cache: Add StarFive StarLink cache management

Add StarFive Starlink cache management driver.
The driver enables RISC-V non-standard cache
operation on SoC that does not support Zicbom
extension instructions.

Signed-off-by: Joshua Yeong <joshua.yeong@starfivetech.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

drivers/cache/Kconfig

@@ -14,4 +14,13 @@ config SIFIVE_CCACHE
 	help
 	  Support for the composable cache controller on SiFive platforms.
 
+config STARFIVE_STARLINK_CACHE
+	bool "StarFive StarLink Cache controller"
+	depends on RISCV
+	depends on ARCH_STARFIVE
+	select RISCV_DMA_NONCOHERENT
+	select RISCV_NONSTANDARD_CACHE_OPS
+	help
+	  Support for the StarLink cache controller IP from StarFive.
+
 endmenu

drivers/cache/Makefile

@@ -2,3 +2,4 @@
 
 obj-$(CONFIG_AX45MP_L2_CACHE)		+= ax45mp_cache.o
 obj-$(CONFIG_SIFIVE_CCACHE)		+= sifive_ccache.o
+obj-$(CONFIG_STARFIVE_STARLINK_CACHE)	+= starfive_starlink_cache.o

drivers/cache/starfive_starlink_cache.c

@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Cache Management Operations for StarFive's Starlink 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/iopoll.h>
+#include <linux/of_address.h>
+
+#include <asm/dma-noncoherent.h>
+
+#define STARLINK_CACHE_FLUSH_START_ADDR			0x0
+#define STARLINK_CACHE_FLUSH_END_ADDR			0x8
+#define STARLINK_CACHE_FLUSH_CTL			0x10
+#define STARLINK_CACHE_ALIGN				0x40
+
+#define STARLINK_CACHE_ADDRESS_RANGE_MASK		GENMASK(39, 0)
+#define STARLINK_CACHE_FLUSH_CTL_MODE_MASK		GENMASK(2, 1)
+#define STARLINK_CACHE_FLUSH_CTL_ENABLE_MASK		BIT(0)
+
+#define STARLINK_CACHE_FLUSH_CTL_CLEAN_INVALIDATE	0
+#define STARLINK_CACHE_FLUSH_CTL_MAKE_INVALIDATE	1
+#define STARLINK_CACHE_FLUSH_CTL_CLEAN_SHARED		2
+#define STARLINK_CACHE_FLUSH_POLL_DELAY_US		1
+#define STARLINK_CACHE_FLUSH_TIMEOUT_US			5000000
+
+static void __iomem *starlink_cache_base;
+
+static void starlink_cache_flush_complete(void)
+{
+	volatile void __iomem *ctl = starlink_cache_base + STARLINK_CACHE_FLUSH_CTL;
+	u64 v;
+	int ret;
+
+	ret = readq_poll_timeout_atomic(ctl, v, !(v & STARLINK_CACHE_FLUSH_CTL_ENABLE_MASK),
+					STARLINK_CACHE_FLUSH_POLL_DELAY_US,
+					STARLINK_CACHE_FLUSH_TIMEOUT_US);
+	if (ret)
+		WARN(1, "StarFive Starlink cache flush operation timeout\n");
+}
+
+static void starlink_cache_dma_cache_wback(phys_addr_t paddr, unsigned long size)
+{
+	writeq(FIELD_PREP(STARLINK_CACHE_ADDRESS_RANGE_MASK, paddr),
+	       starlink_cache_base + STARLINK_CACHE_FLUSH_START_ADDR);
+	writeq(FIELD_PREP(STARLINK_CACHE_ADDRESS_RANGE_MASK, paddr + size),
+	       starlink_cache_base + STARLINK_CACHE_FLUSH_END_ADDR);
+
+	mb();
+	writeq(FIELD_PREP(STARLINK_CACHE_FLUSH_CTL_MODE_MASK,
+			  STARLINK_CACHE_FLUSH_CTL_CLEAN_SHARED),
+	       starlink_cache_base + STARLINK_CACHE_FLUSH_CTL);
+
+	starlink_cache_flush_complete();
+}
+
+static void starlink_cache_dma_cache_invalidate(phys_addr_t paddr, unsigned long size)
+{
+	writeq(FIELD_PREP(STARLINK_CACHE_ADDRESS_RANGE_MASK, paddr),
+	       starlink_cache_base + STARLINK_CACHE_FLUSH_START_ADDR);
+	writeq(FIELD_PREP(STARLINK_CACHE_ADDRESS_RANGE_MASK, paddr + size),
+	       starlink_cache_base + STARLINK_CACHE_FLUSH_END_ADDR);
+
+	mb();
+	writeq(FIELD_PREP(STARLINK_CACHE_FLUSH_CTL_MODE_MASK,
+			  STARLINK_CACHE_FLUSH_CTL_MAKE_INVALIDATE),
+	       starlink_cache_base + STARLINK_CACHE_FLUSH_CTL);
+
+	starlink_cache_flush_complete();
+}
+
+static void starlink_cache_dma_cache_wback_inv(phys_addr_t paddr, unsigned long size)
+{
+	writeq(FIELD_PREP(STARLINK_CACHE_ADDRESS_RANGE_MASK, paddr),
+	       starlink_cache_base + STARLINK_CACHE_FLUSH_START_ADDR);
+	writeq(FIELD_PREP(STARLINK_CACHE_ADDRESS_RANGE_MASK, paddr + size),
+	       starlink_cache_base + STARLINK_CACHE_FLUSH_END_ADDR);
+
+	mb();
+	writeq(FIELD_PREP(STARLINK_CACHE_FLUSH_CTL_MODE_MASK,
+			  STARLINK_CACHE_FLUSH_CTL_CLEAN_INVALIDATE),
+	       starlink_cache_base + STARLINK_CACHE_FLUSH_CTL);
+
+	starlink_cache_flush_complete();
+}
+
+static const struct riscv_nonstd_cache_ops starlink_cache_ops = {
+	.wback = &starlink_cache_dma_cache_wback,
+	.inv = &starlink_cache_dma_cache_invalidate,
+	.wback_inv = &starlink_cache_dma_cache_wback_inv,
+};
+
+static const struct of_device_id starlink_cache_ids[] = {
+	{ .compatible = "starfive,jh8100-starlink-cache" },
+	{ /* sentinel */ }
+};
+
+static int __init starlink_cache_init(void)
+{
+	struct device_node *np;
+	u32 block_size;
+	int ret;
+
+	np = of_find_matching_node(NULL, starlink_cache_ids);
+	if (!of_device_is_available(np))
+		return -ENODEV;
+
+	ret = of_property_read_u32(np, "cache-block-size", &block_size);
+	if (ret)
+		return ret;
+
+	if (block_size % STARLINK_CACHE_ALIGN)
+		return -EINVAL;
+
+	starlink_cache_base = of_iomap(np, 0);
+	if (!starlink_cache_base)
+		return -ENOMEM;
+
+	riscv_cbom_block_size = block_size;
+	riscv_noncoherent_supported();
+	riscv_noncoherent_register_cache_ops(&starlink_cache_ops);
+
+	return 0;
+}
+arch_initcall(starlink_cache_init);