CACHE) += sifive_cache.o
>>>    ifeq ($(CONFIG_$(SPL_)RISCV_MMODE),y)
>>>    obj-$(CONFIG_$(SPL_)SIFIVE_CLINT) += sifive_clint.o
>>>    obj-$(CONFIG_ANDES_PLIC) += andes_plic.o
>>> diff --git a/arch/riscv/lib/cache.c b/arch/riscv/lib/cache.c
>>> index b1d42bcc2b..2cd66504c6 100644
>>> --- a/arch/riscv/lib/cache.c
>>> +++ b/arch/riscv/lib/cache.c
>>> @@ -70,3 +70,8 @@ __weak int dcache_status(void)
>>>    {
>>>        return 0;
>>>    }
>>> +
>>> +__weak int cache_init(void)
>>> +{
>>> +     return 0;
>>> +}
>>> diff --git a/arch/riscv/lib/sifive_cache.c b/arch/riscv/lib/sifive_cache.c
>>> new file mode 100644
>>> index 0000000000..94e84e024e
>>> --- /dev/null
>>> +++ b/arch/riscv/lib/sifive_cache.c
>>> @@ -0,0 +1,27 @@
>>> +// SPDX-License-Identifier: GPL-2.0+
>>> +/*
>>> + * Copyright (C) 2021 SiFive, Inc
>>> + */
>>> +
>>> +#include <common.h>
>>> +#include <cache.h>
>>> +#include <dm.h>
>>> +
>>> +int cache_init(void)
>>> +{
>>> +     struct udevice *dev;
>>> +     int ret;
>>> +
>>> +     /* Enable ways of ccache */
>>> +     ret = uclass_get_device_by_driver(UCLASS_CACHE,
>>> +                                       DM_DRIVER_GET(sifive_ccache),
>>> +                                       &dev);
>>> +     if (ret)
>>> +             return log_msg_ret("Cannot enable cache ways", ret);
>>> +
>>> +     ret = cache_enable(dev);
>>> +     if (ret)
>>> +             return log_msg_ret("ccache enable failed", ret);
>>> +
>>> +     return 0;
>>> +}
>>>
>>
>> Otherwise LGTM