RISC-V: sifive_l2_cache: Add L2 cache controller driver for SiFive SoCs

The driver currently supports only SiFive FU540-C000 platform.

The initial version of L2 cache controller driver includes:
- Initial configuration reporting at boot up.
- Support for ECC related functionality.
Signed-off-by: Yash Shah <yash.shah@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

arch/riscv/include/asm/sifive_l2_cache.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * SiFive L2 Cache Controller header file
+ *
+ */
+
+#ifndef _ASM_RISCV_SIFIVE_L2_CACHE_H
+#define _ASM_RISCV_SIFIVE_L2_CACHE_H
+
+extern int register_sifive_l2_error_notifier(struct notifier_block *nb);
+extern int unregister_sifive_l2_error_notifier(struct notifier_block *nb);
+
+#define SIFIVE_L2_ERR_TYPE_CE 0
+#define SIFIVE_L2_ERR_TYPE_UE 1
+
+#endif /* _ASM_RISCV_SIFIVE_L2_CACHE_H */

arch/riscv/mm/Makefile

@@ -10,3 +10,4 @@ obj-y += extable.o
 obj-y += ioremap.o
 obj-y += cacheflush.o
 obj-y += context.o
+obj-y += sifive_l2_cache.o

arch/riscv/mm/sifive_l2_cache.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SiFive L2 cache controller Driver
+ *
+ * Copyright (C) 2018-2019 SiFive, Inc.
+ *
+ */
+#include <linux/debugfs.h>
+#include <linux/interrupt.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <asm/sifive_l2_cache.h>
+
+#define SIFIVE_L2_DIRECCFIX_LOW 0x100
+#define SIFIVE_L2_DIRECCFIX_HIGH 0x104
+#define SIFIVE_L2_DIRECCFIX_COUNT 0x108
+
+#define SIFIVE_L2_DATECCFIX_LOW 0x140
+#define SIFIVE_L2_DATECCFIX_HIGH 0x144
+#define SIFIVE_L2_DATECCFIX_COUNT 0x148
+
+#define SIFIVE_L2_DATECCFAIL_LOW 0x160
+#define SIFIVE_L2_DATECCFAIL_HIGH 0x164
+#define SIFIVE_L2_DATECCFAIL_COUNT 0x168
+
+#define SIFIVE_L2_CONFIG 0x00
+#define SIFIVE_L2_WAYENABLE 0x08
+#define SIFIVE_L2_ECCINJECTERR 0x40
+
+#define SIFIVE_L2_MAX_ECCINTR 3
+
+static void __iomem *l2_base;
+static int g_irq[SIFIVE_L2_MAX_ECCINTR];
+
+enum {
+	DIR_CORR = 0,
+	DATA_CORR,
+	DATA_UNCORR,
+};
+
+#ifdef CONFIG_DEBUG_FS
+static struct dentry *sifive_test;
+
+static ssize_t l2_write(struct file *file, const char __user *data,
+			size_t count, loff_t *ppos)
+{
+	unsigned int val;
+
+	if (kstrtouint_from_user(data, count, 0, &val))
+		return -EINVAL;
+	if ((val >= 0 && val < 0xFF) || (val >= 0x10000 && val < 0x100FF))
+		writel(val, l2_base + SIFIVE_L2_ECCINJECTERR);
+	else
+		return -EINVAL;
+	return count;
+}
+
+static const struct file_operations l2_fops = {
+	.owner = THIS_MODULE,
+	.open = simple_open,
+	.write = l2_write
+};
+
+static void setup_sifive_debug(void)
+{
+	sifive_test = debugfs_create_dir("sifive_l2_cache", NULL);
+
+	debugfs_create_file("sifive_debug_inject_error", 0200,
+			    sifive_test, NULL, &l2_fops);
+}
+#endif
+
+static void l2_config_read(void)
+{
+	u32 regval, val;
+
+	regval = readl(l2_base + SIFIVE_L2_CONFIG);
+	val = regval & 0xFF;
+	pr_info("L2CACHE: No. of Banks in the cache: %d\n", val);
