Re: [PATCH v3 2/2] RISC-V: sifive_l2_cache: Add L2 cache controller driver for SiFive SoCs

["Andrew F. Davis" <afd@ti.com>]

On 5/6/19 6:48 AM, Yash Shah wrote:
> 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>
> ---
>  arch/riscv/include/asm/sifive_l2_cache.h |  16 +++
>  arch/riscv/mm/Makefile                   |   1 +
>  arch/riscv/mm/sifive_l2_cache.c          | 175 +++++++++++++++++++++++++++++++
>  3 files changed, 192 insertions(+)
>  create mode 100644 arch/riscv/include/asm/sifive_l2_cache.h
>  create mode 100644 arch/riscv/mm/sifive_l2_cache.c
> 
> diff --git a/arch/riscv/include/asm/sifive_l2_cache.h b/arch/riscv/include/asm/sifive_l2_cache.h
> new file mode 100644
> index 0000000..04f6748
> --- /dev/null
> +++ b/arch/riscv/include/asm/sifive_l2_cache.h
> @@ -0,0 +1,16 @@
> +/* 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 */
> diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
> index eb22ab4..1523ee5 100644
> --- a/arch/riscv/mm/Makefile
> +++ b/arch/riscv/mm/Makefile
> @@ -3,3 +3,4 @@ obj-y += fault.o
>  obj-y += extable.o
>  obj-y += ioremap.o
>  obj-y += cacheflush.o
> +obj-y += sifive_l2_cache.o
> diff --git a/arch/riscv/mm/sifive_l2_cache.c b/arch/riscv/mm/sifive_l2_cache.c
> new file mode 100644
> index 0000000..4eb6461
> --- /dev/null
> +++ b/arch/riscv/mm/sifive_l2_cache.c
> @@ -0,0 +1,175 @@
> +// 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))

I'm guessing bit 16 is the enable and the lower 8 are some kind of
region to enable the error? This is probably a bad interface, it looks
useful for testing but doesn't provide any debugging info useful for
running systems. Do you really want userspace to be able to do this?

Andrew

> +		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);
> 

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