Re: [PATCH 3/4] cache: Add StarLink-500 cache management for StarFive JH8100 RISC-V core

[Samuel Holland <samuel.holland@sifive.com>]

On 2024-03-14 1:12 AM, Joshua Yeong wrote:
> Add software workaround for StarFive StarLink-500
> on JH8100 SoC for CMO extension instructions.
> 
> Signed-off-by: Joshua Yeong <joshua.yeong@starfivetech.com>
> ---
>  drivers/cache/Kconfig             |   9 ++
>  drivers/cache/Makefile            |   1 +
>  drivers/cache/starlink500_cache.c | 137 ++++++++++++++++++++++++++++++
>  3 files changed, 147 insertions(+)
>  create mode 100644 drivers/cache/starlink500_cache.c
> 
> diff --git a/drivers/cache/Kconfig b/drivers/cache/Kconfig
> index 9345ce4976d7..e215379f6a73 100644
> --- a/drivers/cache/Kconfig
> +++ b/drivers/cache/Kconfig
> @@ -14,4 +14,13 @@ config SIFIVE_CCACHE
>  	help
>  	  Support for the composable cache controller on SiFive platforms.
>  
> +config STARLINK_500_CACHE
> +	bool "StarLink-500 Cache controller"
> +	depends on RISCV_DMA_NONCOHERENT
> +	depends on ERRATA_STARFIVE
> +	select RISCV_NONSTANDARD_CACHE_OPS
> +	default y
> +	help
> +	  Support for the StarLink-500 cache controller on StarFive platforms.
> +
>  endmenu
> diff --git a/drivers/cache/Makefile b/drivers/cache/Makefile
> index 7657cff3bd6c..c515eb5714ea 100644
> --- a/drivers/cache/Makefile
> +++ b/drivers/cache/Makefile
> @@ -2,3 +2,4 @@
>  
>  obj-$(CONFIG_AX45MP_L2_CACHE)	+= ax45mp_cache.o
>  obj-$(CONFIG_SIFIVE_CCACHE)	+= sifive_ccache.o
> +obj-$(CONFIG_STARLINK_500_CACHE) += starlink500_cache.o
> diff --git a/drivers/cache/starlink500_cache.c b/drivers/cache/starlink500_cache.c
> new file mode 100644
> index 000000000000..eaf8303cb086
> --- /dev/null
> +++ b/drivers/cache/starlink500_cache.c
> @@ -0,0 +1,137 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Non-coherent cache functions for StarFive's StarLink-500 cache controller
> + *
> + * Copyright (C) 2024 Shanghai StarFive Technology Co., Ltd.
> + *
> + * Author: Joshua Yeong <joshua.yeong@starfivetech.com>
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/cacheflush.h>
> +#include <linux/cacheinfo.h>
> +#include <linux/delay.h>
> +#include <linux/dma-direction.h>
> +#include <linux/io.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
> +#include <linux/processor.h>
> +
> +#include <asm/dma-noncoherent.h>
> +
> +#define STARFIVE_SL500_CMO_FLUSH_START_ADDR		0x0
> +#define STARFIVE_SL500_CMO_FLUSH_END_ADDR		0x8
> +#define STARFIVE_SL500_CMO_FLUSH_CTL			0x10
> +#define STARFIVE_SL500_CMO_CACHE_ALIGN			0x40
> +
> +#define STARFIVE_SL500_ADDRESS_RANGE_MASK		GENMASK(39, 0)
> +#define STARFIVE_SL500_FLUSH_CTL_MODE_MASK		GENMASK(2, 1)
> +#define STARFIVE_SL500_FLUSH_CTL_ENABLE_MASK		BIT(0)
> +
> +#define STARFIVE_SL500_FLUSH_CTL_CLEAN_INVALIDATE	0
> +#define STARFIVE_SL500_FLUSH_CTL_MAKE_INVALIDATE	1
> +#define STARFIVE_SL500_FLUSH_CTL_CLEAN_SHARED		2
> +
> +struct starfive_sl500_cache_priv {
> +	void __iomem *base_addr;
> +};
> +
> +static struct starfive_sl500_cache_priv starfive_sl500_cache_priv;
> +
> +static void starfive_sl500_cmo_flush_complete(void)
> +{
> +	ktime_t timeout;
> +
> +	volatile void __iomem *_ctl = starfive_sl500_cache_priv.base_addr +
> +                                      STARFIVE_SL500_CMO_FLUSH_CTL;
> +	timeout = ktime_add_ms(ktime_get(), 5000);
> +
> +	do {
> +		if(!(ioread64(_ctl) & STARFIVE_SL500_FLUSH_CTL_ENABLE_MASK))
> +			return;
> +		msleep(50);

These callbacks can be called from an atomic context, so you cannot use msleep()
here.

> +	} while (ktime_before(ktime_get(), timeout));

I suggest using one of the helpers from linux/iopoll.h, e.g. readq_poll_timeout().

