linux-kernel - [PATCH 09/11] powerpc/64s: Allow control of RFI flush via sysfs

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Message-Id: <20180108165453.26066-9-mpe@ellerman.id.au>
Date:   Tue,  9 Jan 2018 03:54:51 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     linuxppc-dev@...abs.org
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        peterz@...radead.org, npiggin@...il.com, anton@...ba.org,
        mikey@...ling.org, oohall@...il.com, paulus@...ba.org
Subject: [PATCH 09/11] powerpc/64s: Allow control of RFI flush via sysfs

From: Nicholas Piggin <npiggin@...il.com>

Expose the state of the RFI flush (enabled/disabled) via sysfs, and
allow it to be enabled/dissabled at runtime.

Signed-off-by: Nicholas Piggin <npiggin@...il.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
---
 arch/powerpc/kernel/setup.h |  2 ++
 arch/powerpc/kernel/sysfs.c | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/arch/powerpc/kernel/setup.h b/arch/powerpc/kernel/setup.h
index 21c18071d9d5..493b03b0a966 100644
--- a/arch/powerpc/kernel/setup.h
+++ b/arch/powerpc/kernel/setup.h
@@ -61,4 +61,6 @@ void kvm_cma_reserve(void);
 static inline void kvm_cma_reserve(void) { };
 #endif
 
+extern bool rfi_flush;
+
 #endif /* __ARCH_POWERPC_KERNEL_SETUP_H */
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index b8d4a1dac39f..8c19d014cffc 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -20,6 +20,7 @@
 #include <asm/firmware.h>
 
 #include "cacheinfo.h"
+#include "setup.h"
 
 #ifdef CONFIG_PPC64
 #include <asm/paca.h>
@@ -496,6 +497,43 @@ static DEVICE_ATTR(spurr, 0400, show_spurr, NULL);
 static DEVICE_ATTR(purr, 0400, show_purr, store_purr);
 static DEVICE_ATTR(pir, 0400, show_pir, NULL);
 
+#ifdef CONFIG_PPC_BOOK3S_64
+static ssize_t show_rfi_flush(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", rfi_flush ? 1 : 0);
+}
+
+static ssize_t __used store_rfi_flush(struct device *dev,
+		struct device_attribute *attr, const char *buf,
+		size_t count)
+{
+	int val;
+	int ret = 0;
+
+	ret = sscanf(buf, "%d", &val);
+	if (ret != 1)
+		return -EINVAL;
+
+	if (val == 1)
+		rfi_flush_enable(true);
+	else if (val == 0)
+		rfi_flush_enable(false);
+	else
+		return -EINVAL;
+
+	return count;
+}
+
+static DEVICE_ATTR(rfi_flush, 0600,
+		show_rfi_flush, store_rfi_flush);
+
+static void sysfs_create_rfi_flush(void)
+{
+	device_create_file(cpu_subsys.dev_root, &dev_attr_rfi_flush);
+}
+#endif /* CONFIG_PPC_BOOK3S_64 */
+
 /*
  * This is the system wide DSCR register default value. Any
  * change to this default value through the sysfs interface
@@ -1047,6 +1085,9 @@ static int __init topology_init(void)
 	WARN_ON(r < 0);
 #ifdef CONFIG_PPC64
 	sysfs_create_dscr_default();
+#ifdef CONFIG_PPC_BOOK3S
+	sysfs_create_rfi_flush();
+#endif
 #endif /* CONFIG_PPC64 */
 
 	return 0;
-- 
2.14.3