linux-kernel - [PATCH v3 2/2] riscv: Add support to determine no. of L2 cache way enabled

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Date:   Mon, 13 Jan 2020 12:08:20 +0530
From:   Yash Shah <yash.shah@...ive.com>
To:     paul.walmsley@...ive.com, palmer@...belt.com
Cc:     aou@...s.berkeley.edu, allison@...utok.net,
        alexios.zavras@...el.com, gregkh@...uxfoundation.org,
        tglx@...utronix.de, bp@...e.de, anup@...infault.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        sachin.ghadi@...ive.com, Yash Shah <yash.shah@...ive.com>
Subject: [PATCH v3 2/2] riscv: 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 ("number_of_ways_enabled"). Reading this
attribute returns the number of enabled L2 cache ways at runtime.

Using riscv_set_cacheinfo_ops() hook a custom function, that returns
this private attribute, to the generic ops structure which is used by
cache_get_priv_group() in cacheinfo framework.

Signed-off-by: Yash Shah <yash.shah@...ive.com>
---
 drivers/soc/sifive/sifive_l2_cache.c | 38 ++++++++++++++++++++++++++++++++++++
 include/soc/sifive/sifive_l2_cache.h |  2 ++
 2 files changed, 40 insertions(+)

diff --git a/drivers/soc/sifive/sifive_l2_cache.c b/drivers/soc/sifive/sifive_l2_cache.c
index a506939..8741885 100644
--- a/drivers/soc/sifive/sifive_l2_cache.c
+++ b/drivers/soc/sifive/sifive_l2_cache.c
@@ -9,6 +9,8 @@
 #include <linux/interrupt.h>
 #include <linux/of_irq.h>
 #include <linux/of_address.h>
+#include <linux/device.h>
+#include <asm/cacheinfo.h>
 #include <soc/sifive/sifive_l2_cache.h>
 
 #define SIFIVE_L2_DIRECCFIX_LOW 0x100
@@ -31,6 +33,7 @@
 
 static void __iomem *l2_base;
 static int g_irq[SIFIVE_L2_MAX_ECCINTR];
+static struct riscv_cacheinfo_ops l2_cache_ops;
 
 enum {
 	DIR_CORR = 0,
@@ -107,6 +110,38 @@ 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 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 *l2_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;
+}
+
 static irqreturn_t l2_int_handler(int irq, void *device)
 {
 	unsigned int add_h, add_l;
@@ -170,6 +205,9 @@ static int __init sifive_l2_init(void)
 
 	l2_config_read();
 
+	l2_cache_ops.get_priv_group = l2_get_priv_group;
+	riscv_set_cacheinfo_ops(&l2_cache_ops);
+
 #ifdef CONFIG_DEBUG_FS
 	setup_sifive_debug();
 #endif
diff --git a/include/soc/sifive/sifive_l2_cache.h b/include/soc/sifive/sifive_l2_cache.h
index 92ade10..55feff5 100644
--- a/include/soc/sifive/sifive_l2_cache.h
+++ b/include/soc/sifive/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
 
-- 
2.7.4