> +
> +	pr_err("StarFive CMO operation timeout\n");
> +	dump_stack();

WARN or WARN_ON would be idiomatic here.

> +}
> +
> +void starfive_sl500_dma_cache_wback(phys_addr_t paddr, unsigned long size)
> +{
> +	writeq(FIELD_PREP(STARFIVE_SL500_ADDRESS_RANGE_MASK, paddr),
> +	       starfive_sl500_cache_priv.base_addr + STARFIVE_SL500_CMO_FLUSH_START_ADDR);
> +	writeq(FIELD_PREP(STARFIVE_SL500_ADDRESS_RANGE_MASK, paddr + size),
> +	       starfive_sl500_cache_priv.base_addr + STARFIVE_SL500_CMO_FLUSH_END_ADDR);
> +
> +	mb();
> +	writeq(FIELD_PREP(STARFIVE_SL500_FLUSH_CTL_MODE_MASK,
> +	       STARFIVE_SL500_FLUSH_CTL_CLEAN_SHARED),
> +	       starfive_sl500_cache_priv.base_addr + STARFIVE_SL500_CMO_FLUSH_CTL);
> +
> +	starfive_sl500_cmo_flush_complete();
> +}
> +
> +void starfive_sl500_dma_cache_invalidate(phys_addr_t paddr, unsigned long size)
> +{
> +	writeq(FIELD_PREP(STARFIVE_SL500_ADDRESS_RANGE_MASK, paddr),
> +	       starfive_sl500_cache_priv.base_addr + STARFIVE_SL500_CMO_FLUSH_START_ADDR);
> +	writeq(FIELD_PREP(STARFIVE_SL500_ADDRESS_RANGE_MASK, paddr + size),
> +	       starfive_sl500_cache_priv.base_addr + STARFIVE_SL500_CMO_FLUSH_END_ADDR);
> +
> +	mb();
> +	writeq(FIELD_PREP(STARFIVE_SL500_FLUSH_CTL_MODE_MASK,
> +	       STARFIVE_SL500_FLUSH_CTL_MAKE_INVALIDATE),
> +	       starfive_sl500_cache_priv.base_addr + STARFIVE_SL500_CMO_FLUSH_CTL);
> +
> +	starfive_sl500_cmo_flush_complete();
> +}
> +
> +void starfive_sl500_dma_cache_wback_inv(phys_addr_t paddr, unsigned long size)
> +{
> +	writeq(FIELD_PREP(STARFIVE_SL500_ADDRESS_RANGE_MASK, paddr),
> +	       starfive_sl500_cache_priv.base_addr + STARFIVE_SL500_CMO_FLUSH_START_ADDR);
> +	writeq(FIELD_PREP(STARFIVE_SL500_ADDRESS_RANGE_MASK, paddr + size),
> +	       starfive_sl500_cache_priv.base_addr + STARFIVE_SL500_CMO_FLUSH_END_ADDR);
> +
> +	mb();
> +	writeq(FIELD_PREP(STARFIVE_SL500_FLUSH_CTL_MODE_MASK,
> +	       STARFIVE_SL500_FLUSH_CTL_CLEAN_INVALIDATE),
> +	       starfive_sl500_cache_priv.base_addr + STARFIVE_SL500_CMO_FLUSH_CTL);
> +
> +	starfive_sl500_cmo_flush_complete();
> +}
> +
> +static const struct riscv_nonstd_cache_ops starfive_sl500_cmo_ops = {
> +	.wback = &starfive_sl500_dma_cache_wback,
> +	.inv = &starfive_sl500_dma_cache_invalidate,
> +	.wback_inv = &starfive_sl500_dma_cache_wback_inv,
> +};
> +
> +static const struct of_device_id starfive_sl500_cache_ids[] = {
> +	{ .compatible = "starfive,starlink-500-cache" },
> +	{ /* sentinel */ }
> +};
> +
> +static int __init starfive_sl500_cache_init(void)
> +{
> +	struct device_node *np;
> +	struct resource res;
> +	int ret;
> +
> +	np = of_find_matching_node(NULL, starfive_sl500_cache_ids);
> +	if (!of_device_is_available(np))
> +		return -ENODEV;
> +
> +	ret = of_address_to_resource(np, 0, &res);
> +	if (ret)
> +		return ret;
> +
> +	starfive_sl500_cache_priv.base_addr = ioremap(res.start, resource_size(&res));
> +	if (!starfive_sl500_cache_priv.base_addr)
> +		return -ENOMEM;

of_address_to_resource() + ioremap() simplifies to of_iomap().

Regards,
Samuel

> +
> +	riscv_noncoherent_register_cache_ops(&starfive_sl500_cmo_ops);
> +
> +	return 0;
> +}
> +early_initcall(starfive_sl500_cache_init);


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