cache: add sifive private L2 cache driver

This driver is currently responsible for enabling the clock gating
feature of SiFive pre core's private L2 cache.

Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

drivers/cache/Kconfig

@@ -45,4 +45,11 @@ config SIFIVE_CCACHE
 	  This driver is for SiFive Composable L2/L3 cache. It enables cache
 	  ways of composable cache.
 
+config SIFIVE_PL2
+	bool "SiFive private L2 cache"
+	select CACHE
+	help
+	  This driver is for SiFive Private L2 cache. It configures registers
+	  to enable the clock gating feature.
+
 endmenu

drivers/cache/Makefile

@@ -5,3 +5,4 @@ obj-$(CONFIG_L2X0_CACHE) += cache-l2x0.o
 obj-$(CONFIG_NCORE_CACHE) += cache-ncore.o
 obj-$(CONFIG_V5L2_CACHE) += cache-v5l2.o
 obj-$(CONFIG_SIFIVE_CCACHE) += cache-sifive-ccache.o
+obj-$(CONFIG_SIFIVE_PL2) += cache-sifive-pl2.o

drivers/cache/cache-sifive-pl2.c

@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 SiFive
+ */
+
+#include <cache.h>
+#include <dm.h>
+#include <malloc.h>
+#include <asm/io.h>
+#include <dm/device.h>
+#include <dm/device-internal.h>
+
+#define	SIFIVE_PL2CHICKENBIT_OFFSET			0x1000
+#define	SIFIVE_PL2CHICKENBIT_REGIONCLOCKDISABLE_MASK	BIT(3)
+
+static int sifive_pl2_probe(struct udevice *dev)
+{
+	fdt_addr_t base;
+	u32 val;
+
+	base = dev_read_addr(dev);
+	if (base == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	/* Enable regionClockDisable bit */
+	val = readl((void __iomem *)(base + SIFIVE_PL2CHICKENBIT_OFFSET));
+	writel(val & ~SIFIVE_PL2CHICKENBIT_REGIONCLOCKDISABLE_MASK,
+	       (void __iomem *)(base + SIFIVE_PL2CHICKENBIT_OFFSET));
+
+	return 0;
+}
+
+static const struct udevice_id sifive_pl2_ids[] = {
+	{ .compatible = "sifive,pl2cache0" },
+	{ .compatible = "sifive,pl2cache1" },
+	{}
+};
+
+U_BOOT_DRIVER(sifive_pl2) = {
+	.name = "sifive_pl2",
+	.id = UCLASS_CACHE,
+	.of_match = sifive_pl2_ids,
+	.probe = sifive_pl2_probe,
+};