When debugging or examining the performance of a system it can be useful
to examine the effect of L2 prefetching. Provide an optional debugfs
entry to allow a user to enable or disable L2 prefetching.
Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
---
arch/mips/Kconfig.debug | 10 ++++++
arch/mips/mm/Makefile | 1 +
arch/mips/mm/sc-debugfs.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 92 insertions(+)
create mode 100644 arch/mips/mm/sc-debugfs.c
diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
index e250524..d1962cb 100644
--- a/arch/mips/Kconfig.debug
+++ b/arch/mips/Kconfig.debug
@@ -113,4 +113,14 @@ config SPINLOCK_TEST
help
Add several files to the debugfs to test spinlock speed.
+config SCACHE_DEBUGFS
+ bool "L2 cache debugfs entries"
+ depends on DEBUG_FS
+ help
+ Enable this to allow parts of the L2 cache configuration, such as
+ whether or not prefetching is enabled, to be exposed to userland
+ via debugfs.
+
+ If unsure, say N.
+
endmenu
diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index 67ede4e..b4c64bd 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -28,3 +28,4 @@ obj-$(CONFIG_IP22_CPU_SCACHE) += sc-ip22.o
obj-$(CONFIG_R5000_CPU_SCACHE) += sc-r5k.o
obj-$(CONFIG_RM7000_CPU_SCACHE) += sc-rm7k.o
obj-$(CONFIG_MIPS_CPU_SCACHE) += sc-mips.o
+obj-$(CONFIG_SCACHE_DEBUGFS) += sc-debugfs.o
diff --git a/arch/mips/mm/sc-debugfs.c b/arch/mips/mm/sc-debugfs.c
new file mode 100644
index 0000000..5eefe32
--- /dev/null
+++ b/arch/mips/mm/sc-debugfs.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2015 Imagination Technologies
+ * Author: Paul Burton <paul.burton@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <asm/bcache.h>
+#include <asm/debug.h>
+#include <asm/uaccess.h>
+#include <linux/debugfs.h>
+#include <linux/init.h>
+
+static ssize_t sc_prefetch_read(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ bool enabled = bc_prefetch_is_enabled();
+ char buf[3];
+
+ buf[0] = enabled ? 'Y' : 'N';
+ buf[1] = '\n';
+ buf[2] = 0;
+
+ return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
+}
+
+static ssize_t sc_prefetch_write(struct file *file,
+ const char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ char buf[32];
+ ssize_t buf_size;
+ bool enabled;
+ int err;
+
+ buf_size = min(count, sizeof(buf) - 1);
+ if (copy_from_user(buf, user_buf, buf_size))
+ return -EFAULT;
+
+ buf[buf_size] = '\0';
+ err = strtobool(buf, &enabled);
+ if (err)
+ return err;
+
+ if (enabled)
+ bc_prefetch_enable();
+ else
+ bc_prefetch_disable();
+
+ return count;
+}
+
+static const struct file_operations sc_prefetch_fops = {
+ .open = simple_open,
+ .llseek = default_llseek,
+ .read = sc_prefetch_read,
+ .write = sc_prefetch_write,
+};
+
+static int __init sc_debugfs_init(void)
+{
+ struct dentry *dir, *file;
+
+ if (!mips_debugfs_dir)
+ return -ENODEV;
+
+ dir = debugfs_create_dir("l2cache", mips_debugfs_dir);
+ if (IS_ERR(dir))
+ return PTR_ERR(dir);
+
+ file = debugfs_create_file("prefetch", S_IRUGO | S_IWUSR, dir,
+ NULL, &sc_prefetch_fops);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ return 0;
+}
+late_initcall(sc_debugfs_init);
--
2.5.3
