linux-kernel - [PATCH 4/4] soc: sifive: ccache: Support cache management operations

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Message-ID: <CAJM55Z8XPo=NfzGcu0UVOb2pwGhkuL6nx+Mae7eLy4EDN0=cAw@mail.gmail.com>
Date:   Wed, 25 Oct 2023 11:56:43 -0700
From:   emil.renner.berthing@...onical.com
To:     linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Conor Dooley <conor@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Emil Renner Berthing <emil.renner.berthing@...onical.com>
Subject: [PATCH 4/4] soc: sifive: ccache: Support cache management operations

This cache controller also supports flushing cache lines by writing
their address to a register. This can be used for cache management on
SoCs with non-coherent DMAs that predate the RISC-V Zicbom extension
such as the StarFive JH7100 SoC.

Signed-off-by: Emil Renner Berthing <kernel@...il.dk>
---
 drivers/soc/sifive/sifive_ccache.c | 45 +++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/sifive/sifive_ccache.c
b/drivers/soc/sifive/sifive_ccache.c
index 676468c35859..9bf94c22cad9 100644
--- a/drivers/soc/sifive/sifive_ccache.c
+++ b/drivers/soc/sifive/sifive_ccache.c
@@ -8,13 +8,16 @@

 #define pr_fmt(fmt) "CCACHE: " fmt

+#include <linux/align.h>
 #include <linux/debugfs.h>
 #include <linux/interrupt.h>
 #include <linux/of_irq.h>
 #include <linux/of_address.h>
 #include <linux/device.h>
 #include <linux/bitfield.h>
+#include <asm/cacheflush.h>
 #include <asm/cacheinfo.h>
+#include <asm/dma-noncoherent.h>
 #include <soc/sifive/sifive_ccache.h>

 #define SIFIVE_CCACHE_DIRECCFIX_LOW 0x100
@@ -39,10 +42,14 @@
 #define SIFIVE_CCACHE_CONFIG_SETS_MASK GENMASK_ULL(23, 16)
 #define SIFIVE_CCACHE_CONFIG_BLKS_MASK GENMASK_ULL(31, 24)

+#define SIFIVE_CCACHE_FLUSH64 0x200
+#define SIFIVE_CCACHE_FLUSH32 0x240
+
 #define SIFIVE_CCACHE_WAYENABLE 0x08
 #define SIFIVE_CCACHE_ECCINJECTERR 0x40

 #define SIFIVE_CCACHE_MAX_ECCINTR 4
+#define SIFIVE_CCACHE_LINE_SIZE 64

 static void __iomem *ccache_base;
 static int g_irq[SIFIVE_CCACHE_MAX_ECCINTR];
@@ -125,6 +132,34 @@ int
unregister_sifive_ccache_error_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL_GPL(unregister_sifive_ccache_error_notifier);

+#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS
+static void ccache_flush_range(phys_addr_t start, size_t len)
+{
+	phys_addr_t end = start + len;
+	phys_addr_t line;
+
+	if (!len)
+		return;
+
+	mb();
+	for (line = ALIGN_DOWN(start, SIFIVE_CCACHE_LINE_SIZE); line < end;
+			line += SIFIVE_CCACHE_LINE_SIZE) {
+#ifdef CONFIG_32BIT
+		writel(line >> 4, ccache_base + SIFIVE_CCACHE_FLUSH32);
+#else
+		writeq(line, ccache_base + SIFIVE_CCACHE_FLUSH64);
+#endif
+		mb();
+	}
+}
+
+static const struct riscv_nonstd_cache_ops ccache_mgmt_ops __initdata = {
+	.wback = &ccache_flush_range,
+	.inv = &ccache_flush_range,
+	.wback_inv = &ccache_flush_range,
+};
+#endif /* CONFIG_RISCV_NONSTANDARD_CACHE_OPS */
+
 static int ccache_largest_wayenabled(void)
 {
 	return readl(ccache_base + SIFIVE_CCACHE_WAYENABLE) & 0xFF;
@@ -258,6 +293,14 @@ static int __init sifive_ccache_init(void)
 	}
 	of_node_put(np);

+#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS
+	if (of_property_read_bool(np, "sifive,cache-ops")) {
+		riscv_cbom_block_size = SIFIVE_CCACHE_LINE_SIZE;
+		riscv_noncoherent_supported();
+		riscv_noncoherent_register_cache_ops(&ccache_mgmt_ops);
+	}
+#endif
+
 	ccache_config_read();

 	ccache_cache_ops.get_priv_group = ccache_get_priv_group;
@@ -278,4 +321,4 @@ static int __init sifive_ccache_init(void)
 	return rc;
 }

-device_initcall(sifive_ccache_init);
+arch_initcall(sifive_ccache_init);
-- 
2.40.1