linux-kernel - [PATCH 2/2] riscv: cacheinfo: Add support to determine no. of L2 cache way enabled

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Date:   Mon,  9 Dec 2019 16:55:06 +0530
From:   Yash Shah <yash.shah@...ive.com>
To:     robh+dt@...nel.org, mark.rutland@....com, paul.walmsley@...ive.com
Cc:     palmer@...belt.com, aou@...s.berkeley.edu, bmeng.cn@...il.com,
        allison@...utok.net, alexios.zavras@...el.com, atish.patra@....com,
        tglx@...utronix.de, gregkh@...uxfoundation.org,
        devicetree@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Yash Shah <yash.shah@...ive.com>
Subject: [PATCH 2/2] riscv: cacheinfo: Add support to determine no. of L2 cache way enabled

In order to determine the number of L2 cache ways enabled at runtime,
implement a private attribute using cache_get_priv_group() in cacheinfo
framework. Reading this attribute ("number_of_ways_enabled") will return
the number of enabled L2 cache ways at runtime.

Signed-off-by: Yash Shah <yash.shah@...ive.com>
---
 arch/riscv/include/asm/sifive_l2_cache.h |  2 ++
 arch/riscv/kernel/cacheinfo.c            | 31 +++++++++++++++++++++++++++++++
 drivers/soc/sifive/sifive_l2_cache.c     |  5 +++++
 3 files changed, 38 insertions(+)

diff --git a/arch/riscv/include/asm/sifive_l2_cache.h b/arch/riscv/include/asm/sifive_l2_cache.h
index 04f6748..217a42f 100644
--- a/arch/riscv/include/asm/sifive_l2_cache.h
+++ b/arch/riscv/include/asm/sifive_l2_cache.h
@@ -10,6 +10,8 @@
 extern int register_sifive_l2_error_notifier(struct notifier_block *nb);
 extern int unregister_sifive_l2_error_notifier(struct notifier_block *nb);
 
+int sifive_l2_largest_wayenabled(void);
+
 #define SIFIVE_L2_ERR_TYPE_CE 0
 #define SIFIVE_L2_ERR_TYPE_UE 1
 
diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c
index 4c90c07..29bdb21 100644
--- a/arch/riscv/kernel/cacheinfo.c
+++ b/arch/riscv/kernel/cacheinfo.c
@@ -7,6 +7,7 @@
 #include <linux/cpu.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <asm/sifive_l2_cache.h>
 
 static void ci_leaf_init(struct cacheinfo *this_leaf,
 			 struct device_node *node,
@@ -16,6 +17,36 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
 	this_leaf->type = type;
 }
 
+#ifdef CONFIG_SIFIVE_L2
+static ssize_t number_of_ways_enabled_show(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	return sprintf(buf, "%u\n", sifive_l2_largest_wayenabled());
+}
+
+static DEVICE_ATTR_RO(number_of_ways_enabled);
+
+static struct attribute *priv_attrs[] = {
+	&dev_attr_number_of_ways_enabled.attr,
+	NULL,
+};
+
+static const struct attribute_group priv_attr_group = {
+	.attrs = priv_attrs,
+};
+
+const struct attribute_group *
+cache_get_priv_group(struct cacheinfo *this_leaf)
+{
+	/* We want to use private group for L2 cache only */
+	if (this_leaf->level == 2)
+		return &priv_attr_group;
+	else
+		return NULL;
+}
+#endif /* CONFIG_SIFIVE_L2 */
+
 static int __init_cache_level(unsigned int cpu)
 {
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
diff --git a/drivers/soc/sifive/sifive_l2_cache.c b/drivers/soc/sifive/sifive_l2_cache.c
index a9ffff3..f1a5f2c 100644
--- a/drivers/soc/sifive/sifive_l2_cache.c
+++ b/drivers/soc/sifive/sifive_l2_cache.c
@@ -107,6 +107,11 @@ int unregister_sifive_l2_error_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL_GPL(unregister_sifive_l2_error_notifier);
 
+int sifive_l2_largest_wayenabled(void)
+{
+	return readl(l2_base + SIFIVE_L2_WAYENABLE);
+}
+
 static irqreturn_t l2_int_handler(int irq, void *device)
 {
 	unsigned int add_h, add_l;
-- 
2.7.4