+	val = (regval & 0xFF00) >> 8;
+	pr_info("L2CACHE: No. of ways per bank: %d\n", val);
+	val = (regval & 0xFF0000) >> 16;
+	pr_info("L2CACHE: Sets per bank: %llu\n", (uint64_t)1 << val);
+	val = (regval & 0xFF000000) >> 24;
+	pr_info("L2CACHE: Bytes per cache block: %llu\n", (uint64_t)1 << val);
+
+	regval = readl(l2_base + SIFIVE_L2_WAYENABLE);
+	pr_info("L2CACHE: Index of the largest way enabled: %d\n", regval);
+}
+
+static const struct of_device_id sifive_l2_ids[] = {
+	{ .compatible = "sifive,fu540-c000-ccache" },
+	{ /* end of table */ },
+};
+
+static ATOMIC_NOTIFIER_HEAD(l2_err_chain);
+
+int register_sifive_l2_error_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_register(&l2_err_chain, nb);
+}
+EXPORT_SYMBOL_GPL(register_sifive_l2_error_notifier);
+
+int unregister_sifive_l2_error_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&l2_err_chain, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_sifive_l2_error_notifier);
+
+static irqreturn_t l2_int_handler(int irq, void *device)
+{
+	unsigned int regval, add_h, add_l;
+
+	if (irq == g_irq[DIR_CORR]) {
+		add_h = readl(l2_base + SIFIVE_L2_DIRECCFIX_HIGH);
+		add_l = readl(l2_base + SIFIVE_L2_DIRECCFIX_LOW);
+		pr_err("L2CACHE: DirError @ 0x%08X.%08X\n", add_h, add_l);
+		regval = readl(l2_base + SIFIVE_L2_DIRECCFIX_COUNT);
+		atomic_notifier_call_chain(&l2_err_chain, SIFIVE_L2_ERR_TYPE_CE,
+					   "DirECCFix");
+	}
+	if (irq == g_irq[DATA_CORR]) {
+		add_h = readl(l2_base + SIFIVE_L2_DATECCFIX_HIGH);
+		add_l = readl(l2_base + SIFIVE_L2_DATECCFIX_LOW);
+		pr_err("L2CACHE: DataError @ 0x%08X.%08X\n", add_h, add_l);
+		regval = readl(l2_base + SIFIVE_L2_DATECCFIX_COUNT);
+		atomic_notifier_call_chain(&l2_err_chain, SIFIVE_L2_ERR_TYPE_CE,
+					   "DatECCFix");
+	}
+	if (irq == g_irq[DATA_UNCORR]) {
+		add_h = readl(l2_base + SIFIVE_L2_DATECCFAIL_HIGH);
+		add_l = readl(l2_base + SIFIVE_L2_DATECCFAIL_LOW);
+		pr_err("L2CACHE: DataFail @ 0x%08X.%08X\n", add_h, add_l);
+		regval = readl(l2_base + SIFIVE_L2_DATECCFAIL_COUNT);
+		atomic_notifier_call_chain(&l2_err_chain, SIFIVE_L2_ERR_TYPE_UE,
+					   "DatECCFail");
+	}
+
+	return IRQ_HANDLED;
+}
+
+int __init sifive_l2_init(void)
+{
+	struct device_node *np;
+	struct resource res;
+	int i, rc;
+
+	np = of_find_matching_node(NULL, sifive_l2_ids);
+	if (!np)
+		return -ENODEV;
+
+	if (of_address_to_resource(np, 0, &res))
+		return -ENODEV;
+
+	l2_base = ioremap(res.start, resource_size(&res));
+	if (!l2_base)
+		return -ENOMEM;
+
+	for (i = 0; i < SIFIVE_L2_MAX_ECCINTR; i++) {
+		g_irq[i] = irq_of_parse_and_map(np, i);
+		rc = request_irq(g_irq[i], l2_int_handler, 0, "l2_ecc", NULL);
+		if (rc) {
+			pr_err("L2CACHE: Could not request IRQ %d\n", g_irq[i]);
+			return rc;
+		}
+	}
+
+	l2_config_read();
+
+#ifdef CONFIG_DEBUG_FS
+	setup_sifive_debug();
+#endif
+	return 0;
+}
+device_initcall(sifive_l2_init);