linux-kernel - [PATCH v8 08/12] iommu/exynos: remove prefetch buffer setting when enabling System MMU

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Message-id: <003e01ce89f3$4cdb45e0$e691d1a0$@samsung.com>
Date:	Fri, 26 Jul 2013 20:28:49 +0900
From:	Cho KyongHo <pullip.cho@...sung.com>
To:	'Linux ARM Kernel' <linux-arm-kernel@...ts.infradead.org>,
	'Linux IOMMU' <iommu@...ts.linux-foundation.org>,
	'Linux Kernel' <linux-kernel@...r.kernel.org>,
	'Linux Samsung SOC' <linux-samsung-soc@...r.kernel.org>
Cc:	'Hyunwoong Kim' <khw0178.kim@...sung.com>,
	'Joerg Roedel' <joro@...tes.org>,
	'Kukjin Kim' <kgene.kim@...sung.com>,
	'Prathyush' <prathyush.k@...sung.com>,
	'Rahul Sharma' <rahul.sharma@...sung.com>,
	'Subash Patel' <supash.ramaswamy@...aro.org>,
	'Keyyoung Park' <keyyoung.park@...sung.com>,
	'Grant Grundler' <grundler@...omium.org>,
	'Antonios Motakis' <a.motakis@...tualopensystems.com>,
	kvmarm@...ts.cs.columbia.edu,
	'Sachin Kamat' <sachin.kamat@...aro.org>
Subject: [PATCH v8 08/12] iommu/exynos: remove prefetch buffer setting when
 enabling System MMU

Prefetch buffer must be handled accurately, exact range of a buffer,
frame by frame manually. Otherwise, it may causes page fault or
deadlock in System MMU.
Thus this patch removes prefetch buffer setting when System MMU is
initialized(enabled).

Signed-off-by: Cho KyongHo <pullip.cho@...sung.com>
---
 drivers/iommu/exynos-iommu.c |   32 +++++++++++++++++++++++++++-----
 1 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index cfc02ed..87f6bb7 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -80,6 +80,8 @@
 #define CTRL_BLOCK	0x7
 #define CTRL_DISABLE	0x0
 
+#define CFG_FLPDCACHE	(1 << 20) /* System MMU 3.2+ only */
+
 #define REG_MMU_CTRL		0x000
 #define REG_MMU_CFG		0x004
 #define REG_MMU_STATUS		0x008
@@ -96,6 +98,9 @@
 
 #define REG_MMU_VERSION		0x034
 
+#define MMU_MAJ_VER(reg)	(reg >> 28)
+#define MMU_MIN_VER(reg)	((reg >> 21) & 0x7F)
+
 #define REG_PB0_SADDR		0x04C
 #define REG_PB0_EADDR		0x050
 #define REG_PB1_SADDR		0x054
@@ -200,6 +205,22 @@ static bool is_sysmmu_active(struct sysmmu_drvdata *data)
 	return data->activations > 0;
 }
 
+static unsigned int __sysmmu_version(struct sysmmu_drvdata *data,
+				     int idx, unsigned int *minor)
+{
+	unsigned long major;
+
+	major = readl(data->sfrbases[idx] + REG_MMU_VERSION);
+
+	if (minor)
+		*minor = MMU_MIN_VER(major);
+
+	if (MMU_MAJ_VER(major) > 3)
+		return 1;
+
+	return MMU_MAJ_VER(major);
+}
+
 static void sysmmu_unblock(void __iomem *sfrbase)
 {
 	__raw_writel(CTRL_ENABLE, sfrbase + REG_MMU_CTRL);
@@ -460,14 +481,15 @@ static int __exynos_sysmmu_enable(struct sysmmu_drvdata *data,
 	data->pgtable = pgtable;
 
 	for (i = 0; i < data->nsfrs; i++) {
+		unsigned int min;
+
 		__sysmmu_set_ptbase(data->sfrbases[i], pgtable);
 
-		if ((readl(data->sfrbases[i] + REG_MMU_VERSION) >> 28) == 3) {
-			/* System MMU version is 3.x */
-			__raw_writel((1 << 12) | (2 << 28),
+		if ((__sysmmu_version(data, i, &min) == 3) && (min > 1)) {
+			unsigned long cfg;
+			cfg = __raw_readl(data->sfrbases[i] + REG_MMU_CFG);
+			__raw_writel(cfg | CFG_FLPDCACHE,
 					data->sfrbases[i] + REG_MMU_CFG);
-			__sysmmu_set_prefbuf(data->sfrbases[i], 0, -1, 0);
-			__sysmmu_set_prefbuf(data->sfrbases[i], 0, -1, 1);
 		}
 
 		__raw_writel(CTRL_ENABLE, data->sfrbases[i] + REG_MMU_CTRL);
-- 
1.7.2.5


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